crypto/rsa/rsa_oaep.c - third_party/openssl - Git at Google

 /* crypto/rsa/rsa_oaep.c */
 /* Written by Ulf Moeller. This software is distributed on an "AS IS"
    basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */

 /* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */

 /* See Victor Shoup, "OAEP reconsidered," Nov. 2000,
  * <URL: http://www.shoup.net/papers/oaep.ps.Z>
  * for problems with the security proof for the
  * original OAEP scheme, which EME-OAEP is based on.
  *
  * A new proof can be found in E. Fujisaki, T. Okamoto,
  * D. Pointcheval, J. Stern, "RSA-OEAP is Still Alive!",
  * Dec. 2000, <URL: http://eprint.iacr.org/2000/061/>.
  * The new proof has stronger requirements for the
  * underlying permutation: "partial-one-wayness" instead
  * of one-wayness.  For the RSA function, this is
  * an equivalent notion.
  */

 #define OPENSSL_FIPSAPI


 #if !defined(OPENSSL_NO_SHA) && !defined(OPENSSL_NO_SHA1)
 #include <stdio.h>
 #include "cryptlib.h"
 #include <openssl/bn.h>
 #include <openssl/rsa.h>
 #include <openssl/evp.h>
 #include <openssl/rand.h>
 #include <openssl/sha.h>

 int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
 	const unsigned char *from, int flen,
 	const unsigned char *param, int plen)
 	{
 	return RSA_padding_add_PKCS1_OAEP_mgf1(to, tlen, from, flen,
 						param, plen, NULL, NULL);
 	}

 int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
 	const unsigned char *from, int flen,
 	const unsigned char *param, int plen,
 	const EVP_MD *md, const EVP_MD *mgf1md)
 	{
 	int i, emlen = tlen - 1;
 	unsigned char *db, *seed;
 	unsigned char *dbmask, seedmask[EVP_MAX_MD_SIZE];
 	int mdlen;

 	if (md == NULL)
 		md = EVP_sha1();
 	if (mgf1md == NULL)
 		mgf1md = md;

 	mdlen = EVP_MD_size(md);

 	if (flen > emlen - 2 * mdlen - 1)
 		{
 		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1,
 		   RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
 		return 0;
 		}

 	if (emlen < 2 * mdlen + 1)
 		{
 		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, RSA_R_KEY_SIZE_TOO_SMALL);
 		return 0;
 		}

 	to[0] = 0;
 	seed = to + 1;
 	db = to + mdlen + 1;

 	if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL))
 		return 0;
 	memset(db + mdlen, 0,
 		emlen - flen - 2 * mdlen - 1);
 	db[emlen - flen - mdlen - 1] = 0x01;
 	memcpy(db + emlen - flen - mdlen, from, (unsigned int) flen);
 	if (RAND_bytes(seed, mdlen) <= 0)
 		return 0;
 #ifdef PKCS_TESTVECT
 	memcpy(seed,
 	   "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
 	   20);
 #endif

 	dbmask = OPENSSL_malloc(emlen - mdlen);
 	if (dbmask == NULL)
 		{
 		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
 		return 0;
 		}

 	if (PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md) < 0)
 		return 0;
 	for (i = 0; i < emlen - mdlen; i++)
 		db[i] ^= dbmask[i];

 	if (PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md) < 0)
 		return 0;
 	for (i = 0; i < mdlen; i++)
 		seed[i] ^= seedmask[i];

