[thirdparty/openssl.git] / crypto / rsa / rsa_pk1.c

/* crypto/rsa/rsa_pk1.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include "constant_time_locl.h"

#include <stdio.h>
#include "cryptlib.h"
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/rand.h>

int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
	     const unsigned char *from, int flen)
	{
	int j;
	unsigned char *p;

	if (flen > (tlen-RSA_PKCS1_PADDING_SIZE))
		{
		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_1,RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
		return(0);
		}
	
	p=(unsigned char *)to;

	*(p++)=0;
	*(p++)=1; /* Private Key BT (Block Type) */

	/* pad out with 0xff data */
	j=tlen-3-flen;
	memset(p,0xff,j);
	p+=j;
	*(p++)='\0';
	memcpy(p,from,(unsigned int)flen);
	return(1);
	}

int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
	     const unsigned char *from, int flen, int num)
	{
	int i,j;
	const unsigned char *p;

	p=from;
	if ((num != (flen+1)) || (*(p++) != 01))
		{
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_BLOCK_TYPE_IS_NOT_01);
		return(-1);
		}

	/* scan over padding data */
	j=flen-1; /* one for type. */
	for (i=0; i<j; i++)
		{
		if (*p != 0xff) /* should decrypt to 0xff */
			{
			if (*p == 0)
				{ p++; break; }
			else	{
				RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_BAD_FIXED_HEADER_DECRYPT);
				return(-1);
				}
			}
		p++;
		}

	if (i == j)
		{
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_NULL_BEFORE_BLOCK_MISSING);
		return(-1);
		}

	if (i < 8)
		{
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_BAD_PAD_BYTE_COUNT);
		return(-1);
		}
	i++; /* Skip over the '\0' */
	j-=i;
	if (j > tlen)
		{
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_DATA_TOO_LARGE);
		return(-1);
		}
	memcpy(to,p,(unsigned int)j);

	return(j);
	}

int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
	     const unsigned char *from, int flen)
	{
	int i,j;
	unsigned char *p;
	
	if (flen > (tlen-11))
		{
		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2,RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
		return(0);
		}
	
	p=(unsigned char *)to;

	*(p++)=0;
	*(p++)=2; /* Public Key BT (Block Type) */

	/* pad out with non-zero random data */
	j=tlen-3-flen;

	if (RAND_bytes(p,j) <= 0)
		return(0);
	for (i=0; i<j; i++)
		{
		if (*p == '\0')
			do	{
				if (RAND_bytes(p,1) <= 0)
					return(0);
				} while (*p == '\0');
		p++;
		}

	*(p++)='\0';

	memcpy(p,from,(unsigned int)flen);
	return(1);
	}

int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
	     const unsigned char *from, int flen, int num)
	{
	int i;
	/* |em| is the encoded message, zero-padded to exactly |num| bytes */
	unsigned char *em = NULL;
	unsigned int good, found_zero_byte;
	int zero_index = 0, msg_index, mlen = -1;

        if (tlen < 0 || flen < 0)
		return -1;

	/* PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography
	 * Standard", section 7.2.2. */

	if (flen > num)
		goto err;

	if (num < 11)
		goto err;

	em = OPENSSL_malloc(num);
	if (em == NULL)
		{
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE);
		return -1;
		}
	memset(em, 0, num);
	/*
	 * Always do this zero-padding copy (even when num == flen) to avoid
	 * leaking that information. The copy still leaks some side-channel
	 * information, but it's impossible to have a fixed  memory access
	 * pattern since we can't read out of the bounds of |from|.
	 *
	 * TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL.
	 */
	memcpy(em + num - flen, from, flen);

	good = constant_time_is_zero(em[0]);
	good &= constant_time_eq(em[1], 2);

	found_zero_byte = 0;
	for (i = 2; i < num; i++)
		{
		unsigned int equals0 = constant_time_is_zero(em[i]);
		zero_index = constant_time_select_int(~found_zero_byte & equals0, i, zero_index);
		found_zero_byte |= equals0;
		}

	/*
	 * PS must be at least 8 bytes long, and it starts two bytes into |em|.
         * If we never found a 0-byte, then |zero_index| is 0 and the check
	 * also fails.
	 */
	good &= constant_time_ge((unsigned int)(zero_index), 2 + 8);

	/* Skip the zero byte. This is incorrect if we never found a zero-byte
	 * but in this case we also do not copy the message out. */
	msg_index = zero_index + 1;
	mlen = num - msg_index;

	/* For good measure, do this check in constant time as well; it could
	 * leak something if |tlen| was assuming valid padding. */
	good &= constant_time_ge((unsigned int)(tlen), (unsigned int)(mlen));

