Merge remote-tracking branch 'origin/released'

Conflicts:
	tools/plink/misc.h
	tools/plink/ssh.c
	tools/plink/sshbn.c
	tools/plink/winplink.c

1 files changed, 1227 insertions, 1217 deletions

diff --git a/tools/plink/sshpubk.c b/tools/plink/sshpubk.c
index c1386108a..ac9e0fa7e 100644
--- a/tools/plink/sshpubk.c
+++ b/tools/plink/sshpubk.c
@@ -1,1217 +1,1227 @@
-/*

- * Generic SSH public-key handling operations. In particular,

- * reading of SSH public-key files, and also the generic `sign'

- * operation for SSH-2 (which checks the type of the key and

- * dispatches to the appropriate key-type specific function).

- */

-

-#include <stdio.h>

-#include <stdlib.h>

-#include <assert.h>

-

-#include "putty.h"

-#include "ssh.h"

-#include "misc.h"

-

-#define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n"

-

-#define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\

-                          (x)-'a'<26 ? (x)-'a'+26 :\

-                          (x)-'0'<10 ? (x)-'0'+52 :\

-                          (x)=='+' ? 62 : \

-                          (x)=='/' ? 63 : 0 )

-

-static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only,

-			   char **commentptr, char *passphrase,

-			   const char **error)

-{

-    unsigned char buf[16384];

-    unsigned char keybuf[16];

-    int len;

-    int i, j, ciphertype;

-    int ret = 0;

-    struct MD5Context md5c;

-    char *comment;

-

-    *error = NULL;

-

-    /* Slurp the whole file (minus the header) into a buffer. */

-    len = fread(buf, 1, sizeof(buf), fp);

-    fclose(fp);

-    if (len < 0 || len == sizeof(buf)) {

-	*error = "error reading file";

-	goto end;		       /* file too big or not read */

-    }

-

-    i = 0;

-    *error = "file format error";

-

-    /*

-     * A zero byte. (The signature includes a terminating NUL.)

-     */

-    if (len - i < 1 || buf[i] != 0)

-	goto end;

-    i++;

-

-    /* One byte giving encryption type, and one reserved uint32. */

-    if (len - i < 1)

-	goto end;

-    ciphertype = buf[i];

-    if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES)

-	goto end;

-    i++;

-    if (len - i < 4)

-	goto end;		       /* reserved field not present */

-    if (buf[i] != 0 || buf[i + 1] != 0 || buf[i + 2] != 0

-	|| buf[i + 3] != 0) goto end;  /* reserved field nonzero, panic! */

-    i += 4;

-

-    /* Now the serious stuff. An ordinary SSH-1 public key. */

-    i += makekey(buf + i, len, key, NULL, 1);

-    if (i < 0)

-	goto end;		       /* overran */

-

-    /* Next, the comment field. */

-    j = GET_32BIT(buf + i);

-    i += 4;

-    if (len - i < j)

-	goto end;

-    comment = snewn(j + 1, char);

-    if (comment) {

-	memcpy(comment, buf + i, j);

-	comment[j] = '\0';

-    }

-    i += j;

-    if (commentptr)

-	*commentptr = dupstr(comment);

-    if (key)

-	key->comment = comment;

-    else

-	sfree(comment);

-

-    if (pub_only) {

-	ret = 1;

-	goto end;

-    }

-

-    if (!key) {

-	ret = ciphertype != 0;

-	*error = NULL;

-	goto end;

-    }

-

-    /*

-     * Decrypt remainder of buffer.

-     */

-    if (ciphertype) {

-	MD5Init(&md5c);

-	MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));

-	MD5Final(keybuf, &md5c);

-	des3_decrypt_pubkey(keybuf, buf + i, (len - i + 7) & ~7);

-	memset(keybuf, 0, sizeof(keybuf));	/* burn the evidence */

-    }

-

-    /*

-     * We are now in the secret part of the key. The first four

-     * bytes should be of the form a, b, a, b.

-     */

-    if (len - i < 4)

-	goto end;

-    if (buf[i] != buf[i + 2] || buf[i + 1] != buf[i + 3]) {

-	*error = "wrong passphrase";

-	ret = -1;

-	goto end;

-    }

-    i += 4;

-

-    /*

-     * After that, we have one further bignum which is our

-     * decryption exponent, and then the three auxiliary values

-     * (iqmp, q, p).

-     */

-    j = makeprivate(buf + i, len - i, key);

-    if (j < 0) goto end;

-    i += j;

-    j = ssh1_read_bignum(buf + i, len - i, &key->iqmp);

-    if (j < 0) goto end;

-    i += j;

-    j = ssh1_read_bignum(buf + i, len - i, &key->q);

-    if (j < 0) goto end;

-    i += j;

-    j = ssh1_read_bignum(buf + i, len - i, &key->p);

-    if (j < 0) goto end;

-    i += j;

-

-    if (!rsa_verify(key)) {

-	*error = "rsa_verify failed";

-	freersakey(key);

-	ret = 0;

-    } else

-	ret = 1;

-

-  end:

-    memset(buf, 0, sizeof(buf));       /* burn the evidence */

-    return ret;

-}

-

-int loadrsakey(const Filename *filename, struct RSAKey *key, char *passphrase,

-	       const char **errorstr)

-{

-    FILE *fp;

-    char buf[64];

-    int ret = 0;

-    const char *error = NULL;

-

-    fp = f_open(filename, "rb", FALSE);

-    if (!fp) {

-	error = "can't open file";

-	goto end;

-    }

-

-    /*

-     * Read the first line of the file and see if it's a v1 private

-     * key file.

-     */

-    if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) {

-	/*

-	 * This routine will take care of calling fclose() for us.

-	 */

-	ret = loadrsakey_main(fp, key, FALSE, NULL, passphrase, &error);

-	fp = NULL;

-	goto end;

-    }

-

-    /*

-     * Otherwise, we have nothing. Return empty-handed.

-     */

-    error = "not an SSH-1 RSA file";

-

-  end:

-    if (fp)

-	fclose(fp);

-    if ((ret != 1) && errorstr)

-	*errorstr = error;

-    return ret;

-}

-

-/*

- * See whether an RSA key is encrypted. Return its comment field as

- * well.

- */

-int rsakey_encrypted(const Filename *filename, char **comment)

-{

-    FILE *fp;

-    char buf[64];

-

-    fp = f_open(filename, "rb", FALSE);

-    if (!fp)

-	return 0;		       /* doesn't even exist */

-

-    /*

-     * Read the first line of the file and see if it's a v1 private

-     * key file.

-     */

-    if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) {

-	const char *dummy;

-	/*

-	 * This routine will take care of calling fclose() for us.

-	 */

-	return loadrsakey_main(fp, NULL, FALSE, comment, NULL, &dummy);

-    }

-    fclose(fp);

-    return 0;			       /* wasn't the right kind of file */

-}

-

-/*

- * Return a malloc'ed chunk of memory containing the public blob of

- * an RSA key, as given in the agent protocol (modulus bits,

- * exponent, modulus).

- */

-int rsakey_pubblob(const Filename *filename, void **blob, int *bloblen,

-		   char **commentptr, const char **errorstr)

-{

-    FILE *fp;

-    char buf[64];

-    struct RSAKey key;

-    int ret;

-    const char *error = NULL;

-

-    /* Default return if we fail. */

-    *blob = NULL;

-    *bloblen = 0;

-    ret = 0;

-

-    fp = f_open(filename, "rb", FALSE);

-    if (!fp) {

-	error = "can't open file";

-	goto end;

-    }

-

-    /*

-     * Read the first line of the file and see if it's a v1 private

-     * key file.

-     */

-    if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) {

-	memset(&key, 0, sizeof(key));

-	if (loadrsakey_main(fp, &key, TRUE, commentptr, NULL, &error)) {

-	    *blob = rsa_public_blob(&key, bloblen);

-	    freersakey(&key);

-	    ret = 1;

-	    fp = NULL;

-	}

-    } else {

-	error = "not an SSH-1 RSA file";

-    }

-

-  end:

-    if (fp)

-	fclose(fp);

-    if ((ret != 1) && errorstr)

-	*errorstr = error;

-    return ret;

-}

-

-/*

- * Save an RSA key file. Return nonzero on success.

- */

-int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase)

-{

-    unsigned char buf[16384];

-    unsigned char keybuf[16];

-    struct MD5Context md5c;

-    unsigned char *p, *estart;

-    FILE *fp;

-

-    /*

-     * Write the initial signature.

-     */

-    p = buf;

-    memcpy(p, rsa_signature, sizeof(rsa_signature));

-    p += sizeof(rsa_signature);

-

-    /*

-     * One byte giving encryption type, and one reserved (zero)

-     * uint32.

-     */

-    *p++ = (passphrase ? SSH_CIPHER_3DES : 0);

-    PUT_32BIT(p, 0);

-    p += 4;

-

-    /*

-     * An ordinary SSH-1 public key consists of: a uint32

-     * containing the bit count, then two bignums containing the

-     * modulus and exponent respectively.

-     */

-    PUT_32BIT(p, bignum_bitcount(key->modulus));

-    p += 4;

-    p += ssh1_write_bignum(p, key->modulus);

-    p += ssh1_write_bignum(p, key->exponent);

-

-    /*

-     * A string containing the comment field.

