/* * Code for PuTTY to import and export private key files in other * SSH clients' formats. */ #include #include #include #include #include "ssh.h" #include "misc.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])) int openssh_encrypted(char *filename); struct ssh2_userkey *openssh_read(char *filename, char *passphrase); int sshcom_encrypted(char *filename, char **comment); struct ssh2_userkey *sshcom_read(char *filename, char *passphrase); /* * Given a key type, determine whether we know how to import it. */ int import_possible(int type) { if (type == SSH_KEYTYPE_OPENSSH) return 1; if (type == SSH_KEYTYPE_SSHCOM) return 1; return 0; } /* * Given a key type, determine what native key type * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once * we've imported it. */ int import_target_type(int type) { /* * There are no known foreign SSH1 key formats. */ return SSH_KEYTYPE_SSH2; } /* * Determine whether a foreign key is encrypted. */ int import_encrypted(char *filename, int type, char **comment) { if (type == SSH_KEYTYPE_OPENSSH) { *comment = filename; /* OpenSSH doesn't do key comments */ return openssh_encrypted(filename); } if (type == SSH_KEYTYPE_SSHCOM) { return sshcom_encrypted(filename, comment); } return 0; } /* * Import an SSH1 key. */ int import_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) { return 0; } /* * Import an SSH2 key. */ struct ssh2_userkey *import_ssh2(char *filename, int type, char *passphrase) { if (type == SSH_KEYTYPE_OPENSSH) return openssh_read(filename, passphrase); if (type == SSH_KEYTYPE_SSHCOM) return sshcom_read(filename, passphrase); return NULL; } /* ---------------------------------------------------------------------- * Helper routines. (The base64 ones are defined in sshpubk.c.) */ #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ ((c) >= 'a' && (c) <= 'z') || \ ((c) >= '0' && (c) <= '9') || \ (c) == '+' || (c) == '/' || (c) == '=' \ ) extern int base64_decode_atom(char *atom, unsigned char *out); extern int base64_lines(int datalen); extern void base64_encode_atom(unsigned char *data, int n, char *out); extern void base64_encode(FILE * fp, unsigned char *data, int datalen); /* * Read an ASN.1/BER identifier and length pair. * * Flags are a combination of the #defines listed below. * * Returns -1 if unsuccessful; otherwise returns the number of * bytes used out of the source data. */ /* ASN.1 tag classes. */ #define ASN1_CLASS_UNIVERSAL (0 << 6) #define ASN1_CLASS_APPLICATION (1 << 6) #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) #define ASN1_CLASS_PRIVATE (3 << 6) #define ASN1_CLASS_MASK (3 << 6) /* Primitive versus constructed bit. */ #define ASN1_CONSTRUCTED (1 << 5) int ber_read_id_len(void *source, int sourcelen, int *id, int *length, int *flags) { unsigned char *p = (unsigned char *) source; if (sourcelen == 0) return -1; *flags = (*p & 0xE0); if ((*p & 0x1F) == 0x1F) { *id = 0; while (*p & 0x80) { *id = (*id << 7) | (*p & 0x7F); p++, sourcelen--; if (sourcelen == 0) return -1; } *id = (*id << 7) | (*p & 0x7F); p++, sourcelen--; } else { *id = *p & 0x1F; p++, sourcelen--; } if (sourcelen == 0) return -1; if (*p & 0x80) { int n = *p & 0x7F; p++, sourcelen--; if (sourcelen < n) return -1; *length = 0; while (n--) *length = (*length << 8) | (*p++); sourcelen -= n; } else { *length = *p; p++, sourcelen--; } return p - (unsigned char *) source; } static int put_string(void *target, void *data, int len) { unsigned char *d = (unsigned char *)target; PUT_32BIT(d, len); memcpy(d+4, data, len); return len+4; } static int put_mp(void *target, void *data, int len) { unsigned char *d = (unsigned char *)target; unsigned char *i = (unsigned char *)data; if (*i & 0x80) { PUT_32BIT(d, len+1); d[4] = 0; memcpy(d+5, data, len); return len+5; } else { PUT_32BIT(d, len); memcpy(d+4, data, len); return len+4; } } /* ---------------------------------------------------------------------- * Code