ssh-rsa.c - platform/external/openssh - Git at Google

 /* $OpenBSD: ssh-rsa.c,v 1.52 2014/06/24 01:13:21 djm Exp $ */
 /*
  * 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"

 #ifdef WITH_OPENSSL

 #include <sys/types.h>

 #include <openssl/evp.h>
 #include <openssl/err.h>

 #include <stdarg.h>
 #include <string.h>

 #include "sshbuf.h"
 #include "compat.h"
 #include "ssherr.h"
 #define SSHKEY_INTERNAL
 #include "sshkey.h"
 #include "digest.h"

 static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);

 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
 int
 ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat)
 {
 	int hash_alg;
 	u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;
 	size_t slen;
 	u_int dlen, len;
 	int nid, ret = SSH_ERR_INTERNAL_ERROR;
 	struct sshbuf *b = NULL;

 	if (lenp != NULL)
 		*lenp = 0;
 	if (sigp != NULL)
 		*sigp = NULL;

 	if (key == NULL || key->rsa == NULL ||
 	    sshkey_type_plain(key->type) != KEY_RSA)
 		return SSH_ERR_INVALID_ARGUMENT;
 	slen = RSA_size(key->rsa);
 	if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)
 		return SSH_ERR_INVALID_ARGUMENT;

 	/* hash the data */
 	hash_alg = SSH_DIGEST_SHA1;
 	nid = NID_sha1;
 	if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
 		return SSH_ERR_INTERNAL_ERROR;
 	if ((ret = ssh_digest_memory(hash_alg, data, datalen,
 	    digest, sizeof(digest))) != 0)
 		goto out;

 	if ((sig = malloc(slen)) == NULL) {
 		ret = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}

 	if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
 		ret = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}
 	if (len < slen) {
 		size_t diff = slen - len;
 		memmove(sig + diff, sig, len);
 		explicit_bzero(sig, diff);
 	} else if (len > slen) {
 		ret = SSH_ERR_INTERNAL_ERROR;
 		goto out;
 	}
 	/* encode signature */
 	if ((b = sshbuf_new()) == NULL) {
 		ret = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
 	if ((ret = sshbuf_put_cstring(b, "ssh-rsa")) != 0 ||
 	    (ret = sshbuf_put_string(b, sig, slen)) != 0)
 		goto out;
 	len = sshbuf_len(b);
 	if (sigp != NULL) {
 		if ((*sigp = malloc(len)) == NULL) {
 			ret = SSH_ERR_ALLOC_FAIL;
 			goto out;
 		}
 		memcpy(*sigp, sshbuf_ptr(b), len);
 	}
 	if (lenp != NULL)
 		*lenp = len;
 	ret = 0;
  out:
 	explicit_bzero(digest, sizeof(digest));
 	if (sig != NULL) {
 		explicit_bzero(sig, slen);
 		free(sig);
 	}
 	if (b != NULL)
 		sshbuf_free(b);
 	return 0;
 }

 int
 ssh_rsa_verify(const struct sshkey *key,
     const u_char *signature, size_t signaturelen,
     const u_char *data, size_t datalen, u_int compat)
 {
 	char *ktype = NULL;
 	int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
 	size_t len, diff, modlen, dlen;
 	struct sshbuf *b = NULL;
 	u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL;

 	if (key == NULL || key->rsa == NULL ||
 	    sshkey_type_plain(key->type) != KEY_RSA ||
 	    BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
 		return SSH_ERR_INVALID_ARGUMENT;

 	if ((b = sshbuf_from(signature, signaturelen)) == NULL)
 		return SSH_ERR_ALLOC_FAIL;
 	if (sshbuf_get_cstring(b, &ktype, NULL) != 0) {
 		ret = SSH_ERR_INVALID_FORMAT;
 		goto out;
 	}
 	if (strcmp("ssh-rsa", ktype) != 0) {
 		ret = SSH_ERR_KEY_TYPE_MISMATCH;
 		goto out;
 	}
 	if (sshbuf_get_string(b, &sigblob, &len) != 0) {
 		ret = SSH_ERR_INVALID_FORMAT;
 		goto out;
 	}
 	if (sshbuf_len(b) != 0) {
 		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
 		goto out;
 	}
 	/* RSA_verify expects a signature of RSA_size */
 	modlen = RSA_size(key->rsa);
 	if (len > modlen) {
 		ret = SSH_ERR_KEY_BITS_MISMATCH;
 		goto out;
 	} else if (len < modlen) {
 		diff = modlen - len;
 		osigblob = sigblob;
 		if ((sigblob = realloc(sigblob, modlen)) == NULL) {
 			sigblob = osigblob; /* put it back for clear/free */
 			ret = SSH_ERR_ALLOC_FAIL;
 			goto out;
 		}
 		memmove(sigblob + diff, sigblob, len);
 		explicit_bzero(sigblob, diff);
 		len = modlen;
 	}
 	hash_alg = SSH_DIGEST_SHA1;
 	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
 		ret = SSH_ERR_INTERNAL_ERROR;
 		goto out;
 	}
 	if ((ret = ssh_digest_memory(hash_alg, data, datalen,
 	    digest, sizeof(digest))) != 0)
 		goto out;

