diff options
Diffstat (limited to 'src/keyimport.c')
| -rw-r--r-- | src/keyimport.c | 1147 |
1 files changed, 1147 insertions, 0 deletions
diff --git a/src/keyimport.c b/src/keyimport.c new file mode 100644 index 0000000..e88ef46 --- /dev/null +++ b/src/keyimport.c @@ -0,0 +1,1147 @@ +/* + * Based on PuTTY's import.c for importing/exporting OpenSSH and SSH.com + * keyfiles. + * + * Modifications copyright 2003-2022 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" +#include "ssh.h" +#include "rsa.h" +#include "dss.h" +#include "ed25519.h" +#include "ecdsa.h" +#include "signkey_ossh.h" + +static const unsigned char OSSH_PKEY_BLOB[] = + "openssh-key-v1\0" /* AUTH_MAGIC */ + "\0\0\0\4none" /* cipher name*/ + "\0\0\0\4none" /* kdf name */ + "\0\0\0\0" /* kdf */ + "\0\0\0\1"; /* key num */ +#define OSSH_PKEY_BLOBLEN (sizeof(OSSH_PKEY_BLOB) - 1) +#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. + */ +#if DROPBEAR_DSS +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; +} +#endif /* DROPBEAR_DSS */ + + +/* 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, OSSH_PKEY }; +struct openssh_key { + int type; + int encrypted; + char iv[32]; + /* keyblob is publickey1 onwards (ref OpenSSH PROTOCOL.key) */ + unsigned char *keyblob; + unsigned int keyblob_len, keyblob_size; +}; + +static struct openssh_key *load_openssh_key(const char *filename) +{ + struct openssh_key *ret; + buffer *buf = NULL; + FILE *fp = NULL; + char buffer[256]; + char *errmsg = NULL, *p = NULL; + int headers_done; + unsigned long len; + + 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 if (!strcmp(buffer, "-----BEGIN OPENSSH PRIVATE KEY-----\n")) + ret->type = OSSH_PKEY; + else { + errmsg = "Unrecognised key type"; + goto error; + } + + headers_done = 0; + buf = buf_new(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); + buf = buf_resize(buf, buf->size + len); + buf_putbytes(buf, buffer, len); + } + } + + if (buf && buf->len) { + ret->keyblob_size = ret->keyblob_len + buf->len*4/3 + 256; + ret->keyblob = (unsigned char*)m_realloc(ret->keyblob, ret->keyblob_size); + len = ret->keyblob_size; + if (base64_decode((const unsigned char *)buf->data, buf->len, + ret->keyblob, &len) != CRYPT_OK){ + errmsg = "Error decoding base64"; + goto error; + } + ret->keyblob_len = len; + } + + if (ret->type == OSSH_PKEY) { + if (ret->keyblob_len < OSSH_PKEY_BLOBLEN || + memcmp(ret->keyblob, OSSH_PKEY_BLOB, OSSH_PKEY_BLOBLEN)) { + errmsg = "Error decoding OpenSSH key"; + goto error; + } + ret->keyblob_len -= OSSH_PKEY_BLOBLEN; + memmove(ret->keyblob, ret->keyblob + OSSH_PKEY_BLOBLEN, ret->keyblob_len); + } + + 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; + } + + if (buf) { + buf_burn_free(buf); + } + m_burn(buffer, sizeof(buffer)); + return ret; + +error: + if (buf) { + buf_burn_free(buf); + } + 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 are not supported. Please convert with ssh-keygen first"; + goto error; + } + + /* + * Now we have a decrypted key blob, which contains OpenSSH + * encoded private key. We must now untangle the OpenSSH format. + */ + if (key->type == OSSH_PKEY) { + blobbuf = buf_new(key->keyblob_len); + buf_putbytes(blobbuf, key->keyblob, key->keyblob_len); + buf_setpos(blobbuf, 0); + + /* limit length of public key blob */ + len = buf_getint(blobbuf); + + type = DROPBEAR_SIGNKEY_ANY; + if (buf_get_pub_key(blobbuf, retkey, &type) + != DROPBEAR_SUCCESS) { + errmsg = "Error parsing OpenSSH key"; + goto ossh_error; + } + + /* restore