From 8fd6c61557d06a2434cf0e296df38f218ba2c186 Mon Sep 17 00:00:00 2001 From: marha Date: Fri, 19 Nov 2010 10:48:58 +0000 Subject: Remove tools again. Should have done it with svn merge --reintegrate --- tools/plink/sshrsa.c | 1010 -------------------------------------------------- 1 file changed, 1010 deletions(-) delete mode 100644 tools/plink/sshrsa.c (limited to 'tools/plink/sshrsa.c') diff --git a/tools/plink/sshrsa.c b/tools/plink/sshrsa.c deleted file mode 100644 index d06e9d6f4..000000000 --- a/tools/plink/sshrsa.c +++ /dev/null @@ -1,1010 +0,0 @@ -/* - * RSA implementation for PuTTY. - */ - -#include -#include -#include -#include - -#include "ssh.h" -#include "misc.h" - -int makekey(unsigned char *data, int len, struct RSAKey *result, - unsigned char **keystr, int order) -{ - unsigned char *p = data; - int i, n; - - if (len < 4) - return -1; - - if (result) { - result->bits = 0; - for (i = 0; i < 4; i++) - result->bits = (result->bits << 8) + *p++; - } else - p += 4; - - len -= 4; - - /* - * order=0 means exponent then modulus (the keys sent by the - * server). order=1 means modulus then exponent (the keys - * stored in a keyfile). - */ - - if (order == 0) { - n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL); - if (n < 0) return -1; - p += n; - len -= n; - } - - n = ssh1_read_bignum(p, len, result ? &result->modulus : NULL); - if (n < 0 || (result && bignum_bitcount(result->modulus) == 0)) return -1; - if (result) - result->bytes = n - 2; - if (keystr) - *keystr = p + 2; - p += n; - len -= n; - - if (order == 1) { - n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL); - if (n < 0) return -1; - p += n; - len -= n; - } - return p - data; -} - -int makeprivate(unsigned char *data, int len, struct RSAKey *result) -{ - return ssh1_read_bignum(data, len, &result->private_exponent); -} - -int rsaencrypt(unsigned char *data, int length, struct RSAKey *key) -{ - Bignum b1, b2; - int i; - unsigned char *p; - - if (key->bytes < length + 4) - return 0; /* RSA key too short! */ - - memmove(data + key->bytes - length, data, length); - data[0] = 0; - data[1] = 2; - - for (i = 2; i < key->bytes - length - 1; i++) { - do { - data[i] = random_byte(); - } while (data[i] == 0); - } - data[key->bytes - length - 1] = 0; - - b1 = bignum_from_bytes(data, key->bytes); - - b2 = modpow(b1, key->exponent, key->modulus); - - p = data; - for (i = key->bytes; i--;) { - *p++ = bignum_byte(b2, i); - } - - freebn(b1); - freebn(b2); - - return 1; -} - -static void sha512_mpint(SHA512_State * s, Bignum b) -{ - unsigned char lenbuf[4]; - int len; - len = (bignum_bitcount(b) + 8) / 8; - PUT_32BIT(lenbuf, len); - SHA512_Bytes(s, lenbuf, 4); - while (len-- > 0) { - lenbuf[0] = bignum_byte(b, len); - SHA512_Bytes(s, lenbuf, 1); - } - memset(lenbuf, 0, sizeof(lenbuf)); -} - -/* - * This function is a wrapper on modpow(). It has the same effect - * as modpow(), but employs RSA blinding to protect against timing - * attacks. - */ -static Bignum rsa_privkey_op(Bignum input, struct RSAKey *key) -{ - Bignum random, random_encrypted, random_inverse; - Bignum input_blinded, ret_blinded; - Bignum ret; - - SHA512_State ss; - unsigned char digest512[64]; - int digestused = lenof(digest512); - int hashseq = 0; - - /* - * Start by inventing a random number chosen uniformly from the - * range 2..modulus-1. (We do this by preparing a random number - * of the right length and retrying if it's greater than the - * modulus, to prevent any potential Bleichenbacher-like - * attacks making use of the uneven distribution within the - * range that would arise from just reducing our