-     */

-    if (key->comment) {

-	PUT_32BIT(p, strlen(key->comment));

-	p += 4;

-	memcpy(p, key->comment, strlen(key->comment));

-	p += strlen(key->comment);

-    } else {

-	PUT_32BIT(p, 0);

-	p += 4;

-    }

-

-    /*

-     * The encrypted portion starts here.

-     */

-    estart = p;

-

-    /*

-     * Two bytes, then the same two bytes repeated.

-     */

-    *p++ = random_byte();

-    *p++ = random_byte();

-    p[0] = p[-2];

-    p[1] = p[-1];

-    p += 2;

-

-    /*

-     * Four more bignums: the decryption exponent, then iqmp, then

-     * q, then p.

-     */

-    p += ssh1_write_bignum(p, key->private_exponent);

-    p += ssh1_write_bignum(p, key->iqmp);

-    p += ssh1_write_bignum(p, key->q);

-    p += ssh1_write_bignum(p, key->p);

-

-    /*

-     * Now write zeros until the encrypted portion is a multiple of

-     * 8 bytes.

-     */

-    while ((p - estart) % 8)

-	*p++ = '\0';

-

-    /*

-     * Now encrypt the encrypted portion.

-     */

-    if (passphrase) {

-	MD5Init(&md5c);

-	MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));

-	MD5Final(keybuf, &md5c);

-	des3_encrypt_pubkey(keybuf, estart, p - estart);

-	memset(keybuf, 0, sizeof(keybuf));	/* burn the evidence */

-    }

-

-    /*

-     * Done. Write the result to the file.

-     */

-    fp = f_open(filename, "wb", TRUE);

-    if (fp) {

-	int ret = (fwrite(buf, 1, p - buf, fp) == (size_t) (p - buf));

-        if (fclose(fp))

-            ret = 0;

-	return ret;

-    } else

-	return 0;

-}

-

-/* ----------------------------------------------------------------------

- * SSH-2 private key load/store functions.

- */

-

-/*

- * PuTTY's own format for SSH-2 keys is as follows:

- *

- * The file is text. Lines are terminated by CRLF, although CR-only

- * and LF-only are tolerated on input.

- *

- * The first line says "PuTTY-User-Key-File-2: " plus the name of the

- * algorithm ("ssh-dss", "ssh-rsa" etc).

- *

- * The next line says "Encryption: " plus an encryption type.

- * Currently the only supported encryption types are "aes256-cbc"

- * and "none".

- *

- * The next line says "Comment: " plus the comment string.

- *

- * Next there is a line saying "Public-Lines: " plus a number N.

- * The following N lines contain a base64 encoding of the public

- * part of the key. This is encoded as the standard SSH-2 public key

- * blob (with no initial length): so for RSA, for example, it will

- * read

- *

- *    string "ssh-rsa"

- *    mpint  exponent

- *    mpint  modulus

- *

- * Next, there is a line saying "Private-Lines: " plus a number N,

- * and then N lines containing the (potentially encrypted) private

- * part of the key. For the key type "ssh-rsa", this will be

- * composed of

- *

- *    mpint  private_exponent

- *    mpint  p                  (the larger of the two primes)

- *    mpint  q                  (the smaller prime)

- *    mpint  iqmp               (the inverse of q modulo p)

- *    data   padding            (to reach a multiple of the cipher block size)

- *

- * And for "ssh-dss", it will be composed of

- *

- *    mpint  x                  (the private key parameter)

- *  [ string hash   20-byte hash of mpints p || q || g   only in old format ]

- * 

- * Finally, there is a line saying "Private-MAC: " plus a hex

- * representation of a HMAC-SHA-1 of:

- *

- *    string  name of algorithm ("ssh-dss", "ssh-rsa")

- *    string  encryption type

- *    string  comment

- *    string  public-blob

- *    string  private-plaintext (the plaintext version of the

- *                               private part, including the final

- *                               padding)

- * 

- * The key to the MAC is itself a SHA-1 hash of:

- * 

- *    data    "putty-private-key-file-mac-key"

- *    data    passphrase

- *

- * (An empty passphrase is used for unencrypted keys.)

- *

- * If the key is encrypted, the encryption key is derived from the

- * passphrase by means of a succession of SHA-1 hashes. Each hash

- * is the hash of:

- *

- *    uint32  sequence-number

- *    data    passphrase

- *

- * where the sequence-number increases from zero. As many of these

- * hashes are used as necessary.

- *

- * For backwards compatibility with snapshots between 0.51 and

- * 0.52, we also support the older key file format, which begins

- * with "PuTTY-User-Key-File-1" (version number differs). In this

- * format the Private-MAC: field only covers the private-plaintext

- * field and nothing else (and without the 4-byte string length on

- * the front too). Moreover, the Private-MAC: field can be replaced

- * with a Private-Hash: field which is a plain SHA-1 hash instead of

- * an HMAC (this was generated for unencrypted keys).

- */

-

-static int read_header(FILE * fp, char *header)

-{

-    int len = 39;

-    int c;

-

-    while (len > 0) {

-	c = fgetc(fp);

-	if (c == '\n' || c == '\r' || c == EOF)

-	    return 0;		       /* failure */

-	if (c == ':') {

-	    c = fgetc(fp);

-	    if (c != ' ')

-		return 0;

-	    *header = '\0';

-	    return 1;		       /* success! */

-	}

-	if (len == 0)

-	    return 0;		       /* failure */

-	*header++ = c;

-	len--;

-    }

-    return 0;			       /* failure */

-}

-

-static char *read_body(FILE * fp)

-{

-    char *text;

-    int len;

-    int size;

-    int c;

-

-    size = 128;

-    text = snewn(size, char);

-    len = 0;

-    text[len] = '\0';

-

-    while (1) {

-	c = fgetc(fp);

-	if (c == '\r' || c == '\n' || c == EOF) {

-	    if (c != EOF) {

-		c = fgetc(fp);

-		if (c != '\r' && c != '\n')

-		    ungetc(c, fp);

-	    }

-	    return text;

-	}

-	if (len + 1 >= size) {

-	    size += 128;

-	    text = sresize(text, size, char);

-	}

-	text[len++] = c;

-	text[len] = '\0';

-    }

-}

-

-int base64_decode_atom(char *atom, unsigned char *out)

-{

-    int vals[4];

-    int i, v, len;

-    unsigned word;

-    char c;

-

-    for (i = 0; i < 4; i++) {

-	c = atom[i];

-	if (c >= 'A' && c <= 'Z')

-	    v = c - 'A';

-	else if (c >= 'a' && c <= 'z')

-	    v = c - 'a' + 26;

-	else if (c >= '0' && c <= '9')

-	    v = c - '0' + 52;

-	else if (c == '+')

-	    v = 62;

-	else if (c == '/')

-	    v = 63;

-	else if (c == '=')

-	    v = -1;

-	else

-	    return 0;		       /* invalid atom */

-	vals[i] = v;

-    }

-

-    if (vals[0] == -1 || vals[1] == -1)

-	return 0;

-    if (vals[2] == -1 && vals[3] != -1)

-	return 0;

-

-    if (vals[3] != -1)

-	len = 3;

-    else if (vals[2] != -1)

-	len = 2;

-    else

-	len = 1;

-

-    word = ((vals[0] << 18) |

-	    (vals[1] << 12) | ((vals[2] & 0x3F) << 6) | (vals[3] & 0x3F));

-    out[0] = (word >> 16) & 0xFF;

-    if (len > 1)

-	out[1] = (word >> 8) & 0xFF;

-    if (len > 2)

-	out[2] = word & 0xFF;

-    return len;

-}

-

-static unsigned char *read_blob(FILE * fp, int nlines, int *bloblen)

-{

-    unsigned char *blob;

-    char *line;

-    int linelen, len;

-    int i, j, k;

-

-    /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */

-    blob = snewn(48 * nlines, unsigned char);

-    len = 0;

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

-	line = read_body(fp);

-	if (!line) {

-	    sfree(blob);

-	    return NULL;

-	}

-	linelen = strlen(line);

-	if (linelen % 4 != 0 || linelen > 64) {

-	    sfree(blob);

-	    sfree(line);

-	    return NULL;

-	}

-	for (j = 0; j < linelen; j += 4) {

-	    k = base64_decode_atom(line + j, blob + len);

-	    if (!k) {

-		sfree(line);

-		sfree(blob);

-		return NULL;

-	    }

-	    len += k;

-	}

-	sfree(line);

-    }

-    *bloblen = len;

-    return blob;

-}

-

-/*

- * Magic error return value for when the passphrase is wrong.

