X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/32874aeac8dacbca26663777b39a79efc5d8dc4b..HEAD:/sshpubk.c diff --git a/sshpubk.c b/sshpubk.c index d5576e8b..ac9e0fa7 100644 --- a/sshpubk.c +++ b/sshpubk.c @@ -1,7 +1,7 @@ /* * Generic SSH public-key handling operations. In particular, * reading of SSH public-key files, and also the generic `sign' - * operation for ssh2 (which checks the type of the key and + * operation for SSH-2 (which checks the type of the key and * dispatches to the appropriate key-type specific function). */ @@ -9,19 +9,9 @@ #include #include +#include "putty.h" #include "ssh.h" - -#define PUT_32BIT(cp, value) do { \ - (cp)[3] = (value); \ - (cp)[2] = (value) >> 8; \ - (cp)[1] = (value) >> 16; \ - (cp)[0] = (value) >> 24; } while (0) - -#define GET_32BIT(cp) \ - (((unsigned long)(unsigned char)(cp)[0] << 24) | \ - ((unsigned long)(unsigned char)(cp)[1] << 16) | \ - ((unsigned long)(unsigned char)(cp)[2] << 8) | \ - ((unsigned long)(unsigned char)(cp)[3])) +#include "misc.h" #define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n" @@ -31,8 +21,9 @@ (x)=='+' ? 62 : \ (x)=='/' ? 63 : 0 ) -static int loadrsakey_main(FILE * fp, struct RSAKey *key, - char **commentptr, char *passphrase) +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]; @@ -42,13 +33,18 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, 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)) + 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.) @@ -70,28 +66,39 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, || 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, key, NULL, 1); - if (len - i < 0) + /* 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 = GET_32BIT(buf + i); + j = toint(GET_32BIT(buf + i)); i += 4; - if (len - i < j) + if (j < 0 || len - i < j) goto end; - comment = smalloc(j + 1); + comment = snewn(j + 1, char); if (comment) { memcpy(comment, buf + i, j); comment[j] = '\0'; } i += j; if (commentptr) - *commentptr = comment; + *commentptr = dupstr(comment); if (key) key->comment = comment; + else + sfree(comment); + + if (pub_only) { + ret = 1; + goto end; + } + if (!key) { - return ciphertype != 0; + ret = ciphertype != 0; + *error = NULL; + goto end; } /* @@ -99,10 +106,10 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, */ if (ciphertype) { MD5Init(&md5c); - MD5Update(&md5c, passphrase, strlen(passphrase)); + 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 */ + smemclr(keybuf, sizeof(keybuf)); /* burn the evidence */ } /* @@ -112,6 +119,7 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, 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; } @@ -122,64 +130,81 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, * decryption exponent, and then the three auxiliary values * (iqmp, q, p). */ - i += makeprivate(buf + i, key); - if (len - i < 0) - goto end; - i += ssh1_read_bignum(buf + i, &key->iqmp); - if (len - i < 0) - goto end; - i += ssh1_read_bignum(buf + i, &key->q); - if (len - i < 0) - goto end; - i += ssh1_read_bignum(buf + i, &key->p); - if (len - i < 0) - goto end; + 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 */ + smemclr(buf, sizeof(buf)); /* burn the evidence */ return ret; } -int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) +int loadrsakey(const Filename *filename, struct RSAKey *key, char *passphrase, + const char **errorstr) { FILE *fp; - unsigned char buf[64]; + char buf[64]; + int ret = 0; + const char *error = NULL; - fp = fopen(filename, "rb"); - if (!fp) - return 0; /* doesn't even exist */ + 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)) { - return loadrsakey_main(fp, key, NULL, passphrase); + /* + * 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. */ - fclose(fp); - return 0; + 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(char *filename, char **comment) +int rsakey_encrypted(const Filename *filename, char **comment) { FILE *fp; - unsigned char buf[64]; + char buf[64]; - fp = fopen(filename, "rb"); + fp = f_open(filename, "rb", FALSE); if (!fp) return 0; /* doesn't even exist */ @@ -188,16 +213,69 @@ int rsakey_encrypted(char *filename, char **comment) * key file. */ if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) { - return loadrsakey_main(fp, NULL, comment, NULL); + 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(char *filename, struct RSAKey *key, char *passphrase) +int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase) { unsigned