to read OpenSSH private keys. */ enum { OSSH_DSA, OSSH_RSA }; struct openssh_key { int type; int encrypted; char iv[32]; unsigned char *keyblob; int keyblob_len, keyblob_size; }; struct openssh_key *load_openssh_key(char *filename) { struct openssh_key *ret; FILE *fp; char buffer[256]; char *errmsg, *p; int headers_done; char base64_bit[4]; int base64_chars = 0; ret = smalloc(sizeof(*ret)); ret->keyblob = NULL; ret->keyblob_len = ret->keyblob_size = 0; ret->encrypted = 0; memset(ret->iv, 0, sizeof(ret->iv)); fp = fopen(filename, "r"); if (!fp) { errmsg = "Unable to open key file"; goto error; } if (!fgets(buffer, sizeof(buffer), fp) || 0 != strncmp(buffer, "-----BEGIN ", 11) || 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { errmsg = "File does not begin with OpenSSH key header"; goto error; } if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) ret->type = OSSH_RSA; else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) ret->type = OSSH_DSA; else { errmsg = "Unrecognised key type"; goto error; } headers_done = 0; while (1) { if (!fgets(buffer, sizeof(buffer), fp)) { errmsg = "Unexpected end of file"; goto error; } if (0 == strncmp(buffer, "-----END ", 9) && 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) break; /* done */ if ((p = strchr(buffer, ':')) != NULL) { if (headers_done) { errmsg = "Header found in body of key data"; goto error; } *p++ = '\0'; while (*p && isspace((unsigned char)*p)) p++; if (!strcmp(buffer, "Proc-Type")) { if (p[0] != '4' || p[1] != ',') { errmsg = "Proc-Type is not 4 (only 4 is supported)"; goto error; } p += 2; if (!strcmp(p, "ENCRYPTED\n")) ret->encrypted = 1; } else if (!strcmp(buffer, "DEK-Info")) { int i, j; if (strncmp(p, "DES-EDE3-CBC,", 13)) { errmsg = "Ciphers other than DES-EDE3-CBC not supported"; goto error; } p += 13; for (i = 0; i < 8; i++) { if (1 != sscanf(p, "%2x", &j)) break; ret->iv[i] = j; p += 2; } if (i < 8) { errmsg = "Expected 16-digit iv in DEK-Info"; goto error; } } } else { headers_done = 1; p = buffer; while (isbase64(*p)) { base64_bit[base64_chars++] = *p; if (base64_chars == 4) { unsigned char out[3]; int len; base64_chars = 0; len = base64_decode_atom(base64_bit, out); if (len <= 0) { errmsg = "Invalid base64 encoding"; goto error; } if (ret->keyblob_len + len > ret->keyblob_size) { ret->keyblob_size = ret->keyblob_len + len + 256; ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); } memcpy(ret->keyblob + ret->keyblob_len, out, len); ret->keyblob_len += len; memset(out, 0, sizeof(out)); } p++; } } } if (ret->keyblob_len == 0 || !ret->keyblob) { errmsg = "Key body not present"; goto error; } if (ret->encrypted && ret->keyblob_len % 8 != 0) { errmsg = "Encrypted key blob is not a multiple of cipher block size"; goto error; } memset(buffer, 0, sizeof(buffer)); memset(base64_bit, 0, sizeof(base64_bit)); return ret; error: memset(buffer, 0, sizeof(buffer)); memset(base64_bit, 0, sizeof(base64_bit)); if (ret) { if (ret->keyblob) { memset(ret->keyblob, 0, ret->keyblob_size); sfree(ret->keyblob); } memset(&ret, 0, sizeof(ret)); sfree(ret); } return NULL; } int openssh_encrypted(char *filename) { struct openssh_key *key = load_openssh_key(filename); int ret; if (!key) return 0; ret = key->encrypted; memset(key->keyblob, 0, key->keyblob_size); sfree(key->keyblob); memset(&key, 0, sizeof(key)); sfree(key); return ret; } struct ssh2_userkey *openssh_read(char *filename, char *passphrase) { struct openssh_key *key = load_openssh_key(filename); struct ssh2_userkey *retkey; unsigned char *p; int ret, id, len, flags; int i, num_integers; struct ssh2_userkey *retval = NULL; char *errmsg; unsigned char *blob; int blobsize, blobptr, privptr; char *modptr; int modlen; if (!key) return NULL; if (key->encrypted) { /* * Derive encryption key from passphrase and iv/salt: * * - let block A equal