plink: updated to revision 10170 of putty

1 files changed, 1088 insertions, 1031 deletions

diff --git a/tools/plink/sshdes.c b/tools/plink/sshdes.c
index 0beb273ce..f54990e7c 100644
--- a/tools/plink/sshdes.c
+++ b/tools/plink/sshdes.c
@@ -1,1031 +1,1088 @@
-#include <assert.h>

-#include "ssh.h"

-

-

-/* des.c - implementation of DES

- */

-

-/*

- * Description of DES

- * ------------------

- *

- * Unlike the description in FIPS 46, I'm going to use _sensible_ indices:

- * bits in an n-bit word are numbered from 0 at the LSB to n-1 at the MSB.

- * And S-boxes are indexed by six consecutive bits, not by the outer two

- * followed by the middle four.

- *

- * The DES encryption routine requires a 64-bit input, and a key schedule K

- * containing 16 48-bit elements.

- *

- *   First the input is permuted by the initial permutation IP.

- *   Then the input is split into 32-bit words L and R. (L is the MSW.)

- *   Next, 16 rounds. In each round:

- *     (L, R) <- (R, L xor f(R, K[i]))

- *   Then the pre-output words L and R are swapped.

- *   Then L and R are glued back together into a 64-bit word. (L is the MSW,

- *     again, but since we just swapped them, the MSW is the R that came out

- *     of the last round.)

- *   The 64-bit output block is permuted by the inverse of IP and returned.

- *

- * Decryption is identical except that the elements of K are used in the

- * opposite order. (This wouldn't work if that word swap didn't happen.)

- *

- * The function f, used in each round, accepts a 32-bit word R and a

- * 48-bit key block K. It produces a 32-bit output.

- *

- *   First R is expanded to 48 bits using the bit-selection function E.

- *   The resulting 48-bit block is XORed with the key block K to produce

- *     a 48-bit block X.

- *   This block X is split into eight groups of 6 bits. Each group of 6

- *     bits is then looked up in one of the eight S-boxes to convert

- *     it to 4 bits. These eight groups of 4 bits are glued back

- *     together to produce a 32-bit preoutput block.

- *   The preoutput block is permuted using the permutation P and returned.

- *

- * Key setup maps a 64-bit key word into a 16x48-bit key schedule. Although

- * the approved input format for the key is a 64-bit word, eight of the

- * bits are discarded, so the actual quantity of key used is 56 bits.

- *

- *   First the input key is converted to two 28-bit words C and D using

- *     the bit-selection function PC1.

- *   Then 16 rounds of key setup occur. In each round, C and D are each

- *     rotated left by either 1 or 2 bits (depending on which round), and

- *     then converted into a key schedule element using the bit-selection

- *     function PC2.

- *

- * That's the actual algorithm. Now for the tedious details: all those

- * painful permutations and lookup tables.

- *

- * IP is a 64-to-64 bit permutation. Its output contains the following

- * bits of its input (listed in order MSB to LSB of output).

- *

- *    6 14 22 30 38 46 54 62  4 12 20 28 36 44 52 60

- *    2 10 18 26 34 42 50 58  0  8 16 24 32 40 48 56

- *    7 15 23 31 39 47 55 63  5 13 21 29 37 45 53 61

- *    3 11 19 27 35 43 51 59  1  9 17 25 33 41 49 57

- *

- * E is a 32-to-48 bit selection function. Its output contains the following

- * bits of its input (listed in order MSB to LSB of output).

- *

- *    0 31 30 29 28 27 28 27 26 25 24 23 24 23 22 21 20 19 20 19 18 17 16 15

- *   16 15 14 13 12 11 12 11 10  9  8  7  8  7  6  5  4  3  4  3  2  1  0 31

- *

- * The S-boxes are arbitrary table-lookups each mapping a 6-bit input to a

- * 4-bit output. In other words, each S-box is an array[64] of 4-bit numbers.

- * The S-boxes are listed below. The first S-box listed is applied to the

- * most significant six bits of the block X; the last one is applied to the

- * least significant.

- *

- *   14  0  4 15 13  7  1  4  2 14 15  2 11 13  8  1

- *    3 10 10  6  6 12 12 11  5  9  9  5  0  3  7  8

- *    4 15  1 12 14  8  8  2 13  4  6  9  2  1 11  7

- *   15  5 12 11  9  3  7 14  3 10 10  0  5  6  0 13

- *

- *   15  3  1 13  8  4 14  7  6 15 11  2  3  8  4 14

- *    9 12  7  0  2  1 13 10 12  6  0  9  5 11 10  5

- *    0 13 14  8  7 10 11  1 10  3  4 15 13  4  1  2

- *    5 11  8  6 12  7  6 12  9  0  3  5  2 14 15  9

- *

- *   10 13  0  7  9  0 14  9  6  3  3  4 15  6  5 10

- *    1  2 13  8 12  5  7 14 11 12  4 11  2 15  8  1

- *   13  1  6 10  4 13  9  0  8  6 15  9  3  8  0  7

- *   11  4  1 15  2 14 12  3  5 11 10  5 14  2  7 12

- *

- *    7 13 13  8 14 11  3  5  0  6  6 15  9  0 10  3

- *    1  4  2  7  8  2  5 12 11  1 12 10  4 14 15  9

- *   10  3  6 15  9  0  0  6 12 10 11  1  7 13 13  8

- *   15  9  1  4  3  5 14 11  5 12  2  7  8  2  4 14

- *

- *    2 14 12 11  4  2  1 12  7  4 10  7 11 13  6  1

- *    8  5  5  0  3 15 15 10 13  3  0  9 14  8  9  6

- *    4 11  2  8  1 12 11  7 10  1 13 14  7  2  8 13

- *   15  6  9 15 12  0  5  9  6 10  3  4  0  5 14  3

- *

- *   12 10  1 15 10  4 15  2  9  7  2 12  6  9  8  5

- *    0  6 13  1  3 13  4 14 14  0  7 11  5  3 11  8

- *    9  4 14  3 15  2  5 12  2  9  8  5 12 15  3 10

- *    7 11  0 14  4  1 10  7  1  6 13  0 11  8  6 13

- *

- *    4 13 11  0  2 11 14  7 15  4  0  9  8  1 13 10

- *    3 14 12  3  9  5  7 12  5  2 10 15  6  8  1  6

- *    1  6  4 11 11 13 13  8 12  1  3  4  7 10 14  7

- *   10  9 15  5  6  0  8 15  0 14  5  2  9  3  2 12

- *

- *   13  1  2 15  8 13  4  8  6 10 15  3 11  7  1  4

- *   10 12  9  5  3  6 14 11  5  0  0 14 12  9  7  2

- *    7  2 11  1  4 14  1  7  9  4 12 10 14  8  2 13

- *    0 15  6 12 10  9 13  0 15  3  3  5  5  6  8 11

- *

- * P is a 32-to-32 bit permutation. Its output contains the following

- * bits of its input (listed in order MSB to LSB of output).

- *

- *   16 25 12 11  3 20  4 15 31 17  9  6 27 14  1 22

- *   30 24  8 18  0  5 29 23 13 19  2 26 10 21 28  7

- *

- * PC1 is a 64-to-56 bit selection function. Its output is in two words,

- * C and D. The word C contains the following bits of its input (listed

- * in order MSB to LSB of output).

- *

- *    7 15 23 31 39 47 55 63  6 14 22 30 38 46

- *   54 62  5 13 21 29 37 45 53 61  4 12 20 28

- *

- * And the word D contains these bits.

- *

- *    1  9 17 25 33 41 49 57  2 10 18 26 34 42

- *   50 58  3 11 19 27 35 43 51 59 36 44 52 60

- *

- * PC2 is a 56-to-48 bit selection function. Its input is in two words,

- * C and D. These are treated as one 56-bit word (with C more significant,

- * so that bits 55 to 28 of the word are bits 27 to 0 of C, and bits 27 to

- * 0 of the word are bits 27 to 0 of D). The output contains the following

- * bits of this 56-bit input word (listed in order MSB to LSB of output).

- *

- *   42 39 45 32 55 51 53 28 41 50 35 46 33 37 44 52 30 48 40 49 29 36 43 54

- *   15  4 25 19  9  1 26 16  5 11 23  8 12  7 17  0 22  3 10 14  6 20 27 24

- */

-

-/*

- * Implementation details

- * ----------------------

- * 

- * If you look at the code in this module, you'll find it looks

- * nothing _like_ the above algorithm. Here I explain the

- * differences...

- *

- * Key setup has not been heavily optimised here. We are not

- * concerned with key agility: we aren't codebreakers. We don't

- * mind a little delay (and it really is a little one; it may be a

- * factor of five or so slower than it could be but it's still not

- * an appreciable length of time) while setting up. The only tweaks

- * in the key setup are ones which change the format of the key

- * schedule to speed up the actual encryption. I'll describe those

- * below.

- *

- * The first and most obvious optimisation is the S-boxes. Since

- * each S-box always targets the same four bits in the final 32-bit

- * word, so the output from (for example) S-box 0 must always be

- * shifted left 28 bits, we can store the already-shifted outputs

- * in the lookup tables. This reduces lookup-and-shift to lookup,

- * so the S-box step is now just a question of ORing together eight

- * table lookups.

- *

- * The permutation P is just a bit order change; it's invariant

- * with respect to OR, in that P(x)|P(y) = P(x|y). Therefore, we

- * can apply P to every entry of the S-box tables and then we don't

- * have to do it in the code of f(). This yields a set of tables

- * which might be called SP-boxes.

- *

- * The bit-selection function E is our next target. Note that E is

- * immediately followed by the operation of splitting into 6-bit

- * chunks. Examining the 6-bit chunks coming out of E we notice

- * they're all contiguous within the word (speaking cyclically -

- * the end two wrap round); so we can extract those bit strings

- * individually rather than explicitly running E. This would yield

- * code such as

- *

- *     y |= SPboxes[0][ (rotl(R, 5) ^  top6bitsofK) & 0x3F ];

- *     t |= SPboxes[1][ (rotl(R,11) ^ next6bitsofK) & 0x3F ];

- *

- * and so on; and the key schedule preparation would have to

- * provide each 6-bit chunk separately.

- *

- * Really we'd like to XOR in the key schedule element before

- * looking up bit strings in R. This we can't do, naively, because

- * the 6-bit strings we want overlap. But look at the strings:

- *

- *       3322222222221111111111

- * bit   10987654321098765432109876543210

- * 

- * box0  XXXXX                          X

- * box1     XXXXXX

- * box2         XXXXXX

- * box3             XXXXXX

- * box4                 XXXXXX

- * box5                     XXXXXX

- * box6                         XXXXXX

- * box7  X                          XXXXX

- *

- * The bit strings we need to XOR in for boxes 0, 2, 4 and 6 don't

- * overlap with each other. Neither do the ones for boxes 1, 3, 5

- * and 7. So we could provide the key schedule in the form of two

- * words that we can separately XOR into R, and then every S-box

- * index is available as a (cyclically) contiguous 6-bit substring

- * of one or the other of the results.

- *

- * The comments in Eric Young's libdes implementation point out

- * that two of these bit strings require a rotation (rather than a

- * simple shift) to extract. It's unavoidable that at least _one_

- * must do; but we can actually run the whole inner algorithm (all

- * 16 rounds) rotated one bit to the left, so that what the `real'

- * DES description sees as L=0x80000001 we see as L=0x00000003.

- * This requires rotating all our SP-box entries one bit to the

- * left, and rotating each word of the key schedule elements one to

- * the left, and rotating L and R one bit left just after IP and

- * one bit right again just before FP. And in each round we convert

- * a rotate into a shift, so we've saved a few per cent.