 	ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
 	    key->rsa);
  out:
 	if (sigblob != NULL) {
 		explicit_bzero(sigblob, len);
 		free(sigblob);
 	}
 	if (ktype != NULL)
 		free(ktype);
 	if (b != NULL)
 		sshbuf_free(b);
 	explicit_bzero(digest, sizeof(digest));
 	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 */
 };

 static int
 openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
     u_char *sigbuf, size_t siglen, RSA *rsa)
 {
 	size_t ret, rsasize = 0, oidlen = 0, hlen = 0;
 	int len, oidmatch, hashmatch;
 	const u_char *oid = NULL;
 	u_char *decrypted = NULL;

 	ret = SSH_ERR_INTERNAL_ERROR;
 	switch (hash_alg) {
 	case SSH_DIGEST_SHA1:
 		oid = id_sha1;
 		oidlen = sizeof(id_sha1);
 		hlen = 20;
 		break;
 	default:
 		goto done;
 	}
 	if (hashlen != hlen) {
 		ret = SSH_ERR_INVALID_ARGUMENT;
 		goto done;
 	}
 	rsasize = RSA_size(rsa);
 	if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM ||
 	    siglen == 0 || siglen > rsasize) {
 		ret = SSH_ERR_INVALID_ARGUMENT;
 		goto done;
 	}
 	if ((decrypted = malloc(rsasize)) == NULL) {
 		ret = SSH_ERR_ALLOC_FAIL;
 		goto done;
 	}
 	if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
 	    RSA_PKCS1_PADDING)) < 0) {
 		ret = SSH_ERR_LIBCRYPTO_ERROR;
 		goto done;
 	}
 	if (len < 0 || (size_t)len != hlen + oidlen) {
 		ret = SSH_ERR_INVALID_FORMAT;
 		goto done;
 	}
 	oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
 	hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
 	if (!oidmatch || !hashmatch) {
 		ret = SSH_ERR_SIGNATURE_INVALID;
 		goto done;
 	}
 	ret = 0;
 done:
 	if (decrypted) {
 		explicit_bzero(decrypted, rsasize);
 		free(decrypted);
 	}
 	return ret;
 }
 #endif /* WITH_OPENSSL */
	/* $OpenBSD: ssh-rsa.c,v 1.52 2014/06/24 01:13:21 djm Exp $ */
	/*
	* 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"

	#ifdef WITH_OPENSSL

	#include <sys/types.h>

	#include <openssl/evp.h>
	#include <openssl/err.h>

	#include <stdarg.h>
	#include <string.h>

	#include "sshbuf.h"
	#include "compat.h"
	#include "ssherr.h"
	#define SSHKEY_INTERNAL
	#include "sshkey.h"
	#include "digest.h"

	static int openssh_RSA_verify(int, u_char , size_t, u_char , size_t, RSA *);

	/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
	int
	ssh_rsa_sign(const struct sshkey key, u_char sigp, size_t lenp,
	const u_char *data, size_t datalen, u_int compat)
	{
	int hash_alg;
	u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;
	size_t slen;
	u_int dlen, len;
	int nid, ret = SSH_ERR_INTERNAL_ERROR;
	struct sshbuf *b = NULL;

	if (lenp != NULL)
	*lenp = 0;
	if (sigp != NULL)
	*sigp = NULL;

	if (key == NULL \|\| key->rsa == NULL \|\|
	sshkey_type_plain(key->type) != KEY_RSA)
	return SSH_ERR_INVALID_ARGUMENT;
	slen = RSA_size(key->rsa);
	if (slen <= 0 \|\| slen > SSHBUF_MAX_BIGNUM)
	return SSH_ERR_INVALID_ARGUMENT;

	/* hash the data */
	hash_alg = SSH_DIGEST_SHA1;
	nid = NID_sha1;
	if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
	return SSH_ERR_INTERNAL_ERROR;
	if ((ret = ssh_digest_memory(hash_alg, data, datalen,
	digest, sizeof(digest))) != 0)
	goto out;

	if ((sig = malloc(slen)) == NULL) {
	ret = SSH_ERR_ALLOC_FAIL;
	goto out;
	}

	if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
	ret = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}
	if (len < slen) {
	size_t diff = slen - len;
	memmove(sig + diff, sig, len);
	explicit_bzero(sig, diff);
	} else if (len > slen) {
	ret = SSH_ERR_INTERNAL_ERROR;
	goto out;
	}
	/* encode signature */
	if ((b = sshbuf_new()) == NULL) {
	ret = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	if ((ret = sshbuf_put_cstring(b, "ssh-rsa")) != 0 \|\|
	(ret = sshbuf_put_string(b, sig, slen)) != 0)
	goto out;
	len = sshbuf_len(b);
	if (sigp != NULL) {
	if ((*sigp = malloc(len)) == NULL) {
	ret = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	memcpy(*sigp, sshbuf_ptr(b), len);
	}
	if (lenp != NULL)
	*lenp = len;
	ret = 0;
	out:
	explicit_bzero(digest, sizeof(digest));
	if (sig != NULL) {
	explicit_bzero(sig, slen);
	free(sig);
	}
	if (b != NULL)
	sshbuf_free(b);
	return 0;
	}

