| /* |
| * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org> |
| * |
| * Permission to use, copy, modify, and distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
| * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
| * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| */ |
| #include "includes.h" |
| |
| #include <openssl/evp.h> |
| #include <openssl/err.h> |
| |
| #include "xmalloc.h" |
| #include "log.h" |
| #include "buffer.h" |
| #include "bufaux.h" |
| #include "key.h" |
| #include "compat.h" |
| #include "ssh.h" |
| |
| static int openssh_RSA_verify(int, u_char *, u_int, u_char *, u_int, RSA *); |
| |
| /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ |
| int |
| ssh_rsa_sign(const Key *key, u_char **sigp, u_int *lenp, |
| const u_char *data, u_int datalen) |
| { |
| const EVP_MD *evp_md; |
| EVP_MD_CTX md; |
| u_char digest[EVP_MAX_MD_SIZE], *sig; |
| u_int slen, dlen, len; |
| int ok, nid; |
| Buffer b; |
| |
| if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { |
| error("ssh_rsa_sign: no RSA key"); |
| return -1; |
| } |
| nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; |
| if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { |
| error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid); |
| return -1; |
| } |
| EVP_DigestInit(&md, evp_md); |
| EVP_DigestUpdate(&md, data, datalen); |
| EVP_DigestFinal(&md, digest, &dlen); |
| |
| slen = RSA_size(key->rsa); |
| sig = xmalloc(slen); |
| |
| ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa); |
| memset(digest, 'd', sizeof(digest)); |
| |
| if (ok != 1) { |
| int ecode = ERR_get_error(); |
| error("ssh_rsa_sign: RSA_sign failed: %s", |
| ERR_error_string(ecode, NULL)); |
| xfree(sig); |
| return -1; |
| } |
| if (len < slen) { |
| u_int diff = slen - len; |
| debug("slen %u > len %u", slen, len); |
| memmove(sig + diff, sig, len); |
| memset(sig, 0, diff); |
| } else if (len > slen) { |
| error("ssh_rsa_sign: slen %u slen2 %u", slen, len); |
| xfree(sig); |
| return -1; |
| } |
| /* encode signature */ |
| buffer_init(&b); |
| buffer_put_cstring(&b, "ssh-rsa"); |
| buffer_put_string(&b, sig, slen); |
| len = buffer_len(&b); |
| if (lenp != NULL) |
| *lenp = len; |
| if (sigp != NULL) { |
| *sigp = xmalloc(len); |
| memcpy(*sigp, buffer_ptr(&b), len); |
| } |
| buffer_free(&b); |
| memset(sig, 's', slen); |
| xfree(sig); |
| |
| return 0; |
| } |
| |
| int |
| ssh_rsa_verify(const Key *key, const u_char *signature, u_int signaturelen, |
| const u_char *data, u_int datalen) |
| { |
| Buffer b; |
| const EVP_MD *evp_md; |
| EVP_MD_CTX md; |
| char *ktype; |
| u_char digest[EVP_MAX_MD_SIZE], *sigblob; |
| u_int len, dlen, modlen; |
| int rlen, ret, nid; |
| |
| if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { |
| error("ssh_rsa_verify: no RSA key"); |
| return -1; |
| } |
| if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) { |
| error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits", |
| BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE); |
| return -1; |
| } |
| buffer_init(&b); |
| buffer_append(&b, signature, signaturelen); |
| ktype = buffer_get_string(&b, NULL); |
| if (strcmp("ssh-rsa", ktype) != 0) { |
| error("ssh_rsa_verify: cannot handle type %s", ktype); |
| buffer_free(&b); |
| xfree(ktype); |
| return -1; |
| } |
| xfree(ktype); |
| sigblob = buffer_get_string(&b, &len); |
| rlen = buffer_len(&b); |
| buffer_free(&b); |
| if (rlen != 0) { |
| error("ssh_rsa_verify: remaining bytes in signature %d", rlen); |
| xfree(sigblob); |
| return -1; |