MD5(passphrase || iv) * - let block B equal MD5(A || passphrase || iv) * - block C would be MD5(B || passphrase || iv) and so on * - encryption key is the first N bytes of A || B */ struct MD5Context md5c; unsigned char keybuf[32]; MD5Init(&md5c); MD5Update(&md5c, passphrase, strlen(passphrase)); MD5Update(&md5c, key->iv, 8); MD5Final(keybuf, &md5c); MD5Init(&md5c); MD5Update(&md5c, keybuf, 16); MD5Update(&md5c, passphrase, strlen(passphrase)); MD5Update(&md5c, key->iv, 8); MD5Final(keybuf+16, &md5c); /* * Now decrypt the key blob. */ des3_decrypt_pubkey_ossh(keybuf, key->iv, key->keyblob, key->keyblob_len); memset(&md5c, 0, sizeof(md5c)); memset(keybuf, 0, sizeof(keybuf)); } /* * Now we have a decrypted key blob, which contains an ASN.1 * encoded private key. We must now untangle the ASN.1. * * We expect the whole key blob to be formatted as a SEQUENCE * (0x30 followed by a length code indicating that the rest of * the blob is part of the sequence). Within that SEQUENCE we * expect to see a bunch of INTEGERs. What those integers mean * depends on the key type: * * - For RSA, we expect the integers to be 0, n, e, d, p, q, * dmp1, dmq1, iqmp in that order. (The last three are d mod * (p-1), d mod (q-1), inverse of q mod p respectively.) * * - For DSA, we expect them to be 0, p, q, g, y, x in that * order. */ p = key->keyblob; /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); p += ret; if (ret < 0 || id != 16) { errmsg = "ASN.1 decoding failure"; retval = SSH2_WRONG_PASSPHRASE; goto error; } /* Expect a load of INTEGERs. */ if (key->type == OSSH_RSA) num_integers = 9; else if (key->type == OSSH_DSA) num_integers = 6; /* * Space to create key blob in. */ blobsize = 256+key->keyblob_len; blob = smalloc(blobsize); PUT_32BIT(blob, 7); if (key->type == OSSH_DSA) memcpy(blob+4, "ssh-dss", 7); else if (key->type == OSSH_RSA) memcpy(blob+4, "ssh-rsa", 7); blobptr = 4+7; privptr = -1; for (i = 0; i < num_integers; i++) { ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, &id, &len, &flags); p += ret; if (ret < 0 || id != 2 || key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure"; goto error; } if (i == 0) { /* * The first integer should be zero always (I think * this is some sort of version indication). */ if (len != 1 || p[0] != 0) { errmsg = "Version number mismatch"; goto error; } } else if (key->type == OSSH_RSA) { /* * Integers 1 and 2 go into the public blob but in the * opposite order; integers 3, 4, 5 and 8 go into the * private blob. The other two (6 and 7) are ignored. */ if (i == 1) { /* Save the details for after we deal with number 2. */ modptr = p; modlen = len; } else if (i != 6 && i != 7) { PUT_32BIT(blob+blobptr, len); memcpy(blob+blobptr+4, p, len); blobptr += 4+len; if (i == 2) { PUT_32BIT(blob+blobptr, modlen); memcpy(blob+blobptr+4, modptr, modlen); blobptr += 4+modlen; privptr = blobptr; } } } else if (key->type == OSSH_DSA) { /* * Integers 1-4 go into the public blob; integer 5 goes * into the private blob. */ PUT_32BIT(blob+blobptr, len); memcpy(blob+blobptr+4, p, len); blobptr += 4+len; if (i == 4) privptr = blobptr; } /* Skip past the number. */ p += len; } /* * Now put together the actual key. Simplest way to do this is * to assemble our own key blobs and feed them to the createkey * functions; this is a bit faffy but it does mean we get all * the sanity checks for free. */ assert(privptr > 0); /* should have bombed by now if not */ retkey = smalloc(sizeof(struct ssh2_userkey)); retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); retkey->data = retkey->alg->createkey(blob, privptr, blob+privptr, blobptr-privptr); if (!retkey->data) { sfree(retkey); errmsg = "unable to create key data structure"; goto error; } retkey->comment = dupstr("imported-openssh-key"); errmsg = NULL; /* no error */ retval = retkey; error: if (blob) { memset(blob, 