- */

-struct ssh2_userkey ssh2_wrong_passphrase = {

-    NULL, NULL, NULL

-};

-

-const struct ssh_signkey *find_pubkey_alg(const char *name)

-{

-    if (!strcmp(name, "ssh-rsa"))

-	return &ssh_rsa;

-    else if (!strcmp(name, "ssh-dss"))

-	return &ssh_dss;

-    else

-	return NULL;

-}

-

-struct ssh2_userkey *ssh2_load_userkey(const Filename *filename,

-				       char *passphrase, const char **errorstr)

-{

-    FILE *fp;

-    char header[40], *b, *encryption, *comment, *mac;

-    const struct ssh_signkey *alg;

-    struct ssh2_userkey *ret;

-    int cipher, cipherblk;

-    unsigned char *public_blob, *private_blob;

-    int public_blob_len, private_blob_len;

-    int i, is_mac, old_fmt;

-    int passlen = passphrase ? strlen(passphrase) : 0;

-    const char *error = NULL;

-

-    ret = NULL;			       /* return NULL for most errors */

-    encryption = comment = mac = NULL;

-    public_blob = private_blob = NULL;

-

-    fp = f_open(filename, "rb", FALSE);

-    if (!fp) {

-	error = "can't open file";

-	goto error;

-    }

-

-    /* Read the first header line which contains the key type. */

-    if (!read_header(fp, header))

-	goto error;

-    if (0 == strcmp(header, "PuTTY-User-Key-File-2")) {

-	old_fmt = 0;

-    } else if (0 == strcmp(header, "PuTTY-User-Key-File-1")) {

-	/* this is an old key file; warn and then continue */

-	old_keyfile_warning();

-	old_fmt = 1;

-    } else {

-	error = "not a PuTTY SSH-2 private key";

-	goto error;

-    }

-    error = "file format error";

-    if ((b = read_body(fp)) == NULL)

-	goto error;

-    /* Select key algorithm structure. */

-    alg = find_pubkey_alg(b);

-    if (!alg) {

-	sfree(b);

-	goto error;

-    }

-    sfree(b);

-

-    /* Read the Encryption header line. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Encryption"))

-	goto error;

-    if ((encryption = read_body(fp)) == NULL)

-	goto error;

-    if (!strcmp(encryption, "aes256-cbc")) {

-	cipher = 1;

-	cipherblk = 16;

-    } else if (!strcmp(encryption, "none")) {

-	cipher = 0;

-	cipherblk = 1;

-    } else {

-	sfree(encryption);

-	goto error;

-    }

-

-    /* Read the Comment header line. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Comment"))

-	goto error;

-    if ((comment = read_body(fp)) == NULL)

-	goto error;

-

-    /* Read the Public-Lines header line and the public blob. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines"))

-	goto error;

-    if ((b = read_body(fp)) == NULL)

-	goto error;

-    i = atoi(b);

-    sfree(b);

-    if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL)

-	goto error;

-

-    /* Read the Private-Lines header line and the Private blob. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Private-Lines"))

-	goto error;

-    if ((b = read_body(fp)) == NULL)

-	goto error;

-    i = atoi(b);

-    sfree(b);

-    if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL)

-	goto error;

-

-    /* Read the Private-MAC or Private-Hash header line. */

-    if (!read_header(fp, header))

-	goto error;

-    if (0 == strcmp(header, "Private-MAC")) {

-	if ((mac = read_body(fp)) == NULL)

-	    goto error;

-	is_mac = 1;

-    } else if (0 == strcmp(header, "Private-Hash") && old_fmt) {

-	if ((mac = read_body(fp)) == NULL)

-	    goto error;

-	is_mac = 0;

-    } else

-	goto error;

-

-    fclose(fp);

-    fp = NULL;

-

-    /*

-     * Decrypt the private blob.

-     */

-    if (cipher) {

-	unsigned char key[40];

-	SHA_State s;

-

-	if (!passphrase)

-	    goto error;

-	if (private_blob_len % cipherblk)

-	    goto error;

-

-	SHA_Init(&s);

-	SHA_Bytes(&s, "\0\0\0\0", 4);

-	SHA_Bytes(&s, passphrase, passlen);

-	SHA_Final(&s, key + 0);

-	SHA_Init(&s);

-	SHA_Bytes(&s, "\0\0\0\1", 4);

-	SHA_Bytes(&s, passphrase, passlen);

-	SHA_Final(&s, key + 20);

-	aes256_decrypt_pubkey(key, private_blob, private_blob_len);

-    }

-

-    /*

-     * Verify the MAC.

-     */

-    {

-	char realmac[41];

-	unsigned char binary[20];

-	unsigned char *macdata;

-	int maclen;

-	int free_macdata;

-

-	if (old_fmt) {

-	    /* MAC (or hash) only covers the private blob. */

-	    macdata = private_blob;

-	    maclen = private_blob_len;

-	    free_macdata = 0;

-	} else {

-	    unsigned char *p;

-	    int namelen = strlen(alg->name);

-	    int enclen = strlen(encryption);

-	    int commlen = strlen(comment);

-	    maclen = (4 + namelen +

-		      4 + enclen +

-		      4 + commlen +

-		      4 + public_blob_len +

-		      4 + private_blob_len);

-	    macdata = snewn(maclen, unsigned char);

-	    p = macdata;

-#define DO_STR(s,len) PUT_32BIT(p,(len));memcpy(p+4,(s),(len));p+=4+(len)

-	    DO_STR(alg->name, namelen);

-	    DO_STR(encryption, enclen);

-	    DO_STR(comment, commlen);

-	    DO_STR(public_blob, public_blob_len);

-	    DO_STR(private_blob, private_blob_len);

-

-	    free_macdata = 1;

-	}

-

-	if (is_mac) {

-	    SHA_State s;

-	    unsigned char mackey[20];

-	    char header[] = "putty-private-key-file-mac-key";

-

-	    SHA_Init(&s);

-	    SHA_Bytes(&s, header, sizeof(header)-1);

-	    if (cipher && passphrase)

-		SHA_Bytes(&s, passphrase, passlen);

-	    SHA_Final(&s, mackey);

-

-	    hmac_sha1_simple(mackey, 20, macdata, maclen, binary);

-

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

-	    memset(&s, 0, sizeof(s));

-	} else {

-	    SHA_Simple(macdata, maclen, binary);

-	}

-

-	if (free_macdata) {

-	    memset(macdata, 0, maclen);

-	    sfree(macdata);

-	}

-

-	for (i = 0; i < 20; i++)

-	    sprintf(realmac + 2 * i, "%02x", binary[i]);

-

-	if (strcmp(mac, realmac)) {

-	    /* An incorrect MAC is an unconditional Error if the key is

-	     * unencrypted. Otherwise, it means Wrong Passphrase. */

-	    if (cipher) {

-		error = "wrong passphrase";

-		ret = SSH2_WRONG_PASSPHRASE;

-	    } else {

-		error = "MAC failed";

-		ret = NULL;

-	    }

-	    goto error;

-	}

-    }

-    sfree(mac);

-

-    /*

-     * Create and return the key.

-     */

-    ret = snew(struct ssh2_userkey);

-    ret->alg = alg;

-    ret->comment = comment;

-    ret->data = alg->createkey(public_blob, public_blob_len,

-			       private_blob, private_blob_len);

-    if (!ret->data) {

-	sfree(ret->comment);

-	sfree(ret);

-	ret = NULL;

-	error = "createkey failed";

-	goto error;

-    }

-    sfree(public_blob);

-    sfree(private_blob);

-    sfree(encryption);

-    if (errorstr)

-	*errorstr = NULL;

-    return ret;

-

-    /*

-     * Error processing.

-     */

-  error:

-    if (fp)

-	fclose(fp);

-    if (comment)

-	sfree(comment);

-    if (encryption)

-	sfree(encryption);

-    if (mac)

-	sfree(mac);

-    if (public_blob)

-	sfree(public_blob);

-    if (private_blob)

-	sfree(private_blob);

-    if (errorstr)

-	*errorstr = error;

-    return ret;

-}

-

-unsigned char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm,

-				    int *pub_blob_len, char **commentptr,

-				    const char **errorstr)

-{

-    FILE *fp;

-    char header[40], *b;

-    const struct ssh_signkey *alg;

-    unsigned char *public_blob;

-    int public_blob_len;

-    int i;

-    const char *error = NULL;

-    char *comment;

-

-    public_blob = NULL;

-

-    fp = f_open(filename, "rb", FALSE);

-    if (!fp) {

-	error = "can't open file";

-	goto error;

-    }

-

-    /* Read the first header line which contains the key type. */

-    if (!read_header(fp, header)

-	|| (0 != strcmp(header, "PuTTY-User-Key-File-2") &&

-	    0 != strcmp(header, "PuTTY-User-Key-File-1"))) {

-	error = "not a PuTTY SSH-2 private key";

-	goto error;

-    }

-    error = "file format error";

-    if ((b = read_body(fp)) == NULL)

-	goto error;

-    /* Select key algorithm structure. */

-    alg = find_pubkey_alg(b);

-    if (!alg) {

-	sfree(b);

-	goto error;

-    }

-    sfree(b);

-

-    /* Read the Encryption header line. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Encryption"))

-	goto error;

-    if ((b = read_body(fp)) == NULL)

-	goto error;

-    sfree(b);			       /* we don't care */

-

-    /* Read the Comment header line. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Comment"))

-	goto error;

-    if ((comment = read_body(fp)) == NULL)

-	goto error;

-

-    if (commentptr)

-	*commentptr = comment;

-    else

-	sfree(comment);

-

-    /* Read the Public-Lines header line and the public blob. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines"))

-	goto error;

-    if ((b = read_body(fp)) == NULL)

-	goto error;

-    i = atoi(b);

-    sfree(b);

-    if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL)

-	goto error;

-

-    fclose(fp);

-    if (pub_blob_len)

-	*pub_blob_len = public_blob_len;

-    if (algorithm)

-	*algorithm = alg->name;

-    return public_blob;

-

-    /*

-     * Error processing.