- *

- * That's about it for the inner loop; the SP-box tables as listed

- * below are what I've described here (the original S value,

- * shifted to its final place in the input to P, run through P, and

- * then rotated one bit left). All that remains is to optimise the

- * initial permutation IP.

- *

- * IP is not an arbitrary permutation. It has the nice property

- * that if you take any bit number, write it in binary (6 bits),

- * permute those 6 bits and invert some of them, you get the final

- * position of that bit. Specifically, the bit whose initial

- * position is given (in binary) as fedcba ends up in position

- * AcbFED (where a capital letter denotes the inverse of a bit).

- *

- * We have the 64-bit data in two 32-bit words L and R, where bits

- * in L are those with f=1 and bits in R are those with f=0. We

- * note that we can do a simple transformation: suppose we exchange

- * the bits with f=1,c=0 and the bits with f=0,c=1. This will cause

- * the bit fedcba to be in position cedfba - we've `swapped' bits c

- * and f in the position of each bit!

- * 

- * Better still, this transformation is easy. In the example above,

- * bits in L with c=0 are bits 0x0F0F0F0F, and those in R with c=1

- * are 0xF0F0F0F0. So we can do

- *

- *     difference = ((R >> 4) ^ L) & 0x0F0F0F0F

- *     R ^= (difference << 4)

- *     L ^= difference

- *

- * to perform the swap. Let's denote this by bitswap(4,0x0F0F0F0F).

- * Also, we can invert the bit at the top just by exchanging L and

- * R. So in a few swaps and a few of these bit operations we can

- * do:

- * 

- * Initially the position of bit fedcba is     fedcba

- * Swap L with R to make it                    Fedcba

- * Perform bitswap( 4,0x0F0F0F0F) to make it   cedFba

- * Perform bitswap(16,0x0000FFFF) to make it   ecdFba

- * Swap L with R to make it                    EcdFba

- * Perform bitswap( 2,0x33333333) to make it   bcdFEa

- * Perform bitswap( 8,0x00FF00FF) to make it   dcbFEa

- * Swap L with R to make it                    DcbFEa

- * Perform bitswap( 1,0x55555555) to make it   acbFED

- * Swap L with R to make it                    AcbFED

- *

- * (In the actual code the four swaps are implicit: R and L are

- * simply used the other way round in the first, second and last

- * bitswap operations.)

- *

- * The final permutation is just the inverse of IP, so it can be

- * performed by a similar set of operations.

- */

-

-typedef struct {

-    word32 k0246[16], k1357[16];

-    word32 iv0, iv1;

-} DESContext;

-

-#define rotl(x, c) ( (x << c) | (x >> (32-c)) )

-#define rotl28(x, c) ( ( (x << c) | (x >> (28-c)) ) & 0x0FFFFFFF)

-

-static word32 bitsel(word32 * input, const int *bitnums, int size)

-{

-    word32 ret = 0;

-    while (size--) {

-	int bitpos = *bitnums++;

-	ret <<= 1;

-	if (bitpos >= 0)

-	    ret |= 1 & (input[bitpos / 32] >> (bitpos % 32));

-    }

-    return ret;

-}

-

-static void des_key_setup(word32 key_msw, word32 key_lsw, DESContext * sched)

-{

-

-    static const int PC1_Cbits[] = {

-	7, 15, 23, 31, 39, 47, 55, 63, 6, 14, 22, 30, 38, 46,

-	54, 62, 5, 13, 21, 29, 37, 45, 53, 61, 4, 12, 20, 28

-    };

-    static const int PC1_Dbits[] = {

-	1, 9, 17, 25, 33, 41, 49, 57, 2, 10, 18, 26, 34, 42,

-	50, 58, 3, 11, 19, 27, 35, 43, 51, 59, 36, 44, 52, 60

-    };

-    /*

-     * The bit numbers in the two lists below don't correspond to

-     * the ones in the above description of PC2, because in the

-     * above description C and D are concatenated so `bit 28' means

-     * bit 0 of C. In this implementation we're using the standard

-     * `bitsel' function above and C is in the second word, so bit

-     * 0 of C is addressed by writing `32' here.

-     */

-    static const int PC2_0246[] = {

-	49, 36, 59, 55, -1, -1, 37, 41, 48, 56, 34, 52, -1, -1, 15, 4,

-	25, 19, 9, 1, -1, -1, 12, 7, 17, 0, 22, 3, -1, -1, 46, 43

-    };

-    static const int PC2_1357[] = {

-	-1, -1, 57, 32, 45, 54, 39, 50, -1, -1, 44, 53, 33, 40, 47, 58,

-	-1, -1, 26, 16, 5, 11, 23, 8, -1, -1, 10, 14, 6, 20, 27, 24

-    };

-    static const int leftshifts[] =

-	{ 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };

-

-    word32 C, D;

-    word32 buf[2];

-    int i;

-

-    buf[0] = key_lsw;

-    buf[1] = key_msw;

-

-    C = bitsel(buf, PC1_Cbits, 28);

-    D = bitsel(buf, PC1_Dbits, 28);

-

-    for (i = 0; i < 16; i++) {

-	C = rotl28(C, leftshifts[i]);

-	D = rotl28(D, leftshifts[i]);

-	buf[0] = D;

-	buf[1] = C;

-	sched->k0246[i] = bitsel(buf, PC2_0246, 32);

-	sched->k1357[i] = bitsel(buf, PC2_1357, 32);

-    }

-

-    sched->iv0 = sched->iv1 = 0;

