ssh-rsa.c - security/openssh-library - Rivoreo Source Code Repositories

 /* $OpenBSD: ssh-rsa.c,v 1.51 2014/02/02 03:44:31 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"

 #include <sys/types.h>

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

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

 #include "xmalloc.h"
 #include "log.h"
 #include "buffer.h"
 #include "key.h"
 #include "compat.h"
 #include "misc.h"
 #include "ssh.h"
 #include "digest.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)
 {
 	int hash_alg;
 	u_char digest[SSH_DIGEST_MAX_LENGTH], *sig;
 	u_int slen, dlen, len;
 	int ok, nid;
 	Buffer b;

 	if (key == NULL || key_type_plain(key->type) != KEY_RSA ||
 	    key->rsa == NULL) {
 		error("%s: no RSA key", __func__);
 		return -1;
 	}

 	/* hash the data */
 	hash_alg = SSH_DIGEST_SHA1;
 	nid = NID_sha1;
 	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
 		error("%s: bad hash algorithm %d", __func__, hash_alg);
 		return -1;
 	}
 	if (ssh_digest_memory(hash_alg, data, datalen,
 	    digest, sizeof(digest)) != 0) {
 		error("%s: ssh_digest_memory failed", __func__);
 		return -1;
 	}

 	slen = RSA_size(key->rsa);
 	sig = xmalloc(slen);

 	ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
 	explicit_bzero(digest, sizeof(digest));

 	if (ok != 1) {
 		int ecode = ERR_get_error();

 		error("%s: RSA_sign failed: %s", __func__,
 		    ERR_error_string(ecode, NULL));
 		free(sig);
 		return -1;
 	}
 	if (len < slen) {
 		u_int diff = slen - len;
 		debug("slen %u > len %u", slen, len);
 		memmove(sig + diff, sig, len);
 		explicit_bzero(sig, diff);
 	} else if (len > slen) {
 		error("%s: slen %u slen2 %u", __func__, slen, len);
 		free(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);
 	explicit_bzero(sig, slen);
 	free(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;
 	int hash_alg;
 	char *ktype;
 	u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob;
 	u_int len, dlen, modlen;
 	int rlen, ret;

 	if (key == NULL || key_type_plain(key->type) != KEY_RSA ||
 	    key->rsa == NULL) {
 		error("%s: no RSA key", __func__);
 		return -1;
 	}

 	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
 		error("%s: RSA modulus too small: %d < minimum %d bits",
 		    __func__, BN_num_bits(key->rsa->n),
 		    SSH_RSA_MINIMUM_MODULUS_SIZE);
 		return -1;
 	}
 	buffer_init(&b);
 	buffer_append(&b, signature, signaturelen);
 	ktype = buffer_get_cstring(&b, NULL);
 	if (strcmp("ssh-rsa", ktype) != 0) {
 		error("%s: cannot handle type %s", __func__, ktype);
 		buffer_free(&b);
 		free(ktype);
 		return -1;
 	}
 	free(ktype);
 	sigblob = buffer_get_string(&b, &len);
 	rlen = buffer_len(&b);
 	buffer_free(&b);
 	if (rlen != 0) {
 		error("%s: remaining bytes in signature %d", __func__, rlen);
 		free(sigblob);
 		return -1;
 	}
 	/* RSA_verify expects a signature of RSA_size */
 	modlen = RSA_size(key->rsa);
 	if (len > modlen) {
 		error("%s: len %u > modlen %u", __func__, len, modlen);
 		free(sigblob);
 		return -1;
 	} else if (len < modlen) {
 		u_int diff = modlen - len;
 		debug("%s: add padding: modlen %u > len %u", __func__,
 		    modlen, len);
 		sigblob = xrealloc(sigblob, 1, modlen);
 		memmove(sigblob + diff, sigblob, len);
 		explicit_bzero(sigblob, diff);
 		len = modlen;
 	}
 	/* hash the data */
 	hash_alg = SSH_DIGEST_SHA1;
 	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
 		error("%s: bad hash algorithm %d", __func__, hash_alg);
 		return -1;
 	}
 	if (ssh_digest_memory(hash_alg, data, datalen,
 	    digest, sizeof(digest)) != 0) {
 		error("%s: ssh_digest_memory failed", __func__);
 		return -1;
 	}

 	ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
 	    key->rsa);
 	explicit_bzero(digest, sizeof(digest));
 	explicit_bzero(sigblob, len);
 	free(sigblob);
 	debug("%s: signature %scorrect", __func__, (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 */
 };

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

 	ret = 0;
 	switch (hash_alg) {
 	case SSH_DIGEST_SHA1:
 		oid = id_sha1;
 		oidlen = sizeof(id_sha1);
 		hlen = 20;
 		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;
 	}
 	oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
 	hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
 	if (!oidmatch) {
 		error("oid mismatch");
 		goto done;
 	}
 	if (!hashmatch) {
 		error("hash mismatch");
 		goto done;
 	}
 	ret = 1;
 done:
 	free(decrypted);
 	return ret;
 }
	/* $OpenBSD: ssh-rsa.c,v 1.51 2014/02/02 03:44:31 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"

