/* * Based on PuTTY's import.c for importing/exporting OpenSSH and SSH.com * keyfiles. * * Modifications copyright 2003 Matt Johnston * * PuTTY is copyright 1997-2003 Simon Tatham. * * Portions copyright Robert de Bath, Joris van Rantwijk, Delian * Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry, * Justin Bradford, and CORE SDI S.A. * * Permission is hereby granted, free of charge, to any person * obtaining a copy of this software and associated documentation files * (the "Software"), to deal in the Software without restriction, * including without limitation the rights to use, copy, modify, merge, * publish, distribute, sublicense, and/or sell copies of the Software, * and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "keyimport.h" #include "bignum.h" #include "buffer.h" #include "dbutil.h" #include "ecc.h" #if DROPBEAR_ECDSA static const unsigned char OID_SEC256R1_BLOB[] = {0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07}; static const unsigned char OID_SEC384R1_BLOB[] = {0x2b, 0x81, 0x04, 0x00, 0x22}; static const unsigned char OID_SEC521R1_BLOB[] = {0x2b, 0x81, 0x04, 0x00, 0x23}; #endif #define PUT_32BIT(cp, value) do { \ (cp)[3] = (unsigned char)(value); \ (cp)[2] = (unsigned char)((value) >> 8); \ (cp)[1] = (unsigned char)((value) >> 16); \ (cp)[0] = (unsigned char)((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])) static int openssh_encrypted(const char *filename); static sign_key *openssh_read(const char *filename, const char *passphrase); static int openssh_write(const char *filename, sign_key *key, const char *passphrase); static int dropbear_write(const char*filename, sign_key * key); static sign_key *dropbear_read(const char* filename); static int toint(unsigned u); #if 0 static int sshcom_encrypted(const char *filename, char **comment); static struct ssh2_userkey *sshcom_read(const char *filename, char *passphrase); static int sshcom_write(const char *filename, struct ssh2_userkey *key, char *passphrase); #endif int import_encrypted(const char* filename, int filetype) { if (filetype == KEYFILE_OPENSSH) { return openssh_encrypted(filename); #if 0 } else if (filetype == KEYFILE_SSHCOM) { return sshcom_encrypted(filename, NULL); #endif } return 0; } sign_key *import_read(const char *filename, const char *passphrase, int filetype) { if (filetype == KEYFILE_OPENSSH) { return openssh_read(filename, passphrase); } else if (filetype == KEYFILE_DROPBEAR) { return dropbear_read(filename); #if 0 } else if (filetype == KEYFILE_SSHCOM) { return sshcom_read(filename, passphrase); #endif } return NULL; } int import_write(const char *filename, sign_key *key, const char *passphrase, int filetype) { if (filetype == KEYFILE_OPENSSH) { return openssh_write(filename, key, passphrase); } else if (filetype == KEYFILE_DROPBEAR) { return dropbear_write(filename, key); #if 0 } else if (filetype == KEYFILE_SSHCOM) { return sshcom_write(filename, key, passphrase); #endif } return 0; } static sign_key *dropbear_read(const char* filename) { buffer * buf = NULL; sign_key *ret = NULL; enum signkey_type type; buf = buf_new(MAX_PRIVKEY_SIZE); if (buf_readfile(buf, filename) == DROPBEAR_FAILURE) { goto error; } buf_setpos(buf, 0); ret = new_sign_key(); type = DROPBEAR_SIGNKEY_ANY; if (buf_get_priv_key(buf, ret, &type) == DROPBEAR_FAILURE){ goto error; } buf_free(buf); ret->type = type; return ret; error: if (buf) { buf_free(buf); } if (ret) { sign_key_free(ret); } return NULL; } /* returns 0 on fail, 1 on success */ static int dropbear_write(const char*filename, sign_key * key) { buffer * buf; FILE*fp; int len; int ret; buf = buf_new(MAX_PRIVKEY_SIZE); buf_put_priv_key(buf, key, key->type); fp = fopen(filename, "w"); if (!fp) { ret = 0; goto out; } buf_setpos(buf, 0); do { len = fwrite(buf_getptr(buf, buf->len - buf->pos), 1, buf->len - buf->pos, fp); buf_incrpos(buf, len); } while (len > 0 && buf->len != buf->pos); fclose(fp); if (buf->pos != buf->len) { ret = 0; } else { ret = 1; } out: buf_free(buf); return ret; } /* ---------------------------------------------------------------------- * 