full length */ + buf_setlen(blobbuf, key->keyblob_len); + + /* length of private key part. we can discard it */ + buf_getint(blobbuf); + + /* discard checkkey1 */ + buf_getint(blobbuf); + /* discard checkkey2 */ + buf_getint(blobbuf); + + errmsg = "Unsupported OpenSSH key type"; + retkey->type = type; + ret = DROPBEAR_FAILURE; + /* Parse private key part */ +#if DROPBEAR_RSA + if (type == DROPBEAR_SIGNKEY_RSA) { + errmsg = "Error parsing OpenSSH RSA key"; + ret = buf_get_rsa_priv_ossh(blobbuf, retkey); + } +#endif +#if DROPBEAR_ED25519 + if (type == DROPBEAR_SIGNKEY_ED25519) { + errmsg = "Error parsing OpenSSH ed25519 key"; + ret = buf_get_ed25519_priv_ossh(blobbuf, retkey); + } +#endif +#if DROPBEAR_ECDSA + if (signkey_is_ecdsa(type)) { + errmsg = "Error parsing OpenSSH ecdsa key"; + ret = buf_get_ecdsa_priv_ossh(blobbuf, retkey); + } +#endif + if (ret == DROPBEAR_SUCCESS) { + errmsg = NULL; + retval = retkey; + goto error; + } + +ossh_error: + sign_key_free(retkey); + retkey = NULL; + goto error; + } + + /* + * 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_from_ubin(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_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; + int pos = 0, len = 0, i; + char *header = NULL, *footer = NULL; + int ret = 0; + FILE *fp; + +#if DROPBEAR_DSS + if (key->type == DROPBEAR_SIGNKEY_DSS) { + char zero[1]; + struct mpint_pos numbers[9]; + int nnumbers = -1, seqlen; + /* + * 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'; + + 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"; + } + + /* + * 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 DSS handling */ +#endif /* DROPBEAR_DSS */ + + if (0 +#if DROPBEAR_RSA + || key->type == DROPBEAR_SIGNKEY_RSA +#endif +#if DROPBEAR_ED25519 + || key->type == DROPBEAR_SIGNKEY_ED25519 +#endif +#if DROPBEAR_ECDSA + || signkey_is_ecdsa(key->type) +#endif + ) { + buffer *buf = buf_new(3200); + keyblob = buf_new(3000); + extrablob = buf_new(3100); + + /* private key blob w/o header */ +#if DROPBEAR_RSA + if (key->type == DROPBEAR_SIGNKEY_RSA) { + buf_put_rsa_priv_ossh(keyblob, key); + } +#endif +#if DROPBEAR_ED25519 + if (key->type == DROPBEAR_SIGNKEY_ED25519) { + buf_put_ed25519_priv_ossh(keyblob, key); + } +#endif +#if DROPBEAR_ECDSA + if (signkey_is_ecdsa(key->type)) { + buf_put_ecdsa_priv_ossh(keyblob, key); + } +#endif + + /* header */ + buf_putbytes(buf, OSSH_PKEY_BLOB, OSSH_PKEY_BLOBLEN); + + /* public key */ + buf_put_pub_key(buf, key, key->type); + + /* private key */ + buf_putint(extrablob, 0); /* checkint 1 */ + buf_putint(extrablob, 0); /* checkint 2 */ + /* raw openssh private key */ + buf_putbytes(extrablob, keyblob->data, keyblob->len); + /* comment */ + buf_putstring(extrablob, "", 0); + /* padding to cipher block length */ + len = (extrablob->len+8) & ~7; + for (i = 1; len - extrablob->len > 0; i++) + buf_putbyte(extrablob, i); + buf_setpos(extrablob, 0); + buf_putbytes(extrablob, "\0\0\0\0\0\0\0\0", 8); + buf_putbufstring(buf, extrablob); + + outlen = len = pos = buf->len; + outblob = (unsigned char*)m_malloc(outlen); + memcpy(outblob, buf->data, buf->len); + + buf_burn_free(buf); + buf = NULL; + + header = "-----BEGIN OPENSSH PRIVATE KEY-----\n"; + footer = "-----END OPENSSH PRIVATE KEY-----\n"; + } + + /* + * 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_free(keyblob); + } + if (extrablob) { + buf_burn_free(extrablob); + } + return ret; +} + +/* 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 */ +} |