-}

-

-static const word32 SPboxes[8][64] = {

-    {0x01010400, 0x00000000, 0x00010000, 0x01010404,

-     0x01010004, 0x00010404, 0x00000004, 0x00010000,

-     0x00000400, 0x01010400, 0x01010404, 0x00000400,

-     0x01000404, 0x01010004, 0x01000000, 0x00000004,

-     0x00000404, 0x01000400, 0x01000400, 0x00010400,

-     0x00010400, 0x01010000, 0x01010000, 0x01000404,

-     0x00010004, 0x01000004, 0x01000004, 0x00010004,

-     0x00000000, 0x00000404, 0x00010404, 0x01000000,

-     0x00010000, 0x01010404, 0x00000004, 0x01010000,

-     0x01010400, 0x01000000, 0x01000000, 0x00000400,

-     0x01010004, 0x00010000, 0x00010400, 0x01000004,

-     0x00000400, 0x00000004, 0x01000404, 0x00010404,

-     0x01010404, 0x00010004, 0x01010000, 0x01000404,

-     0x01000004, 0x00000404, 0x00010404, 0x01010400,

-     0x00000404, 0x01000400, 0x01000400, 0x00000000,

-     0x00010004, 0x00010400, 0x00000000, 0x01010004L},

-

-    {0x80108020, 0x80008000, 0x00008000, 0x00108020,

-     0x00100000, 0x00000020, 0x80100020, 0x80008020,

-     0x80000020, 0x80108020, 0x80108000, 0x80000000,

-     0x80008000, 0x00100000, 0x00000020, 0x80100020,

-     0x00108000, 0x00100020, 0x80008020, 0x00000000,

-     0x80000000, 0x00008000, 0x00108020, 0x80100000,

-     0x00100020, 0x80000020, 0x00000000, 0x00108000,

-     0x00008020, 0x80108000, 0x80100000, 0x00008020,

-     0x00000000, 0x00108020, 0x80100020, 0x00100000,

-     0x80008020, 0x80100000, 0x80108000, 0x00008000,

-     0x80100000, 0x80008000, 0x00000020, 0x80108020,

-     0x00108020, 0x00000020, 0x00008000, 0x80000000,

-     0x00008020, 0x80108000, 0x00100000, 0x80000020,

-     0x00100020, 0x80008020, 0x80000020, 0x00100020,

-     0x00108000, 0x00000000, 0x80008000, 0x00008020,

-     0x80000000, 0x80100020, 0x80108020, 0x00108000L},

-

-    {0x00000208, 0x08020200, 0x00000000, 0x08020008,

-     0x08000200, 0x00000000, 0x00020208, 0x08000200,

-     0x00020008, 0x08000008, 0x08000008, 0x00020000,

-     0x08020208, 0x00020008, 0x08020000, 0x00000208,

-     0x08000000, 0x00000008, 0x08020200, 0x00000200,

-     0x00020200, 0x08020000, 0x08020008, 0x00020208,

-     0x08000208, 0x00020200, 0x00020000, 0x08000208,

-     0x00000008, 0x08020208, 0x00000200, 0x08000000,

-     0x08020200, 0x08000000, 0x00020008, 0x00000208,

-     0x00020000, 0x08020200, 0x08000200, 0x00000000,

-     0x00000200, 0x00020008, 0x08020208, 0x08000200,

-     0x08000008, 0x00000200, 0x00000000, 0x08020008,

-     0x08000208, 0x00020000, 0x08000000, 0x08020208,

-     0x00000008, 0x00020208, 0x00020200, 0x08000008,

-     0x08020000, 0x08000208, 0x00000208, 0x08020000,

-     0x00020208, 0x00000008, 0x08020008, 0x00020200L},

-

-    {0x00802001, 0x00002081, 0x00002081, 0x00000080,

-     0x00802080, 0x00800081, 0x00800001, 0x00002001,

-     0x00000000, 0x00802000, 0x00802000, 0x00802081,

-     0x00000081, 0x00000000, 0x00800080, 0x00800001,

-     0x00000001, 0x00002000, 0x00800000, 0x00802001,

-     0x00000080, 0x00800000, 0x00002001, 0x00002080,

-     0x00800081, 0x00000001, 0x00002080, 0x00800080,

-     0x00002000, 0x00802080, 0x00802081, 0x00000081,

-     0x00800080, 0x00800001, 0x00802000, 0x00802081,

-     0x00000081, 0x00000000, 0x00000000, 0x00802000,

-     0x00002080, 0x00800080, 0x00800081, 0x00000001,

-     0x00802001, 0x00002081, 0x00002081, 0x00000080,

-     0x00802081, 0x00000081, 0x00000001, 0x00002000,

-     0x00800001, 0x00002001, 0x00802080, 0x00800081,

-     0x00002001, 0x00002080, 0x00800000, 0x00802001,

-     0x00000080, 0x00800000, 0x00002000, 0x00802080L},

-

-    {0x00000100, 0x02080100, 0x02080000, 0x42000100,

-     0x00080000, 0x00000100, 0x40000000, 0x02080000,

-     0x40080100, 0x00080000, 0x02000100, 0x40080100,

-     0x42000100, 0x42080000, 0x00080100, 0x40000000,

-     0x02000000, 0x40080000, 0x40080000, 0x00000000,

-     0x40000100, 0x42080100, 0x42080100, 0x02000100,

-     0x42080000, 0x40000100, 0x00000000, 0x42000000,

-     0x02080100, 0x02000000, 0x42000000, 0x00080100,

-     0x00080000, 0x42000100, 0x00000100, 0x02000000,

-     0x40000000, 0x02080000, 0x42000100, 0x40080100,

-     0x02000100, 0x40000000, 0x42080000, 0x02080100,

-     0x40080100, 0x00000100, 0x02000000, 0x42080000,

-     0x42080100, 0x00080100, 0x42000000, 0x42080100,

-     0x02080000, 0x00000000, 0x40080000, 0x42000000,

-     0x00080100, 0x02000100, 0x40000100, 0x00080000,

-     0x00000000, 0x40080000, 0x02080100, 0x40000100L},

-

-    {0x20000010, 0x20400000, 0x00004000, 0x20404010,

-     0x20400000, 0x00000010, 0x20404010, 0x00400000,

-     0x20004000, 0x00404010, 0x00400000, 0x20000010,

-     0x00400010, 0x20004000, 0x20000000, 0x00004010,

-     0x00000000, 0x00400010, 0x20004010, 0x00004000,

-     0x00404000, 0x20004010, 0x00000010, 0x20400010,

-     0x20400010, 0x00000000, 0x00404010, 0x20404000,

-     0x00004010, 0x00404000, 0x20404000, 0x20000000,

-     0x20004000, 0x00000010, 0x20400010, 0x00404000,

-     0x20404010, 0x00400000, 0x00004010, 0x20000010,

-     0x00400000, 0x20004000, 0x20000000, 0x00004010,

-     0x20000010, 0x20404010, 0x00404000, 0x20400000,

-     0x00404010, 0x20404000, 0x00000000, 0x20400010,

-     0x00000010, 0x00004000, 0x20400000, 0x00404010,

-     0x00004000, 0x00400010, 0x20004010, 0x00000000,

-     0x20404000, 0x20000000, 0x00400010, 0x20004010L},

-

-    {0x00200000, 0x04200002, 0x04000802, 0x00000000,

-     0x00000800, 0x04000802, 0x00200802, 0x04200800,

-     0x04200802, 0x00200000, 0x00000000, 0x04000002,

-     0x00000002, 0x04000000, 0x04200002, 0x00000802,

-     0x04000800, 0x00200802, 0x00200002, 0x04000800,

-     0x04000002, 0x04200000, 0x04200800, 0x00200002,

-     0x04200000, 0x00000800, 0x00000802, 0x04200802,

-     0x00200800, 0x00000002, 0x04000000, 0x00200800,

-     0x04000000, 0x00200800, 0x00200000, 0x04000802,

-     0x04000802, 0x04200002, 0x04200002, 0x00000002,

-     0x00200002, 0x04000000, 0x04000800, 0x00200000,

-     0x04200800, 0x00000802, 0x00200802, 0x04200800,

-     0x00000802, 0x04000002, 0x04200802, 0x04200000,

-     0x00200800, 0x00000000, 0x00000002, 0x04200802,

-     0x00000000, 0x00200802, 0x04200000, 0x00000800,

-     0x04000002, 0x04000800, 0x00000800, 0x00200002L},

-

-    {0x10001040, 0x00001000, 0x00040000, 0x10041040,

-     0x10000000, 0x10001040, 0x00000040, 0x10000000,

-     0x00040040, 0x10040000, 0x10041040, 0x00041000,

-     0x10041000, 0x00041040, 0x00001000, 0x00000040,

-     0x10040000, 0x10000040, 0x10001000, 0x00001040,

-     0x00041000, 0x00040040, 0x10040040, 0x10041000,

-     0x00001040, 0x00000000, 0x00000000, 0x10040040,

-     0x10000040, 0x10001000, 0x00041040, 0x00040000,

-     0x00041040, 0x00040000, 0x10041000, 0x00001000,

-     0x00000040, 0x10040040, 0x00001000, 0x00041040,

-     0x10001000, 0x00000040, 0x10000040, 0x10040000,

-     0x10040040, 0x10000000, 0x00040000, 0x10001040,

-     0x00000000, 0x10041040, 0x00040040, 0x10000040,

-     0x10040000, 0x10001000, 0x10001040, 0x00000000,

-     0x10041040, 0x00041000, 0x00041000, 0x00001040,

-     0x00001040, 0x00040040, 0x10000000, 0x10041000L}

-};

-

-#define f(R, K0246, K1357) (\

-    s0246 = R ^ K0246, \

-    s1357 = R ^ K1357, \

-    s0246 = rotl(s0246, 28), \

-    SPboxes[0] [(s0246 >> 24) & 0x3F] | \

-    SPboxes[1] [(s1357 >> 24) & 0x3F] | \

-    SPboxes[2] [(s0246 >> 16) & 0x3F] | \

-    SPboxes[3] [(s1357 >> 16) & 0x3F] | \

-    SPboxes[4] [(s0246 >>  8) & 0x3F] | \

-    SPboxes[5] [(s1357 >>  8) & 0x3F] | \

-    SPboxes[6] [(s0246      ) & 0x3F] | \

-    SPboxes[7] [(s1357      ) & 0x3F])

-

-#define bitswap(L, R, n, mask) (\

-    swap = mask & ( (R >> n) ^ L ), \

-    R ^= swap << n, \

-    L ^= swap)

-

-/* Initial permutation */

-#define IP(L, R) (\

-    bitswap(R, L,  4, 0x0F0F0F0F), \

-    bitswap(R, L, 16, 0x0000FFFF), \

-    bitswap(L, R,  2, 0x33333333), \

-    bitswap(L, R,  8, 0x00FF00FF), \

-    bitswap(R, L,  1, 0x55555555))

-

-/* Final permutation */

-#define FP(L, R) (\

-    bitswap(R, L,  1, 0x55555555), \

-    bitswap(L, R,  8, 0x00FF00FF), \

-    bitswap(L, R,  2, 0x33333333), \

-    bitswap(R, L, 16, 0x0000FFFF), \

-    bitswap(R, L,  4, 0x0F0F0F0F))

-

-static void des_encipher(word32 * output, word32 L, word32 R,

-			 DESContext * sched)

-{

-    word32 swap, s0246, s1357;

-

-    IP(L, R);

-

-    L = rotl(L, 1);

-    R = rotl(R, 1);

-

-    L ^= f(R, sched->k0246[0], sched->k1357[0]);

-    R ^= f(L, sched->k0246[1], sched->k1357[1]);

-    L ^= f(R, sched->k0246[2], sched->k1357[2]);

-    R ^= f(L, sched->k0246[3], sched->k1357[3]);

-    L ^= f(R, sched->k0246[4], sched->k1357[4]);

-    R ^= f(L, sched->k0246[5], sched->k1357[5]);

-    L ^= f(R, sched->k0246[6], sched->k1357[6]);

-    R ^= f(L, sched->k0246[7], sched->k1357[7]);

-    L ^= f(R, sched->k0246[8], sched->k1357[8]);

-    R ^= f(L, sched->k0246[9], sched->k1357[9]);

-    L ^= f(R, sched->k0246[10], sched->k1357[10]);

-    R ^= f(L, sched->k0246[11], sched->k1357[11]);

-    L ^= f(R, sched->k0246[12], sched->k1357[12]);

-    R ^= f(L, sched->k0246[13], sched->k1357[13]);

-    L ^= f(R, sched->k0246[14], sched->k1357[14]);

-    R ^= f(L, sched->k0246[15], sched->k1357[15]);

-

-    L = rotl(L, 31);

-    R = rotl(R, 31);

-

-    swap = L;

-    L = R;

-    R = swap;

-

-    FP(L, R);

-

-    output[0] = L;

-    output[1] = R;

-}

-

-static void des_decipher(word32 * output, word32 L, word32 R,

-			 DESContext * sched)

-{

-    word32 swap, s0246, s1357;

-

-    IP(L, R);

-

-    L = rotl(L, 1);

-    R = rotl(R, 1);

-

-    L ^= f(R, sched->k0246[15], sched->k1357[15]);

-    R ^= f(L, sched->k0246[14], sched->k1357[14]);

-    L ^= f(R, sched->k0246[13], sched->k1357[13]);

-    R ^= f(L, sched->k0246[12], sched->k1357[12]);

-    L ^= f(R, sched->k0246[11], sched->k1357[11]);

-    R ^= f(L, sched->k0246[10], sched->k1357[10]);

-    L ^= f(R, sched->k0246[9], sched->k1357[9]);

-    R ^= f(L, sched->k0246[8], sched->k1357[8]);

-    L ^= f(R, sched->k0246[7], sched->k1357[7]);

-    R ^= f(L, sched->k0246[6], sched->k1357[6]);

-    L ^= f(R, sched->k0246[5], sched->k1357[5]);

-    R ^= f(L, sched->k0246[4], sched->k1357[4]);

-    L ^= f(R, sched->k0246[3], sched->k1357[3]);

-    R ^= f(L, sched->k0246[2], sched->k1357[2]);

-    L ^= f(R, sched->k0246[1], sched->k1357[1]);

-    R ^= f(L, sched->k0246[0], sched->k1357[0]);

-

-    L = rotl(L, 31);

-    R = rotl(R, 31);

-

-    swap = L;

-    L = R;

-    R = swap;

-

-    FP(L, R);

-

-    output[0] = L;

-    output[1] = R;

-}

-

-static void des_cbc_encrypt(unsigned char *blk,

-			    unsigned int len, DESContext * sched)

-{

-    word32 out[2], iv0, iv1;

-    unsigned int i;

-

-    assert((len & 7) == 0);

-

-    iv0 = sched->iv0;

-    iv1 = sched->iv1;

-    for (i = 0; i < len; i += 8) {

-	iv0 ^= GET_32BIT_MSB_FIRST(blk);

-	iv1 ^= GET_32BIT_MSB_FIRST(blk + 4);

-	des_encipher(out, iv0, iv1, sched);

-	iv0 = out[0];

-	iv1 = out[1];

-	PUT_32BIT_MSB_FIRST(blk, iv0);

-	PUT_32BIT_MSB_FIRST(blk + 4, iv1);

-	blk += 8;

-    }

-    sched->iv0 = iv0;

-    sched->iv1 = iv1;

-}

-

-static void des_cbc_decrypt(unsigned char *blk,

-			    unsigned int len, DESContext * sched)

-{

-    word32 out[2], iv0, iv1, xL, xR;

-    unsigned int i;

-

-    assert((len & 7) == 0);

-

-    iv0 = sched->iv0;

-    iv1 = sched->iv1;

-    for (i = 0; i < len; i += 8) {

-	xL = GET_32BIT_MSB_FIRST(blk);

-	xR = GET_32BIT_MSB_FIRST(blk + 4);

-	des_decipher(out, xL, xR, sched);

-	iv0 ^= out[0];

-	iv1 ^= out[1];

-	PUT_32BIT_MSB_FIRST(blk, iv0);

-	PUT_32BIT_MSB_FIRST(blk + 4, iv1);

-	blk += 8;

-	iv0 = xL;

-	iv1 = xR;

-    }

-    sched->iv0 = iv0;

-    sched->iv1 = iv1;

-}

-

-static void des_3cbc_encrypt(unsigned char *blk,

-			     unsigned int len, DESContext * scheds)

-{

-    des_cbc_encrypt(blk, len, &scheds[0]);

-    des_cbc_decrypt(blk, len, &scheds[1]);

-    des_cbc_encrypt(blk, len, &scheds[2]);

-}

-

-static void des_cbc3_encrypt(unsigned char *blk,

-			     unsigned int len, DESContext * scheds)

-{

-    word32 out[2], iv0, iv1;

-    unsigned int i;

-

-    assert((len & 7) == 0);

-

-    iv0 = scheds->iv0;

-    iv1 = scheds->iv1;

-    for (i = 0; i < len; i += 8) {

-	iv0 ^= GET_32BIT_MSB_FIRST(blk);

-	iv1 ^= GET_32BIT_MSB_FIRST(blk + 4);

-	des_encipher(out, iv0, iv1, &scheds[0]);

-	des_decipher(out, out[0], out[1], &scheds[1]);

-	des_encipher(out, out[0], out[1], &scheds[2]);

-	iv0 = out[0];

-	iv1 = out[1];

-	PUT_32BIT_MSB_FIRST(blk, iv0);

-	PUT_32BIT_MSB_FIRST(blk + 4, iv1);

-	blk += 8;

-    }

-    scheds->iv0 = iv0;

-    scheds->iv1 = iv1;

-}

-

-static void des_3cbc_decrypt(unsigned char *blk,

-			     unsigned int len, DESContext * scheds)

-{

-    des_cbc_decrypt(blk, len, &scheds[2]);

-    des_cbc_encrypt(blk, len, &scheds[1]);

-    des_cbc_decrypt(blk, len, &scheds[0]);

-}

-

-static void des_cbc3_decrypt(unsigned char *blk,

-			     unsigned int len, DESContext * scheds)