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) == '=' \ ) /* cpl has to be less than 100 */ static void base64_encode_fp(FILE * fp, const unsigned char *data, int datalen, int cpl) { unsigned char out[100]; int n; unsigned long outlen; int rawcpl; rawcpl = cpl * 3 / 4; dropbear_assert((unsigned int)cpl < sizeof(out)); while (datalen > 0) { n = (datalen < rawcpl ? datalen : rawcpl); outlen = sizeof(out); base64_encode(data, n, out, &outlen); data += n; datalen -= n; fwrite(out, 1, outlen, fp); fputc('\n', fp); } } /* * 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) static 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) { 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) { unsigned len; int n = *p & 0x7F; p++, sourcelen--; if (sourcelen < n) return -1; len = 0; while (n--) len = (len << 8) | (*p++); sourcelen -= n; *length = toint(len); } else { *length = *p; p++, sourcelen--; } if (*length < 0) { printf("Negative ASN.1 length\n"); return -1; } return p - (unsigned char *) source; } /* * Write an ASN.1/BER identifier and length pair. Returns the * number of bytes consumed. Assumes dest contains enough space. * Will avoid writing anything if dest is NULL, but still return * amount of space required. */ static int ber_write_id_len(void *dest, int id, int length, int flags) { unsigned char *d = (unsigned char *)dest; int len = 0; if (id <= 30) { /* * Identifier is one byte. */ len++; if (d) *d++ = id | flags; } else { int n; /* * Identifier is multiple bytes: the first byte is 11111 * plus the flags, and subsequent bytes encode the value of * the identifier, 7 bits at a time, with the top bit of * each byte 1 except the last one which is 0. */ len++; if (d) *d++ = 0x1F | flags; for (n = 1; (id >> (7*n)) > 0; n++) continue; /* count the bytes */ while (n--) { len++; if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); } } if (length < 128) { /* * Length is one byte. */ len++; if (d) *d++ = length; } else { int n; /* * Length is multiple bytes. The first is 0x80 plus the * number of subsequent bytes, and the subsequent bytes * encode the actual length. */ for (n = 1; (length >> (8*n)) > 0; n++) continue; /* count the bytes */ len++; if (d) *d++ = 0x80 | n; while (n--) { len++; if (d) *d++ = (length >> (8*n)) & 0xFF; } } return len; } /* Simple structure to point to an mp-int within a blob. */ struct mpint_pos { void *start; int bytes; }; /* ---------------------------------------------------------------------- * Code to read and write OpenSSH private keys. */ enum { OSSH_DSA, OSSH_RSA, OSSH_EC }; struct openssh_key { int type; int encrypted; char iv[32]; unsigned char *keyblob; unsigned int keyblob_len, keyblob_size; }; static struct openssh_key *load_openssh_key(const char *filename) { struct openssh_key *ret; FILE *fp = NULL; char buffer[256]; char *errmsg = NULL, *p = NULL; int headers_done; unsigned long len, outlen; ret = (struct openssh_key*)m_malloc(sizeof(struct openssh_key)); ret->keyblob = NULL; ret->keyblob_len = ret->keyblob_size = 0; ret->encrypted = 0; memset(ret->iv, 0, sizeof(ret->iv)); if (strlen(filename) == 1 && filename[0] == '-') { fp = stdin; } else { 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 if (!strcmp(buffer, "-----BEGIN EC PRIVATE KEY-----\n")) ret->type = OSSH_EC; 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; len = strlen(buffer); outlen = len*4/3; if (ret->keyblob_len + outlen > ret->keyblob_size) { ret->keyblob_size = ret->keyblob_len + outlen + 256; ret->keyblob = (unsigned char*)m_realloc(ret->keyblob, ret->keyblob_size); } outlen = ret->keyblob_size - ret->keyblob_len; if (base64_decode((const unsigned char *)buffer, len, ret->keyblob + ret->keyblob_len, &outlen) != CRYPT_OK){ errmsg = "Error decoding base64"; goto error; } ret->keyblob_len += outlen; } } 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; } m_burn(buffer, sizeof(buffer)); return ret; error: m_burn(buffer, sizeof(buffer)); if (ret) { if (ret->keyblob) { m_burn(ret->keyblob, ret->keyblob_size); m_free(ret->keyblob); } m_free(ret); } if (fp) { fclose(fp); } if (errmsg) { fprintf(stderr, "Error: %s\n", errmsg); } return NULL; } static int openssh_encrypted(const char *filename) { struct openssh_key *key = load_openssh_key(filename); int ret; if (!key) return 0; ret = key->encrypted; m_burn(key->keyblob, key->keyblob_size); m_free(key->keyblob); m_free(key); return ret; } static sign_key *openssh_read(const char *filename, const char * UNUSED(passphrase)) { struct openssh_key *key; unsigned char *p; int ret, id, len, flags; int i, num_integers = 0; sign_key *retval = NULL; char *errmsg; unsigned char *modptr = NULL; int modlen = -9999; enum signkey_type type; sign_key *retkey; buffer * blobbuf = NULL; retkey = new_sign_key(); key = load_openssh_key(filename); if (!key) return NULL; if (key->encrypted) { errmsg = "encrypted keys not supported currently"; goto error; #if 0 /* matt TODO */ /* * 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, (unsigned char *)passphrase, strlen(passphrase)); MD5Update(&md5c, (unsigned char *)key->iv, 8); MD5Final(keybuf, &md5c); MD5Init(&md5c); MD5Update(&md5c, keybuf, 16); MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); MD5Update(&md5c, (unsigned char *)key->iv, 8); MD5Final(keybuf+16, &md5c); /* * Now decrypt the key blob. */ des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv, key->keyblob, key->keyblob_len); memset(&md5c, 0, sizeof(md5c)); memset(keybuf, 0, sizeof(keybuf)); #endif } /* * 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 || len < 0 || key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure"; goto error; } /* Expect a load of INTEGERs. */ if (key->type == OSSH_RSA) num_integers = 9; else if (key->type == OSSH_DSA) num_integers = 6; else if (key->type == OSSH_EC) num_integers = 1; /* * Space to create key blob in. */ blobbuf = buf_new(3000); #if DROPBEAR_DSS if (key->type == OSSH_DSA) { buf_putstring(blobbuf, "ssh-dss", 7); retkey->type = DROPBEAR_SIGNKEY_DSS; } #endif #if DROPBEAR_RSA if (key->type == OSSH_RSA) { buf_putstring(blobbuf, "ssh-rsa", 7); retkey->type = DROPBEAR_SIGNKEY_RSA; } #endif 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 || len < 0 || key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure"; goto error; } if (i == 0) { /* First integer is a version indicator */ int expected = -1; switch (key->type) { case OSSH_RSA: case OSSH_DSA: expected = 0; break; case OSSH_EC: expected = 1; break; } if (len != 1 || p[0] != expected) { errmsg = "Version number mismatch"; goto error; } } else if (key->type == OSSH_RSA) { /* * OpenSSH key order is n, e, d, p, q, dmp1, dmq1, iqmp * but we want e, n, d, p, q */ if (i == 1) { /* Save the details for after we deal with number 2. */ modptr = p; modlen = len; } else if (i >= 2 && i <= 5) { buf_putstring(blobbuf, (const char*)p, len); if (i == 2) { buf_putstring(blobbuf, (const char*)modptr, modlen); } } } else if (key->type == OSSH_DSA) { /* * OpenSSH key order is p, q, g, y, x, * we want the same. */ buf_putstring(blobbuf, (const char*)p, len); } /* Skip past the number. */ p += len; } #if DROPBEAR_ECDSA if (key->type == OSSH_EC) { unsigned char* private_key_bytes = NULL; int private_key_len = 0; unsigned char* public_key_bytes = NULL; int public_key_len = 0; ecc_key *ecc = NULL; const struct dropbear_ecc_curve *curve = NULL; /* See SEC1 v2, Appendix C.4 */ /* OpenSSL (so OpenSSH) seems to include the optional parts. */ /* privateKey OCTET STRING, */ ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, &id, &len, &flags); p += ret; /* id==4 for octet string */ if (ret < 0 || id != 4 || len < 0 || key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure"; goto error; } private_key_bytes = p; private_key_len = len; p += len; /* parameters [0] ECDomainParameters {{ SECGCurveNames }} OPTIONAL, */ ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, &id, &len, &flags); p += ret; /* id==0 */ if (ret < 0 || id != 0 || len < 0) { errmsg = "ASN.1 decoding failure"; goto error; } ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, &id, &len, &flags); p += ret; /* id==6 for object */ if (ret < 0 || id != 6 || len < 0 || key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure"; goto error; } if (0) {} #if DROPBEAR_ECC_256 else if (len == sizeof(OID_SEC256R1_BLOB) && memcmp(p, OID_SEC256R1_BLOB, len) == 0) { retkey->type = DROPBEAR_SIGNKEY_ECDSA_NISTP256; curve = &ecc_curve_nistp256; } #endif #if DROPBEAR_ECC_384 else if (len == sizeof(OID_SEC384R1_BLOB) && memcmp(p, OID_SEC384R1_BLOB, len) == 0) { retkey->type = DROPBEAR_SIGNKEY_ECDSA_NISTP384; curve = &ecc_curve_nistp384; } #endif #if DROPBEAR_ECC_521 else if (len == sizeof(OID_SEC521R1_BLOB) && memcmp(p, OID_SEC521R1_BLOB, len) == 0) { retkey->type = DROPBEAR_SIGNKEY_ECDSA_NISTP521; curve = &ecc_curve_nistp521; } #endif else { errmsg = "Unknown ECC key type"; goto error; } p += len; /* publicKey [1] BIT STRING OPTIONAL */ ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, &id, &len, &flags); p += ret; /* id==1 */ if (ret < 0 || id != 1 || len < 0) { errmsg = "ASN.1 decoding failure"; goto error; } ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, &id, &len, &flags); p += ret; /* id==3 for bit string */ if (ret < 0 || id != 3 || len < 0 || key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure"; goto error; } public_key_bytes = p+1; public_key_len = len-1; p += len; buf_putbytes(blobbuf, public_key_bytes, public_key_len); ecc = buf_get_ecc_raw_pubkey(blobbuf, curve); if (!ecc) { errmsg = "Error parsing ECC key"; goto error; } m_mp_alloc_init_multi((mp_int**)&ecc->k, NULL); if (mp_read_unsigned_bin(ecc->k, private_key_bytes, private_key_len) != MP_OKAY) { errmsg = "Error parsing ECC key"; goto error; } *signkey_key_ptr(retkey, retkey->type) = ecc; } #endif /* DROPBEAR_ECDSA */ /* * 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. */ if (key->type == OSSH_RSA || key->type == OSSH_DSA) { buf_setpos(blobbuf, 0); type = DROPBEAR_SIGNKEY_ANY; if (buf_get_priv_key(blobbuf, retkey, &type) != DROPBEAR_SUCCESS) { errmsg = "unable to create key structure"; sign_key_free(retkey); retkey = NULL; goto error; } } errmsg = NULL; /* no error */ retval = retkey; error: if (blobbuf) { buf_burn(blobbuf); buf_free(blobbuf); } m_burn(key->keyblob, key->keyblob_size); m_free(key->keyblob); m_burn(key, sizeof(*key)); m_free(key); if (errmsg) { fprintf(stderr, "Error: %s\n", errmsg); } return retval; } static int openssh_write(const char *filename, sign_key *key, const char *passphrase) { buffer * keyblob = NULL; buffer * extrablob = NULL; /* used for calculated values to write */ unsigned char *outblob = NULL; int outlen = -9999; struct mpint_pos numbers[9]; int nnumbers = -1, pos = 0, len = 0, seqlen, i; char *header = NULL, *footer = NULL; char zero[1]; int ret = 0; FILE *fp; #if DROPBEAR_RSA mp_int dmp1, dmq1, iqmp, tmpval; /* for rsa */ #endif if ( #if DROPBEAR_RSA key->type == DROPBEAR_SIGNKEY_RSA || #endif #if DROPBEAR_DSS key->type == DROPBEAR_SIGNKEY_DSS || #endif 0) { /* * Fetch the key blobs. */ keyblob = buf_new(3000); buf_put_priv_key(keyblob, key, key->type); buf_setpos(keyblob, 0); /* skip the "ssh-rsa" or "ssh-dss" header */ buf_incrpos(keyblob, buf_getint(keyblob)); /* * Find the sequence of integers to be encoded into the OpenSSH * key blob, and also decide on the header line. */ numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; #ifdef DROPBEAR_RSA if (key->type == DROPBEAR_SIGNKEY_RSA) { if (key->rsakey->p == NULL || key->rsakey->q == NULL) { fprintf(stderr, "Pre-0.33 Dropbear keys cannot be converted to OpenSSH keys.\n"); goto error; } /* e */ numbers[2].bytes = buf_getint(keyblob); numbers[2].start = buf_getptr(keyblob, numbers[2].bytes); buf_incrpos(keyblob, numbers[2].bytes); /* n */ numbers[1].bytes = buf_getint(keyblob); numbers[1].start = buf_getptr(keyblob, numbers[1].bytes); buf_incrpos(keyblob, numbers[1].bytes); /* d */ numbers[3].bytes = buf_getint(keyblob); numbers[3].start = buf_getptr(keyblob, numbers[3].bytes); buf_incrpos(keyblob, numbers[3].bytes); /* p */ numbers[4].bytes = buf_getint(keyblob); numbers[4].start = buf_getptr(keyblob, numbers[4].bytes); buf_incrpos(keyblob, numbers[4].bytes); /* q */ numbers[5].bytes = buf_getint(keyblob); numbers[5].start = buf_getptr(keyblob, numbers[5].bytes); buf_incrpos(keyblob, numbers[5].bytes); /* now calculate some extra parameters: */ m_mp_init(&tmpval); m_mp_init(&dmp1); m_mp_init(&dmq1); m_mp_init(&iqmp); /* dmp1 = d mod (p-1) */ if (mp_sub_d(key->rsakey->p, 1, &tmpval) != MP_OKAY) { fprintf(stderr, "Bignum error for p-1\n"); goto error; } if (mp_mod(key->rsakey->d, &tmpval, &dmp1) != MP_OKAY) { fprintf(stderr, "Bignum error for dmp1\n"); goto error; } /* dmq1 = d mod (q-1) */ if (mp_sub_d(key->rsakey->q, 1, &tmpval) != MP_OKAY) { fprintf(stderr, "Bignum error for q-1\n"); goto error; } if (mp_mod(key->rsakey->d, &tmpval, &dmq1) != MP_OKAY) { fprintf(stderr, "Bignum error for dmq1\n"); goto error; } /* iqmp = (q^-1) mod p */ if (mp_invmod(key->rsakey->q, key->rsakey->p, &iqmp) != MP_OKAY) { fprintf(stderr, "Bignum error for iqmp\n"); goto error; } extrablob = buf_new(2000); buf_putmpint(extrablob, &dmp1); buf_putmpint(extrablob, &dmq1); buf_putmpint(extrablob, &iqmp); buf_setpos(extrablob, 0); mp_clear(&dmp1); mp_clear(&dmq1); mp_clear(&iqmp); mp_clear(&tmpval); /* dmp1 */ numbers[6].bytes = buf_getint(extrablob); numbers[6].start = buf_getptr(extrablob, numbers[6].bytes); buf_incrpos(extrablob, numbers[6].bytes); /* dmq1 */ numbers[7].bytes = buf_getint(extrablob); numbers[7].start = buf_getptr(extrablob, numbers[7].bytes); buf_incrpos(extrablob, numbers[7].bytes); /* iqmp */ numbers[8].bytes = buf_getint(extrablob); numbers[8].start = buf_getptr(extrablob, numbers[8].bytes); buf_incrpos(extrablob, numbers[8].bytes); nnumbers = 9; header = "-----BEGIN RSA PRIVATE KEY-----\n"; footer = "-----END RSA PRIVATE KEY-----\n"; } #endif /* DROPBEAR_RSA */ #ifdef DROPBEAR_DSS if (key->type == DROPBEAR_SIGNKEY_DSS) { /* p */ numbers[1].bytes = buf_getint(keyblob); numbers[1].start = buf_getptr(keyblob, numbers[1].bytes); buf_incrpos(keyblob, numbers[1].bytes); /* q */ numbers[2].bytes = buf_getint(keyblob); numbers[2].start = buf_getptr(keyblob, numbers[2].bytes); buf_incrpos(keyblob, numbers[2].bytes); /* g */ numbers[3].bytes = buf_getint(keyblob); numbers[3].start = buf_getptr(keyblob, numbers[3].bytes); buf_incrpos(keyblob, numbers[3].bytes); /* y */ numbers[4].bytes = buf_getint(keyblob); numbers[4].start = buf_getptr(keyblob, numbers[4].bytes); buf_incrpos(keyblob, numbers[4].bytes); /* x */ numbers[5].bytes = buf_getint(keyblob); numbers[5].start = buf_getptr(keyblob, numbers[5].bytes); buf_incrpos(keyblob, numbers[5].bytes); nnumbers = 6; header = "-----BEGIN DSA PRIVATE KEY-----\n"; footer = "-----END DSA PRIVATE KEY-----\n"; } #endif /* DROPBEAR_DSS */ /* * Now count up the total size of the ASN.1 encoded integers, * so as to determine the length of the containing SEQUENCE. */ len = 0; for (i = 0; i < nnumbers; i++) { len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); len += numbers[i].bytes; } seqlen = len; /* Now add on the SEQUENCE header. */ len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); /* Round up to the cipher block size, ensuring we have at least one * byte of padding (see below). */ outlen = len; if (passphrase) outlen = (outlen+8) &~ 7; /* * Now we know how big outblob needs to be. Allocate it. */ outblob = (unsigned char*)m_malloc(outlen); /* * And write the data into it. */ pos = 0; pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); for (i = 0; i < nnumbers; i++) { pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); pos += numbers[i].bytes; } } /* end RSA and DSS handling */ #if DROPBEAR_ECDSA if (key->type == DROPBEAR_SIGNKEY_ECDSA_NISTP256 || key->type == DROPBEAR_SIGNKEY_ECDSA_NISTP384 || key->type == DROPBEAR_SIGNKEY_ECDSA_NISTP521) { /* SEC1 V2 appendix c.4 ECPrivateKey ::= SEQUENCE { version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), privateKey OCTET STRING, parameters [0] ECDomainParameters {{ SECGCurveNames }} OPTIONAL, publicKey [1] BIT STRING OPTIONAL } */ buffer *seq_buf = buf_new(400); ecc_key **eck = (ecc_key**)signkey_key_ptr(key, key->type); const long curve_size = (*eck)->dp->size; int