	#include <sys/types.h>

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

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

	#include "xmalloc.h"
	#include "log.h"
	#include "buffer.h"
	#include "key.h"
	#include "compat.h"
	#include "misc.h"
	#include "ssh.h"
	#include "digest.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)
	{
	int hash_alg;
	u_char digest[SSH_DIGEST_MAX_LENGTH], *sig;
	u_int slen, dlen, len;
	int ok, nid;
	Buffer b;

	if (key == NULL \|\| key_type_plain(key->type) != KEY_RSA \|\|
	key->rsa == NULL) {
	error("%s: no RSA key", __func__);
	return -1;
	}

	/* hash the data */
	hash_alg = SSH_DIGEST_SHA1;
	nid = NID_sha1;
	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
	error("%s: bad hash algorithm %d", __func__, hash_alg);
	return -1;
	}
	if (ssh_digest_memory(hash_alg, data, datalen,
	digest, sizeof(digest)) != 0) {
	error("%s: ssh_digest_memory failed", __func__);
	return -1;
	}

	slen = RSA_size(key->rsa);
	sig = xmalloc(slen);

	ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
	explicit_bzero(digest, sizeof(digest));

	if (ok != 1) {
	int ecode = ERR_get_error();

	error("%s: RSA_sign failed: %s", __func__,
	ERR_error_string(ecode, NULL));
	free(sig);
	return -1;
	}
	if (len < slen) {
	u_int diff = slen - len;
	debug("slen %u > len %u", slen, len);
	memmove(sig + diff, sig, len);
	explicit_bzero(sig, diff);
	} else if (len > slen) {
	error("%s: slen %u slen2 %u", __func__, slen, len);
	free(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);
	explicit_bzero(sig, slen);
	free(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;
	int hash_alg;
	char *ktype;
	u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob;
	u_int len, dlen, modlen;
	int rlen, ret;

	if (key == NULL \|\| key_type_plain(key->type) != KEY_RSA \|\|
	key->rsa == NULL) {
	error("%s: no RSA key", __func__);
	return -1;
	}

	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
	error("%s: RSA modulus too small: %d < minimum %d bits",
	__func__, BN_num_bits(key->rsa->n),
	SSH_RSA_MINIMUM_MODULUS_SIZE);
	return -1;
	}
	buffer_init(&b);
	buffer_append(&b, signature, signaturelen);
	ktype = buffer_get_cstring(&b, NULL);
	if (strcmp("ssh-rsa", ktype) != 0) {
	error("%s: cannot handle type %s", __func__, ktype);
	buffer_free(&b);
	free(ktype);
	return -1;
	}
	free(ktype);
	sigblob = buffer_get_string(&b, &len);
	rlen = buffer_len(&b);
	buffer_free(&b);
	if (rlen != 0) {
	error("%s: remaining bytes in signature %d", __func__, rlen);
	free(sigblob);
	return -1;
	}
	/* RSA_verify expects a signature of RSA_size */
	modlen = RSA_size(key->rsa);
	if (len > modlen) {
	error("%s: len %u > modlen %u", __func__, len, modlen);
	free(sigblob);
	return -1;
	} else if (len < modlen) {
	u_int diff = modlen - len;
	debug("%s: add padding: modlen %u > len %u", __func__,
	modlen, len);
	sigblob = xrealloc(sigblob, 1, modlen);
	memmove(sigblob + diff, sigblob, len);
	explicit_bzero(sigblob, diff);
	len = modlen;
	}
	/* hash the data */
	hash_alg = SSH_DIGEST_SHA1;
	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
	error("%s: bad hash algorithm %d", __func__, hash_alg);
	return -1;
	}
	if (ssh_digest_memory(hash_alg, data, datalen,
	digest, sizeof(digest)) != 0) {
	error("%s: ssh_digest_memory failed", __func__);
	return -1;
	}

	ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
	key->rsa);
	explicit_bzero(digest, sizeof(digest));
	explicit_bzero(sigblob, len);
	free(sigblob);
	debug("%s: signature %scorrect", __func__, (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 */
	};

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

	ret = 0;
	switch (hash_alg) {
	case SSH_DIGEST_SHA1:
	oid = id_sha1;
	oidlen = sizeof(id_sha1);
	hlen = 20;
	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;
	}
	oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
	hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
	if (!oidmatch) {
	error("oid mismatch");
	goto done;
	}
	if (!hashmatch) {
	error("hash mismatch");
	goto done;
	}
	ret = 1;
	done:
	free(decrypted);
	return ret;
	}