number mod n. - * There are timing implications to the potential retries, of - * course, but all they tell you is the modulus, which you - * already knew.) - * - * To preserve determinism and avoid Pageant needing to share - * the random number pool, we actually generate this `random' - * number by hashing stuff with the private key. - */ - while (1) { - int bits, byte, bitsleft, v; - random = copybn(key->modulus); - /* - * Find the topmost set bit. (This function will return its - * index plus one.) Then we'll set all bits from that one - * downwards randomly. - */ - bits = bignum_bitcount(random); - byte = 0; - bitsleft = 0; - while (bits--) { - if (bitsleft <= 0) { - bitsleft = 8; - /* - * Conceptually the following few lines are equivalent to - * byte = random_byte(); - */ - if (digestused >= lenof(digest512)) { - unsigned char seqbuf[4]; - PUT_32BIT(seqbuf, hashseq); - SHA512_Init(&ss); - SHA512_Bytes(&ss, "RSA deterministic blinding", 26); - SHA512_Bytes(&ss, seqbuf, sizeof(seqbuf)); - sha512_mpint(&ss, key->private_exponent); - SHA512_Final(&ss, digest512); - hashseq++; - - /* - * Now hash that digest plus the signature - * input. - */ - SHA512_Init(&ss); - SHA512_Bytes(&ss, digest512, sizeof(digest512)); - sha512_mpint(&ss, input); - SHA512_Final(&ss, digest512); - - digestused = 0; - } - byte = digest512[digestused++]; - } - v = byte & 1; - byte >>= 1; - bitsleft--; - bignum_set_bit(random, bits, v); - } - - /* - * Now check that this number is strictly greater than - * zero, and strictly less than modulus. - */ - if (bignum_cmp(random, Zero) <= 0 || - bignum_cmp(random, key->modulus) >= 0) { - freebn(random); - continue; - } else { - break; - } - } - - /* - * RSA blinding relies on the fact that (xy)^d mod n is equal - * to (x^d mod n) * (y^d mod n) mod n. We invent a random pair - * y and y^d; then we multiply x by y, raise to the power d mod - * n as usual, and divide by y^d to recover x^d. Thus an - * attacker can't correlate the timing of the modpow with the - * input, because they don't know anything about the number - * that was input to the actual modpow. - * - * The clever bit is that we don't have to do a huge modpow to - * get y and y^d; we will use the number we just invented as - * _y^d_, and use the _public_ exponent to compute (y^d)^e = y - * from it, which is much faster to do. - */ - random_encrypted = modpow(random, key->exponent, key->modulus); - random_inverse = modinv(random, key->modulus); - input_blinded = modmul(input, random_encrypted, key->modulus); - ret_blinded = modpow(input_blinded, key->private_exponent, key->modulus); - ret = modmul(ret_blinded, random_inverse, key->modulus); - - freebn(ret_blinded); - freebn(input_blinded); - freebn(random_inverse); - freebn(random_encrypted); - freebn(random); - - return ret; -} - -Bignum rsadecrypt(Bignum input, struct RSAKey *key) -{ - return rsa_privkey_op(input, key); -} - -int rsastr_len(struct RSAKey *key) -{ - Bignum md, ex; - int mdlen, exlen; - - md = key->modulus; - ex = key->exponent; - mdlen = (bignum_bitcount(md) + 15) / 16; - exlen = (bignum_bitcount(ex) + 15) / 16; - return 4 * (mdlen + exlen) + 20; -} - -void rsastr_fmt(char *str, struct RSAKey *key) -{ - Bignum md, ex; - int len = 0, i, nibbles; - static const char hex[] = "0123456789abcdef"; - - md = key->modulus; - ex = key->exponent; - - len += sprintf(str + len, "0x"); - - nibbles = (3 + bignum_bitcount(ex)) / 4; - if (nibbles < 1) - nibbles = 1; - for (i = nibbles; i--;) - str[len++] = hex[(bignum_byte(ex, i / 2) >> (4 * (i % 2))) & 0xF]; - - len += sprintf(str + len, ",0x"); - - nibbles = (3 + bignum_bitcount(md)) / 4; - if (nibbles < 1) - nibbles = 1; - for (i = nibbles; i--;) - str[len++] = hex[(bignum_byte(md, i / 2) >> (4 * (i % 2))) & 0xF]; - - str[len] = '\0'; -} - -/* - * Generate a fingerprint string for the key. Compatible with the - * OpenSSH fingerprint code. - */ -void rsa_fingerprint(char *str, int len, struct RSAKey *key) -{ - struct MD5Context md5c; - unsigned char digest[16]; - char buffer[16 * 3 + 40]; - int numlen, slen, i; - - MD5Init(&md5c); - numlen = ssh1_bignum_length(key->modulus) - 2; - for (i = numlen; i--;) { - unsigned char c = bignum_byte(key->modulus, i); - MD5Update(&md5c, &c, 1); - } - numlen = ssh1_bignum_length(key->exponent) - 2; - for (i = numlen; i--;) { - unsigned char c = bignum_byte(key->exponent, i); - MD5Update(&md5c, &c, 1); - } - MD5Final(digest, &md5c); - - sprintf(buffer, "%d ", bignum_bitcount(key->modulus)); - for (i = 0; i < 16; i++) - sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "", - digest[i]); - strncpy(str, buffer, len); - str[len - 1] = '\0'; - slen = strlen(str); - if (key->comment && slen < len - 1) { - str[slen] = ' '; - strncpy(str + slen + 1, key->comment, len - slen - 1); - str[len - 1] = '\0'; - } -} - -/* - * Verify that the public data in an RSA key matches the private - * data. We also check the private data itself: we ensure that p > - * q and that iqmp really is the inverse of q mod p. - */ -int rsa_verify(struct RSAKey *key) -{ - Bignum n, ed, pm1, qm1; - int cmp; - - /* n must equal pq. */ - n = bigmul(key->p, key->q); - cmp = bignum_cmp(n, key->modulus); - freebn(n); - if (cmp != 0) - return 0; - - /* e * d must be congruent to 1, modulo (p-1) and modulo (q-1). */ - pm1 = copybn(key->p); - decbn(pm1); - ed = modmul(key->exponent, key->private_exponent, pm1); - cmp = bignum_cmp(ed, One); - sfree(ed); - if (cmp != 0) - return 0; - - qm1 = copybn(key->q); - decbn(qm1); - ed = modmul(key->exponent, key->private_exponent, qm1); - cmp = bignum_cmp(ed, One); - sfree(ed); - if (cmp != 0) - return 0; - - /* - * Ensure p > q. - * - * I have seen key blobs in the wild which were generated with - * p < q, so instead of rejecting the key in this case we - * should instead flip them round into the canonical order of - * p > q. This also involves regenerating iqmp. - */ - if (bignum_cmp(key->p, key->q) <= 0) { - Bignum tmp = key->p; - key->p = key->q; - key->q = tmp; - - freebn(key->iqmp); - key->iqmp = modinv(key->q, key->p); - } - - /* - * Ensure iqmp * q is congruent to 1, modulo p. - */ - n = modmul(key->iqmp, key->q, key->p); - cmp = bignum_cmp(n, One); - sfree(n); - if (cmp != 0) - return 0; - - return 1; -} - -/* Public key blob as used by Pageant: exponent before modulus. */ -unsigned char *rsa_public_blob(struct RSAKey *key, int *len) -{ - int length, pos; - unsigned char *ret; - - length = (ssh1_bignum_length(key->modulus) + - ssh1_bignum_length(key->exponent) + 4); - ret = snewn(length, unsigned char); - - PUT_32BIT(ret, bignum_bitcount(key->modulus)); - pos = 4; - pos += ssh1_write_bignum(ret + pos, key->exponent); - pos += ssh1_write_bignum(ret + pos, key->modulus); - - *len = length; - return ret; -} - -/* Given a public blob, determine its length. */ -int rsa_public_blob_len(void *data, int maxlen) -{ - unsigned char *p = (unsigned char *)data; - int n; - - if (maxlen < 4) - return -1; - p += 4; /* length word */ - maxlen -= 4; - - n = ssh1_read_bignum(p, maxlen, NULL); /* exponent */ - if (n < 0) - return -1; - p += n; - - n = ssh1_read_bignum(p, maxlen, NULL); /* modulus */ - if (n < 0) - return -1; - p += n; - - return p - (unsigned char *)data; -} - -void