	/*
	 * We can't continue in constant-time because we need to copy the result
	 * and we cannot fake its length. This unavoidably leaks timing
	 * information at the API boundary.
	 * TODO(emilia): this could be addressed at the call site,
	 * see BoringSSL commit 0aa0767340baf925bda4804882aab0cb974b2d26.
	 */
	if (!good)
		{
		mlen = -1;
		goto err;
		}

	memcpy(to, em + msg_index, mlen);

err:
	if (em != NULL)
		OPENSSL_free(em);
	if (mlen == -1)
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, RSA_R_PKCS_DECODING_ERROR);
	return mlen;
	}
Commit	Line	Data
58964a49 RE	1	/* crypto/rsa/rsa_pk1.c */
	2	/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
	3	* All rights reserved.
	4	*
	5	* This package is an SSL implementation written
	6	* by Eric Young (eay@cryptsoft.com).
	7	* The implementation was written so as to conform with Netscapes SSL.
	8	*
	9	* This library is free for commercial and non-commercial use as long as
	10	* the following conditions are aheared to. The following conditions
	11	* apply to all code found in this distribution, be it the RC4, RSA,
	12	* lhash, DES, etc., code; not just the SSL code. The SSL documentation
	13	* included with this distribution is covered by the same copyright terms
	14	* except that the holder is Tim Hudson (tjh@cryptsoft.com).
	15	*
	16	* Copyright remains Eric Young's, and as such any Copyright notices in
	17	* the code are not to be removed.
	18	* If this package is used in a product, Eric Young should be given attribution
	19	* as the author of the parts of the library used.
	20	* This can be in the form of a textual message at program startup or
	21	* in documentation (online or textual) provided with the package.
	22	*
	23	* Redistribution and use in source and binary forms, with or without
	24	* modification, are permitted provided that the following conditions
	25	* are met:
	26	* 1. Redistributions of source code must retain the copyright
	27	* notice, this list of conditions and the following disclaimer.
	28	* 2. Redistributions in binary form must reproduce the above copyright
	29	* notice, this list of conditions and the following disclaimer in the
	30	* documentation and/or other materials provided with the distribution.
	31	* 3. All advertising materials mentioning features or use of this software
	32	* must display the following acknowledgement:
	33	* "This product includes cryptographic software written by
	34	* Eric Young (eay@cryptsoft.com)"
	35	* The word 'cryptographic' can be left out if the rouines from the library
	36	* being used are not cryptographic related :-).
	37	* 4. If you include any Windows specific code (or a derivative thereof) from
	38	* the apps directory (application code) you must include an acknowledgement:
	39	* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
	40	*
	41	* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
	42	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	43	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	44	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	45	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	46	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	47	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	48	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	49	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	50	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	51	* SUCH DAMAGE.
	52	*
	53	* The licence and distribution terms for any publically available version or
	54	* derivative of this code cannot be changed. i.e. this code cannot simply be
	55	* copied and put under another distribution licence
	56	* [including the GNU Public Licence.]
	57	*/
	58
15b7f5bf	59	#include "constant_time_locl.h"
96e1015e	60
58964a49 RE	61	#include <stdio.h>
58964a49 RE	62	#include "cryptlib.h"
ec577822 BM	63	#include <openssl/bn.h>
	64	#include <openssl/rsa.h>
	65	#include <openssl/rand.h>
58964a49	66
6b691a5c	67	int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
29c1f061	68	const unsigned char *from, int flen)
58964a49 RE	69	{
	70	int j;
	71	unsigned char *p;
	72
ba8ad074	73	if (flen > (tlen-RSA_PKCS1_PADDING_SIZE))
58964a49 RE	74	{
	75	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_1,RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
	76	return(0);
	77	}
	78
	79	p=(unsigned char *)to;
	80
	81	*(p++)=0;
	82	(p++)=1; / Private Key BT (Block Type) */
	83
17ef2916	84	/* pad out with 0xff data */
58964a49 RE	85	j=tlen-3-flen;
	86	memset(p,0xff,j);
	87	p+=j;
	88	*(p++)='\0';
	89	memcpy(p,from,(unsigned int)flen);
	90	return(1);
	91	}
	92
6b691a5c	93	int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
29c1f061	94	const unsigned char *from, int flen, int num)
58964a49 RE	95	{
58964a49 RE	96	int i,j;
29c1f061	97	const unsigned char *p;
58964a49 RE	98
58964a49 RE	99	p=from;
dfeab068	100	if ((num != (flen+1)) \|\| (*(p++) != 01))
58964a49 RE	101	{
	102	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_BLOCK_TYPE_IS_NOT_01);