 	OPENSSL_free(dbmask);
 	return 1;
 	}

 int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
 	const unsigned char *from, int flen, int num,
 	const unsigned char *param, int plen)
 	{
 	return RSA_padding_check_PKCS1_OAEP_mgf1(to, tlen, from , flen, num,
 							param, plen,
 							NULL, NULL);
 	}

 int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
 	const unsigned char *from, int flen, int num,
 	const unsigned char *param, int plen,
 	const EVP_MD *md, const EVP_MD *mgf1md)
 	{
 	int i, dblen, mlen = -1;
 	const unsigned char *maskeddb;
 	int lzero;
 	unsigned char *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
 	unsigned char *padded_from;
 	int bad = 0;
 	int mdlen;

 	if (md == NULL)
 		md = EVP_sha1();
 	if (mgf1md == NULL)
 		mgf1md = md;

 	mdlen = EVP_MD_size(md);

 	if (--num < 2 * mdlen + 1)
 		/* 'num' is the length of the modulus, i.e. does not depend on the
 		 * particular ciphertext. */
 		goto decoding_err;

 	lzero = num - flen;
 	if (lzero < 0)
 		{
 		/* signalling this error immediately after detection might allow
 		 * for side-channel attacks (e.g. timing if 'plen' is huge
 		 * -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA Optimal
 		 * Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001),
 		 * so we use a 'bad' flag */
 		bad = 1;
 		lzero = 0;
 		flen = num; /* don't overflow the memcpy to padded_from */
 		}

 	dblen = num - mdlen;
 	db = OPENSSL_malloc(dblen + num);
 	if (db == NULL)
 		{
 		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
 		return -1;
 		}

 	/* Always do this zero-padding copy (even when lzero == 0)
 	 * to avoid leaking timing info about the value of lzero. */
 	padded_from = db + dblen;
 	memset(padded_from, 0, lzero);
 	memcpy(padded_from + lzero, from, flen);

 	maskeddb = padded_from + mdlen;

 	if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))
 		return -1;
 	for (i = 0; i < mdlen; i++)
 		seed[i] ^= padded_from[i];

 	if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md))
 		return -1;
 	for (i = 0; i < dblen; i++)
 		db[i] ^= maskeddb[i];

 	if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL))
 		return -1;

 	if (CRYPTO_memcmp(db, phash, mdlen) != 0 || bad)
 		goto decoding_err;
 	else
 		{
 		for (i = mdlen; i < dblen; i++)
 			if (db[i] != 0x00)
 				break;
 		if (i == dblen || db[i] != 0x01)
 			goto decoding_err;
 		else
 			{
 			/* everything looks OK */

 			mlen = dblen - ++i;
 			if (tlen < mlen)
 				{
 				RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, RSA_R_DATA_TOO_LARGE);
 				mlen = -1;
 				}
 			else
 				memcpy(to, db + i, mlen);
 			}
 		}
 	OPENSSL_free(db);
 	return mlen;

 decoding_err:
 	/* to avoid chosen ciphertext attacks, the error message should not reveal
 	 * which kind of decoding error happened */
 	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, RSA_R_OAEP_DECODING_ERROR);
 	if (db != NULL) OPENSSL_free(db);
 	return -1;
 	}

 int PKCS1_MGF1(unsigned char *mask, long len,
 	const unsigned char *seed, long seedlen, const EVP_MD *dgst)
 	{
 	long i, outlen = 0;
 	unsigned char cnt[4];
 	EVP_MD_CTX c;
 	unsigned char md[EVP_MAX_MD_SIZE];
 	int mdlen;
 	int rv = -1;

 	EVP_MD_CTX_init(&c);
 	mdlen = M_EVP_MD_size(dgst);
 	if (mdlen < 0)
 		goto err;
 	for (i = 0; outlen < len; i++)
 		{
 		cnt[0] = (unsigned char)((i >> 24) & 255);
 		cnt[1] = (unsigned char)((i >> 16) & 255);
 		cnt[2] = (unsigned char)((i >> 8)) & 255;
 		cnt[3] = (unsigned char)(i & 255);
 		if (!EVP_DigestInit_ex(&c,dgst, NULL)
 			|| !EVP_DigestUpdate(&c, seed, seedlen)
 			|| !EVP_DigestUpdate(&c, cnt, 4))
 			goto err;
 		if (outlen + mdlen <= len)
 			{
 			if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))
 				goto err;
 			outlen += mdlen;
 			}
 		else
 			{
 			if (!EVP_DigestFinal_ex(&c, md, NULL))
 				goto err;
 			memcpy(mask + outlen, md, len - outlen);
 			outlen = len;
 			}
 		}
 	rv = 0;
 	err:
 	EVP_MD_CTX_cleanup(&c);
 	return rv;
 	}