-     */

-  error:

-    if (fp)

-	fclose(fp);

-    if (public_blob)

-	sfree(public_blob);

-    if (errorstr)

-	*errorstr = error;

-    return NULL;

-}

-

-int ssh2_userkey_encrypted(const Filename *filename, char **commentptr)

-{

-    FILE *fp;

-    char header[40], *b, *comment;

-    int ret;

-

-    if (commentptr)

-	*commentptr = NULL;

-

-    fp = f_open(filename, "rb", FALSE);

-    if (!fp)

-	return 0;

-    if (!read_header(fp, header)

-	|| (0 != strcmp(header, "PuTTY-User-Key-File-2") &&

-	    0 != strcmp(header, "PuTTY-User-Key-File-1"))) {

-	fclose(fp);

-	return 0;

-    }

-    if ((b = read_body(fp)) == NULL) {

-	fclose(fp);

-	return 0;

-    }

-    sfree(b);			       /* we don't care about key type here */

-    /* Read the Encryption header line. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) {

-	fclose(fp);

-	return 0;

-    }

-    if ((b = read_body(fp)) == NULL) {

-	fclose(fp);

-	return 0;

-    }

-

-    /* Read the Comment header line. */

-    if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) {

-	fclose(fp);

-	sfree(b);

-	return 1;

-    }

-    if ((comment = read_body(fp)) == NULL) {

-	fclose(fp);

-	sfree(b);

-	return 1;

-    }

-

-    if (commentptr)

-	*commentptr = comment;

-

-    fclose(fp);

-    if (!strcmp(b, "aes256-cbc"))

-	ret = 1;

-    else

-	ret = 0;

-    sfree(b);

-    return ret;

-}

-

-int base64_lines(int datalen)

-{

-    /* When encoding, we use 64 chars/line, which equals 48 real chars. */

-    return (datalen + 47) / 48;

-}

-

-void base64_encode(FILE * fp, unsigned char *data, int datalen, int cpl)

-{

-    int linelen = 0;

-    char out[4];

-    int n, i;

-

-    while (datalen > 0) {

-	n = (datalen < 3 ? datalen : 3);

-	base64_encode_atom(data, n, out);

-	data += n;

-	datalen -= n;

-	for (i = 0; i < 4; i++) {

-	    if (linelen >= cpl) {

-		linelen = 0;

-		fputc('\n', fp);

-	    }

-	    fputc(out[i], fp);

-	    linelen++;

-	}

-    }

-    fputc('\n', fp);

-}

-

-int ssh2_save_userkey(const Filename *filename, struct ssh2_userkey *key,

-		      char *passphrase)

-{

-    FILE *fp;

-    unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted;

-    int pub_blob_len, priv_blob_len, priv_encrypted_len;

-    int passlen;

-    int cipherblk;

-    int i;

-    char *cipherstr;

-    unsigned char priv_mac[20];

-

-    /*

-     * Fetch the key component blobs.

-     */

-    pub_blob = key->alg->public_blob(key->data, &pub_blob_len);

-    priv_blob = key->alg->private_blob(key->data, &priv_blob_len);

-    if (!pub_blob || !priv_blob) {

-	sfree(pub_blob);

-	sfree(priv_blob);

-	return 0;

-    }

-

-    /*

-     * Determine encryption details, and encrypt the private blob.

-     */

-    if (passphrase) {

-	cipherstr = "aes256-cbc";

-	cipherblk = 16;

-    } else {

-	cipherstr = "none";

-	cipherblk = 1;

-    }

-    priv_encrypted_len = priv_blob_len + cipherblk - 1;

-    priv_encrypted_len -= priv_encrypted_len % cipherblk;

-    priv_blob_encrypted = snewn(priv_encrypted_len, unsigned char);

-    memset(priv_blob_encrypted, 0, priv_encrypted_len);

-    memcpy(priv_blob_encrypted, priv_blob, priv_blob_len);

-    /* Create padding based on the SHA hash of the unpadded blob. This prevents

-     * too easy a known-plaintext attack on the last block. */

-    SHA_Simple(priv_blob, priv_blob_len, priv_mac);

-    assert(priv_encrypted_len - priv_blob_len < 20);

-    memcpy(priv_blob_encrypted + priv_blob_len, priv_mac,

-	   priv_encrypted_len - priv_blob_len);

-

-    /* Now create the MAC. */

-    {

-	unsigned char *macdata;

-	int maclen;

-	unsigned char *p;

-	int namelen = strlen(key->alg->name);

-	int enclen = strlen(cipherstr);

-	int commlen = strlen(key->comment);

-	SHA_State s;

-	unsigned char mackey[20];

-	char header[] = "putty-private-key-file-mac-key";

-

-	maclen = (4 + namelen +

-		  4 + enclen +

-		  4 + commlen +

-		  4 + pub_blob_len +

-		  4 + priv_encrypted_len);

-	macdata = snewn(maclen, unsigned char);

-	p = macdata;

-#define DO_STR(s,len) PUT_32BIT(p,(len));memcpy(p+4,(s),(len));p+=4+(len)

-	DO_STR(key->alg->name, namelen);

-	DO_STR(cipherstr, enclen);

-	DO_STR(key->comment, commlen);

-	DO_STR(pub_blob, pub_blob_len);

-	DO_STR(priv_blob_encrypted, priv_encrypted_len);

-

-	SHA_Init(&s);

-	SHA_Bytes(&s, header, sizeof(header)-1);

-	if (passphrase)

-	    SHA_Bytes(&s, passphrase, strlen(passphrase));

-	SHA_Final(&s, mackey);

-	hmac_sha1_simple(mackey, 20, macdata, maclen, priv_mac);

-	memset(macdata, 0, maclen);

-	sfree(macdata);

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

-	memset(&s, 0, sizeof(s));

-    }

-

-    if (passphrase) {

-	unsigned char key[40];

-	SHA_State s;

-

-	passlen = strlen(passphrase);

-

-	SHA_Init(&s);

-	SHA_Bytes(&s, "\0\0\0\0", 4);

-	SHA_Bytes(&s, passphrase, passlen);

-	SHA_Final(&s, key + 0);

-	SHA_Init(&s);

-	SHA_Bytes(&s, "\0\0\0\1", 4);

-	SHA_Bytes(&s, passphrase, passlen);

-	SHA_Final(&s, key + 20);

-	aes256_encrypt_pubkey(key, priv_blob_encrypted,

-			      priv_encrypted_len);

-

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

-	memset(&s, 0, sizeof(s));

-    }

-

-    fp = f_open(filename, "w", TRUE);

-    if (!fp)

-	return 0;

-    fprintf(fp, "PuTTY-User-Key-File-2: %s\n", key->alg->name);

-    fprintf(fp, "Encryption: %s\n", cipherstr);

-    fprintf(fp, "Comment: %s\n", key->comment);

-    fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len));

-    base64_encode(fp, pub_blob, pub_blob_len, 64);

-    fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len));

-    base64_encode(fp, priv_blob_encrypted, priv_encrypted_len, 64);

-    fprintf(fp, "Private-MAC: ");

-    for (i = 0; i < 20; i++)

-	fprintf(fp, "%02x", priv_mac[i]);

-    fprintf(fp, "\n");

-    fclose(fp);

-

-    sfree(pub_blob);

-    memset(priv_blob, 0, priv_blob_len);

-    sfree(priv_blob);

-    sfree(priv_blob_encrypted);

-    return 1;

-}

-

-/* ----------------------------------------------------------------------

- * A function to determine the type of a private key file. Returns

- * 0 on failure, 1 or 2 on success.

- */

-int key_type(const Filename *filename)

-{

-    FILE *fp;

-    char buf[32];

-    const char putty2_sig[] = "PuTTY-User-Key-File-";

-    const char sshcom_sig[] = "---- BEGIN SSH2 ENCRYPTED PRIVAT";

-    const char openssh_sig[] = "-----BEGIN ";

-    int i;

-

-    fp = f_open(filename, "r", FALSE);

-    if (!fp)

-	return SSH_KEYTYPE_UNOPENABLE;

-    i = fread(buf, 1, sizeof(buf), fp);

-    fclose(fp);

-    if (i < 0)

-	return SSH_KEYTYPE_UNOPENABLE;

-    if (i < 32)

-	return SSH_KEYTYPE_UNKNOWN;

-    if (!memcmp(buf, rsa_signature, sizeof(rsa_signature)-1))

-	return SSH_KEYTYPE_SSH1;

-    if (!memcmp(buf, putty2_sig, sizeof(putty2_sig)-1))

-	return SSH_KEYTYPE_SSH2;

-    if (!memcmp(buf, openssh_sig, sizeof(openssh_sig)-1))

-	return SSH_KEYTYPE_OPENSSH;

-    if (!memcmp(buf, sshcom_sig, sizeof(sshcom_sig)-1))

-	return SSH_KEYTYPE_SSHCOM;

-    return SSH_KEYTYPE_UNKNOWN;	       /* unrecognised or EOF */

-}

-

-/*

- * Convert the type word to a string, for `wrong type' error

- * messages.