freersakey(struct RSAKey *key) -{ - if (key->modulus) - freebn(key->modulus); - if (key->exponent) - freebn(key->exponent); - if (key->private_exponent) - freebn(key->private_exponent); - if (key->p) - freebn(key->p); - if (key->q) - freebn(key->q); - if (key->iqmp) - freebn(key->iqmp); - if (key->comment) - sfree(key->comment); -} - -/* ---------------------------------------------------------------------- - * Implementation of the ssh-rsa signing key type. - */ - -static void getstring(char **data, int *datalen, char **p, int *length) -{ - *p = NULL; - if (*datalen < 4) - return; - *length = GET_32BIT(*data); - *datalen -= 4; - *data += 4; - if (*datalen < *length) - return; - *p = *data; - *data += *length; - *datalen -= *length; -} -static Bignum getmp(char **data, int *datalen) -{ - char *p; - int length; - Bignum b; - - getstring(data, datalen, &p, &length); - if (!p) - return NULL; - b = bignum_from_bytes((unsigned char *)p, length); - return b; -} - -static void *rsa2_newkey(char *data, int len) -{ - char *p; - int slen; - struct RSAKey *rsa; - - rsa = snew(struct RSAKey); - if (!rsa) - return NULL; - getstring(&data, &len, &p, &slen); - - if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) { - sfree(rsa); - return NULL; - } - rsa->exponent = getmp(&data, &len); - rsa->modulus = getmp(&data, &len); - rsa->private_exponent = NULL; - rsa->p = rsa->q = rsa->iqmp = NULL; - rsa->comment = NULL; - - return rsa; -} - -static void rsa2_freekey(void *key) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - freersakey(rsa); - sfree(rsa); -} - -static char *rsa2_fmtkey(void *key) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - char *p; - int len; - - len = rsastr_len(rsa); - p = snewn(len, char); - rsastr_fmt(p, rsa); - return p; -} - -static unsigned char *rsa2_public_blob(void *key, int *len) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - int elen, mlen, bloblen; - int i; - unsigned char *blob, *p; - - elen = (bignum_bitcount(rsa->exponent) + 8) / 8; - mlen = (bignum_bitcount(rsa->modulus) + 8) / 8; - - /* - * string "ssh-rsa", mpint exp, mpint mod. Total 19+elen+mlen. - * (three length fields, 12+7=19). - */ - bloblen = 19 + elen + mlen; - blob = snewn(bloblen, unsigned char); - p = blob; - PUT_32BIT(p, 7); - p += 4; - memcpy(p, "ssh-rsa", 7); - p += 7; - PUT_32BIT(p, elen); - p += 4; - for (i = elen; i--;) - *p++ = bignum_byte(rsa->exponent, i); - PUT_32BIT(p, mlen); - p += 4; - for (i = mlen; i--;) - *p++ = bignum_byte(rsa->modulus, i); - assert(p == blob + bloblen); - *len = bloblen; - return blob; -} - -static unsigned char *rsa2_private_blob(void *key, int *len) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - int dlen, plen, qlen, ulen, bloblen; - int i; - unsigned char *blob, *p; - - dlen = (bignum_bitcount(rsa->private_exponent) + 8) / 8; - plen = (bignum_bitcount(rsa->p) + 8) / 8; - qlen = (bignum_bitcount(rsa->q) + 8) / 8; - ulen = (bignum_bitcount(rsa->iqmp) + 8) / 8; - - /* - * mpint private_exp, mpint p, mpint q, mpint iqmp. Total 16 + - * sum of lengths. - */ - bloblen = 16 + dlen + plen + qlen + ulen; - blob = snewn(bloblen, unsigned char); - p = blob; - PUT_32BIT(p, dlen); - p += 4; - for (i = dlen; i--;) - *p++ = bignum_byte(rsa->private_exponent, i); - PUT_32BIT(p, plen); - p += 4; - for (i = plen; i--;) - *p++ = bignum_byte(rsa->p, i); - PUT_32BIT(p, qlen); - p += 4; - for (i = qlen; i--;) - *p++ = bignum_byte(rsa->q, i); - PUT_32BIT(p, ulen); - p += 4; - for (i = ulen; i--;) - *p++ = bignum_byte(rsa->iqmp, i); - assert(p == blob + bloblen); - *len = bloblen; - return blob; -} - -static void *rsa2_createkey(unsigned char *pub_blob, int pub_len, - unsigned char *priv_blob, int priv_len) -{ - struct RSAKey *rsa; - char *pb = (char *) priv_blob; - - rsa = rsa2_newkey((char *) pub_blob, pub_len); - rsa->private_exponent = getmp(&pb, &priv_len); - rsa->p = getmp(&pb, &priv_len); - rsa->q = getmp(&pb, &priv_len); - rsa->iqmp = getmp(&pb, &priv_len); - - if (!rsa_verify(rsa)) { - rsa2_freekey(rsa); - return NULL; - } - - return rsa; -} - -static void *rsa2_openssh_createkey(unsigned char **blob, int *len) -{ - char **b = (char **) blob; - struct RSAKey *rsa; - - rsa = snew(struct RSAKey); - if (!rsa) - return NULL; - rsa->comment = NULL; - - rsa->modulus = getmp(b, len); - rsa->exponent = getmp(b, len); - rsa->private_exponent = getmp(b, len); - rsa->iqmp = getmp(b, len); - rsa->p = getmp(b, len); - rsa->q = getmp(b, len); - - if (!rsa->modulus || !rsa->exponent || !rsa->private_exponent || - !rsa->iqmp || !rsa->p || !rsa->q) { - sfree(rsa->modulus); - sfree(rsa->exponent); - sfree(rsa->private_exponent); - sfree(rsa->iqmp); - sfree(rsa->p); - sfree(rsa->q); - sfree(rsa); - return NULL; - } - - return rsa; -} - -static int rsa2_openssh_fmtkey(void *key, unsigned char *blob, int len) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - int bloblen, i; - - bloblen = - ssh2_bignum_length(rsa->modulus) + - ssh2_bignum_length(rsa->exponent) + - ssh2_bignum_length(rsa->private_exponent) + - ssh2_bignum_length(rsa->iqmp) + - ssh2_bignum_length(rsa->p) + ssh2_bignum_length(rsa->q); - - if (bloblen > len) - return bloblen; - - bloblen = 0; -#define ENC(x) \ - PUT_32BIT(blob+bloblen, ssh2_bignum_length((x))-4); bloblen += 4; \ - for (i = ssh2_bignum_length((x))-4; i-- ;) blob[bloblen++]=bignum_byte((x),i); - ENC(rsa->modulus); - ENC(rsa->exponent); - ENC(rsa->private_exponent); - ENC(rsa->iqmp); - ENC(rsa->p); - ENC(rsa->q); - - return bloblen; -} - -static int rsa2_pubkey_bits(void *blob, int len) -{ - struct RSAKey *rsa; - int ret; - - rsa = rsa2_newkey((char *) blob, len); - ret = bignum_bitcount(rsa->modulus); - rsa2_freekey(rsa); - - return ret; -} - -static char *rsa2_fingerprint(void *key) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - struct MD5Context md5c; - unsigned char digest[16], lenbuf[4]; - char buffer[16 * 3 + 40]; - char *ret; - int numlen, i; - - MD5Init(&md5c); - MD5Update(&md5c, (unsigned char *)"\0\0\0\7ssh-rsa", 11); - -#define ADD_BIGNUM(bignum) \ - numlen = (bignum_bitcount(bignum)+8)/8; \ - PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \ - for (i = numlen; i-- ;) { \ - unsigned char c = bignum_byte(bignum, i); \ - MD5Update(&md5c, &c, 1); \ - } - ADD_BIGNUM(rsa->exponent); - ADD_BIGNUM(rsa->modulus); -#undef ADD_BIGNUM - - MD5Final(digest, &md5c); - - sprintf(buffer, "ssh-rsa %d ", bignum_bitcount(rsa->modulus)); - for (i = 0; i < 16; i++) - sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "", - digest[i]); - ret = snewn(strlen(buffer) + 1, char); - if (ret) - strcpy(ret, buffer); - return ret; -} - -/* - * This is the magic ASN.1/DER prefix that goes in the decoded - * signature, between the string of FFs and the actual SHA hash - * value. The meaning of it is: - * - * 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself - * - * 30 21 -- a constructed SEQUENCE of length 0x21 - * 30 09 -- a constructed sub-SEQUENCE of length 9 - * 06 05 -- an object identifier, length 5 - * 2B 0E 03 02 1A -- object id { 1 3 14 3 2 26 } - * (the 1,3 comes from 0x2B = 43 = 40*1+3) - * 05 00 -- NULL - * 04 14 -- a primitive OCTET STRING of length 0x14 - * [0x14 bytes of hash data follows] - * - * The object id in the