-{

-    word32 out[2], iv0, iv1, xL, xR;

-    unsigned int i;

-

-    assert((len & 7) == 0);

-

-    iv0 = scheds->iv0;

-    iv1 = scheds->iv1;

-    for (i = 0; i < len; i += 8) {

-	xL = GET_32BIT_MSB_FIRST(blk);

-	xR = GET_32BIT_MSB_FIRST(blk + 4);

-	des_decipher(out, xL, xR, &scheds[2]);

-	des_encipher(out, out[0], out[1], &scheds[1]);

-	des_decipher(out, out[0], out[1], &scheds[0]);

-	iv0 ^= out[0];

-	iv1 ^= out[1];

-	PUT_32BIT_MSB_FIRST(blk, iv0);

-	PUT_32BIT_MSB_FIRST(blk + 4, iv1);

-	blk += 8;

-	iv0 = xL;

-	iv1 = xR;

-    }

-    scheds->iv0 = iv0;

-    scheds->iv1 = iv1;

-}

-

-static void des_sdctr3(unsigned char *blk,

-			     unsigned int len, DESContext * scheds)

-{

-    word32 b[2], iv0, iv1, tmp;

-    unsigned int i;

-

-    assert((len & 7) == 0);

-

-    iv0 = scheds->iv0;

-    iv1 = scheds->iv1;

-    for (i = 0; i < len; i += 8) {

-	des_encipher(b, iv0, iv1, &scheds[0]);

-	des_decipher(b, b[0], b[1], &scheds[1]);

-	des_encipher(b, b[0], b[1], &scheds[2]);

-	tmp = GET_32BIT_MSB_FIRST(blk);

-	PUT_32BIT_MSB_FIRST(blk, tmp ^ b[0]);

-	blk += 4;

-	tmp = GET_32BIT_MSB_FIRST(blk);

-	PUT_32BIT_MSB_FIRST(blk, tmp ^ b[1]);

-	blk += 4;

-	if ((iv1 = (iv1 + 1) & 0xffffffff) == 0)

-	    iv0 = (iv0 + 1) & 0xffffffff;

-    }

-    scheds->iv0 = iv0;

-    scheds->iv1 = iv1;

-}

-

-static void *des3_make_context(void)

-{

-    return snewn(3, DESContext);

-}

-

-static void *des3_ssh1_make_context(void)

-{

-    /* Need 3 keys for each direction, in SSH-1 */

-    return snewn(6, DESContext);

-}

-

-static void *des_make_context(void)

-{

-    return snew(DESContext);

-}

-

-static void *des_ssh1_make_context(void)

-{

-    /* Need one key for each direction, in SSH-1 */

-    return snewn(2, DESContext);

-}

-

-static void des3_free_context(void *handle)   /* used for both 3DES and DES */

-{

-    sfree(handle);

-}

-

-static void des3_key(void *handle, unsigned char *key)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &keys[0]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),

-		  GET_32BIT_MSB_FIRST(key + 12), &keys[1]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 16),

-		  GET_32BIT_MSB_FIRST(key + 20), &keys[2]);

-}

-

-static void des3_iv(void *handle, unsigned char *key)

-{

-    DESContext *keys = (DESContext *) handle;

-    keys[0].iv0 = GET_32BIT_MSB_FIRST(key);

-    keys[0].iv1 = GET_32BIT_MSB_FIRST(key + 4);

-}

-

-static void des_key(void *handle, unsigned char *key)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &keys[0]);

-}

-

-static void des3_sesskey(void *handle, unsigned char *key)

-{

-    DESContext *keys = (DESContext *) handle;

-    des3_key(keys, key);

-    des3_key(keys+3, key);

-}

-

-static void des3_encrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_3cbc_encrypt(blk, len, keys);

-}

-

-static void des3_decrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_3cbc_decrypt(blk, len, keys+3);

-}

-

-static void des3_ssh2_encrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_cbc3_encrypt(blk, len, keys);

-}

-

-static void des3_ssh2_decrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_cbc3_decrypt(blk, len, keys);

-}

-

-static void des3_ssh2_sdctr(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_sdctr3(blk, len, keys);

-}

-

-static void des_ssh2_encrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_cbc_encrypt(blk, len, keys);

-}

-

-static void des_ssh2_decrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_cbc_decrypt(blk, len, keys);

-}

-

-void des3_decrypt_pubkey(unsigned char *key, unsigned char *blk, int len)

-{

-    DESContext ourkeys[3];

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),

-		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[2]);

-    des_3cbc_decrypt(blk, len, ourkeys);

-    memset(ourkeys, 0, sizeof(ourkeys));

-}

-

-void des3_encrypt_pubkey(unsigned char *key, unsigned char *blk, int len)

-{

-    DESContext ourkeys[3];

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),

-		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[2]);

-    des_3cbc_encrypt(blk, len, ourkeys);

-    memset(ourkeys, 0, sizeof(ourkeys));

-}

-

-void des3_decrypt_pubkey_ossh(unsigned char *key, unsigned char *iv,

-			      unsigned char *blk, int len)

-{

-    DESContext ourkeys[3];

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),

-		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 16),

-		  GET_32BIT_MSB_FIRST(key + 20), &ourkeys[2]);

-    ourkeys[0].iv0 = GET_32BIT_MSB_FIRST(iv);

-    ourkeys[0].iv1 = GET_32BIT_MSB_FIRST(iv+4);

-    des_cbc3_decrypt(blk, len, ourkeys);

-    memset(ourkeys, 0, sizeof(ourkeys));

-}

-

-void des3_encrypt_pubkey_ossh(unsigned char *key, unsigned char *iv,

-			      unsigned char *blk, int len)

-{

-    DESContext ourkeys[3];

-    des_key_setup(GET_32BIT_MSB_FIRST(key),

-		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),

-		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);

-    des_key_setup(GET_32BIT_MSB_FIRST(key + 16),

-		  GET_32BIT_MSB_FIRST(key + 20), &ourkeys[2]);

-    ourkeys[0].iv0 = GET_32BIT_MSB_FIRST(iv);

-    ourkeys[0].iv1 = GET_32BIT_MSB_FIRST(iv+4);

-    des_cbc3_encrypt(blk, len, ourkeys);

-    memset(ourkeys, 0, sizeof(ourkeys));

-}

-

-static void des_keysetup_xdmauth(unsigned char *keydata, DESContext *dc)

-{

-    unsigned char key[8];

-    int i, nbits, j;

-    unsigned int bits;

-

-    bits = 0;

-    nbits = 0;

-    j = 0;

-    for (i = 0; i < 8; i++) {

-	if (nbits < 7) {

-	    bits = (bits << 8) | keydata[j];

-	    nbits += 8;

-	    j++;

-	}

-	key[i] = (bits >> (nbits - 7)) << 1;

-	bits &= ~(0x7F << (nbits - 7));

-	nbits -= 7;

-    }

-

-    des_key_setup(GET_32BIT_MSB_FIRST(key), GET_32BIT_MSB_FIRST(key + 4), dc);

-}

-

-void des_encrypt_xdmauth(unsigned char *keydata, unsigned char *blk, int len)

-{

-    DESContext dc;

-    des_keysetup_xdmauth(keydata, &dc);

-    des_cbc_encrypt(blk, 24, &dc);

-}

-

-void des_decrypt_xdmauth(unsigned char *keydata, unsigned char *blk, int len)

-{

-    DESContext dc;

-    des_keysetup_xdmauth(keydata, &dc);

-    des_cbc_decrypt(blk, 24, &dc);

-}

-

-static const struct ssh2_cipher ssh_3des_ssh2 = {

-    des3_make_context, des3_free_context, des3_iv, des3_key,

-    des3_ssh2_encrypt_blk, des3_ssh2_decrypt_blk,

-    "3des-cbc",

-    8, 168, SSH_CIPHER_IS_CBC, "triple-DES CBC"

-};

-

-static const struct ssh2_cipher ssh_3des_ssh2_ctr = {

-    des3_make_context, des3_free_context, des3_iv, des3_key,

-    des3_ssh2_sdctr, des3_ssh2_sdctr,

-    "3des-ctr",

-    8, 168, 0, "triple-DES SDCTR"

-};

-

-/*

- * Single DES in SSH-2. "des-cbc" is marked as HISTORIC in

- * RFC 4250, referring to

- * FIPS-46-3.  ("Single DES (i.e., DES) will be permitted 

- * for legacy systems only.") , but ssh.com support it and 

- * apparently aren't the only people to do so, so we sigh 

- * and implement it anyway.

- */

-static const struct ssh2_cipher ssh_des_ssh2 = {

-    des_make_context, des3_free_context, des3_iv, des_key,

-    des_ssh2_encrypt_blk, des_ssh2_decrypt_blk,

-    "des-cbc",

-    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC"

-};

-

-static const struct ssh2_cipher ssh_des_sshcom_ssh2 = {

-    des_make_context, des3_free_context, des3_iv, des_key,

-    des_ssh2_encrypt_blk, des_ssh2_decrypt_blk,

-    "des-cbc@ssh.com",

-    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC"

-};

-

-static const struct ssh2_cipher *const des3_list[] = {

-    &ssh_3des_ssh2_ctr,

-    &ssh_3des_ssh2

-};

-

-const struct ssh2_ciphers ssh2_3des = {

-    sizeof(des3_list) / sizeof(*des3_list),

-    des3_list

-};

-

-static const struct ssh2_cipher *const des_list[] = {

-    &ssh_des_ssh2,

-    &ssh_des_sshcom_ssh2

-};

-

-const struct ssh2_ciphers ssh2_des = {

-    sizeof(des_list) / sizeof(*des_list),

-    des_list

-};

-

-const struct ssh_cipher ssh_3des = {

-    des3_ssh1_make_context, des3_free_context, des3_sesskey,

-    des3_encrypt_blk, des3_decrypt_blk,

-    8, "triple-DES inner-CBC"

-};

-

-static void des_sesskey(void *handle, unsigned char *key)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_key(keys, key);

-    des_key(keys+1, key);

-}

-

-static void des_encrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_cbc_encrypt(blk, len, keys);

-}

-

-static void des_decrypt_blk(void *handle, unsigned char *blk, int len)

-{

-    DESContext *keys = (DESContext *) handle;

-    des_cbc_decrypt(blk, len, keys+1);

-}

-

-const struct ssh_cipher ssh_des = {

-    des_ssh1_make_context, des3_free_context, des_sesskey,

-    des_encrypt_blk, des_decrypt_blk,

-    8, "single-DES CBC"

-};