- */

-char *key_type_to_str(int type)

-{

-    switch (type) {

-      case SSH_KEYTYPE_UNOPENABLE: return "unable to open file"; break;

-      case SSH_KEYTYPE_UNKNOWN: return "not a private key"; break;

-      case SSH_KEYTYPE_SSH1: return "SSH-1 private key"; break;

-      case SSH_KEYTYPE_SSH2: return "PuTTY SSH-2 private key"; break;

-      case SSH_KEYTYPE_OPENSSH: return "OpenSSH SSH-2 private key"; break;

-      case SSH_KEYTYPE_SSHCOM: return "ssh.com SSH-2 private key"; break;

-      default: return "INTERNAL ERROR"; break;

-    }

-}

+/*
+ * Generic SSH public-key handling operations. In particular,
+ * reading of SSH public-key files, and also the generic `sign'
+ * operation for SSH-2 (which checks the type of the key and
+ * dispatches to the appropriate key-type specific function).
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include "putty.h"
+#include "ssh.h"
+#include "misc.h"
+
+#define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n"
+
+#define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\
+                          (x)-'a'<26 ? (x)-'a'+26 :\
+                          (x)-'0'<10 ? (x)-'0'+52 :\
+                          (x)=='+' ? 62 : \
+                          (x)=='/' ? 63 : 0 )
+
+static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only,
+			   char **commentptr, char *passphrase,
+			   const char **error)
+{
+    unsigned char buf[16384];
+    unsigned char keybuf[16];
+    int len;
+    int i, j, ciphertype;
+    int ret = 0;
+    struct MD5Context md5c;
+    char *comment;
+
+    *error = NULL;
+
+    /* Slurp the whole file (minus the header) into a buffer. */
+    len = fread(buf, 1, sizeof(buf), fp);
+    fclose(fp);
+    if (len < 0 || len == sizeof(buf)) {
+	*error = "error reading file";
+	goto end;		       /* file too big or not read */
+    }
+
+    i = 0;
+    *error = "file format error";
+
+    /*
+     * A zero byte. (The signature includes a terminating NUL.)
+     */
+    if (len - i < 1 || buf[i] != 0)
+	goto end;
+    i++;
+
+    /* One byte giving encryption type, and one reserved uint32. */
+    if (len - i < 1)
+	goto end;
+    ciphertype = buf[i];
+    if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES)
+	goto end;
+    i++;
+    if (len - i < 4)
+	goto end;		       /* reserved field not present */
+    if (buf[i] != 0 || buf[i + 1] != 0 || buf[i + 2] != 0
+	|| buf[i + 3] != 0) goto end;  /* reserved field nonzero, panic! */
+    i += 4;
+
+    /* Now the serious stuff. An ordinary SSH-1 public key. */
+    j = makekey(buf + i, len, key, NULL, 1);
+    if (j < 0)
+	goto end;		       /* overran */
+    i += j;
+
+    /* Next, the comment field. */
+    j = toint(GET_32BIT(buf + i));
+    i += 4;
+    if (j < 0 || len - i < j)
+	goto end;
+    comment = snewn(j + 1, char);
+    if (comment) {
+	memcpy(comment, buf + i, j);
+	comment[j] = '\0';
+    }
+    i += j;
+    if (commentptr)
+	*commentptr = dupstr(comment);
+    if (key)
+	key->comment = comment;
+    else
+	sfree(comment);
+
+    if (pub_only) {
+	ret = 1;
+	goto end;
+    }
+
+    if (!key) {
+	ret = ciphertype != 0;
+	*error = NULL;
+	goto end;
+    }
+
+    /*
+     * Decrypt remainder of buffer.
+     */
+    if (ciphertype) {
+	MD5Init(&md5c);
+	MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
+	MD5Final(keybuf, &md5c);
+	des3_decrypt_pubkey(keybuf, buf + i, (len - i + 7) & ~7);
+	smemclr(keybuf, sizeof(keybuf));	/* burn the evidence */
+    }
+
+    /*
+     * We are now in the secret part of the key. The first four
+     * bytes should be of the form a, b, a, b.
+     */
+    if (len - i < 4)
+	goto end;
+    if (buf[i] != buf[i + 2] || buf[i + 1] != buf[i + 3]) {
+	*error = "wrong passphrase";
+	ret = -1;
+	goto end;
+    }
+    i += 4;
+
+    /*
+     * After that, we have one further bignum which is our
+     * decryption exponent, and then the three auxiliary values
+     * (iqmp, q, p).
+     */
+    j = makeprivate(buf + i, len - i, key);
+    if (j < 0) goto end;
+    i += j;
+    j = ssh1_read_bignum(buf + i, len - i, &key->iqmp);
+    if (j < 0) goto end;
+    i += j;
+    j = ssh1_read_bignum(buf + i, len - i, &key->q);
+    if (j < 0) goto end;
+    i += j;
+    j = ssh1_read_bignum(buf + i, len - i, &key->p);
+    if (j < 0) goto end;
+    i += j;
+
+    if (!rsa_verify(key)) {
+	*error = "rsa_verify failed";
+	freersakey(key);
+	ret = 0;
+    } else
+	ret = 1;
+
+  end:
+    smemclr(buf, sizeof(buf));       /* burn the evidence */
+    return ret;
+}
+
+int loadrsakey(const Filename *filename, struct RSAKey *key, char *passphrase,
+	       const char **errorstr)
+{
+    FILE *fp;
+    char buf[64];
+    int ret = 0;
+    const char *error = NULL;
+
+    fp = f_open(filename, "rb", FALSE);
+    if (!fp) {
+	error = "can't open file";
+	goto end;
+    }
+
+    /*
+     * Read the first line of the file and see if it's a v1 private
+     * key file.
+     */
+    if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) {
+	/*
+	 * This routine will take care of calling fclose() for us.
+	 */
+	ret = loadrsakey_main(fp, key, FALSE, NULL, passphrase, &error);
+	fp = NULL;
+	goto end;
+    }
+
+    /*
+     * Otherwise, we have nothing. Return empty-handed.
+     */
+    error = "not an SSH-1 RSA file";
+
+  end:
+    if (fp)
+	fclose(fp);
+    if ((ret != 1) && errorstr)
+	*errorstr = error;
+    return ret;
+}
+
+/*
+ * See whether an RSA key is encrypted. Return its comment field as
+ * well.
+ */
+int rsakey_encrypted(const Filename *filename, char **comment)
+{
+    FILE *fp;
+    char buf[64];
+
+    fp = f_open(filename, "rb", FALSE);
+    if (!fp)
+	return 0;		       /* doesn't even exist */
+
+    /*
+     * Read the first line of the file and see if it's a v1 private
+     * key file.
+     */
+    if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) {
+	const char *dummy;
+	/*
+	 * This routine will take care of calling fclose() for us.
+	 */
+	return loadrsakey_main(fp, NULL, FALSE, comment, NULL, &dummy);
+    }
+    fclose(fp);
+    return 0;			       /* wasn't the right kind of file */
+}
+
+/*
+ * Return a malloc'ed chunk of memory containing the public blob of
+ * an RSA key, as given in the agent protocol (modulus bits,
+ * exponent, modulus).
+ */
+int rsakey_pubblob(const Filename *filename, void **blob, int *bloblen,
+		   char **commentptr, const char **errorstr)
+{
+    FILE *fp;
+    char buf[64];
+    struct RSAKey key;
+    int ret;
+    const char *error = NULL;
+
+    /* Default return if we fail. */
+    *blob = NULL;
+    *bloblen = 0;
+    ret = 0;
+
+    fp = f_open(filename, "rb", FALSE);
+    if (!fp) {
+	error = "can't open file";
+	goto end;
+    }
+
+    /*
+     * Read the first line of the file and see if it's a v1 private
+     * key file.
+     */
+    if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) {
+	memset(&key, 0, sizeof(key));
+	if (loadrsakey_main(fp, &key, TRUE, commentptr, NULL, &error)) {
+	    *blob = rsa_public_blob(&key, bloblen);
+	    freersakey(&key);
+	    ret = 1;
+	}
+	fp = NULL; /* loadrsakey_main unconditionally closes fp */
+    } else {
+	error = "not an SSH-1 RSA file";
+    }
+
+  end:
+    if (fp)
+	fclose(fp);
+    if ((ret != 1) && errorstr)
+	*errorstr = error;
+    return ret;
+}
+
+/*
+ * Save an RSA key file. Return nonzero on success.
+ */
+int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase)
+{
+    unsigned char buf[16384];
+    unsigned char keybuf[16];
+    struct MD5Context md5c;
+    unsigned char *p, *estart;
+    FILE *fp;
+
+    /*
+     * Write the initial signature.
+     */
+    p = buf;
+    memcpy(p, rsa_signature, sizeof(rsa_signature));
+    p += sizeof(rsa_signature);
+
+    /*
+     * One byte giving encryption type, and one reserved (zero)
+     * uint32.
+     */
+    *p++ = (passphrase ? SSH_CIPHER_3DES : 0);
+    PUT_32BIT(p, 0);
+    p += 4;
+
+    /*
+     * An ordinary SSH-1 public key consists of: a uint32
+     * containing the bit count, then two bignums containing the
+     * modulus and exponent respectively.