 #endif
	/* crypto/rsa/rsa_oaep.c */
	/* Written by Ulf Moeller. This software is distributed on an "AS IS"
	basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */

	/* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */

	/* See Victor Shoup, "OAEP reconsidered," Nov. 2000,
	* <URL: http://www.shoup.net/papers/oaep.ps.Z>
	* for problems with the security proof for the
	* original OAEP scheme, which EME-OAEP is based on.
	*
	* A new proof can be found in E. Fujisaki, T. Okamoto,
	* D. Pointcheval, J. Stern, "RSA-OEAP is Still Alive!",
	* Dec. 2000, <URL: http://eprint.iacr.org/2000/061/>.
	* The new proof has stronger requirements for the
	* underlying permutation: "partial-one-wayness" instead
	* of one-wayness. For the RSA function, this is
	* an equivalent notion.
	*/

	#define OPENSSL_FIPSAPI


	#if !defined(OPENSSL_NO_SHA) && !defined(OPENSSL_NO_SHA1)
	#include <stdio.h>
	#include "cryptlib.h"
	#include <openssl/bn.h>
	#include <openssl/rsa.h>
	#include <openssl/evp.h>
	#include <openssl/rand.h>
	#include <openssl/sha.h>

	int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
	const unsigned char *from, int flen,
	const unsigned char *param, int plen)
	{
	return RSA_padding_add_PKCS1_OAEP_mgf1(to, tlen, from, flen,
	param, plen, NULL, NULL);
	}

	int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
	const unsigned char *from, int flen,
	const unsigned char *param, int plen,
	const EVP_MD md, const EVP_MD mgf1md)
	{
	int i, emlen = tlen - 1;
	unsigned char db, seed;
	unsigned char *dbmask, seedmask[EVP_MAX_MD_SIZE];
	int mdlen;

	if (md == NULL)
	md = EVP_sha1();
	if (mgf1md == NULL)
	mgf1md = md;

	mdlen = EVP_MD_size(md);

	if (flen > emlen - 2 * mdlen - 1)
	{
	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1,
	RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
	return 0;
	}

	if (emlen < 2 * mdlen + 1)
	{
	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, RSA_R_KEY_SIZE_TOO_SMALL);
	return 0;
	}

	to[0] = 0;
	seed = to + 1;
	db = to + mdlen + 1;

	if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL))
	return 0;
	memset(db + mdlen, 0,
	emlen - flen - 2 * mdlen - 1);
	db[emlen - flen - mdlen - 1] = 0x01;
	memcpy(db + emlen - flen - mdlen, from, (unsigned int) flen);
	if (RAND_bytes(seed, mdlen) <= 0)
	return 0;
	#ifdef PKCS_TESTVECT
	memcpy(seed,
	"\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
	20);
	#endif

	dbmask = OPENSSL_malloc(emlen - mdlen);
	if (dbmask == NULL)
	{
	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
	return 0;
	}

	if (PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md) < 0)
	return 0;
	for (i = 0; i < emlen - mdlen; i++)
	db[i] ^= dbmask[i];

	if (PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md) < 0)
	return 0;
	for (i = 0; i < mdlen; i++)
	seed[i] ^= seedmask[i];