curve_oid_len = 0; const void* curve_oid = NULL; unsigned long pubkey_size = 2*curve_size+1; int k_size; int err = 0; /* version. less than 10 bytes */ buf_incrwritepos(seq_buf, ber_write_id_len(buf_getwriteptr(seq_buf, 10), 2, 1, 0)); buf_putbyte(seq_buf, 1); /* privateKey */ k_size = mp_unsigned_bin_size((*eck)->k); dropbear_assert(k_size <= curve_size); buf_incrwritepos(seq_buf, ber_write_id_len(buf_getwriteptr(seq_buf, 10), 4, k_size, 0)); mp_to_unsigned_bin((*eck)->k, buf_getwriteptr(seq_buf, k_size)); buf_incrwritepos(seq_buf, k_size); /* SECGCurveNames */ switch (key->type) { case DROPBEAR_SIGNKEY_ECDSA_NISTP256: curve_oid_len = sizeof(OID_SEC256R1_BLOB); curve_oid = OID_SEC256R1_BLOB; break; case DROPBEAR_SIGNKEY_ECDSA_NISTP384: curve_oid_len = sizeof(OID_SEC384R1_BLOB); curve_oid = OID_SEC384R1_BLOB; break; case DROPBEAR_SIGNKEY_ECDSA_NISTP521: curve_oid_len = sizeof(OID_SEC521R1_BLOB); curve_oid = OID_SEC521R1_BLOB; break; default: dropbear_exit("Internal error"); } buf_incrwritepos(seq_buf, ber_write_id_len(buf_getwriteptr(seq_buf, 10), 0, 2+curve_oid_len, 0xa0)); /* object == 6 */ buf_incrwritepos(seq_buf, ber_write_id_len(buf_getwriteptr(seq_buf, 10), 6, curve_oid_len, 0)); buf_putbytes(seq_buf, curve_oid, curve_oid_len); buf_incrwritepos(seq_buf, ber_write_id_len(buf_getwriteptr(seq_buf, 10), 1, 2+1+pubkey_size, 0xa0)); buf_incrwritepos(seq_buf, ber_write_id_len(buf_getwriteptr(seq_buf, 10), 3, 1+pubkey_size, 0)); buf_putbyte(seq_buf, 0); err = ecc_ansi_x963_export(*eck, buf_getwriteptr(seq_buf, pubkey_size), &pubkey_size); if (err != CRYPT_OK) { dropbear_exit("ECC error"); } buf_incrwritepos(seq_buf, pubkey_size); buf_setpos(seq_buf, 0); outblob = (unsigned char*)m_malloc(1000); pos = 0; pos += ber_write_id_len(outblob+pos, 16, seq_buf->len, ASN1_CONSTRUCTED); memcpy(&outblob[pos], seq_buf->data, seq_buf->len); pos += seq_buf->len; len = pos; outlen = len; buf_burn(seq_buf); buf_free(seq_buf); seq_buf = NULL; header = "-----BEGIN EC PRIVATE KEY-----\n"; footer = "-----END EC PRIVATE KEY-----\n"; } #endif /* * Padding on OpenSSH keys is deterministic. The number of * padding bytes is always more than zero, and always at most * the cipher block length. The value of each padding byte is * equal to the number of padding bytes. So a plaintext that's * an exact multiple of the block size will be padded with 08 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a * plaintext one byte less than a multiple of the block size * will be padded with just 01. * * This enables the OpenSSL key decryption function to strip * off the padding algorithmically and return the unpadded * plaintext to the next layer: it looks at the final byte, and * then expects to find that many bytes at the end of the data * with the same value. Those are all removed and the rest is * returned. */ dropbear_assert(pos == len); while (pos < outlen) { outblob[pos++] = outlen - len; } /* * Encrypt the key. */ if (passphrase) { fprintf(stderr, "Encrypted keys aren't supported currently\n"); goto error; } /* * And save it. We'll use Unix line endings just in case it's * subsequently transferred in binary mode. */ if (strlen(filename) == 1 && filename[0] == '-') { fp = stdout; } else { fp = fopen(filename, "wb"); /* ensure Unix line endings */ } if (!fp) { fprintf(stderr, "Failed opening output file\n"); goto error; } fputs(header, fp); base64_encode_fp(fp, outblob, outlen, 64); fputs(footer, fp); fclose(fp); ret = 1; error: if (outblob) { memset(outblob, 0, outlen); m_free(outblob); } if (keyblob) { buf_burn(keyblob); buf_free(keyblob); } if (extrablob) { buf_burn(extrablob); buf_free(extrablob); } return ret; } #if 0 /* XXX TODO ssh.com stuff isn't going yet */ /* ---------------------------------------------------------------------- * 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. */ #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb struct sshcom_key { char comment[256]; /* allowing any length is overkill */ unsigned char *keyblob; int keyblob_len, keyblob_size; }; static struct sshcom_key *load_sshcom_key(const 