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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libcrypto/crypto/../../libssl/src/crypto/rsa/rsa_oaep.c	Lines:	0	100	0.0 %
Date:	2016-12-06	Branches:	0	62	0.0 %


/* $OpenBSD: rsa_oaep.c,v 1.25 2015/06/20 12:01:14 jsing Exp $ */
/* 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.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/opensslconf.h>

#if !defined(OPENSSL_NO_SHA) && !defined(OPENSSL_NO_SHA1)

#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/sha.h>

static int MGF1(unsigned char *mask, long len, const unsigned char *seed,
    long seedlen);

int
RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
    const unsigned char *from, int flen, const unsigned char *param, int plen)
{
	int i, emlen = tlen - 1;
	unsigned char *db, *seed;
	unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];

	if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1) {
		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
		    RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
		return 0;
	}

	if (emlen < 2 * SHA_DIGEST_LENGTH + 1) {
		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
		    RSA_R_KEY_SIZE_TOO_SMALL);
		return 0;
	}

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

	if (!EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL))
		return 0;
	memset(db + SHA_DIGEST_LENGTH, 0,
	    emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
	db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
	memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, flen);
	arc4random_buf(seed, SHA_DIGEST_LENGTH);

	dbmask = malloc(emlen - SHA_DIGEST_LENGTH);
	if (dbmask == NULL) {
		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
		return 0;
	}

	if (MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed,
	    SHA_DIGEST_LENGTH) < 0)
		return 0;
	for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
		db[i] ^= dbmask[i];

	if (MGF1(seedmask, SHA_DIGEST_LENGTH, db,
	    emlen - SHA_DIGEST_LENGTH) < 0)
		return 0;
	for (i = 0; i < SHA_DIGEST_LENGTH; i++)
		seed[i] ^= seedmask[i];

	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)
{
	int i, dblen, mlen = -1;
	const unsigned char *maskeddb;
	int lzero;
	unsigned char *db = NULL;
	unsigned char seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
	unsigned char *padded_from;
	int bad = 0;

	if (--num < 2 * SHA_DIGEST_LENGTH + 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 - SHA_DIGEST_LENGTH;
	db = malloc(dblen + num);
	if (db == NULL) {
		RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
		    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 + SHA_DIGEST_LENGTH;

	if (MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen))
		return -1;
	for (i = 0; i < SHA_DIGEST_LENGTH; i++)
		seed[i] ^= padded_from[i];

	if (MGF1(db, dblen, seed, SHA_DIGEST_LENGTH))
		return -1;
	for (i = 0; i < dblen; i++)
		db[i] ^= maskeddb[i];

	if (!EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL))
		return -1;

	if (timingsafe_memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 || bad)
		goto decoding_err;
	else {
		for (i = SHA_DIGEST_LENGTH; 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,
				    RSA_R_DATA_TOO_LARGE);
				mlen = -1;
			} else
				memcpy(to, db + i, mlen);
		}
	}
	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, RSA_R_OAEP_DECODING_ERROR);
	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 = 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;
}

static int
MGF1(unsigned char *mask, long len, const unsigned char *seed, long seedlen)
{
	return PKCS1_MGF1(mask, len, seed, seedlen, EVP_sha1());
}
#endif