middle there is listed as `id-sha1' in - * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1d2.asn (the - * ASN module for PKCS #1) and its expanded form is as follows: - * - * id-sha1 OBJECT IDENTIFIER ::= { - * iso(1) identified-organization(3) oiw(14) secsig(3) - * algorithms(2) 26 } - */ -static const unsigned char asn1_weird_stuff[] = { - 0x00, 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B, - 0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14, -}; - -#define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) ) - -static int rsa2_verifysig(void *key, char *sig, int siglen, - char *data, int datalen) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - Bignum in, out; - char *p; - int slen; - int bytes, i, j, ret; - unsigned char hash[20]; - - getstring(&sig, &siglen, &p, &slen); - if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) { - return 0; - } - in = getmp(&sig, &siglen); - out = modpow(in, rsa->exponent, rsa->modulus); - freebn(in); - - ret = 1; - - bytes = (bignum_bitcount(rsa->modulus)+7) / 8; - /* Top (partial) byte should be zero. */ - if (bignum_byte(out, bytes - 1) != 0) - ret = 0; - /* First whole byte should be 1. */ - if (bignum_byte(out, bytes - 2) != 1) - ret = 0; - /* Most of the rest should be FF. */ - for (i = bytes - 3; i >= 20 + ASN1_LEN; i--) { - if (bignum_byte(out, i) != 0xFF) - ret = 0; - } - /* Then we expect to see the asn1_weird_stuff. */ - for (i = 20 + ASN1_LEN - 1, j = 0; i >= 20; i--, j++) { - if (bignum_byte(out, i) != asn1_weird_stuff[j]) - ret = 0; - } - /* Finally, we expect to see the SHA-1 hash of the signed data. */ - SHA_Simple(data, datalen, hash); - for (i = 19, j = 0; i >= 0; i--, j++) { - if (bignum_byte(out, i) != hash[j]) - ret = 0; - } - freebn(out); - - return ret; -} - -static unsigned char *rsa2_sign(void *key, char *data, int datalen, - int *siglen) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - unsigned char *bytes; - int nbytes; - unsigned char hash[20]; - Bignum in, out; - int i, j; - - SHA_Simple(data, datalen, hash); - - nbytes = (bignum_bitcount(rsa->modulus) - 1) / 8; - assert(1 <= nbytes - 20 - ASN1_LEN); - bytes = snewn(nbytes, unsigned char); - - bytes[0] = 1; - for (i = 1; i < nbytes - 20 - ASN1_LEN; i++) - bytes[i] = 0xFF; - for (i = nbytes - 20 - ASN1_LEN, j = 0; i < nbytes - 20; i++, j++) - bytes[i] = asn1_weird_stuff[j]; - for (i = nbytes - 20, j = 0; i < nbytes; i++, j++) - bytes[i] = hash[j]; - - in = bignum_from_bytes(bytes, nbytes); - sfree(bytes); - - out = rsa_privkey_op(in, rsa); - freebn(in); - - nbytes = (bignum_bitcount(out) + 7) / 8; - bytes = snewn(4 + 7 + 4 + nbytes, unsigned char); - PUT_32BIT(bytes, 7); - memcpy(bytes + 4, "ssh-rsa", 7); - PUT_32BIT(bytes + 4 + 7, nbytes); - for (i = 0; i < nbytes; i++) - bytes[4 + 7 + 4 + i] = bignum_byte(out, nbytes - 1 - i); - freebn(out); - - *siglen = 4 + 7 + 4 + nbytes; - return bytes; -} - -const struct ssh_signkey ssh_rsa = { - rsa2_newkey, - rsa2_freekey, - rsa2_fmtkey, - rsa2_public_blob, - rsa2_private_blob, - rsa2_createkey, - rsa2_openssh_createkey, - rsa2_openssh_fmtkey, - rsa2_pubkey_bits, - rsa2_fingerprint, - rsa2_verifysig, - rsa2_sign, - "ssh-rsa", - "rsa2" -}; - -void *ssh_rsakex_newkey(char *data, int len) -{ - return rsa2_newkey(data, len); -} - -void ssh_rsakex_freekey(void *key) -{ - rsa2_freekey(key); -} - -int ssh_rsakex_klen(void *key) -{ - struct RSAKey *rsa = (struct RSAKey *) key; - - return bignum_bitcount(rsa->modulus); -} - -static void oaep_mask(const struct ssh_hash *h, void *seed, int seedlen, - void *vdata, int datalen) -{ - unsigned char *data = (unsigned