	103	return(-1);
	104	}
	105
	106	/* scan over padding data */
	107	j=flen-1; /* one for type. */
	108	for (i=0; i<j; i++)
	109	{
	110	if (p != 0xff) / should decrypt to 0xff */
	111	{
	112	if (*p == 0)
	113	{ p++; break; }
	114	else {
	115	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_BAD_FIXED_HEADER_DECRYPT);
	116	return(-1);
	117	}
	118	}
	119	p++;
	120	}
	121
	122	if (i == j)
	123	{
	124	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_NULL_BEFORE_BLOCK_MISSING);
	125	return(-1);
	126	}
	127
	128	if (i < 8)
	129	{
	130	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_BAD_PAD_BYTE_COUNT);
	131	return(-1);
	132	}
	133	i++; /* Skip over the '\0' */
	134	j-=i;
17ef2916 UM	135	if (j > tlen)
	136	{
	137	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,RSA_R_DATA_TOO_LARGE);
	138	return(-1);
	139	}
58964a49 RE	140	memcpy(to,p,(unsigned int)j);
	141
	142	return(j);
	143	}
	144
6b691a5c	145	int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
29c1f061	146	const unsigned char *from, int flen)
58964a49 RE	147	{
	148	int i,j;
	149	unsigned char *p;
	150
	151	if (flen > (tlen-11))
	152	{
	153	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2,RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
	154	return(0);
	155	}
	156
	157	p=(unsigned char *)to;
	158
	159	*(p++)=0;
	160	(p++)=2; / Public Key BT (Block Type) */
	161
	162	/* pad out with non-zero random data */
	163	j=tlen-3-flen;
	164
eb952088 UM	165	if (RAND_bytes(p,j) <= 0)
eb952088 UM	166	return(0);
58964a49 RE	167	for (i=0; i<j; i++)
	168	{
	169	if (*p == '\0')
	170	do {
eb952088 UM	171	if (RAND_bytes(p,1) <= 0)
eb952088 UM	172	return(0);
58964a49 RE	173	} while (*p == '\0');
	174	p++;
	175	}
	176
	177	*(p++)='\0';
	178
	179	memcpy(p,from,(unsigned int)flen);
	180	return(1);
	181	}
	182
6b691a5c	183	int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
29c1f061	184	const unsigned char *from, int flen, int num)
58964a49	185	{
96e1015e EK	186	int i;
	187	/* \|em\| is the encoded message, zero-padded to exactly \|num\| bytes */
	188	unsigned char *em = NULL;
	189	unsigned int good, found_zero_byte;
	190	int zero_index = 0, msg_index, mlen = -1;
58964a49	191
96e1015e EK	192	if (tlen < 0 \|\| flen < 0)
96e1015e EK	193	return -1;
58964a49	194
96e1015e EK	195	/* PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography
96e1015e EK	196	* Standard", section 7.2.2. */
58964a49	197
96e1015e EK	198	if (flen > num)
	199	goto err;
	200
	201	if (num < 11)
	202	goto err;
	203
	204	em = OPENSSL_malloc(num);
	205	if (em == NULL)
58964a49	206	{
96e1015e EK	207	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE);
96e1015e EK	208	return -1;
58964a49	209	}
96e1015e EK	210	memset(em, 0, num);
	211	/*
	212	* Always do this zero-padding copy (even when num == flen) to avoid
	213	* leaking that information. The copy still leaks some side-channel
	214	* information, but it's impossible to have a fixed memory access
	215	* pattern since we can't read out of the bounds of \|from\|.
	216	*
	217	* TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL.
	218	*/
	219	memcpy(em + num - flen, from, flen);
58964a49	220
96e1015e EK	221	good = constant_time_is_zero(em[0]);
	222	good &= constant_time_eq(em[1], 2);
	223
	224	found_zero_byte = 0;
	225	for (i = 2; i < num; i++)
58964a49	226	{
96e1015e EK	227	unsigned int equals0 = constant_time_is_zero(em[i]);
	228	zero_index = constant_time_select_int(~found_zero_byte & equals0, i, zero_index);
	229	found_zero_byte \|= equals0;
58964a49	230	}
96e1015e EK	231
	232	/*
	233	* PS must be at least 8 bytes long, and it starts two bytes into \|em\|.
	234	* If we never found a 0-byte, then \|zero_index\| is 0 and the check
	235	* also fails.
	236	*/
	237	good &= constant_time_ge((unsigned int)(zero_index), 2 + 8);
	238
	239	/* Skip the zero byte. This is incorrect if we never found a zero-byte
	240	* but in this case we also do not copy the message out. */
	241	msg_index = zero_index + 1;
	242	mlen = num - msg_index;
	243
	244	/* For good measure, do this check in constant time as well; it could
	245	* leak something if \|tlen\| was assuming valid padding. */
	246	good &= constant_time_ge((unsigned int)(tlen), (unsigned int)(mlen));
	247
	248	/*
	249	* We can't continue in constant-time because we need to copy the result
	250	* and we cannot fake its length. This unavoidably leaks timing
	251	* information at the API boundary.
	252	* TODO(emilia): this could be addressed at the call site,
	253	* see BoringSSL commit 0aa0767340baf925bda4804882aab0cb974b2d26.
	254	*/
	255	if (!good)
17ef2916	256	{
96e1015e EK	257	mlen = -1;
96e1015e EK	258	goto err;
17ef2916	259	}
58964a49	260
96e1015e	261	memcpy(to, em + msg_index, mlen);
58964a49	262
96e1015e EK	263	err:
	264	if (em != NULL)
	265	OPENSSL_free(em);
	266	if (mlen == -1)
	267	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, RSA_R_PKCS_DECODING_ERROR);
	268	return mlen;
	269	}