+#include <assert.h>
+#include "ssh.h"
+
+
+/* des.c - implementation of DES
+ */
+
+/*
+ * Description of DES
+ * ------------------
+ *
+ * Unlike the description in FIPS 46, I'm going to use _sensible_ indices:
+ * bits in an n-bit word are numbered from 0 at the LSB to n-1 at the MSB.
+ * And S-boxes are indexed by six consecutive bits, not by the outer two
+ * followed by the middle four.
+ *
+ * The DES encryption routine requires a 64-bit input, and a key schedule K
+ * containing 16 48-bit elements.
+ *
+ *   First the input is permuted by the initial permutation IP.
+ *   Then the input is split into 32-bit words L and R. (L is the MSW.)
+ *   Next, 16 rounds. In each round:
+ *     (L, R) <- (R, L xor f(R, K[i]))
+ *   Then the pre-output words L and R are swapped.
+ *   Then L and R are glued back together into a 64-bit word. (L is the MSW,
+ *     again, but since we just swapped them, the MSW is the R that came out
+ *     of the last round.)
+ *   The 64-bit output block is permuted by the inverse of IP and returned.
+ *
+ * Decryption is identical except that the elements of K are used in the
+ * opposite order. (This wouldn't work if that word swap didn't happen.)
+ *
+ * The function f, used in each round, accepts a 32-bit word R and a
+ * 48-bit key block K. It produces a 32-bit output.
+ *
+ *   First R is expanded to 48 bits using the bit-selection function E.
+ *   The resulting 48-bit block is XORed with the key block K to produce
+ *     a 48-bit block X.
+ *   This block X is split into eight groups of 6 bits. Each group of 6
+ *     bits is then looked up in one of the eight S-boxes to convert
+ *     it to 4 bits. These eight groups of 4 bits are glued back
+ *     together to produce a 32-bit preoutput block.
+ *   The preoutput block is permuted using the permutation P and returned.
+ *
+ * Key setup maps a 64-bit key word into a 16x48-bit key schedule. Although
+ * the approved input format for the key is a 64-bit word, eight of the
+ * bits are discarded, so the actual quantity of key used is 56 bits.
+ *
+ *   First the input key is converted to two 28-bit words C and D using
+ *     the bit-selection function PC1.
+ *   Then 16 rounds of key setup occur. In each round, C and D are each
+ *     rotated left by either 1 or 2 bits (depending on which round), and
+ *     then converted into a key schedule element using the bit-selection
+ *     function PC2.
+ *
+ * That's the actual algorithm. Now for the tedious details: all those
+ * painful permutations and lookup tables.
+ *
+ * IP is a 64-to-64 bit permutation. Its output contains the following
+ * bits of its input (listed in order MSB to LSB of output).
+ *
+ *    6 14 22 30 38 46 54 62  4 12 20 28 36 44 52 60
+ *    2 10 18 26 34 42 50 58  0  8 16 24 32 40 48 56
+ *    7 15 23 31 39 47 55 63  5 13 21 29 37 45 53 61
+ *    3 11 19 27 35 43 51 59  1  9 17 25 33 41 49 57
+ *
+ * E is a 32-to-48 bit selection function. Its output contains the following
+ * bits of its input (listed in order MSB to LSB of output).
+ *
+ *    0 31 30 29 28 27 28 27 26 25 24 23 24 23 22 21 20 19 20 19 18 17 16 15
+ *   16 15 14 13 12 11 12 11 10  9  8  7  8  7  6  5  4  3  4  3  2  1  0 31
+ *
+ * The S-boxes are arbitrary table-lookups each mapping a 6-bit input to a
+ * 4-bit output. In other words, each S-box is an array[64] of 4-bit numbers.
+ * The S-boxes are listed below. The first S-box listed is applied to the
+ * most significant six bits of the block X; the last one is applied to the
+ * least significant.
+ *
+ *   14  0  4 15 13  7  1  4  2 14 15  2 11 13  8  1
+ *    3 10 10  6  6 12 12 11  5  9  9  5  0  3  7  8
+ *    4 15  1 12 14  8  8  2 13  4  6  9  2  1 11  7
+ *   15  5 12 11  9  3  7 14  3 10 10  0  5  6  0 13
+ *
+ *   15  3  1 13  8  4 14  7  6 15 11  2  3  8  4 14
+ *    9 12  7  0  2  1 13 10 12  6  0  9  5 11 10  5
+ *    0 13 14  8  7 10 11  1 10  3  4 15 13  4  1  2
+ *    5 11  8  6 12  7  6 12  9  0  3  5  2 14 15  9
+ *
+ *   10 13  0  7  9  0 14  9  6  3  3  4 15  6  5 10
+ *    1  2 13  8 12  5  7 14 11 12  4 11  2 15  8  1
+ *   13  1  6 10  4 13  9  0  8  6 15  9  3  8  0  7
+ *   11  4  1 15  2 14 12  3  5 11 10  5 14  2  7 12
+ *
+ *    7 13 13  8 14 11  3  5  0  6  6 15  9  0 10  3
+ *    1  4  2  7  8  2  5 12 11  1 12 10  4 14 15  9
+ *   10  3  6 15  9  0  0  6 12 10 11  1  7 13 13  8
+ *   15  9  1  4  3  5 14 11  5 12  2  7  8  2  4 14
+ *
+ *    2 14 12 11  4  2  1 12  7  4 10  7 11 13  6  1
+ *    8  5  5  0  3 15 15 10 13  3  0  9 14  8  9  6
+ *    4 11  2  8  1 12 11  7 10  1 13 14  7  2  8 13
+ *   15  6  9 15 12  0  5  9  6 10  3  4  0  5 14  3
+ *
+ *   12 10  1 15 10  4 15  2  9  7  2 12  6  9  8  5
+ *    0  6 13  1  3 13  4 14 14  0  7 11  5  3 11  8
+ *    9  4 14  3 15  2  5 12  2  9  8  5 12 15  3 10
+ *    7 11  0 14  4  1 10  7  1  6 13  0 11  8  6 13
+ *
+ *    4 13 11  0  2 11 14  7 15  4  0  9  8  1 13 10
+ *    3 14 12  3  9  5  7 12  5  2 10 15  6  8  1  6
+ *    1  6  4 11 11 13 13  8 12  1  3  4  7 10 14  7
+ *   10  9 15  5  6  0  8 15  0 14  5  2  9  3  2 12
+ *
+ *   13  1  2 15  8 13  4  8  6 10 15  3 11  7  1  4
+ *   10 12  9  5  3  6 14 11  5  0  0 14 12  9  7  2
+ *    7  2 11  1  4 14  1  7  9  4 12 10 14  8  2 13
+ *    0 15  6 12 10  9 13  0 15  3  3  5  5  6  8 11
+ *
+ * P is a 32-to-32 bit permutation. Its output contains the following
+ * bits of its input (listed in order MSB to LSB of output).
+ *
+ *   16 25 12 11  3 20  4 15 31 17  9  6 27 14  1 22
+ *   30 24  8 18  0  5 29 23 13 19  2 26 10 21 28  7
+ *
+ * PC1 is a 64-to-56 bit selection function. Its output is in two words,
+ * C and D. The word C contains the following bits of its input (listed
+ * in order MSB to LSB of output).
+ *
+ *    7 15 23 31 39 47 55 63  6 14 22 30 38 46
+ *   54 62  5 13 21 29 37 45 53 61  4 12 20 28
+ *
+ * And the word D contains these bits.
+ *
+ *    1  9 17 25 33 41 49 57  2 10 18 26 34 42
+ *   50 58  3 11 19 27 35 43 51 59 36 44 52 60
+ *
+ * PC2 is a 56-to-48 bit selection function. Its input is in two words,
+ * C and D. These are treated as one 56-bit word (with C more significant,
+ * so that bits 55 to 28 of the word are bits 27 to 0 of C, and bits 27 to
+ * 0 of the word are bits 27 to 0 of D). The output contains the following
+ * bits of this 56-bit input word (listed in order MSB to LSB of output).
+ *
+ *   42 39 45 32 55 51 53 28 41 50 35 46 33 37 44 52 30 48 40 49 29 36 43 54
+ *   15  4 25 19  9  1 26 16  5 11 23  8 12  7 17  0 22  3 10 14  6 20 27 24
+ */
+
+/*
+ * Implementation details
+ * ----------------------
+ * 
+ * If you look at the code in this module, you'll find it looks
+ * nothing _like_ the above algorithm. Here I explain the
+ * differences...
+ *
+ * Key setup has not been heavily optimised here. We are not
+ * concerned with key agility: we aren't codebreakers. We don't
+ * mind a little delay (and it really is a little one; it may be a
+ * factor of five or so slower than it could be but it's still not
+ * an appreciable length of time) while setting up. The only tweaks
+ * in the key setup are ones which change the format of the key
+ * schedule to speed up the actual encryption. I'll describe those
+ * below.
+ *
+ * The first and most obvious optimisation is the S-boxes. Since
+ * each S-box always targets the same four bits in the final 32-bit
+ * word, so the output from (for example) S-box 0 must always be
+ * shifted left 28 bits, we can store the already-shifted outputs
+ * in the lookup tables. This reduces lookup-and-shift to lookup,
+ * so the S-box step is now just a question of ORing together eight
+ * table lookups.
+ *
+ * The permutation P is just a bit order change; it's invariant
+ * with respect to OR, in that P(x)|P(y) = P(x|y). Therefore, we
+ * can apply P to every entry of the S-box tables and then we don't
+ * have to do it in the code of f(). This yields a set of tables
+ * which might be called SP-boxes.
+ *
+ * The bit-selection function E is our next target. Note that E is
+ * immediately followed by the operation of splitting into 6-bit
+ * chunks. Examining the 6-bit chunks coming out of E we notice
+ * they're all contiguous within the word (speaking cyclically -
+ * the end two wrap round); so we can extract those bit strings
+ * individually rather than explicitly running E. This would yield
+ * code such as
+ *
+ *     y |= SPboxes[0][ (rotl(R, 5) ^  top6bitsofK) & 0x3F ];
+ *     t |= SPboxes[1][ (rotl(R,11) ^ next6bitsofK) & 0x3F ];
+ *
+ * and so on; and the key schedule preparation would have to
+ * provide each 6-bit chunk separately.
+ *
+ * Really we'd like to XOR in the key schedule element before
+ * looking up bit strings in R. This we can't do, naively, because
+ * the 6-bit strings we want overlap. But look at the strings:
+ *
+ *       3322222222221111111111
+ * bit   10987654321098765432109876543210
+ * 
+ * box0  XXXXX                          X
+ * box1     XXXXXX
+ * box2         XXXXXX
+ * box3             XXXXXX
+ * box4                 XXXXXX
+ * box5                     XXXXXX
+ * box6                         XXXXXX
+ * box7  X                          XXXXX
+ *
+ * The bit strings we need to XOR in for boxes 0, 2, 4 and 6 don't
+ * overlap with each other. Neither do the ones for boxes 1, 3, 5
+ * and 7. So we could provide the key schedule in the form of two
+ * words that we can separately XOR into R, and then every S-box