char *)vdata; - unsigned count = 0; - - while (datalen > 0) { - int i, max = (datalen > h->hlen ? h->hlen : datalen); - void *s; - unsigned char counter[4], hash[SSH2_KEX_MAX_HASH_LEN]; - - assert(h->hlen <= SSH2_KEX_MAX_HASH_LEN); - PUT_32BIT(counter, count); - s = h->init(); - h->bytes(s, seed, seedlen); - h->bytes(s, counter, 4); - h->final(s, hash); - count++; - - for (i = 0; i < max; i++) - data[i] ^= hash[i]; - - data += max; - datalen -= max; - } -} - -void ssh_rsakex_encrypt(const struct ssh_hash *h, unsigned char *in, int inlen, - unsigned char *out, int outlen, - void *key) -{ - Bignum b1, b2; - struct RSAKey *rsa = (struct RSAKey *) key; - int k, i; - char *p; - const int HLEN = h->hlen; - - /* - * Here we encrypt using RSAES-OAEP. Essentially this means: - * - * - we have a SHA-based `mask generation function' which - * creates a pseudo-random stream of mask data - * deterministically from an input chunk of data. - * - * - we have a random chunk of data called a seed. - * - * - we use the seed to generate a mask which we XOR with our - * plaintext. - * - * - then we use _the masked plaintext_ to generate a mask - * which we XOR with the seed. - * - * - then we concatenate the masked seed and the masked - * plaintext, and RSA-encrypt that lot. - * - * The result is that the data input to the encryption function - * is random-looking and (hopefully) contains no exploitable - * structure such as PKCS1-v1_5 does. - * - * For a precise specification, see RFC 3447, section 7.1.1. - * Some of the variable names below are derived from that, so - * it'd probably help to read it anyway. - */ - - /* k denotes the length in octets of the RSA modulus. */ - k = (7 + bignum_bitcount(rsa->modulus)) / 8; - - /* The length of the input data must be at most k - 2hLen - 2. */ - assert(inlen > 0 && inlen <= k - 2*HLEN - 2); - - /* The length of the output data wants to be precisely k. */ - assert(outlen == k); - - /* - * Now perform EME-OAEP encoding. First set up all the unmasked - * output data. - */ - /* Leading byte zero. */ - out[0] = 0; - /* At position 1, the seed: HLEN bytes of random data. */ - for (i = 0; i < HLEN; i++) - out[i + 1] = random_byte(); - /* At position 1+HLEN, the data block DB, consisting of: */ - /* The hash of the label (we only support an empty label here) */ - h->final(h->init(), out + HLEN + 1); - /* A bunch of zero octets */ - memset(out + 2*HLEN + 1, 0, outlen - (2*HLEN + 1)); - /* A single 1 octet, followed by the input message data. */ - out[outlen - inlen - 1] = 1; - memcpy(out + outlen - inlen, in, inlen); - - /* - * Now use the seed data to mask the block DB. - */ - oaep_mask(h, out+1, HLEN, out+HLEN+1, outlen-HLEN-1); - - /* - * And now use the masked DB to mask the seed itself. - */ - oaep_mask(h, out+HLEN+1, outlen-HLEN-1, out+1, HLEN); - - /* - * Now `out' contains precisely the data we want to - * RSA-encrypt. - */ - b1 = bignum_from_bytes(out, outlen); - b2 = modpow(b1, rsa->exponent, rsa->modulus); - p = (char *)out; - for (i = outlen; i--;) { - *p++ = bignum_byte(b2, i); - } - freebn(b1); - freebn(b2); - - /* - * And we're done. - */ -} - -static const struct ssh_kex ssh_rsa_kex_sha1 = { - "rsa1024-sha1", NULL, KEXTYPE_RSA, NULL, NULL, 0, 0, &ssh_sha1 -}; - -static const struct ssh_kex ssh_rsa_kex_sha256 = { - "rsa2048-sha256", NULL, KEXTYPE_RSA, NULL, NULL, 0, 0, &ssh_sha256 -}; - -static const struct ssh_kex *const rsa_kex_list[] = { - &ssh_rsa_kex_sha256, - &ssh_rsa_kex_sha1 -}; - -const struct ssh_kexes ssh_rsa_kex = { - sizeof(rsa_kex_list) / sizeof(*rsa_kex_list), - rsa_kex_list -}; -- cgit v1.2.3