	int
	ssh_rsa_verify(const struct sshkey *key,
	const u_char *signature, size_t signaturelen,
	const u_char *data, size_t datalen, u_int compat)
	{
	char *ktype = NULL;
	int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
	size_t len, diff, modlen, dlen;
	struct sshbuf *b = NULL;
	u_char digest[SSH_DIGEST_MAX_LENGTH], osigblob, sigblob = NULL;

	if (key == NULL \|\| key->rsa == NULL \|\|
	sshkey_type_plain(key->type) != KEY_RSA \|\|
	BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
	return SSH_ERR_INVALID_ARGUMENT;

	if ((b = sshbuf_from(signature, signaturelen)) == NULL)
	return SSH_ERR_ALLOC_FAIL;
	if (sshbuf_get_cstring(b, &ktype, NULL) != 0) {
	ret = SSH_ERR_INVALID_FORMAT;
	goto out;
	}
	if (strcmp("ssh-rsa", ktype) != 0) {
	ret = SSH_ERR_KEY_TYPE_MISMATCH;
	goto out;
	}
	if (sshbuf_get_string(b, &sigblob, &len) != 0) {
	ret = SSH_ERR_INVALID_FORMAT;
	goto out;
	}
	if (sshbuf_len(b) != 0) {
	ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
	goto out;
	}
	/* RSA_verify expects a signature of RSA_size */
	modlen = RSA_size(key->rsa);
	if (len > modlen) {
	ret = SSH_ERR_KEY_BITS_MISMATCH;
	goto out;
	} else if (len < modlen) {
	diff = modlen - len;
	osigblob = sigblob;
	if ((sigblob = realloc(sigblob, modlen)) == NULL) {
	sigblob = osigblob; /* put it back for clear/free */
	ret = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	memmove(sigblob + diff, sigblob, len);
	explicit_bzero(sigblob, diff);
	len = modlen;
	}
	hash_alg = SSH_DIGEST_SHA1;
	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
	ret = SSH_ERR_INTERNAL_ERROR;
	goto out;
	}
	if ((ret = ssh_digest_memory(hash_alg, data, datalen,
	digest, sizeof(digest))) != 0)
	goto out;

	ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
	key->rsa);
	out:
	if (sigblob != NULL) {
	explicit_bzero(sigblob, len);
	free(sigblob);
	}
	if (ktype != NULL)
	free(ktype);
	if (b != NULL)
	sshbuf_free(b);
	explicit_bzero(digest, sizeof(digest));
	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 */
	};

	static int
	openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
	u_char sigbuf, size_t siglen, RSA rsa)
	{
	size_t ret, rsasize = 0, oidlen = 0, hlen = 0;
	int len, oidmatch, hashmatch;
	const u_char *oid = NULL;
	u_char *decrypted = NULL;

	ret = SSH_ERR_INTERNAL_ERROR;
	switch (hash_alg) {
	case SSH_DIGEST_SHA1:
	oid = id_sha1;
	oidlen = sizeof(id_sha1);
	hlen = 20;
	break;
	default:
	goto done;
	}
	if (hashlen != hlen) {
	ret = SSH_ERR_INVALID_ARGUMENT;
	goto done;
	}
	rsasize = RSA_size(rsa);
	if (rsasize <= 0 \|\| rsasize > SSHBUF_MAX_BIGNUM \|\|
	siglen == 0 \|\| siglen > rsasize) {
	ret = SSH_ERR_INVALID_ARGUMENT;
	goto done;
	}
	if ((decrypted = malloc(rsasize)) == NULL) {
	ret = SSH_ERR_ALLOC_FAIL;
	goto done;
	}
	if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
	RSA_PKCS1_PADDING)) < 0) {
	ret = SSH_ERR_LIBCRYPTO_ERROR;
	goto done;
	}
	if (len < 0 \|\| (size_t)len != hlen + oidlen) {
	ret = SSH_ERR_INVALID_FORMAT;
	goto done;
	}
	oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
	hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
	if (!oidmatch \|\| !hashmatch) {
	ret = SSH_ERR_SIGNATURE_INVALID;
	goto done;
	}
	ret = 0;
	done:
	if (decrypted) {
	explicit_bzero(decrypted, rsasize);
	free(decrypted);
	}
	return ret;
	}
	#endif /* WITH_OPENSSL */