+     */
+    PUT_32BIT(p, bignum_bitcount(key->modulus));
+    p += 4;
+    p += ssh1_write_bignum(p, key->modulus);
+    p += ssh1_write_bignum(p, key->exponent);
+
+    /*
+     * A string containing the comment field.
+     */
+    if (key->comment) {
+	PUT_32BIT(p, strlen(key->comment));
+	p += 4;
+	memcpy(p, key->comment, strlen(key->comment));
+	p += strlen(key->comment);
+    } else {
+	PUT_32BIT(p, 0);
+	p += 4;
+    }
+
+    /*
+     * The encrypted portion starts here.
+     */
+    estart = p;
+
+    /*
+     * Two bytes, then the same two bytes repeated.
+     */
+    *p++ = random_byte();
+    *p++ = random_byte();
+    p[0] = p[-2];
+    p[1] = p[-1];
+    p += 2;
+
+    /*
+     * Four more bignums: the decryption exponent, then iqmp, then
+     * q, then p.
+     */
+    p += ssh1_write_bignum(p, key->private_exponent);
+    p += ssh1_write_bignum(p, key->iqmp);
+    p += ssh1_write_bignum(p, key->q);
+    p += ssh1_write_bignum(p, key->p);
+
+    /*
+     * Now write zeros until the encrypted portion is a multiple of
+     * 8 bytes.
+     */
+    while ((p - estart) % 8)
+	*p++ = '\0';
+
+    /*
+     * Now encrypt the encrypted portion.
+     */
+    if (passphrase) {
+	MD5Init(&md5c);
+	MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
+	MD5Final(keybuf, &md5c);
+	des3_encrypt_pubkey(keybuf, estart, p - estart);
+	smemclr(keybuf, sizeof(keybuf));	/* burn the evidence */
+    }
+
+    /*
+     * Done. Write the result to the file.
+     */
+    fp = f_open(filename, "wb", TRUE);
+    if (fp) {
+	int ret = (fwrite(buf, 1, p - buf, fp) == (size_t) (p - buf));
+        if (fclose(fp))
+            ret = 0;
+	return ret;
+    } else
+	return 0;
+}
+
+/* ----------------------------------------------------------------------
+ * SSH-2 private key load/store functions.
+ */
+
+/*
+ * PuTTY's own format for SSH-2 keys is as follows:
+ *
+ * The file is text. Lines are terminated by CRLF, although CR-only
+ * and LF-only are tolerated on input.
+ *
+ * The first line says "PuTTY-User-Key-File-2: " plus the name of the
+ * algorithm ("ssh-dss", "ssh-rsa" etc).
+ *
+ * The next line says "Encryption: " plus an encryption type.
+ * Currently the only supported encryption types are "aes256-cbc"
+ * and "none".
+ *
+ * The next line says "Comment: " plus the comment string.
+ *
+ * Next there is a line saying "Public-Lines: " plus a number N.
+ * The following N lines contain a base64 encoding of the public
+ * part of the key. This is encoded as the standard SSH-2 public key
+ * blob (with no initial length): so for RSA, for example, it will
+ * read
+ *
+ *    string "ssh-rsa"
+ *    mpint  exponent
+ *    mpint  modulus
+ *
+ * Next, there is a line saying "Private-Lines: " plus a number N,
+ * and then N lines containing the (potentially encrypted) private
+ * part of the key. For the key type "ssh-rsa", this will be
+ * composed of
+ *
+ *    mpint  private_exponent
+ *    mpint  p                  (the larger of the two primes)
+ *    mpint  q                  (the smaller prime)
+ *    mpint  iqmp               (the inverse of q modulo p)
+ *    data   padding            (to reach a multiple of the cipher block size)
+ *
+ * And for "ssh-dss", it will be composed of
+ *
+ *    mpint  x                  (the private key parameter)
+ *  [ string hash   20-byte hash of mpints p || q || g   only in old format ]
+ * 
+ * Finally, there is a line saying "Private-MAC: " plus a hex
+ * representation of a HMAC-SHA-1 of:
+ *
+ *    string  name of algorithm ("ssh-dss", "ssh-rsa")
+ *    string  encryption type
+ *    string  comment
+ *    string  public-blob
+ *    string  private-plaintext (the plaintext version of the
+ *                               private part, including the final
+ *                               padding)
+ * 
+ * The key to the MAC is itself a SHA-1 hash of:
+ * 
+ *    data    "putty-private-key-file-mac-key"
+ *    data    passphrase
+ *
+ * (An empty passphrase is used for unencrypted keys.)
+ *
+ * If the key is encrypted, the encryption key is derived from the
+ * passphrase by means of a succession of SHA-1 hashes. Each hash
+ * is the hash of:
+ *
+ *    uint32  sequence-number
+ *    data    passphrase
+ *
+ * where the sequence-number increases from zero. As many of these
+ * hashes are used as necessary.
+ *
+ * For backwards compatibility with snapshots between 0.51 and
+ * 0.52, we also support the older key file format, which begins
+ * with "PuTTY-User-Key-File-1" (version number differs). In this
+ * format the Private-MAC: field only covers the private-plaintext
+ * field and nothing else (and without the 4-byte string length on
+ * the front too). Moreover, the Private-MAC: field can be replaced
+ * with a Private-Hash: field which is a plain SHA-1 hash instead of
+ * an HMAC (this was generated for unencrypted keys).
+ */
+
+static int read_header(FILE * fp, char *header)
+{
+    int len = 39;
+    int c;
+
+    while (1) {
+	c = fgetc(fp);
+	if (c == '\n' || c == '\r' || c == EOF)
+	    return 0;		       /* failure */
+	if (c == ':') {
+	    c = fgetc(fp);
+	    if (c != ' ')
+		return 0;
+	    *header = '\0';
+	    return 1;		       /* success! */
+	}
+	if (len == 0)
+	    return 0;		       /* failure */
+	*header++ = c;
+	len--;
+    }
+    return 0;			       /* failure */
+}
+
+static char *read_body(FILE * fp)
+{
+    char *text;
+    int len;
+    int size;
+    int c;
+
+    size = 128;
+    text = snewn(size, char);
+    len = 0;
+    text[len] = '\0';
+
+    while (1) {
+	c = fgetc(fp);
+	if (c == '\r' || c == '\n' || c == EOF) {
+	    if (c != EOF) {
+		c = fgetc(fp);
+		if (c != '\r' && c != '\n')
+		    ungetc(c, fp);
+	    }
+	    return text;
+	}
+	if (len + 1 >= size) {
+	    size += 128;
+	    text = sresize(text, size, char);
+	}
+	text[len++] = c;
+	text[len] = '\0';
+    }
+}
+
+int base64_decode_atom(char *atom, unsigned char *out)
+{
+    int vals[4];
+    int i, v, len;
+    unsigned word;
+    char c;
+
+    for (i = 0; i < 4; i++) {
+	c = atom[i];
+	if (c >= 'A' && c <= 'Z')
+	    v = c - 'A';
+	else if (c >= 'a' && c <= 'z')
+	    v = c - 'a' + 26;
+	else if (c >= '0' && c <= '9')
+	    v = c - '0' + 52;
+	else if (c == '+')
+	    v = 62;
+	else if (c == '/')
+	    v = 63;
+	else if (c == '=')
+	    v = -1;
+	else
+	    return 0;		       /* invalid atom */
+	vals[i] = v;
+    }
+
+    if (vals[0] == -1 || vals[1] == -1)
+	return 0;
+    if (vals[2] == -1 && vals[3] != -1)
+	return 0;
+
+    if (vals[3] != -1)
+	len = 3;
+    else if (vals[2] != -1)
+	len = 2;
+    else
+	len = 1;
+
+    word = ((vals[0] << 18) |
+	    (vals[1] << 12) | ((vals[2] & 0x3F) << 6) | (vals[3] & 0x3F));
+    out[0] = (word >> 16) & 0xFF;
+    if (len > 1)
+	out[1] = (word >> 8) & 0xFF;
+    if (len > 2)
+	out[2] = word & 0xFF;
+    return len;
+}
+
+static unsigned char *read_blob(FILE * fp, int nlines, int *bloblen)
+{
+    unsigned char *blob;
+    char *line;
+    int linelen, len;
+    int i, j, k;
+
+    /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */
+    blob = snewn(48 * nlines, unsigned char);
+    len = 0;
+    for (i = 0; i < nlines; i++) {
+	line = read_body(fp);
+	if (!line) {
+	    sfree(blob);
+	    return NULL;
+	}
+	linelen = strlen(line);
+	if (linelen % 4 != 0 || linelen > 64) {
+	    sfree(blob);
+	    sfree(line);
+	    return NULL;
+	}
+	for (j = 0; j < linelen; j += 4) {
+	    k = base64_decode_atom(line + j, blob + len);
+	    if (!k) {
+		sfree(line);
+		sfree(blob);
+		return NULL;
+	    }
+	    len += k;
+	}
+	sfree(line);
+    }
+    *bloblen = len;
+    return blob;
+}
+
+/*
+ * Magic error return value for when the passphrase is wrong.
+ */
+struct ssh2_userkey ssh2_wrong_passphrase = {
+    NULL, NULL, NULL
+};
+
+const struct ssh_signkey *find_pubkey_alg(const char *name)
+{
+    if (!strcmp(name, "ssh-rsa"))
+	return &ssh_rsa;
+    else if (!strcmp(name, "ssh-dss"))
+	return &ssh_dss;
+    else
+	return NULL;
+}
+
+struct ssh2_userkey *ssh2_load_userkey(const Filename *filename,