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: rsa_oaep.c,v 1.25 2015/06/20 12:01:14 jsing Exp $ */
2			/* Written by Ulf Moeller. This software is distributed on an "AS IS"
3			basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */
4
5			/* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */
6
7			/* See Victor Shoup, "OAEP reconsidered," Nov. 2000,
8			* <URL: http://www.shoup.net/papers/oaep.ps.Z>
9			* for problems with the security proof for the
10			* original OAEP scheme, which EME-OAEP is based on.
11			*
12			* A new proof can be found in E. Fujisaki, T. Okamoto,
13			* D. Pointcheval, J. Stern, "RSA-OEAP is Still Alive!",
14			* Dec. 2000, <URL: http://eprint.iacr.org/2000/061/>.
15			* The new proof has stronger requirements for the
16			* underlying permutation: "partial-one-wayness" instead
17			* of one-wayness. For the RSA function, this is
18			* an equivalent notion.
19			*/
20
21			#include <stdio.h>
22			#include <stdlib.h>
23			#include <string.h>
24
25			#include <openssl/opensslconf.h>
26
27			#if !defined(OPENSSL_NO_SHA) && !defined(OPENSSL_NO_SHA1)
28
29			#include <openssl/bn.h>
30			#include <openssl/err.h>
31			#include <openssl/evp.h>
32			#include <openssl/rsa.h>
33			#include <openssl/sha.h>
34
35			static int MGF1(unsigned char mask, long len, const unsigned char seed,
36			long seedlen);
37
38			int
39			RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
40			const unsigned char from, int flen, const unsigned char param, int plen)
41			{
42			int i, emlen = tlen - 1;
43			unsigned char db, seed;
44			unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];
45
46			if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1) {
47			RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
48			RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
49			return 0;
50			}
51
52			if (emlen < 2 * SHA_DIGEST_LENGTH + 1) {
53			RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
54			RSA_R_KEY_SIZE_TOO_SMALL);
55			return 0;
56			}
57
58			to[0] = 0;
59			seed = to + 1;
60			db = to + SHA_DIGEST_LENGTH + 1;
61
62			if (!EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL))
63			return 0;
64			memset(db + SHA_DIGEST_LENGTH, 0,
65			emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
66			db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
67			memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, flen);
68			arc4random_buf(seed, SHA_DIGEST_LENGTH);
69
70			dbmask = malloc(emlen - SHA_DIGEST_LENGTH);
71			if (dbmask == NULL) {
72			RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
73			return 0;
74			}
75
76			if (MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed,
77			SHA_DIGEST_LENGTH) < 0)
78			return 0;
79			for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
80			db[i] ^= dbmask[i];
81
82			if (MGF1(seedmask, SHA_DIGEST_LENGTH, db,
83			emlen - SHA_DIGEST_LENGTH) < 0)
84			return 0;
85			for (i = 0; i < SHA_DIGEST_LENGTH; i++)
86			seed[i] ^= seedmask[i];
87
88			free(dbmask);
89			return 1;
90			}
91
92			int
93			RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
94			const unsigned char from, int flen, int num, const unsigned char param,
95			int plen)
96			{
97			int i, dblen, mlen = -1;
98			const unsigned char *maskeddb;
99			int lzero;
100			unsigned char *db = NULL;
101			unsigned char seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
102			unsigned char *padded_from;
103			int bad = 0;
104
105			if (--num < 2 * SHA_DIGEST_LENGTH + 1)
106			/*
107			* 'num' is the length of the modulus, i.e. does not depend
108			* on the particular ciphertext.
109			*/
110			goto decoding_err;
111
112			lzero = num - flen;
113			if (lzero < 0) {
114			/*
115			* signalling this error immediately after detection might allow
116			* for side-channel attacks (e.g. timing if 'plen' is huge
117			* -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA
118			* Optimal Asymmetric Encryption Padding (OAEP) [...]",
119			* CRYPTO 2001), so we use a 'bad' flag
120			*/
121			bad = 1;
122			lzero = 0;
123			flen = num; /* don't overflow the memcpy to padded_from */
124			}
125
126			dblen = num - SHA_DIGEST_LENGTH;
127			db = malloc(dblen + num);
128			if (db == NULL) {
129			RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
130			ERR_R_MALLOC_FAILURE);
131			return -1;
132			}
133
134			/*
135			* Always do this zero-padding copy (even when lzero == 0)
136			* to avoid leaking timing info about the value of lzero.
137			*/
138			padded_from = db + dblen;
139			memset(padded_from, 0, lzero);
140			memcpy(padded_from + lzero, from, flen);
141
142			maskeddb = padded_from + SHA_DIGEST_LENGTH;
143
144			if (MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen))
145			return -1;
146			for (i = 0; i < SHA_DIGEST_LENGTH; i++)
147			seed[i] ^= padded_from[i];
148
149			if (MGF1(db, dblen, seed, SHA_DIGEST_LENGTH))
150			return -1;
151			for (i = 0; i < dblen; i++)
152			db[i] ^= maskeddb[i];
153
154			if (!EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL))
155			return -1;
156
157			if (timingsafe_memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 \|\| bad)
158			goto decoding_err;
159			else {
160			for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
161			if (db[i] != 0x00)
162			break;
163			if (i == dblen \|\| db[i] != 0x01)
164			goto decoding_err;
165			else {
166			/* everything looks OK */
167
168			mlen = dblen - ++i;
169			if (tlen < mlen) {
170			RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
171			RSA_R_DATA_TOO_LARGE);
172			mlen = -1;
173			} else
174			memcpy(to, db + i, mlen);
175			}
176			}
177			free(db);
178			return mlen;
179
180			decoding_err:
181			/*
182			* To avoid chosen ciphertext attacks, the error message should not
183			* reveal which kind of decoding error happened
184			*/
185			RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
186			free(db);
187			return -1;
188			}
189
190			int
191			PKCS1_MGF1(unsigned char mask, long len, const unsigned char seed,
192			long seedlen, const EVP_MD *dgst)
193			{
194			long i, outlen = 0;
195			unsigned char cnt[4];
196			EVP_MD_CTX c;
197			unsigned char md[EVP_MAX_MD_SIZE];
198			int mdlen;
199			int rv = -1;
200
201			EVP_MD_CTX_init(&c);
202			mdlen = EVP_MD_size(dgst);
203			if (mdlen < 0)
204			goto err;
205			for (i = 0; outlen < len; i++) {
206			cnt[0] = (unsigned char)((i >> 24) & 255);
207			cnt[1] = (unsigned char)((i >> 16) & 255);
208			cnt[2] = (unsigned char)((i >> 8)) & 255;
209			cnt[3] = (unsigned char)(i & 255);
210			if (!EVP_DigestInit_ex(&c, dgst, NULL) \|\|
211			!EVP_DigestUpdate(&c, seed, seedlen) \|\|
212			!EVP_DigestUpdate(&c, cnt, 4))
213			goto err;
214			if (outlen + mdlen <= len) {
215			if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))
216			goto err;
217			outlen += mdlen;
218			} else {
219			if (!EVP_DigestFinal_ex(&c, md, NULL))
220			goto err;
221			memcpy(mask + outlen, md, len - outlen);
222			outlen = len;
223			}
224			}
225			rv = 0;
226			err:
227			EVP_MD_CTX_cleanup(&c);
228			return rv;
229			}
230
231			static int
232			MGF1(unsigned char mask, long len, const unsigned char seed, long seedlen)
233			{
234			return PKCS1_MGF1(mask, len, seed, seedlen, EVP_sha1());
235			}
236			#endif