+ * index is available as a (cyclically) contiguous 6-bit substring
+ * of one or the other of the results.
+ *
+ * The comments in Eric Young's libdes implementation point out
+ * that two of these bit strings require a rotation (rather than a
+ * simple shift) to extract. It's unavoidable that at least _one_
+ * must do; but we can actually run the whole inner algorithm (all
+ * 16 rounds) rotated one bit to the left, so that what the `real'
+ * DES description sees as L=0x80000001 we see as L=0x00000003.
+ * This requires rotating all our SP-box entries one bit to the
+ * left, and rotating each word of the key schedule elements one to
+ * the left, and rotating L and R one bit left just after IP and
+ * one bit right again just before FP. And in each round we convert
+ * a rotate into a shift, so we've saved a few per cent.
+ *
+ * That's about it for the inner loop; the SP-box tables as listed
+ * below are what I've described here (the original S value,
+ * shifted to its final place in the input to P, run through P, and
+ * then rotated one bit left). All that remains is to optimise the
+ * initial permutation IP.
+ *
+ * IP is not an arbitrary permutation. It has the nice property
+ * that if you take any bit number, write it in binary (6 bits),
+ * permute those 6 bits and invert some of them, you get the final
+ * position of that bit. Specifically, the bit whose initial
+ * position is given (in binary) as fedcba ends up in position
+ * AcbFED (where a capital letter denotes the inverse of a bit).
+ *
+ * We have the 64-bit data in two 32-bit words L and R, where bits
+ * in L are those with f=1 and bits in R are those with f=0. We
+ * note that we can do a simple transformation: suppose we exchange
+ * the bits with f=1,c=0 and the bits with f=0,c=1. This will cause
+ * the bit fedcba to be in position cedfba - we've `swapped' bits c
+ * and f in the position of each bit!
+ * 
+ * Better still, this transformation is easy. In the example above,
+ * bits in L with c=0 are bits 0x0F0F0F0F, and those in R with c=1
+ * are 0xF0F0F0F0. So we can do
+ *
+ *     difference = ((R >> 4) ^ L) & 0x0F0F0F0F
+ *     R ^= (difference << 4)
+ *     L ^= difference
+ *
+ * to perform the swap. Let's denote this by bitswap(4,0x0F0F0F0F).
+ * Also, we can invert the bit at the top just by exchanging L and
+ * R. So in a few swaps and a few of these bit operations we can
+ * do:
+ * 
+ * Initially the position of bit fedcba is     fedcba
+ * Swap L with R to make it                    Fedcba
+ * Perform bitswap( 4,0x0F0F0F0F) to make it   cedFba
+ * Perform bitswap(16,0x0000FFFF) to make it   ecdFba
+ * Swap L with R to make it                    EcdFba
+ * Perform bitswap( 2,0x33333333) to make it   bcdFEa
+ * Perform bitswap( 8,0x00FF00FF) to make it   dcbFEa
+ * Swap L with R to make it                    DcbFEa
+ * Perform bitswap( 1,0x55555555) to make it   acbFED
+ * Swap L with R to make it                    AcbFED
+ *
+ * (In the actual code the four swaps are implicit: R and L are
+ * simply used the other way round in the first, second and last
+ * bitswap operations.)
+ *
+ * The final permutation is just the inverse of IP, so it can be
+ * performed by a similar set of operations.
+ */
+
+typedef struct {
+    word32 k0246[16], k1357[16];
+    word32 iv0, iv1;
+} DESContext;
+
+#define rotl(x, c) ( (x << c) | (x >> (32-c)) )
+#define rotl28(x, c) ( ( (x << c) | (x >> (28-c)) ) & 0x0FFFFFFF)
+
+static word32 bitsel(word32 * input, const int *bitnums, int size)
+{
+    word32 ret = 0;
+    while (size--) {
+	int bitpos = *bitnums++;
+	ret <<= 1;
+	if (bitpos >= 0)
+	    ret |= 1 & (input[bitpos / 32] >> (bitpos % 32));
+    }
+    return ret;
+}
+
+static void des_key_setup(word32 key_msw, word32 key_lsw, DESContext * sched)
+{
+
+    static const int PC1_Cbits[] = {
+	7, 15, 23, 31, 39, 47, 55, 63, 6, 14, 22, 30, 38, 46,
+	54, 62, 5, 13, 21, 29, 37, 45, 53, 61, 4, 12, 20, 28
+    };
+    static const int PC1_Dbits[] = {
+	1, 9, 17, 25, 33, 41, 49, 57, 2, 10, 18, 26, 34, 42,
+	50, 58, 3, 11, 19, 27, 35, 43, 51, 59, 36, 44, 52, 60
+    };
+    /*
+     * The bit numbers in the two lists below don't correspond to
+     * the ones in the above description of PC2, because in the
+     * above description C and D are concatenated so `bit 28' means
+     * bit 0 of C. In this implementation we're using the standard
+     * `bitsel' function above and C is in the second word, so bit
+     * 0 of C is addressed by writing `32' here.
+     */
+    static const int PC2_0246[] = {
+	49, 36, 59, 55, -1, -1, 37, 41, 48, 56, 34, 52, -1, -1, 15, 4,
+	25, 19, 9, 1, -1, -1, 12, 7, 17, 0, 22, 3, -1, -1, 46, 43
+    };
+    static const int PC2_1357[] = {
+	-1, -1, 57, 32, 45, 54, 39, 50, -1, -1, 44, 53, 33, 40, 47, 58,
+	-1, -1, 26, 16, 5, 11, 23, 8, -1, -1, 10, 14, 6, 20, 27, 24
+    };
+    static const int leftshifts[] =
+	{ 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };
+
+    word32 C, D;
+    word32 buf[2];
+    int i;
+
+    buf[0] = key_lsw;
+    buf[1] = key_msw;
+
+    C = bitsel(buf, PC1_Cbits, 28);
+    D = bitsel(buf, PC1_Dbits, 28);
+
+    for (i = 0; i < 16; i++) {
+	C = rotl28(C, leftshifts[i]);
+	D = rotl28(D, leftshifts[i]);
+	buf[0] = D;
+	buf[1] = C;
+	sched->k0246[i] = bitsel(buf, PC2_0246, 32);
+	sched->k1357[i] = bitsel(buf, PC2_1357, 32);
+    }
+
+    sched->iv0 = sched->iv1 = 0;
+}
+
+static const word32 SPboxes[8][64] = {
+    {0x01010400, 0x00000000, 0x00010000, 0x01010404,
+     0x01010004, 0x00010404, 0x00000004, 0x00010000,
+     0x00000400, 0x01010400, 0x01010404, 0x00000400,
+     0x01000404, 0x01010004, 0x01000000, 0x00000004,
+     0x00000404, 0x01000400, 0x01000400, 0x00010400,
+     0x00010400, 0x01010000, 0x01010000, 0x01000404,
+     0x00010004, 0x01000004, 0x01000004, 0x00010004,
+     0x00000000, 0x00000404, 0x00010404, 0x01000000,
+     0x00010000, 0x01010404, 0x00000004, 0x01010000,
+     0x01010400, 0x01000000, 0x01000000, 0x00000400,
+     0x01010004, 0x00010000, 0x00010400, 0x01000004,
+     0x00000400, 0x00000004, 0x01000404, 0x00010404,
+     0x01010404, 0x00010004, 0x01010000, 0x01000404,
+     0x01000004, 0x00000404, 0x00010404, 0x01010400,
+     0x00000404, 0x01000400, 0x01000400, 0x00000000,
+     0x00010004, 0x00010400, 0x00000000, 0x01010004L},
+
+    {0x80108020, 0x80008000, 0x00008000, 0x00108020,
+     0x00100000, 0x00000020, 0x80100020, 0x80008020,
+     0x80000020, 0x80108020, 0x80108000, 0x80000000,
+     0x80008000, 0x00100000, 0x00000020, 0x80100020,
+     0x00108000, 0x00100020, 0x80008020, 0x00000000,
+     0x80000000, 0x00008000, 0x00108020, 0x80100000,
+     0x00100020, 0x80000020, 0x00000000, 0x00108000,
+     0x00008020, 0x80108000, 0x80100000, 0x00008020,
+     0x00000000, 0x00108020, 0x80100020, 0x00100000,
+     0x80008020, 0x80100000, 0x80108000, 0x00008000,
+     0x80100000, 0x80008000, 0x00000020, 0x80108020,
+     0x00108020, 0x00000020, 0x00008000, 0x80000000,
+     0x00008020, 0x80108000, 0x00100000, 0x80000020,
+     0x00100020, 0x80008020, 0x80000020, 0x00100020,
+     0x00108000, 0x00000000, 0x80008000, 0x00008020,
+     0x80000000, 0x80100020, 0x80108020, 0x00108000L},
+
+    {0x00000208, 0x08020200, 0x00000000, 0x08020008,
+     0x08000200, 0x00000000, 0x00020208, 0x08000200,
+     0x00020008, 0x08000008, 0x08000008, 0x00020000,
+     0x08020208, 0x00020008, 0x08020000, 0x00000208,
+     0x08000000, 0x00000008, 0x08020200, 0x00000200,
+     0x00020200, 0x08020000, 0x08020008, 0x00020208,
+     0x08000208, 0x00020200, 0x00020000, 0x08000208,
+     0x00000008, 0x08020208, 0x00000200, 0x08000000,
+     0x08020200, 0x08000000, 0x00020008, 0x00000208,
+     0x00020000, 0x08020200, 0x08000200, 0x00000000,
+     0x00000200, 0x00020008, 0x08020208, 0x08000200,
+     0x08000008, 0x00000200, 0x00000000, 0x08020008,
+     0x08000208, 0x00020000, 0x08000000, 0x08020208,
+     0x00000008, 0x00020208, 0x00020200, 0x08000008,
+     0x08020000, 0x08000208, 0x00000208, 0x08020000,
+     0x00020208, 0x00000008, 0x08020008, 0x00020200L},
+
+    {0x00802001, 0x00002081, 0x00002081, 0x00000080,
+     0x00802080, 0x00800081, 0x00800001, 0x00002001,
+     0x00000000, 0x00802000, 0x00802000, 0x00802081,
+     0x00000081, 0x00000000, 0x00800080, 0x00800001,
+     0x00000001, 0x00002000, 0x00800000, 0x00802001,
+     0x00000080, 0x00800000, 0x00002001, 0x00002080,
+     0x00800081, 0x00000001, 0x00002080, 0x00800080,
+     0x00002000, 0x00802080, 0x00802081, 0x00000081,
+     0x00800080, 0x00800001, 0x00802000, 0x00802081,
+     0x00000081, 0x00000000, 0x00000000, 0x00802000,
+     0x00002080, 0x00800080, 0x00800081, 0x00000001,
+     0x00802001, 0x00002081, 0x00002081, 0x00000080,
+     0x00802081, 0x00000081, 0x00000001, 0x00002000,
+     0x00800001, 0x00002001, 0x00802080, 0x00800081,
+     0x00002001, 0x00002080, 0x00800000, 0x00802001,
+     0x00000080, 0x00800000, 0x00002000, 0x00802080L},
+
+    {0x00000100, 0x02080100, 0x02080000, 0x42000100,
+     0x00080000, 0x00000100, 0x40000000, 0x02080000,
+     0x40080100, 0x00080000, 0x02000100, 0x40080100,
+     0x42000100, 0x42080000, 0x00080100, 0x40000000,
+     0x02000000, 0x40080000, 0x40080000, 0x00000000,
+     0x40000100, 0x42080100, 0x42080100, 0x02000100,
+     0x42080000, 0x40000100, 0x00000000, 0x42000000,
+     0x02080100, 0x02000000, 0x42000000, 0x00080100,
+     0x00080000, 0x42000100, 0x00000100, 0x02000000,