+				       char *passphrase, const char **errorstr)
+{
+    FILE *fp;
+    char header[40], *b, *encryption, *comment, *mac;
+    const struct ssh_signkey *alg;
+    struct ssh2_userkey *ret;
+    int cipher, cipherblk;
+    unsigned char *public_blob, *private_blob;
+    int public_blob_len, private_blob_len;
+    int i, is_mac, old_fmt;
+    int passlen = passphrase ? strlen(passphrase) : 0;
+    const char *error = NULL;
+
+    ret = NULL;			       /* return NULL for most errors */
+    encryption = comment = mac = NULL;
+    public_blob = private_blob = NULL;
+
+    fp = f_open(filename, "rb", FALSE);
+    if (!fp) {
+	error = "can't open file";
+	goto error;
+    }
+
+    /* Read the first header line which contains the key type. */
+    if (!read_header(fp, header))
+	goto error;
+    if (0 == strcmp(header, "PuTTY-User-Key-File-2")) {
+	old_fmt = 0;
+    } else if (0 == strcmp(header, "PuTTY-User-Key-File-1")) {
+	/* this is an old key file; warn and then continue */
+	old_keyfile_warning();
+	old_fmt = 1;
+    } else if (0 == strncmp(header, "PuTTY-User-Key-File-", 20)) {
+	/* this is a key file FROM THE FUTURE; refuse it, but with a
+         * more specific error message than the generic one below */
+	error = "PuTTY key format too new";
+	goto error;
+    } else {
+	error = "not a PuTTY SSH-2 private key";
+	goto error;
+    }
+    error = "file format error";
+    if ((b = read_body(fp)) == NULL)
+	goto error;
+    /* Select key algorithm structure. */
+    alg = find_pubkey_alg(b);
+    if (!alg) {
+	sfree(b);
+	goto error;
+    }
+    sfree(b);
+
+    /* Read the Encryption header line. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Encryption"))
+	goto error;
+    if ((encryption = read_body(fp)) == NULL)
+	goto error;
+    if (!strcmp(encryption, "aes256-cbc")) {
+	cipher = 1;
+	cipherblk = 16;
+    } else if (!strcmp(encryption, "none")) {
+	cipher = 0;
+	cipherblk = 1;
+    } else {
+	goto error;
+    }
+
+    /* Read the Comment header line. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Comment"))
+	goto error;
+    if ((comment = read_body(fp)) == NULL)
+	goto error;
+
+    /* Read the Public-Lines header line and the public blob. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines"))
+	goto error;
+    if ((b = read_body(fp)) == NULL)
+	goto error;
+    i = atoi(b);
+    sfree(b);
+    if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL)
+	goto error;
+
+    /* Read the Private-Lines header line and the Private blob. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Private-Lines"))
+	goto error;
+    if ((b = read_body(fp)) == NULL)
+	goto error;
+    i = atoi(b);
+    sfree(b);
+    if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL)
+	goto error;
+
+    /* Read the Private-MAC or Private-Hash header line. */
+    if (!read_header(fp, header))
+	goto error;
+    if (0 == strcmp(header, "Private-MAC")) {
+	if ((mac = read_body(fp)) == NULL)
+	    goto error;
+	is_mac = 1;
+    } else if (0 == strcmp(header, "Private-Hash") && old_fmt) {
+	if ((mac = read_body(fp)) == NULL)
+	    goto error;
+	is_mac = 0;
+    } else
+	goto error;
+
+    fclose(fp);
+    fp = NULL;
+
+    /*
+     * Decrypt the private blob.
+     */
+    if (cipher) {
+	unsigned char key[40];
+	SHA_State s;
+
+	if (!passphrase)
+	    goto error;
+	if (private_blob_len % cipherblk)
+	    goto error;
+
+	SHA_Init(&s);
+	SHA_Bytes(&s, "\0\0\0\0", 4);
+	SHA_Bytes(&s, passphrase, passlen);
+	SHA_Final(&s, key + 0);
+	SHA_Init(&s);
+	SHA_Bytes(&s, "\0\0\0\1", 4);
+	SHA_Bytes(&s, passphrase, passlen);
+	SHA_Final(&s, key + 20);
+	aes256_decrypt_pubkey(key, private_blob, private_blob_len);
+    }
+
+    /*
+     * Verify the MAC.
+     */
+    {
+	char realmac[41];
+	unsigned char binary[20];
+	unsigned char *macdata;
+	int maclen;
+	int free_macdata;
+
+	if (old_fmt) {
+	    /* MAC (or hash) only covers the private blob. */
+	    macdata = private_blob;
+	    maclen = private_blob_len;
+	    free_macdata = 0;
+	} else {
+	    unsigned char *p;
+	    int namelen = strlen(alg->name);
+	    int enclen = strlen(encryption);
+	    int commlen = strlen(comment);
+	    maclen = (4 + namelen +
+		      4 + enclen +
+		      4 + commlen +
+		      4 + public_blob_len +
+		      4 + private_blob_len);
+	    macdata = snewn(maclen, unsigned char);
+	    p = macdata;
+#define DO_STR(s,len) PUT_32BIT(p,(len));memcpy(p+4,(s),(len));p+=4+(len)
+	    DO_STR(alg->name, namelen);
+	    DO_STR(encryption, enclen);
+	    DO_STR(comment, commlen);
+	    DO_STR(public_blob, public_blob_len);
+	    DO_STR(private_blob, private_blob_len);
+
+	    free_macdata = 1;
+	}
+
+	if (is_mac) {
+	    SHA_State s;
+	    unsigned char mackey[20];
+	    char header[] = "putty-private-key-file-mac-key";
+
+	    SHA_Init(&s);
+	    SHA_Bytes(&s, header, sizeof(header)-1);
+	    if (cipher && passphrase)
+		SHA_Bytes(&s, passphrase, passlen);
+	    SHA_Final(&s, mackey);
+
+	    hmac_sha1_simple(mackey, 20, macdata, maclen, binary);
+
+	    smemclr(mackey, sizeof(mackey));
+	    smemclr(&s, sizeof(s));
+	} else {
+	    SHA_Simple(macdata, maclen, binary);
+	}
+
+	if (free_macdata) {
+	    smemclr(macdata, maclen);
+	    sfree(macdata);
+	}
+
+	for (i = 0; i < 20; i++)
+	    sprintf(realmac + 2 * i, "%02x", binary[i]);
+
+	if (strcmp(mac, realmac)) {
+	    /* An incorrect MAC is an unconditional Error if the key is
+	     * unencrypted. Otherwise, it means Wrong Passphrase. */
+	    if (cipher) {
+		error = "wrong passphrase";
+		ret = SSH2_WRONG_PASSPHRASE;
+	    } else {
+		error = "MAC failed";
+		ret = NULL;
+	    }
+	    goto error;
+	}
+    }
+    sfree(mac);
+
+    /*
+     * Create and return the key.
+     */
+    ret = snew(struct ssh2_userkey);
+    ret->alg = alg;
+    ret->comment = comment;
+    ret->data = alg->createkey(public_blob, public_blob_len,
+			       private_blob, private_blob_len);
+    if (!ret->data) {
+	sfree(ret->comment);
+	sfree(ret);
+	ret = NULL;
+	error = "createkey failed";
+	goto error;
+    }
+    sfree(public_blob);
+    sfree(private_blob);
+    sfree(encryption);
+    if (errorstr)
+	*errorstr = NULL;
+    return ret;
+
+    /*
+     * Error processing.
+     */
+  error:
+    if (fp)
+	fclose(fp);
+    if (comment)
+	sfree(comment);
+    if (encryption)
+	sfree(encryption);
+    if (mac)
+	sfree(mac);
+    if (public_blob)
+	sfree(public_blob);
+    if (private_blob)
+	sfree(private_blob);
+    if (errorstr)
+	*errorstr = error;
+    return ret;
+}
+
+unsigned char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm,
+				    int *pub_blob_len, char **commentptr,
+				    const char **errorstr)
+{
+    FILE *fp;
+    char header[40], *b;
+    const struct ssh_signkey *alg;
+    unsigned char *public_blob;
+    int public_blob_len;
+    int i;
+    const char *error = NULL;
+    char *comment;
+
+    public_blob = NULL;
+
+    fp = f_open(filename, "rb", FALSE);
+    if (!fp) {
+	error = "can't open file";
+	goto error;
+    }
+
+    /* Read the first header line which contains the key type. */
+    if (!read_header(fp, header)
+	|| (0 != strcmp(header, "PuTTY-User-Key-File-2") &&
+	    0 != strcmp(header, "PuTTY-User-Key-File-1"))) {
+        if (0 == strncmp(header, "PuTTY-User-Key-File-", 20))
+            error = "PuTTY key format too new";
+        else
+            error = "not a PuTTY SSH-2 private key";
+	goto error;
+    }
+    error = "file format error";
+    if ((b = read_body(fp)) == NULL)
+	goto error;
+    /* Select key algorithm structure. */
+    alg = find_pubkey_alg(b);
+    if (!alg) {
+	sfree(b);
+	goto error;
+    }
+    sfree(b);
+
+    /* Read the Encryption header line. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Encryption"))
+	goto error;
+    if ((b = read_body(fp)) == NULL)
+	goto error;
+    sfree(b);			       /* we don't care */
+
+    /* Read the Comment header line. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Comment"))
+	goto error;
+    if ((comment = read_body(fp)) == NULL)
+	goto error;
+
+    if (commentptr)