char buf[16384]; unsigned char keybuf[16]; @@ -221,7 +299,7 @@ int saversakey(char *filename, struct RSAKey *key, char *passphrase) p += 4; /* - * An ordinary SSH 1 public key consists of: a uint32 + * An ordinary SSH-1 public key consists of: a uint32 * containing the bit count, then two bignums containing the * modulus and exponent respectively. */ @@ -278,88 +356,106 @@ int saversakey(char *filename, struct RSAKey *key, char *passphrase) */ if (passphrase) { MD5Init(&md5c); - MD5Update(&md5c, passphrase, strlen(passphrase)); + 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 */ + smemclr(keybuf, sizeof(keybuf)); /* burn the evidence */ } /* * Done. Write the result to the file. */ - fp = fopen(filename, "wb"); + fp = f_open(filename, "wb", TRUE); if (fp) { int ret = (fwrite(buf, 1, p - buf, fp) == (size_t) (p - buf)); - ret = ret && (fclose(fp) == 0); + if (fclose(fp)) + ret = 0; return ret; } else return 0; } /* ---------------------------------------------------------------------- - * SSH2 private key load/store functions. + * SSH-2 private key load/store functions. */ /* - * PuTTY's own format for SSH2 keys is as follows: - * + * 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-1: " plus the name of the - * algorithm ("ssh-dss", "ssh-rsa" etc. Although, of course, this - * being PuTTY, "ssh-dss" is not supported.) - * + * + * 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 SSH2 public key + * 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-Hash: " plus a hex - * representation of a SHA-1 hash of the plaintext version of the - * private part, including the final padding. + * 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 - * string passphrase - * + * data passphrase + * * where the sequence-number increases from zero. As many of these * hashes are used as necessary. - * - * NOTE! It is important that all _public_ data can be verified - * with reference to the _private_ data. There exist attacks based - * on modifying the public key but leaving the private section - * intact. - * - * With RSA, this is easy: verify that n = p*q, and also verify - * that e*d == 1 modulo (p-1)(q-1). With DSA (if we were ever to - * support it), we would need to store extra data in the private - * section other than just x. + * + * 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) @@ -367,7 +463,7 @@ static int read_header(FILE * fp, char *header) int len = 39; int c; - while (len > 0) { + while (1) { c = fgetc(fp); if (c == '\n' || c == '\r' || c == EOF) return 0; /* failure */ @@ -394,25 +490,23 @@ static char *read_body(FILE * fp) int c; size = 128; - text = smalloc(size); + text = snewn(size, char); len = 0; text[len] = '\0'; while (1) { c = fgetc(fp); - if (c == '\r' || c == '\n') { - c = fgetc(fp); - if (c != '\r' && c != '\n' && c != EOF) - ungetc(c, 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 (c == EOF) { - sfree(text); - return NULL; - } - if (len + 1 > size) { + if (len + 1 >= size) { size += 128; - text = srealloc(text, size); + text = sresize(text, size, char); } text[len++] = c; text[len] = '\0'; @@ -467,7 +561,7 @@ int base64_decode_atom(char *atom, unsigned char *out) return len; } -static char *read_blob(FILE * fp, int nlines, int *bloblen) +static unsigned char *read_blob(FILE * fp, int nlines, int *bloblen) { unsigned char *blob; char *line; @@ -475,7 +569,7 @@ static char *read_blob(FILE * fp, int nlines, int *bloblen) int i, j, k; /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */ - blob = smalloc(48 * nlines); + blob = snewn(48 * nlines, unsigned char); len = 0; for (i = 0; i < nlines; i++) { line = read_body(fp); @@ -511,35 +605,64 @@ struct ssh2_userkey ssh2_wrong_passphrase = { NULL, NULL, NULL }; -struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) +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, *comment, *hash; + 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; + int i, is_mac, old_fmt; + int passlen = passphrase ? strlen(passphrase) : 0; + const char *error = NULL; ret = NULL; /* return NULL for most errors */ - comment = hash = NULL; + encryption = comment = mac = NULL; public_blob = private_blob = NULL; - fp = fopen(filename, "rb"); - if (!fp) + 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-1")) + 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. Currently only ssh-rsa. */ - if (!strcmp(b, "ssh-rsa")) - alg = &ssh_rsa; - else { + /* Select key algorithm structure. */ + alg = find_pubkey_alg(b); + if (!alg) { sfree(b); goto error; } @@ -548,19 +671,17 @@ struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) /* Read the Encryption header line. */ if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) goto error; - if ((b = read_body(fp)) == NULL) + if ((encryption = read_body(fp)) == NULL) goto error; - if (!strcmp(b, "aes256-cbc")) { + if (!strcmp(encryption, "aes256-cbc")) { cipher = 1; cipherblk = 16; - } else if (!strcmp(b, "none")) { + } else if (!strcmp(encryption, "none")) { cipher = 0; cipherblk = 1; } else { - sfree(b); goto error; } - sfree(b); /* Read the Comment header line. */ if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) @@ -588,10 +709,18 @@ struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL) goto error; - /* Read the Private-Hash header line. */ - if (!read_header(fp, header) || 0 != strcmp(header, "Private-Hash")) + /* Read the Private-MAC or Private-Hash header line. */ + if (!read_header(fp, header)) goto error; - if ((hash = read_body(fp)) == NULL) + 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); @@ -603,15 +732,12 @@ struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) if (cipher) { unsigned char key[40]; SHA_State s; - int passlen; if (!passphrase) goto error; if (private_blob_len % cipherblk) goto error; - passlen = strlen(passphrase); - SHA_Init(&s); SHA_Bytes(&s, "\0\0\0\0", 4); SHA_Bytes(&s, passphrase, passlen); @@ -624,29 +750,88 @@ struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) } /* - * Verify the private hash. + * Verify the MAC. */ { - char realhash[41]; + 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); + } - SHA_Simple(private_blob, private_blob_len, binary); for (i = 0; i < 20; i++) - sprintf(realhash + 2 * i, "%02x", binary[i]); + sprintf(realmac + 2 * i, "%02x", binary[i]); - if (strcmp(hash, realhash)) { - /* An incorrect hash is an unconditional Error if the key is + if (strcmp(mac, realmac)) { + /* An incorrect MAC is an unconditional Error if the key is * unencrypted. Otherwise, it means Wrong Passphrase. */ - ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL; + if (cipher) { + error = "wrong passphrase"; + ret = SSH2_WRONG_PASSPHRASE; + } else { + error = "MAC failed"; + ret = NULL; + } goto error; } } - sfree(hash); + sfree(mac); /* * Create and return the key. */ - ret = smalloc(sizeof(struct ssh2_userkey)); + ret = snew(struct ssh2_userkey); ret->alg = alg; ret->comment = comment; ret->data = alg->createkey(public_blob, public_blob_len, @@ -655,9 +840,14 @@ struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) 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; /* @@ -668,17 +858,22 @@ struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) fclose(fp); if (comment) sfree(comment); - if (hash) - sfree(hash); + 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; } -char *ssh2_userkey_loadpub(char *filename, char **algorithm, - int *pub_blob_len) +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; @@ -686,23 +881,33 @@ char *ssh2_userkey_loadpub(char *filename, char **algorithm, unsigned char *public_blob; int public_blob_len; int i; + const char *error = NULL; + char *comment; public_blob = NULL; - fp = fopen(filename, "rb"); - if (!fp) + 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-1")) + || (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. Currently only ssh-rsa. */ - if (!strcmp(b, "ssh-rsa")) - alg = &ssh_rsa; - else { + /* Select key algorithm structure. */ + alg = find_pubkey_alg(b); + if (!alg) { sfree(b); goto error; } @@ -718,9 +923,13 @@ char *ssh2_userkey_loadpub(char *filename, char **algorithm, /* Read the Comment header line. */ if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) goto error; - if ((b = read_body(fp)) == NULL) + if ((comment = read_body(fp)) == NULL) goto error; - sfree(b); /* we don't care */ + + 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")) @@ -733,8 +942,10 @@ char *ssh2_userkey_loadpub(char *filename, char **algorithm, goto error; fclose(fp); - *pub_blob_len = public_blob_len; - *algorithm = alg->name; + if (pub_blob_len) + *pub_blob_len = public_blob_len; + if (algorithm) + *algorithm = alg->name; return public_blob; /* @@ -745,10 +956,12 @@ char *ssh2_userkey_loadpub(char *filename, char **algorithm, fclose(fp); if (public_blob) sfree(public_blob); + if (errorstr) + *errorstr = error; return NULL; } -int ssh2_userkey_encrypted(char *filename, char **commentptr) +int ssh2_userkey_encrypted(const Filename *filename, char **commentptr) { FILE *fp; char header[40], *b, *comment; @@ -757,11 +970,12 @@ int ssh2_userkey_encrypted(char *filename, char **commentptr) if (commentptr) *commentptr = NULL; - fp = fopen(filename, "rb"); + fp = f_open(filename, "rb", FALSE); if (!fp) return 0; if (!read_header(fp, header) - || 0 != strcmp(header, "PuTTY-User-Key-File-1")) { + || (0 != strcmp(header, "PuTTY-User-Key-File-2") && + 0 != strcmp(header, "PuTTY-User-Key-File-1"))) { fclose(fp); return 0; } @@ -794,6 +1008,8 @@ int ssh2_userkey_encrypted(char *filename, char **commentptr) if (commentptr) *commentptr = comment; + else + sfree(comment); fclose(fp); if (!strcmp(b, "aes256-cbc")) @@ -810,52 +1026,30 @@ int base64_lines(int datalen) return (datalen + 47) / 48; } -void base64_encode_atom(unsigned char *data, int n, char *out) -{ - static const char base64_chars[] = - "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; - - unsigned word; - - word = data[0] << 16; - if (n > 1) - word |= data[1] << 8; - if (n > 2) - word |= data[2]; - out[0] = base64_chars[(word >> 18) & 0x3F]; - out[1] = base64_chars[(word >> 12) & 0x3F]; - if (n > 1) - out[2] = base64_chars[(word >> 6) & 0x3F]; - else - out[2] = '='; - if (n > 2) - out[3] = base64_chars[word & 0x3F]; - else - out[3] = '='; -} - -void base64_encode(FILE * fp, unsigned char *data, int datalen) +void base64_encode(FILE * fp, unsigned char *data, int datalen, int cpl) { int linelen = 0; char out[4]; - int n; + int n, i; while (datalen > 0) { - if (linelen >= 64) { - linelen = 0; - fputc('\n', fp); - } n = (datalen < 3 ? datalen : 3); base64_encode_atom(data, n, out); data += n; datalen -= n; - fwrite(out, 1, 4, fp); - linelen += 4; + 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(char *filename, struct ssh2_userkey *key, +int ssh2_save_userkey(const Filename *filename, struct ssh2_userkey *key, char *passphrase) { FILE *fp; @@ -865,7 +1059,7 @@ int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, int cipherblk; int i; char *cipherstr; - unsigned char priv_hash[20]; + unsigned char priv_mac[20]; /* * Fetch the key component blobs. @@ -890,21 +1084,56 @@ int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, } priv_encrypted_len = priv_blob_len + cipherblk - 1; priv_encrypted_len -= priv_encrypted_len % cipherblk; - priv_blob_encrypted = smalloc(priv_encrypted_len); + 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_hash); + 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_hash, + memcpy(priv_blob_encrypted + priv_blob_len, priv_mac, priv_encrypted_len - priv_blob_len); - /* Now create the _real_ private hash. */ - SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_hash); + /* 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) { - char key[40]; + unsigned char key[40]; SHA_State s; passlen = strlen(passphrase); @@ -919,43 +1148,80 @@ int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, SHA_Final(&s, key + 20); aes256_encrypt_pubkey(key, priv_blob_encrypted, priv_encrypted_len); + + smemclr(key, sizeof(key)); + smemclr(&s, sizeof(s)); } - fp = fopen(filename, "w"); + fp = f_open(filename, "w", TRUE); if (!fp) return 0; - fprintf(fp, "PuTTY-User-Key-File-1: %s\n", key->alg->name); + 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); + 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); - fprintf(fp, "Private-Hash: "); + base64_encode(fp, priv_blob_encrypted, priv_encrypted_len, 64); + fprintf(fp, "Private-MAC: "); for (i = 0; i < 20; i++) - fprintf(fp, "%02x", priv_hash[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 which version of SSH to try on a private - * key file. Returns 0 on failure, 1 or 2 on success. + * A function to determine the type of a private key file. Returns + * 0 on failure, 1 or 2 on success. */ -int keyfile_version(char *filename) +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 = fopen(filename, "r"); + fp = f_open(filename, "r", FALSE); if (!fp) - return 0; - i = fgetc(fp); + return SSH_KEYTYPE_UNOPENABLE; + i = fread(buf, 1, sizeof(buf), fp); fclose(fp); - if (i == 'S') - return 1; /* "SSH PRIVATE KEY FORMAT" etc */ - if (i == 'P') /* "PuTTY-User-Key-File" etc */ - return 2; - return 0; /* unrecognised or EOF */ + 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; + } }