0, blobsize); sfree(blob); } memset(key->keyblob, 0, key->keyblob_size); sfree(key->keyblob); memset(&key, 0, sizeof(key)); sfree(key); return retval; } /* ---------------------------------------------------------------------- * Code to read ssh.com private keys. */ /* * The format of the base64 blob is largely ssh2-packet-formatted, * except that mpints are a bit different: they're more like the * old ssh1 mpint. You have a 32-bit bit count N, followed by * (N+7)/8 bytes of data. * * So. The blob contains: * * - uint32 0x3f6ff9eb (magic number) * - uint32 size (total blob size) * - string key-type (see below) * - string cipher-type (tells you if key is encrypted) * - string encrypted-blob * * (The first size field includes the size field itself and the * magic number before it. All other size fields are ordinary ssh2 * strings, so the size field indicates how much data is to * _follow_.) * * The encrypted blob, once decrypted, contains a single string * which in turn contains the payload. (This allows padding to be * added after that string while still making it clear where the * real payload ends. Also it probably makes for a reasonable * decryption check.) * * The payload blob, for an RSA key, contains: * - mpint e * - mpint d * - mpint n (yes, the public and private stuff is intermixed) * - mpint u (presumably inverse of p mod q) * - mpint p (p is the smaller prime) * - mpint q (q is the larger) * * For a DSA key, the payload blob contains: * - uint32 0 * - mpint p * - mpint g * - mpint q * - mpint y * - mpint x * * Alternatively, if the parameters are `predefined', that * (0,p,g,q) sequence can be replaced by a uint32 1 and a string * containing some predefined parameter specification. *shudder*, * but I doubt we'll encounter this in real life. * * The key type strings are ghastly. The RSA key I looked at had a * type string of * * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' * * and the DSA key wasn't much better: * * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' * * It isn't clear that these will always be the same. I think it * might be wise just to look at the `if-modn{sign{rsa' and * `dl-modp{sign{dsa' prefixes. * * Finally, the encryption. The cipher-type string appears to be * either `none' or `3des-cbc'. Looks as if this is SSH2-style * 3des-cbc (i.e. outer cbc rather than inner). The key is created * from the passphrase by means of yet another hashing faff: * * - first 16 bytes are MD5(passphrase) * - next 16 bytes are MD5(passphrase || first 16 bytes) * - if there were more, they'd be MD5(passphrase || first 32), * and so on. */ struct sshcom_key { char comment[256]; /* allowing any length is overkill */ unsigned char *keyblob; int keyblob_len, keyblob_size; }; struct sshcom_key *load_sshcom_key(char *filename) { struct sshcom_key *ret; FILE *fp; char buffer[256]; int len; char *errmsg, *p; int headers_done; char base64_bit[4]; int base64_chars = 0; ret = smalloc(sizeof(*ret)); ret->comment[0] = '\0'; ret->keyblob = NULL; ret->keyblob_len = ret->keyblob_size = 0; fp = fopen(filename, "r"); if (!fp) { errmsg = "Unable to open key file"; goto error; } if (!fgets(buffer, sizeof(buffer), fp) || 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { errmsg = "File does not begin with ssh.com key header"; goto error; } headers_done = 0; while (1) { if (!fgets(buffer, sizeof(buffer), fp)) { errmsg = "Unexpected end of file"; goto error; } if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) break; /* done */ if ((p = strchr(buffer, ':')) != NULL) { if (headers_done) { errmsg = "Header found in body of key data"; goto error; } *p++ = '\0'; while (*p && isspace((unsigned char)*p)) p++; /* * Header lines can end in a trailing backslash for * continuation. */ while ((len = strlen(p)) > sizeof(buffer) - (p-buffer) -1 || p[len-1] != '\n' || p[len-2] == '\\') { if (len > (p-buffer) + sizeof(buffer)-2) { errmsg = "Header line too long to deal with"; goto error; } if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { errmsg = "Unexpected end of file"; goto error; } } p[strcspn(p, "\n")] = '\0'; if (!strcmp(buffer, "Comment")) { /* Strip quotes in comment if present. */ if (p[0] == '"' && p[strlen(p)-1] == '"') { p++; p[strlen(p)-1] = '\0'; } strncpy(ret->comment, p, sizeof(ret->comment)); ret->comment[sizeof(ret->comment)-1] = '\0'; } } else { headers_done = 1; p = buffer; while (isbase64(*p)) { base64_bit[base64_chars++] = *p; if (base64_chars == 4) { unsigned char out[3]; base64_chars = 0; len = base64_decode_atom(base64_bit, out); if (len <= 0) { errmsg = "Invalid base64 encoding"; goto error; } if (ret->keyblob_len + len > ret->keyblob_size) { ret->keyblob_size = ret->keyblob_len + len + 256; ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); } memcpy(ret->keyblob + ret->keyblob_len, out, len); ret->keyblob_len += len; } p++; } } } if (ret->keyblob_len == 0 || !ret->keyblob) { errmsg = "Key body not present"; goto error; } return ret; error: if (ret) { if (ret->keyblob) { memset(ret->keyblob, 0, ret->keyblob_size); sfree(ret->keyblob); } memset(&ret, 0, sizeof(ret)); sfree(ret); } return NULL; } int sshcom_encrypted(char *filename, char **comment) { struct sshcom_key *key = load_sshcom_key(filename); int pos, len, answer; *comment = NULL; if (!key) return 0; /* * Check magic number. */ if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) return 0; /* key is invalid */ /* * Find the cipher-type string. */ answer = 0; pos = 8; if (key->keyblob_len < pos+4) goto done; /* key is far too short */ pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ if (key->keyblob_len < pos+4) goto done; /* key is far too short */ len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ if (key->keyblob_len < pos+4+len) goto done; /* cipher type string is incomplete */ if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) answer = 1; done: *comment = dupstr(key->comment); memset(key->keyblob, 0, key->keyblob_size); sfree(key->keyblob); memset(&key, 0, sizeof(key)); sfree(key); return answer; } struct mpint_pos { void *start; int bytes; }; int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) { int bits; int bytes; unsigned char *d = (unsigned char *) data; if (len < 4) goto error; bits = GET_32BIT(d); bytes = (bits + 7) / 8; if (len < 4+bytes) goto error; ret->start = d + 4; ret->bytes = bytes; return bytes+4; error: ret->start = NULL; ret->bytes = -1; return len; /* ensure further calls fail as well */ } struct ssh2_userkey *sshcom_read(char *filename, char *passphrase) { struct sshcom_key *key = load_sshcom_key(filename); char *errmsg; int pos, len; const char prefix_rsa[] = "if-modn{sign{rsa"; const char prefix_dsa[] = "dl-modp{sign{dsa"; enum { RSA, DSA } type; int encrypted; char *ciphertext; int cipherlen; struct ssh2_userkey *ret = NULL, *retkey; const struct ssh_signkey *alg; unsigned char *blob = NULL; int blobsize, publen, privlen; if (!key) return NULL; /* * Check magic number. */ if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) { errmsg = "Key does not begin with magic number"; goto error; } /* * Determine the key type. */ pos = 8; if (key->keyblob_len < pos+4 || (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { errmsg = "Key blob does not contain a key type string"; goto error; } if (len > sizeof(prefix_rsa) - 1 && !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { type = RSA; } else if (len > sizeof(prefix_dsa) - 1 && !