+	*commentptr = comment;
+    else
+	sfree(comment);
+
+    /* Read the Public-Lines header line and the public blob. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines"))
+	goto error;
+    if ((b = read_body(fp)) == NULL)
+	goto error;
+    i = atoi(b);
+    sfree(b);
+    if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL)
+	goto error;
+
+    fclose(fp);
+    if (pub_blob_len)
+	*pub_blob_len = public_blob_len;
+    if (algorithm)
+	*algorithm = alg->name;
+    return public_blob;
+
+    /*
+     * Error processing.
+     */
+  error:
+    if (fp)
+	fclose(fp);
+    if (public_blob)
+	sfree(public_blob);
+    if (errorstr)
+	*errorstr = error;
+    return NULL;
+}
+
+int ssh2_userkey_encrypted(const Filename *filename, char **commentptr)
+{
+    FILE *fp;
+    char header[40], *b, *comment;
+    int ret;
+
+    if (commentptr)
+	*commentptr = NULL;
+
+    fp = f_open(filename, "rb", FALSE);
+    if (!fp)
+	return 0;
+    if (!read_header(fp, header)
+	|| (0 != strcmp(header, "PuTTY-User-Key-File-2") &&
+	    0 != strcmp(header, "PuTTY-User-Key-File-1"))) {
+	fclose(fp);
+	return 0;
+    }
+    if ((b = read_body(fp)) == NULL) {
+	fclose(fp);
+	return 0;
+    }
+    sfree(b);			       /* we don't care about key type here */
+    /* Read the Encryption header line. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) {
+	fclose(fp);
+	return 0;
+    }
+    if ((b = read_body(fp)) == NULL) {
+	fclose(fp);
+	return 0;
+    }
+
+    /* Read the Comment header line. */
+    if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) {
+	fclose(fp);
+	sfree(b);
+	return 1;
+    }
+    if ((comment = read_body(fp)) == NULL) {
+	fclose(fp);
+	sfree(b);
+	return 1;
+    }
+
+    if (commentptr)
+	*commentptr = comment;
+    else
+        sfree(comment);
+
+    fclose(fp);
+    if (!strcmp(b, "aes256-cbc"))
+	ret = 1;
+    else
+	ret = 0;
+    sfree(b);
+    return ret;
+}
+
+int base64_lines(int datalen)
+{
+    /* When encoding, we use 64 chars/line, which equals 48 real chars. */
+    return (datalen + 47) / 48;
+}
+
+void base64_encode(FILE * fp, unsigned char *data, int datalen, int cpl)
+{
+    int linelen = 0;
+    char out[4];
+    int n, i;
+
+    while (datalen > 0) {
+	n = (datalen < 3 ? datalen : 3);
+	base64_encode_atom(data, n, out);
+	data += n;
+	datalen -= n;
+	for (i = 0; i < 4; i++) {
+	    if (linelen >= cpl) {
+		linelen = 0;
+		fputc('\n', fp);
+	    }
+	    fputc(out[i], fp);
+	    linelen++;
+	}
+    }
+    fputc('\n', fp);
+}
+
+int ssh2_save_userkey(const Filename *filename, struct ssh2_userkey *key,
+		      char *passphrase)
+{
+    FILE *fp;
+    unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted;
+    int pub_blob_len, priv_blob_len, priv_encrypted_len;
+    int passlen;
+    int cipherblk;
+    int i;
+    char *cipherstr;
+    unsigned char priv_mac[20];
+
+    /*
+     * Fetch the key component blobs.
+     */
+    pub_blob = key->alg->public_blob(key->data, &pub_blob_len);
+    priv_blob = key->alg->private_blob(key->data, &priv_blob_len);
+    if (!pub_blob || !priv_blob) {
+	sfree(pub_blob);
+	sfree(priv_blob);
+	return 0;
+    }
+
+    /*
+     * Determine encryption details, and encrypt the private blob.
+     */
+    if (passphrase) {
+	cipherstr = "aes256-cbc";
+	cipherblk = 16;
+    } else {
+	cipherstr = "none";
+	cipherblk = 1;
+    }
+    priv_encrypted_len = priv_blob_len + cipherblk - 1;
+    priv_encrypted_len -= priv_encrypted_len % cipherblk;
+    priv_blob_encrypted = snewn(priv_encrypted_len, unsigned char);
+    memset(priv_blob_encrypted, 0, priv_encrypted_len);
+    memcpy(priv_blob_encrypted, priv_blob, priv_blob_len);
+    /* Create padding based on the SHA hash of the unpadded blob. This prevents
+     * too easy a known-plaintext attack on the last block. */
+    SHA_Simple(priv_blob, priv_blob_len, priv_mac);
+    assert(priv_encrypted_len - priv_blob_len < 20);
+    memcpy(priv_blob_encrypted + priv_blob_len, priv_mac,
+	   priv_encrypted_len - priv_blob_len);
+
+    /* Now create the MAC. */
+    {
+	unsigned char *macdata;
+	int maclen;
+	unsigned char *p;
+	int namelen = strlen(key->alg->name);
+	int enclen = strlen(cipherstr);
+	int commlen = strlen(key->comment);
+	SHA_State s;
+	unsigned char mackey[20];
+	char header[] = "putty-private-key-file-mac-key";
+
+	maclen = (4 + namelen +
+		  4 + enclen +
+		  4 + commlen +
+		  4 + pub_blob_len +
+		  4 + priv_encrypted_len);
+	macdata = snewn(maclen, unsigned char);
+	p = macdata;
+#define DO_STR(s,len) PUT_32BIT(p,(len));memcpy(p+4,(s),(len));p+=4+(len)
+	DO_STR(key->alg->name, namelen);
+	DO_STR(cipherstr, enclen);
+	DO_STR(key->comment, commlen);
+	DO_STR(pub_blob, pub_blob_len);
+	DO_STR(priv_blob_encrypted, priv_encrypted_len);
+
+	SHA_Init(&s);
+	SHA_Bytes(&s, header, sizeof(header)-1);
+	if (passphrase)
+	    SHA_Bytes(&s, passphrase, strlen(passphrase));
+	SHA_Final(&s, mackey);
+	hmac_sha1_simple(mackey, 20, macdata, maclen, priv_mac);
+	smemclr(macdata, maclen);
+	sfree(macdata);
+	smemclr(mackey, sizeof(mackey));
+	smemclr(&s, sizeof(s));
+    }
+
+    if (passphrase) {
+	unsigned char key[40];
+	SHA_State s;
+
+	passlen = strlen(passphrase);
+
+	SHA_Init(&s);
+	SHA_Bytes(&s, "\0\0\0\0", 4);
+	SHA_Bytes(&s, passphrase, passlen);
+	SHA_Final(&s, key + 0);
+	SHA_Init(&s);
+	SHA_Bytes(&s, "\0\0\0\1", 4);
+	SHA_Bytes(&s, passphrase, passlen);
+	SHA_Final(&s, key + 20);
+	aes256_encrypt_pubkey(key, priv_blob_encrypted,
+			      priv_encrypted_len);
+
+	smemclr(key, sizeof(key));
+	smemclr(&s, sizeof(s));
+    }
+
+    fp = f_open(filename, "w", TRUE);
+    if (!fp)
+	return 0;
+    fprintf(fp, "PuTTY-User-Key-File-2: %s\n", key->alg->name);
+    fprintf(fp, "Encryption: %s\n", cipherstr);
+    fprintf(fp, "Comment: %s\n", key->comment);
+    fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len));
+    base64_encode(fp, pub_blob, pub_blob_len, 64);
+    fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len));
+    base64_encode(fp, priv_blob_encrypted, priv_encrypted_len, 64);
+    fprintf(fp, "Private-MAC: ");
+    for (i = 0; i < 20; i++)
+	fprintf(fp, "%02x", priv_mac[i]);
+    fprintf(fp, "\n");
+    fclose(fp);
+
+    sfree(pub_blob);
+    smemclr(priv_blob, priv_blob_len);
+    sfree(priv_blob);
+    sfree(priv_blob_encrypted);
+    return 1;
+}
+
+/* ----------------------------------------------------------------------
+ * A function to determine the type of a private key file. Returns
+ * 0 on failure, 1 or 2 on success.
+ */
+int key_type(const Filename *filename)
+{
+    FILE *fp;
+    char buf[32];
+    const char putty2_sig[] = "PuTTY-User-Key-File-";
+    const char sshcom_sig[] = "---- BEGIN SSH2 ENCRYPTED PRIVAT";
+    const char openssh_sig[] = "-----BEGIN ";
+    int i;
+
+    fp = f_open(filename, "r", FALSE);
+    if (!fp)
+	return SSH_KEYTYPE_UNOPENABLE;
+    i = fread(buf, 1, sizeof(buf), fp);
+    fclose(fp);
+    if (i < 0)
+	return SSH_KEYTYPE_UNOPENABLE;
+    if (i < 32)
+	return SSH_KEYTYPE_UNKNOWN;
+    if (!memcmp(buf, rsa_signature, sizeof(rsa_signature)-1))
+	return SSH_KEYTYPE_SSH1;
+    if (!memcmp(buf, putty2_sig, sizeof(putty2_sig)-1))
+	return SSH_KEYTYPE_SSH2;
+    if (!memcmp(buf, openssh_sig, sizeof(openssh_sig)-1))
+	return SSH_KEYTYPE_OPENSSH;
+    if (!memcmp(buf, sshcom_sig, sizeof(sshcom_sig)-1))
+	return SSH_KEYTYPE_SSHCOM;
+    return SSH_KEYTYPE_UNKNOWN;	       /* unrecognised or EOF */
+}
+
+/*
+ * Convert the type word to a string, for `wrong type' error
+ * messages.
+ */
+char *key_type_to_str(int type)
+{
+    switch (type) {
+      case SSH_KEYTYPE_UNOPENABLE: return "unable to open file"; break;
+      case SSH_KEYTYPE_UNKNOWN: return "not a private key"; break;
+      case SSH_KEYTYPE_SSH1: return "SSH-1 private key"; break;
+      case SSH_KEYTYPE_SSH2: return "PuTTY SSH-2 private key"; break;
+      case SSH_KEYTYPE_OPENSSH: return "OpenSSH SSH-2 private key"; break;
+      case SSH_KEYTYPE_SSHCOM: return "ssh.com SSH-2 private key"; break;
+      default: return "INTERNAL ERROR"; break;
+    }
+}