+     0x40000000, 0x02080000, 0x42000100, 0x40080100,
+     0x02000100, 0x40000000, 0x42080000, 0x02080100,
+     0x40080100, 0x00000100, 0x02000000, 0x42080000,
+     0x42080100, 0x00080100, 0x42000000, 0x42080100,
+     0x02080000, 0x00000000, 0x40080000, 0x42000000,
+     0x00080100, 0x02000100, 0x40000100, 0x00080000,
+     0x00000000, 0x40080000, 0x02080100, 0x40000100L},
+
+    {0x20000010, 0x20400000, 0x00004000, 0x20404010,
+     0x20400000, 0x00000010, 0x20404010, 0x00400000,
+     0x20004000, 0x00404010, 0x00400000, 0x20000010,
+     0x00400010, 0x20004000, 0x20000000, 0x00004010,
+     0x00000000, 0x00400010, 0x20004010, 0x00004000,
+     0x00404000, 0x20004010, 0x00000010, 0x20400010,
+     0x20400010, 0x00000000, 0x00404010, 0x20404000,
+     0x00004010, 0x00404000, 0x20404000, 0x20000000,
+     0x20004000, 0x00000010, 0x20400010, 0x00404000,
+     0x20404010, 0x00400000, 0x00004010, 0x20000010,
+     0x00400000, 0x20004000, 0x20000000, 0x00004010,
+     0x20000010, 0x20404010, 0x00404000, 0x20400000,
+     0x00404010, 0x20404000, 0x00000000, 0x20400010,
+     0x00000010, 0x00004000, 0x20400000, 0x00404010,
+     0x00004000, 0x00400010, 0x20004010, 0x00000000,
+     0x20404000, 0x20000000, 0x00400010, 0x20004010L},
+
+    {0x00200000, 0x04200002, 0x04000802, 0x00000000,
+     0x00000800, 0x04000802, 0x00200802, 0x04200800,
+     0x04200802, 0x00200000, 0x00000000, 0x04000002,
+     0x00000002, 0x04000000, 0x04200002, 0x00000802,
+     0x04000800, 0x00200802, 0x00200002, 0x04000800,
+     0x04000002, 0x04200000, 0x04200800, 0x00200002,
+     0x04200000, 0x00000800, 0x00000802, 0x04200802,
+     0x00200800, 0x00000002, 0x04000000, 0x00200800,
+     0x04000000, 0x00200800, 0x00200000, 0x04000802,
+     0x04000802, 0x04200002, 0x04200002, 0x00000002,
+     0x00200002, 0x04000000, 0x04000800, 0x00200000,
+     0x04200800, 0x00000802, 0x00200802, 0x04200800,
+     0x00000802, 0x04000002, 0x04200802, 0x04200000,
+     0x00200800, 0x00000000, 0x00000002, 0x04200802,
+     0x00000000, 0x00200802, 0x04200000, 0x00000800,
+     0x04000002, 0x04000800, 0x00000800, 0x00200002L},
+
+    {0x10001040, 0x00001000, 0x00040000, 0x10041040,
+     0x10000000, 0x10001040, 0x00000040, 0x10000000,
+     0x00040040, 0x10040000, 0x10041040, 0x00041000,
+     0x10041000, 0x00041040, 0x00001000, 0x00000040,
+     0x10040000, 0x10000040, 0x10001000, 0x00001040,
+     0x00041000, 0x00040040, 0x10040040, 0x10041000,
+     0x00001040, 0x00000000, 0x00000000, 0x10040040,
+     0x10000040, 0x10001000, 0x00041040, 0x00040000,
+     0x00041040, 0x00040000, 0x10041000, 0x00001000,
+     0x00000040, 0x10040040, 0x00001000, 0x00041040,
+     0x10001000, 0x00000040, 0x10000040, 0x10040000,
+     0x10040040, 0x10000000, 0x00040000, 0x10001040,
+     0x00000000, 0x10041040, 0x00040040, 0x10000040,
+     0x10040000, 0x10001000, 0x10001040, 0x00000000,
+     0x10041040, 0x00041000, 0x00041000, 0x00001040,
+     0x00001040, 0x00040040, 0x10000000, 0x10041000L}
+};
+
+#define f(R, K0246, K1357) (\
+    s0246 = R ^ K0246, \
+    s1357 = R ^ K1357, \
+    s0246 = rotl(s0246, 28), \
+    SPboxes[0] [(s0246 >> 24) & 0x3F] | \
+    SPboxes[1] [(s1357 >> 24) & 0x3F] | \
+    SPboxes[2] [(s0246 >> 16) & 0x3F] | \
+    SPboxes[3] [(s1357 >> 16) & 0x3F] | \
+    SPboxes[4] [(s0246 >>  8) & 0x3F] | \
+    SPboxes[5] [(s1357 >>  8) & 0x3F] | \
+    SPboxes[6] [(s0246      ) & 0x3F] | \
+    SPboxes[7] [(s1357      ) & 0x3F])
+
+#define bitswap(L, R, n, mask) (\
+    swap = mask & ( (R >> n) ^ L ), \
+    R ^= swap << n, \
+    L ^= swap)
+
+/* Initial permutation */
+#define IP(L, R) (\
+    bitswap(R, L,  4, 0x0F0F0F0F), \
+    bitswap(R, L, 16, 0x0000FFFF), \
+    bitswap(L, R,  2, 0x33333333), \
+    bitswap(L, R,  8, 0x00FF00FF), \
+    bitswap(R, L,  1, 0x55555555))
+
+/* Final permutation */
+#define FP(L, R) (\
+    bitswap(R, L,  1, 0x55555555), \
+    bitswap(L, R,  8, 0x00FF00FF), \
+    bitswap(L, R,  2, 0x33333333), \
+    bitswap(R, L, 16, 0x0000FFFF), \
+    bitswap(R, L,  4, 0x0F0F0F0F))
+
+static void des_encipher(word32 * output, word32 L, word32 R,
+			 DESContext * sched)
+{
+    word32 swap, s0246, s1357;
+
+    IP(L, R);
+
+    L = rotl(L, 1);
+    R = rotl(R, 1);
+
+    L ^= f(R, sched->k0246[0], sched->k1357[0]);
+    R ^= f(L, sched->k0246[1], sched->k1357[1]);
+    L ^= f(R, sched->k0246[2], sched->k1357[2]);
+    R ^= f(L, sched->k0246[3], sched->k1357[3]);
+    L ^= f(R, sched->k0246[4], sched->k1357[4]);
+    R ^= f(L, sched->k0246[5], sched->k1357[5]);
+    L ^= f(R, sched->k0246[6], sched->k1357[6]);
+    R ^= f(L, sched->k0246[7], sched->k1357[7]);
+    L ^= f(R, sched->k0246[8], sched->k1357[8]);
+    R ^= f(L, sched->k0246[9], sched->k1357[9]);
+    L ^= f(R, sched->k0246[10], sched->k1357[10]);
+    R ^= f(L, sched->k0246[11], sched->k1357[11]);
+    L ^= f(R, sched->k0246[12], sched->k1357[12]);
+    R ^= f(L, sched->k0246[13], sched->k1357[13]);
+    L ^= f(R, sched->k0246[14], sched->k1357[14]);
+    R ^= f(L, sched->k0246[15], sched->k1357[15]);
+
+    L = rotl(L, 31);
+    R = rotl(R, 31);
+
+    swap = L;
+    L = R;
+    R = swap;
+
+    FP(L, R);
+
+    output[0] = L;
+    output[1] = R;
+}
+
+static void des_decipher(word32 * output, word32 L, word32 R,
+			 DESContext * sched)
+{
+    word32 swap, s0246, s1357;
+
+    IP(L, R);
+
+    L = rotl(L, 1);
+    R = rotl(R, 1);
+
+    L ^= f(R, sched->k0246[15], sched->k1357[15]);
+    R ^= f(L, sched->k0246[14], sched->k1357[14]);
+    L ^= f(R, sched->k0246[13], sched->k1357[13]);
+    R ^= f(L, sched->k0246[12], sched->k1357[12]);
+    L ^= f(R, sched->k0246[11], sched->k1357[11]);
+    R ^= f(L, sched->k0246[10], sched->k1357[10]);
+    L ^= f(R, sched->k0246[9], sched->k1357[9]);
+    R ^= f(L, sched->k0246[8], sched->k1357[8]);
+    L ^= f(R, sched->k0246[7], sched->k1357[7]);
+    R ^= f(L, sched->k0246[6], sched->k1357[6]);
+    L ^= f(R, sched->k0246[5], sched->k1357[5]);
+    R ^= f(L, sched->k0246[4], sched->k1357[4]);
+    L ^= f(R, sched->k0246[3], sched->k1357[3]);
+    R ^= f(L, sched->k0246[2], sched->k1357[2]);
+    L ^= f(R, sched->k0246[1], sched->k1357[1]);
+    R ^= f(L, sched->k0246[0], sched->k1357[0]);
+
+    L = rotl(L, 31);
+    R = rotl(R, 31);
+
+    swap = L;
+    L = R;
+    R = swap;
+
+    FP(L, R);
+
+    output[0] = L;
+    output[1] = R;
+}
+
+static void des_cbc_encrypt(unsigned char *blk,
+			    unsigned int len, DESContext * sched)
+{
+    word32 out[2], iv0, iv1;
+    unsigned int i;
+
+    assert((len & 7) == 0);
+
+    iv0 = sched->iv0;
+    iv1 = sched->iv1;
+    for (i = 0; i < len; i += 8) {
+	iv0 ^= GET_32BIT_MSB_FIRST(blk);
+	iv1 ^= GET_32BIT_MSB_FIRST(blk + 4);
+	des_encipher(out, iv0, iv1, sched);
+	iv0 = out[0];
+	iv1 = out[1];
+	PUT_32BIT_MSB_FIRST(blk, iv0);
+	PUT_32BIT_MSB_FIRST(blk + 4, iv1);
+	blk += 8;
+    }
+    sched->iv0 = iv0;
+    sched->iv1 = iv1;
+}
+
+static void des_cbc_decrypt(unsigned char *blk,
+			    unsigned int len, DESContext * sched)
+{
+    word32 out[2], iv0, iv1, xL, xR;
+    unsigned int i;
+
+    assert((len & 7) == 0);
+
+    iv0 = sched->iv0;
+    iv1 = sched->iv1;
+    for (i = 0; i < len; i += 8) {
+	xL = GET_32BIT_MSB_FIRST(blk);
+	xR = GET_32BIT_MSB_FIRST(blk + 4);
+	des_decipher(out, xL, xR, sched);
+	iv0 ^= out[0];
+	iv1 ^= out[1];
+	PUT_32BIT_MSB_FIRST(blk, iv0);
+	PUT_32BIT_MSB_FIRST(blk + 4, iv1);
+	blk += 8;
+	iv0 = xL;
+	iv1 = xR;
+    }
+    sched->iv0 = iv0;
+    sched->iv1 = iv1;
+}
+
+static void des_3cbc_encrypt(unsigned char *blk,
+			     unsigned int len, DESContext * scheds)
+{
+    des_cbc_encrypt(blk, len, &scheds[0]);
+    des_cbc_decrypt(blk, len, &scheds[1]);
+    des_cbc_encrypt(blk, len, &scheds[2]);
+}
+
+static void des_cbc3_encrypt(unsigned char *blk,
+			     unsigned int len, DESContext * scheds)
+{
+    word32 out[2], iv0, iv1;
+    unsigned int i;
+
+    assert((len & 7) == 0);
+
+    iv0 = scheds->iv0;
+    iv1 = scheds->iv1;
+    for (i = 0; i < len; i += 8) {
+	iv0 ^= GET_32BIT_MSB_FIRST(blk);
+	iv1 ^= GET_32BIT_MSB_FIRST(blk + 4);
+	des_encipher(out, iv0, iv1, &scheds[0]);
+	des_decipher(out, out[0], out[1], &scheds[1]);
+	des_encipher(out, out[0], out[1], &scheds[2]);
+	iv0 = out[0];
+	iv1 = out[1];
+	PUT_32BIT_MSB_FIRST(blk, iv0);
+	PUT_32BIT_MSB_FIRST(blk + 4, iv1);
+	blk += 8;
+    }
+    scheds->iv0 = iv0;
+    scheds->iv1 = iv1;
+}
+
+static void des_3cbc_decrypt(unsigned char *blk,
+			     unsigned int len, DESContext * scheds)
+{
+    des_cbc_decrypt(blk, len, &scheds[2]);
+    des_cbc_encrypt(blk, len, &scheds[1]);
+    des_cbc_decrypt(blk, len, &scheds[0]);
+}
+
+static void des_cbc3_decrypt(unsigned char *blk,
+			     unsigned int len, DESContext * scheds)
+{
+    word32 out[2], iv0, iv1, xL, xR;
+    unsigned int i;
+
+    assert((len & 7) == 0);
+
+    iv0 = scheds->iv0;
+    iv1 = scheds->iv1;
+    for (i = 0; i < len; i += 8) {
+	xL = GET_32BIT_MSB_FIRST(blk);
+	xR = GET_32BIT_MSB_FIRST(blk + 4);
+	des_decipher(out, xL, xR, &scheds[2]);
+	des_encipher(out, out[0], out[1], &scheds[1]);
+	des_decipher(out, out[0], out[1], &scheds[0]);
+	iv0 ^= out[0];
+	iv1 ^= out[1];
+	PUT_32BIT_MSB_FIRST(blk, iv0);
+	PUT_32BIT_MSB_FIRST(blk + 4, iv1);
+	blk += 8;
+	iv0 = xL;
+	iv1 = xR;
+    }
+    scheds->iv0 = iv0;
+    scheds->iv1 = iv1;
+}
+
+static void des_sdctr3(unsigned char *blk,
+			     unsigned int len, DESContext * scheds)
+{
+    word32 b[2], iv0, iv1, tmp;