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { type = DSA; } else { errmsg = "Key is of unknown type"; goto error; } pos += 4+len; /* * Determine the cipher type. */ if (key->keyblob_len < pos+4 || (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { errmsg = "Key blob does not contain a cipher type string"; goto error; } if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) encrypted = 0; else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) encrypted = 1; else { errmsg = "Key encryption is of unknown type"; goto error; } pos += 4+len; /* * Get hold of the encrypted part of the key. */ if (key->keyblob_len < pos+4 || (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { errmsg = "Key blob does not contain actual key data"; goto error; } ciphertext = key->keyblob + pos + 4; cipherlen = len; if (cipherlen == 0) { errmsg = "Length of key data is zero"; goto error; } /* * Decrypt it if necessary. */ if (encrypted) { /* * Derive encryption key from passphrase and iv/salt: * * - let block A equal MD5(passphrase) * - let block B equal MD5(passphrase || A) * - block C would be MD5(passphrase || A || B) and so on * - encryption key is the first N bytes of A || B */ struct MD5Context md5c; unsigned char keybuf[32], iv[8]; if (cipherlen % 8 != 0) { errmsg = "Encrypted part of key is not a multiple of cipher block" " size"; goto error; } MD5Init(&md5c); MD5Update(&md5c, passphrase, strlen(passphrase)); MD5Final(keybuf, &md5c); MD5Init(&md5c); MD5Update(&md5c, passphrase, strlen(passphrase)); MD5Update(&md5c, keybuf, 16); MD5Final(keybuf+16, &md5c); /* * Now decrypt the key blob. */ memset(iv, 0, sizeof(iv)); des3_decrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); memset(&md5c, 0, sizeof(md5c)); memset(keybuf, 0, sizeof(keybuf)); /* * Hereafter we return WRONG_PASSPHRASE for any parsing * error. (But only if we've just tried to decrypt it! * Returning WRONG_PASSPHRASE for an unencrypted key is * automatic doom.) */ if (encrypted) ret = SSH2_WRONG_PASSPHRASE; } /* * Strip away the containing string to get to the real meat. */ len = GET_32BIT(ciphertext); if (len > cipherlen-4) { errmsg = "containing string was ill-formed"; goto error; } ciphertext += 4; cipherlen = len; /* * Now we break down into RSA versus DSA. In either case we'll * construct public and private blobs in our own format, and * end up feeding them to alg->createkey(). */ blobsize = cipherlen + 256; blob = smalloc(blobsize); privlen = 0; if (type == RSA) { struct mpint_pos n, e, d, u, p, q; int pos = 0; pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); if (!q.start) { errmsg = "key data did not contain six integers"; goto error; } alg = &ssh_rsa; pos = 0; pos += put_string(blob+pos, "ssh-rsa", 7); pos += put_mp(blob+pos, e.start, e.bytes); pos += put_mp(blob+pos, n.start, n.bytes); publen = pos; pos += put_string(blob+pos, d.start, d.bytes); pos += put_mp(blob+pos, q.start, q.bytes); pos += put_mp(blob+pos, p.start, p.bytes); pos += put_mp(blob+pos, u.start, u.bytes); privlen = pos - publen; } else if (type == DSA) { struct mpint_pos p, q, g, x, y; int pos = 4; if (GET_32BIT(ciphertext) != 0) { errmsg = "predefined DSA parameters not supported"; goto error; } pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); if (!x.start) { errmsg = "key data did not contain five integers"; goto error; } alg = &ssh_dss; pos = 0; pos += put_string(blob+pos, "ssh-dss", 7); pos += put_mp(blob+pos, p.start, p.bytes); pos += put_mp(blob+pos, q.start, q.bytes); pos += put_mp(blob+pos, g.start, g.bytes); pos += put_mp(blob+pos, y.start, y.bytes); publen = pos; pos += put_mp(blob+pos, x.start, x.bytes); privlen = pos - publen; } assert(privlen > 0); /* should have bombed by now if not */ retkey = smalloc(sizeof(struct ssh2_userkey)); retkey->alg = alg; retkey->data = alg->createkey(blob, publen, blob+publen, privlen); if (!retkey->data) { sfree(retkey); errmsg = "unable to create key data structure"; goto error; } retkey->comment = dupstr(key->comment); errmsg = NULL; /* no error */ ret = retkey; error: if (blob) { memset(blob, 0, blobsize); sfree(blob); } memset(key->keyblob, 0, key->keyblob_size); sfree(key->keyblob); memset(&key, 0, sizeof(key)); sfree(key); return ret; }