	OPENSSL_free(dbmask);
	return 1;
	}

	int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
	const unsigned char *from, int flen, int num,
	const unsigned char *param, int plen)
	{
	return RSA_padding_check_PKCS1_OAEP_mgf1(to, tlen, from , flen, num,
	param, plen,
	NULL, NULL);
	}

	int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
	const unsigned char *from, int flen, int num,
	const unsigned char *param, int plen,
	const EVP_MD md, const EVP_MD mgf1md)
	{
	int i, dblen, mlen = -1;
	const unsigned char *maskeddb;
	int lzero;
	unsigned char *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
	unsigned char *padded_from;
	int bad = 0;
	int mdlen;

	if (md == NULL)
	md = EVP_sha1();
	if (mgf1md == NULL)
	mgf1md = md;

	mdlen = EVP_MD_size(md);

	if (--num < 2 * mdlen + 1)
	/* 'num' is the length of the modulus, i.e. does not depend on the
	* particular ciphertext. */
	goto decoding_err;

	lzero = num - flen;
	if (lzero < 0)
	{
	/* signalling this error immediately after detection might allow
	* for side-channel attacks (e.g. timing if 'plen' is huge
	* -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA Optimal
	* Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001),
	* so we use a 'bad' flag */
	bad = 1;
	lzero = 0;
	flen = num; /* don't overflow the memcpy to padded_from */
	}

	dblen = num - mdlen;
	db = OPENSSL_malloc(dblen + num);
	if (db == NULL)
	{
	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
	return -1;
	}

	/* Always do this zero-padding copy (even when lzero == 0)
	* to avoid leaking timing info about the value of lzero. */
	padded_from = db + dblen;
	memset(padded_from, 0, lzero);
	memcpy(padded_from + lzero, from, flen);

	maskeddb = padded_from + mdlen;

	if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))
	return -1;
	for (i = 0; i < mdlen; i++)
	seed[i] ^= padded_from[i];

	if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md))
	return -1;
	for (i = 0; i < dblen; i++)
	db[i] ^= maskeddb[i];

	if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL))
	return -1;

	if (CRYPTO_memcmp(db, phash, mdlen) != 0 \|\| bad)
	goto decoding_err;
	else
	{
	for (i = mdlen; i < dblen; i++)
	if (db[i] != 0x00)
	break;
	if (i == dblen \|\| db[i] != 0x01)
	goto decoding_err;
	else
	{
	/* everything looks OK */

	mlen = dblen - ++i;
	if (tlen < mlen)
	{
	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, RSA_R_DATA_TOO_LARGE);
	mlen = -1;
	}
	else
	memcpy(to, db + i, mlen);
	}
	}
	OPENSSL_free(db);
	return mlen;

	decoding_err:
	/* to avoid chosen ciphertext attacks, the error message should not reveal
	* which kind of decoding error happened */
	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, RSA_R_OAEP_DECODING_ERROR);
	if (db != NULL) OPENSSL_free(db);
	return -1;
	}

	int PKCS1_MGF1(unsigned char *mask, long len,
	const unsigned char seed, long seedlen, const EVP_MD dgst)
	{
	long i, outlen = 0;
	unsigned char cnt[4];
	EVP_MD_CTX c;
	unsigned char md[EVP_MAX_MD_SIZE];
	int mdlen;
	int rv = -1;

	EVP_MD_CTX_init(&c);
	mdlen = M_EVP_MD_size(dgst);
	if (mdlen < 0)
	goto err;
	for (i = 0; outlen < len; i++)
	{
	cnt[0] = (unsigned char)((i >> 24) & 255);
	cnt[1] = (unsigned char)((i >> 16) & 255);
	cnt[2] = (unsigned char)((i >> 8)) & 255;
	cnt[3] = (unsigned char)(i & 255);
	if (!EVP_DigestInit_ex(&c,dgst, NULL)
	\|\| !EVP_DigestUpdate(&c, seed, seedlen)
	\|\| !EVP_DigestUpdate(&c, cnt, 4))
	goto err;
	if (outlen + mdlen <= len)
	{
	if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))
	goto err;
	outlen += mdlen;
	}
	else
	{
	if (!EVP_DigestFinal_ex(&c, md, NULL))
	goto err;
	memcpy(mask + outlen, md, len - outlen);
	outlen = len;
	}
	}
	rv = 0;
	err:
	EVP_MD_CTX_cleanup(&c);
	return rv;
	}

	#endif