| } |
| /* RSA_verify expects a signature of RSA_size */ |
| modlen = RSA_size(key->rsa); |
| if (len > modlen) { |
| error("ssh_rsa_verify: len %u > modlen %u", len, modlen); |
| xfree(sigblob); |
| return -1; |
| } else if (len < modlen) { |
| u_int diff = modlen - len; |
| debug("ssh_rsa_verify: add padding: modlen %u > len %u", |
| modlen, len); |
| sigblob = xrealloc(sigblob, modlen); |
| memmove(sigblob + diff, sigblob, len); |
| memset(sigblob, 0, diff); |
| len = modlen; |
| } |
| nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; |
| if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { |
| error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid); |
| xfree(sigblob); |
| return -1; |
| } |
| EVP_DigestInit(&md, evp_md); |
| EVP_DigestUpdate(&md, data, datalen); |
| EVP_DigestFinal(&md, digest, &dlen); |
| |
| ret = openssh_RSA_verify(nid, digest, dlen, sigblob, len, key->rsa); |
| memset(digest, 'd', sizeof(digest)); |
| memset(sigblob, 's', len); |
| xfree(sigblob); |
| debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : ""); |
| return ret; |
| } |
| |
| /* |
| * See: |
| * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/ |
| * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn |
| */ |
| /* |
| * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) |
| * oiw(14) secsig(3) algorithms(2) 26 } |
| */ |
| static const u_char id_sha1[] = { |
| 0x30, 0x21, /* type Sequence, length 0x21 (33) */ |
| 0x30, 0x09, /* type Sequence, length 0x09 */ |
| 0x06, 0x05, /* type OID, length 0x05 */ |
| 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */ |
| 0x05, 0x00, /* NULL */ |
| 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */ |
| }; |
| /* |
| * id-md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) |
| * rsadsi(113549) digestAlgorithm(2) 5 } |
| */ |
| static const u_char id_md5[] = { |
| 0x30, 0x20, /* type Sequence, length 0x20 (32) */ |
| 0x30, 0x0c, /* type Sequence, length 0x09 */ |
| 0x06, 0x08, /* type OID, length 0x05 */ |
| 0x2a, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* id-md5 */ |
| 0x05, 0x00, /* NULL */ |
| 0x04, 0x10 /* Octet string, length 0x10 (16), followed by md5 hash */ |
| }; |
| |
| static int |
| openssh_RSA_verify(int type, u_char *hash, u_int hashlen, |
| u_char *sigbuf, u_int siglen, RSA *rsa) |
| { |
| u_int ret, rsasize, oidlen = 0, hlen = 0; |
| int len; |
| const u_char *oid = NULL; |
| u_char *decrypted = NULL; |
| |
| ret = 0; |
| switch (type) { |
| case NID_sha1: |
| oid = id_sha1; |
| oidlen = sizeof(id_sha1); |
| hlen = 20; |
| break; |
| case NID_md5: |
| oid = id_md5; |
| oidlen = sizeof(id_md5); |
| hlen = 16; |
| break; |
| default: |
| goto done; |
| } |
| if (hashlen != hlen) { |
| error("bad hashlen"); |
| goto done; |
| } |
| rsasize = RSA_size(rsa); |
| if (siglen == 0 || siglen > rsasize) { |
| error("bad siglen"); |
| goto done; |
| } |
| decrypted = xmalloc(rsasize); |
| if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa, |
| RSA_PKCS1_PADDING)) < 0) { |
| error("RSA_public_decrypt failed: %s", |
| ERR_error_string(ERR_get_error(), NULL)); |
| goto done; |
| } |
| if (len < 0 || (u_int)len != hlen + oidlen) { |
| error("bad decrypted len: %d != %d + %d", len, hlen, oidlen); |
| goto done; |
| } |
| if (memcmp(decrypted, oid, oidlen) != 0) { |
| error("oid mismatch"); |
| goto done; |
| } |
| if (memcmp(decrypted + oidlen, hash, hlen) != 0) { |
| error("hash mismatch"); |
| goto done; |
| } |
| ret = 1; |
| done: |
| if (decrypted) |
| xfree(decrypted); |
| return ret; |
| } |