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 = snew(struct sshcom_key); 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)) > (int)(sizeof(buffer) - (p-buffer) -1) || p[len-1] != '\n' || p[len-2] == '\\') { if (len > (int)((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 = sresize(ret->keyblob, ret->keyblob_size, unsigned char); } 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); m_free(ret->keyblob); } memset(ret, 0, sizeof(*ret)); m_free(ret); } return NULL; } int sshcom_encrypted(const 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 */ len = toint(GET_32BIT(key->keyblob + pos)); if (len < 0 || len > key->keyblob_len - pos - 4) goto done; /* key is far too short */ pos += 4 + len; /* skip key type */ len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */ if (len < 0 || len > key->keyblob_len - pos - 4) 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); m_free(key->keyblob); memset(key, 0, sizeof(*key)); m_free(key); return answer; } static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) { unsigned bits, 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 */ } static int sshcom_put_mpint(void *target, void *data, int len) { unsigned char *d = (unsigned char *)target; unsigned char *i = (unsigned char *)data; int bits = len * 8 - 1; while (bits > 0) { if (*i & (1 << (bits & 7))) break; if (!(bits-- & 7)) i++, len--; } PUT_32BIT(d, bits+1); memcpy(d+4, i, len); return len+4; } sign_key *sshcom_read(const 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 = 0, publen, privlen; if (!key) return NULL; /* * Check magic number. */ if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { 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 = (char *)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, (unsigned char *)passphrase, strlen(passphrase)); MD5Final(keybuf, &md5c); MD5Init(&md5c); MD5Update(&md5c, (unsigned char *)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, (unsigned char *)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 = toint(GET_32BIT(ciphertext)); if (len < 0 || 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 = snewn(blobsize, unsigned char); 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; } else return NULL; dropbear_assert(privlen > 0); /* should have bombed by now if not */ retkey = snew(struct ssh2_userkey); retkey->alg = alg; retkey->data = alg->createkey(blob, publen, blob+publen, privlen); if (!retkey->data) { m_free(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); m_free(blob); } memset(key->keyblob, 0, key->keyblob_size); m_free(key->keyblob); memset(key, 0, sizeof(*key)); m_free(key); return ret; } int sshcom_write(const char *filename, sign_key *key, char *passphrase) { unsigned char *pubblob, *privblob; int publen, privlen; unsigned char *outblob; int outlen; struct mpint_pos numbers[6]; int nnumbers, initial_zero, pos, lenpos, i; char *type; char *ciphertext; int cipherlen; int ret = 0; FILE *fp; /* * Fetch the key blobs. */ pubblob = key->alg->public_blob(key->data, &publen); privblob = key->alg->private_blob(key->data, &privlen); outblob = NULL; /* * Find the sequence of integers to be encoded into the OpenSSH * key blob, and also decide on the header line. */ if (key->alg == &ssh_rsa) { int pos; struct mpint_pos n, e, d, p, q, iqmp; pos = 4 + GET_32BIT(pubblob); pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); pos = 0; pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); dropbear_assert(e.start && iqmp.start); /* can't go wrong */ numbers[0] = e; numbers[1] = d; numbers[2] = n; numbers[3] = iqmp; numbers[4] = q; numbers[5] = p; nnumbers = 6; initial_zero = 0; type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; } else if (key->alg == &ssh_dss) { int pos; struct mpint_pos p, q, g, y, x; pos = 4 + GET_32BIT(pubblob); pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); pos = 0; pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); dropbear_assert(y.start && x.start); /* can't go wrong */ numbers[0] = p; numbers[1] = g; numbers[2] = q; numbers[3] = y; numbers[4] = x; nnumbers = 5; initial_zero = 1; type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; } else { dropbear_assert(0); /* zoinks! */ } /* * Total size of key blob will be somewhere under 512 plus * combined length of integers. We'll calculate the more * precise size as we construct the blob. */ outlen = 512; for (i = 0; i < nnumbers; i++) outlen += 4 + numbers[i].bytes; outblob = snewn(outlen, unsigned char); /* * Create the unencrypted key blob. */ pos = 0; PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; pos += 4; /* length field, fill in later */ pos += put_string(outblob+pos, type, strlen(type)); { char *ciphertype = passphrase ? "3des-cbc" : "none"; pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); } lenpos = pos; /* remember this position */ pos += 4; /* encrypted-blob size */ pos += 4; /* encrypted-payload size */ if (initial_zero) { PUT_32BIT(outblob+pos, 0); pos += 4; } for (i = 0; i < nnumbers; i++) pos += sshcom_put_mpint(outblob+pos, numbers[i].start, numbers[i].bytes); /* Now wrap up the encrypted payload. */ PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); /* Pad encrypted blob to a multiple of cipher block size. */ if (passphrase) { int padding = -(pos - (lenpos+4)) & 7; while (padding--) outblob[pos++] = random_byte(); } ciphertext = (char *)outblob+lenpos+4; cipherlen = pos - (lenpos+4); dropbear_assert(!passphrase || cipherlen % 8 == 0); /* Wrap up the encrypted blob string. */ PUT_32BIT(outblob+lenpos, cipherlen); /* And finally fill in the total length field. */ PUT_32BIT(outblob+4, pos); dropbear_assert(pos < outlen); /* * Encrypt the key. */ if (passphrase) { /* * 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]; MD5Init(&md5c); MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); MD5Final(keybuf, &md5c); MD5Init(&md5c); MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); MD5Update(&md5c, keybuf, 16); MD5Final(keybuf+16, &md5c); /* * Now decrypt the key blob. */ memset(iv, 0, sizeof(iv)); des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, cipherlen); memset(&md5c, 0, sizeof(md5c)); memset(keybuf, 0, sizeof(keybuf)); } /* * And save it. We'll use Unix line endings just in case it's * subsequently transferred in binary mode. */ fp = fopen(filename, "wb"); /* ensure Unix line endings */ if (!fp) goto error; fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); fprintf(fp, "Comment: \""); /* * Comment header is broken with backslash-newline if it goes * over 70 chars. Although it's surrounded by quotes, it * _doesn't_ escape backslashes or quotes within the string. * Don't ask me, I didn't design it. */ { int slen = 60; /* starts at 60 due to "Comment: " */ char *c = key->comment; while ((int)strlen(c) > slen) { fprintf(fp, "%.*s\\\n", slen, c); c += slen; slen = 70; /* allow 70 chars on subsequent lines */ } fprintf(fp, "%s\"\n", c); } base64_encode_fp(fp, outblob, pos, 70); fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); fclose(fp); ret = 1; error: if (outblob) { memset(outblob, 0, outlen); m_free(outblob); } if (privblob) { memset(privblob, 0, privlen); m_free(privblob); } if (pubblob) { memset(pubblob, 0, publen); m_free(pubblob); } return ret; } #endif /* ssh.com stuff disabled */ /* From PuTTY misc.c */ static int toint(unsigned u) { /* * Convert an unsigned to an int, without running into the * undefined behaviour which happens by the strict C standard if * the value overflows. You'd hope that sensible compilers would * do the sensible thing in response to a cast, but actually I * don't trust modern compilers not to do silly things like * assuming that _obviously_ you wouldn't have caused an overflow * and so they can elide an 'if (i < 0)' test immediately after * the cast. * * Sensible compilers ought of course to optimise this entire * function into 'just return the input value'! */ if (u <= (unsigned)INT_MAX) return (int)u; else if (u >= (unsigned)INT_MIN) /* wrap in cast _to_ unsigned is OK */ return INT_MIN + (int)(u - (unsigned)INT_MIN); else return INT_MIN; /* fallback; should never occur on binary machines */ }