+    unsigned int i;
+
+    assert((len & 7) == 0);
+
+    iv0 = scheds->iv0;
+    iv1 = scheds->iv1;
+    for (i = 0; i < len; i += 8) {
+	des_encipher(b, iv0, iv1, &scheds[0]);
+	des_decipher(b, b[0], b[1], &scheds[1]);
+	des_encipher(b, b[0], b[1], &scheds[2]);
+	tmp = GET_32BIT_MSB_FIRST(blk);
+	PUT_32BIT_MSB_FIRST(blk, tmp ^ b[0]);
+	blk += 4;
+	tmp = GET_32BIT_MSB_FIRST(blk);
+	PUT_32BIT_MSB_FIRST(blk, tmp ^ b[1]);
+	blk += 4;
+	if ((iv1 = (iv1 + 1) & 0xffffffff) == 0)
+	    iv0 = (iv0 + 1) & 0xffffffff;
+    }
+    scheds->iv0 = iv0;
+    scheds->iv1 = iv1;
+}
+
+static void *des3_make_context(void)
+{
+    return snewn(3, DESContext);
+}
+
+static void *des3_ssh1_make_context(void)
+{
+    /* Need 3 keys for each direction, in SSH-1 */
+    return snewn(6, DESContext);
+}
+
+static void *des_make_context(void)
+{
+    return snew(DESContext);
+}
+
+static void *des_ssh1_make_context(void)
+{
+    /* Need one key for each direction, in SSH-1 */
+    return snewn(2, DESContext);
+}
+
+static void des3_free_context(void *handle)   /* used for both 3DES and DES */
+{
+    sfree(handle);
+}
+
+static void des3_key(void *handle, unsigned char *key)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &keys[0]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),
+		  GET_32BIT_MSB_FIRST(key + 12), &keys[1]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 16),
+		  GET_32BIT_MSB_FIRST(key + 20), &keys[2]);
+}
+
+static void des3_iv(void *handle, unsigned char *key)
+{
+    DESContext *keys = (DESContext *) handle;
+    keys[0].iv0 = GET_32BIT_MSB_FIRST(key);
+    keys[0].iv1 = GET_32BIT_MSB_FIRST(key + 4);
+}
+
+static void des_key(void *handle, unsigned char *key)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &keys[0]);
+}
+
+static void des3_sesskey(void *handle, unsigned char *key)
+{
+    DESContext *keys = (DESContext *) handle;
+    des3_key(keys, key);
+    des3_key(keys+3, key);
+}
+
+static void des3_encrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_3cbc_encrypt(blk, len, keys);
+}
+
+static void des3_decrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_3cbc_decrypt(blk, len, keys+3);
+}
+
+static void des3_ssh2_encrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_cbc3_encrypt(blk, len, keys);
+}
+
+static void des3_ssh2_decrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_cbc3_decrypt(blk, len, keys);
+}
+
+static void des3_ssh2_sdctr(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_sdctr3(blk, len, keys);
+}
+
+static void des_ssh2_encrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_cbc_encrypt(blk, len, keys);
+}
+
+static void des_ssh2_decrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_cbc_decrypt(blk, len, keys);
+}
+
+void des3_decrypt_pubkey(unsigned char *key, unsigned char *blk, int len)
+{
+    DESContext ourkeys[3];
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),
+		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[2]);
+    des_3cbc_decrypt(blk, len, ourkeys);
+    smemclr(ourkeys, sizeof(ourkeys));
+}
+
+void des3_encrypt_pubkey(unsigned char *key, unsigned char *blk, int len)
+{
+    DESContext ourkeys[3];
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),
+		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[2]);
+    des_3cbc_encrypt(blk, len, ourkeys);
+    smemclr(ourkeys, sizeof(ourkeys));
+}
+
+void des3_decrypt_pubkey_ossh(unsigned char *key, unsigned char *iv,
+			      unsigned char *blk, int len)
+{
+    DESContext ourkeys[3];
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),
+		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 16),
+		  GET_32BIT_MSB_FIRST(key + 20), &ourkeys[2]);
+    ourkeys[0].iv0 = GET_32BIT_MSB_FIRST(iv);
+    ourkeys[0].iv1 = GET_32BIT_MSB_FIRST(iv+4);
+    des_cbc3_decrypt(blk, len, ourkeys);
+    smemclr(ourkeys, sizeof(ourkeys));
+}
+
+void des3_encrypt_pubkey_ossh(unsigned char *key, unsigned char *iv,
+			      unsigned char *blk, int len)
+{
+    DESContext ourkeys[3];
+    des_key_setup(GET_32BIT_MSB_FIRST(key),
+		  GET_32BIT_MSB_FIRST(key + 4), &ourkeys[0]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 8),
+		  GET_32BIT_MSB_FIRST(key + 12), &ourkeys[1]);
+    des_key_setup(GET_32BIT_MSB_FIRST(key + 16),
+		  GET_32BIT_MSB_FIRST(key + 20), &ourkeys[2]);
+    ourkeys[0].iv0 = GET_32BIT_MSB_FIRST(iv);
+    ourkeys[0].iv1 = GET_32BIT_MSB_FIRST(iv+4);
+    des_cbc3_encrypt(blk, len, ourkeys);
+    smemclr(ourkeys, sizeof(ourkeys));
+}
+
+static void des_keysetup_xdmauth(const unsigned char *keydata, DESContext *dc)
+{
+    unsigned char key[8];
+    int i, nbits, j;
+    unsigned int bits;
+
+    bits = 0;
+    nbits = 0;
+    j = 0;
+    for (i = 0; i < 8; i++) {
+	if (nbits < 7) {
+	    bits = (bits << 8) | keydata[j];
+	    nbits += 8;
+	    j++;
+	}
+	key[i] = (bits >> (nbits - 7)) << 1;
+	bits &= ~(0x7F << (nbits - 7));
+	nbits -= 7;
+    }
+
+    des_key_setup(GET_32BIT_MSB_FIRST(key), GET_32BIT_MSB_FIRST(key + 4), dc);
+}
+
+void des_encrypt_xdmauth(const unsigned char *keydata,
+                         unsigned char *blk, int len)
+{
+    DESContext dc;
+    des_keysetup_xdmauth(keydata, &dc);
+    des_cbc_encrypt(blk, len, &dc);
+}
+
+void des_decrypt_xdmauth(const unsigned char *keydata,
+                         unsigned char *blk, int len)
+{
+    DESContext dc;
+    des_keysetup_xdmauth(keydata, &dc);
+    des_cbc_decrypt(blk, len, &dc);
+}
+
+static const struct ssh2_cipher ssh_3des_ssh2 = {
+    des3_make_context, des3_free_context, des3_iv, des3_key,
+    des3_ssh2_encrypt_blk, des3_ssh2_decrypt_blk,
+    "3des-cbc",
+    8, 168, SSH_CIPHER_IS_CBC, "triple-DES CBC"
+};
+
+static const struct ssh2_cipher ssh_3des_ssh2_ctr = {
+    des3_make_context, des3_free_context, des3_iv, des3_key,
+    des3_ssh2_sdctr, des3_ssh2_sdctr,
+    "3des-ctr",
+    8, 168, 0, "triple-DES SDCTR"
+};
+
+/*
+ * Single DES in SSH-2. "des-cbc" is marked as HISTORIC in
+ * RFC 4250, referring to
+ * FIPS-46-3.  ("Single DES (i.e., DES) will be permitted 
+ * for legacy systems only.") , but ssh.com support it and 
+ * apparently aren't the only people to do so, so we sigh 
+ * and implement it anyway.
+ */
+static const struct ssh2_cipher ssh_des_ssh2 = {
+    des_make_context, des3_free_context, des3_iv, des_key,
+    des_ssh2_encrypt_blk, des_ssh2_decrypt_blk,
+    "des-cbc",
+    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC"
+};
+
+static const struct ssh2_cipher ssh_des_sshcom_ssh2 = {
+    des_make_context, des3_free_context, des3_iv, des_key,
+    des_ssh2_encrypt_blk, des_ssh2_decrypt_blk,
+    "des-cbc@ssh.com",
+    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC"
+};
+
+static const struct ssh2_cipher *const des3_list[] = {
+    &ssh_3des_ssh2_ctr,
+    &ssh_3des_ssh2
+};
+
+const struct ssh2_ciphers ssh2_3des = {
+    sizeof(des3_list) / sizeof(*des3_list),
+    des3_list
+};
+
+static const struct ssh2_cipher *const des_list[] = {
+    &ssh_des_ssh2,
+    &ssh_des_sshcom_ssh2
+};
+
+const struct ssh2_ciphers ssh2_des = {
+    sizeof(des_list) / sizeof(*des_list),
+    des_list
+};
+
+const struct ssh_cipher ssh_3des = {
+    des3_ssh1_make_context, des3_free_context, des3_sesskey,
+    des3_encrypt_blk, des3_decrypt_blk,
+    8, "triple-DES inner-CBC"
+};
+
+static void des_sesskey(void *handle, unsigned char *key)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_key(keys, key);
+    des_key(keys+1, key);
+}
+
+static void des_encrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_cbc_encrypt(blk, len, keys);
+}
+
+static void des_decrypt_blk(void *handle, unsigned char *blk, int len)
+{
+    DESContext *keys = (DESContext *) handle;
+    des_cbc_decrypt(blk, len, keys+1);
+}
+
+const struct ssh_cipher ssh_des = {
+    des_ssh1_make_context, des3_free_context, des_sesskey,
+    des_encrypt_blk, des_decrypt_blk,
+    8, "single-DES CBC"
+};
+
+#ifdef TEST_XDM_AUTH
+
+/*
+ * Small standalone utility which allows encryption and decryption of
+ * single cipher blocks in the XDM-AUTHORIZATION-1 style. Written
+ * during the rework of X authorisation for connection sharing, to
+ * check the corner case when xa1_firstblock matches but the rest of
+ * the authorisation is bogus.
+ *
+ * Just compile this file on its own with the above ifdef symbol
+ * predefined:
+
+gcc -DTEST_XDM_AUTH -o sshdes sshdes.c
+
+ */
+
+#include <stdlib.h>
+void *safemalloc(size_t n, size_t size) { return calloc(n, size); }
+void safefree(void *p) { return free(p); }
+void smemclr(void *p, size_t size) { memset(p, 0, size); }
+int main(int argc, char **argv)
+{
+    unsigned char words[2][8];
+    unsigned char out[8];
+    int i, j;
+
+    memset(words, 0, sizeof(words));
+
+    for (i = 0; i < 2; i++) {
+        for (j = 0; j < 8 && argv[i+1][2*j]; j++) {
+            char x[3];
+            unsigned u;
+            x[0] = argv[i+1][2*j];
+            x[1] = argv[i+1][2*j+1];
+            x[2] = 0;
+            sscanf(x, "%02x", &u);
+            words[i][j] = u;
+        }
+    }
+
+    memcpy(out, words[0], 8);
+    des_decrypt_xdmauth(words[1], out, 8);
+    printf("decrypt(%s,%s) = ", argv[1], argv[2]);
+    for (i = 0; i < 8; i++) printf("%02x", out[i]);
+    printf("\n");
+
+    memcpy(out, words[0], 8);
+    des_encrypt_xdmauth(words[1], out, 8);
+    printf("encrypt(%s,%s) = ", argv[1], argv[2]);
+    for (i = 0; i < 8; i++) printf("%02x", out[i]);
+    printf("\n");
+}
+
+#endif