|
- /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
- * project 2005.
- */
- /* ====================================================================
- * Copyright (c) 2005 The OpenSSL Project. All rights reserved.
- *
- * 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 above 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 acknowledgment:
- * "This product includes software developed by the OpenSSL Project
- * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
- *
- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
- * endorse or promote products derived from this software without
- * prior written permission. For written permission, please contact
- * licensing@OpenSSL.org.
- *
- * 5. Products derived from this software may not be called "OpenSSL"
- * nor may "OpenSSL" appear in their names without prior written
- * permission of the OpenSSL Project.
- *
- * 6. Redistributions of any form whatsoever must retain the following
- * acknowledgment:
- * "This product includes software developed by the OpenSSL Project
- * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
- *
- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
- * EXPRESSED 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 OpenSSL PROJECT OR
- * ITS 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.
- * ====================================================================
- *
- * This product includes cryptographic software written by Eric Young
- * (eay@cryptsoft.com). This product includes software written by Tim
- * Hudson (tjh@cryptsoft.com). */
-
- #include <openssl/rsa.h>
-
- #include <assert.h>
- #include <string.h>
-
- #include <openssl/digest.h>
- #include <openssl/err.h>
- #include <openssl/mem.h>
- #include <openssl/rand.h>
- #include <openssl/sha.h>
-
- #include "internal.h"
-
- /* TODO(fork): don't the check functions have to be constant time? */
-
- int RSA_padding_add_PKCS1_type_1(uint8_t *to, unsigned tlen,
- const uint8_t *from, unsigned flen) {
- unsigned j;
- uint8_t *p;
-
- if (tlen < RSA_PKCS1_PADDING_SIZE) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_type_1,
- RSA_R_KEY_SIZE_TOO_SMALL);
- return 0;
- }
-
- if (flen > tlen - RSA_PKCS1_PADDING_SIZE) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_type_1,
- RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
- return 0;
- }
-
- p = (uint8_t *)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(uint8_t *to, unsigned tlen,
- const uint8_t *from, unsigned flen) {
- unsigned i, j;
- const uint8_t *p;
-
- if (flen < 2) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_1,
- RSA_R_DATA_TOO_SMALL);
- return -1;
- }
-
- p = from;
- if ((*(p++) != 0) || (*(p++) != 1)) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_1,
- RSA_R_BLOCK_TYPE_IS_NOT_01);
- return -1;
- }
-
- /* scan over padding data */
- j = flen - 2; /* one for leading 00, one for type. */
- for (i = 0; i < j; i++) {
- /* should decrypt to 0xff */
- if (*p != 0xff) {
- if (*p == 0) {
- p++;
- break;
- } else {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_1,
- RSA_R_BAD_FIXED_HEADER_DECRYPT);
- return -1;
- }
- }
- p++;
- }
-
- if (i == j) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_1,
- RSA_R_NULL_BEFORE_BLOCK_MISSING);
- return -1;
- }
-
- if (i < 8) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_1,
- RSA_R_BAD_PAD_BYTE_COUNT);
- return -1;
- }
- i++; /* Skip over the '\0' */
- j -= i;
- if (j > tlen) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_1,
- RSA_R_DATA_TOO_LARGE);
- return -1;
- }
- memcpy(to, p, j);
-
- return j;
- }
-
- int RSA_padding_add_PKCS1_type_2(uint8_t *to, unsigned tlen,
- const uint8_t *from, unsigned flen) {
- unsigned i, j;
- uint8_t *p;
-
- if (tlen < RSA_PKCS1_PADDING_SIZE) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_type_2,
- RSA_R_KEY_SIZE_TOO_SMALL);
- return 0;
- }
-
- if (flen > tlen - RSA_PKCS1_PADDING_SIZE) {
- OPENSSL_PUT_ERROR(RSA, 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)) {
- return 0;
- }
-
- for (i = 0; i < j; i++) {
- while (*p == 0) {
- if (!RAND_bytes(p, 1)) {
- return 0;
- }
- }
- p++;
- }
-
- *(p++) = 0;
-
- memcpy(p, from, (unsigned int)flen);
- return 1;
- }
-
- /* constant_time_byte_eq returns 1 if |x| == |y| and 0 otherwise. */
- static int constant_time_byte_eq(unsigned char a, unsigned char b) {
- unsigned char z = ~(a ^ b);
- z &= z >> 4;
- z &= z >> 2;
- z &= z >> 1;
-
- return z;
- }
-
- /* constant_time_select returns |x| if |v| is 1 and |y| if |v| is 0.
- * Its behavior is undefined if |v| takes any other value. */
- static int constant_time_select(int v, int x, int y) {
- return ((~(v - 1)) & x) | ((v - 1) & y);
- }
-
- /* constant_time_le returns 1 if |x| <= |y| and 0 otherwise.
- * |x| and |y| must be positive. */
- static int constant_time_le(int x, int y) {
- return ((x - y - 1) >> (sizeof(int) * 8 - 1)) & 1;
- }
-
- int RSA_message_index_PKCS1_type_2(const uint8_t *from, size_t from_len,
- size_t *out_index) {
- size_t i;
- int first_byte_is_zero, second_byte_is_two, looking_for_index;
- int valid_index, zero_index = 0;
-
- /* PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography
- * Standard", section 7.2.2. */
- if (from_len < RSA_PKCS1_PADDING_SIZE) {
- /* |from| is zero-padded to the size of the RSA modulus, a public value, so
- * this can be rejected in non-constant time. */
- *out_index = 0;
- return 0;
- }
-
- first_byte_is_zero = constant_time_byte_eq(from[0], 0);
- second_byte_is_two = constant_time_byte_eq(from[1], 2);
-
- looking_for_index = 1;
- for (i = 2; i < from_len; i++) {
- int equals0 = constant_time_byte_eq(from[i], 0);
- zero_index =
- constant_time_select(looking_for_index & equals0, i, zero_index);
- looking_for_index = constant_time_select(equals0, 0, looking_for_index);
- }
-
- /* The input must begin with 00 02. */
- valid_index = first_byte_is_zero;
- valid_index &= second_byte_is_two;
-
- /* We must have found the end of PS. */
- valid_index &= ~looking_for_index;
-
- /* PS must be at least 8 bytes long, and it starts two bytes into |from|. */
- valid_index &= constant_time_le(2 + 8, zero_index);
-
- /* Skip the zero byte. */
- zero_index++;
-
- *out_index = constant_time_select(valid_index, zero_index, 0);
- return valid_index;
- }
-
- int RSA_padding_check_PKCS1_type_2(uint8_t *to, unsigned tlen,
- const uint8_t *from, unsigned flen) {
- size_t msg_index, msg_len;
-
- if (flen == 0) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_2,
- RSA_R_EMPTY_PUBLIC_KEY);
- return -1;
- }
-
- /* NOTE: Although |RSA_message_index_PKCS1_type_2| itself is constant time,
- * the API contracts of this function and |RSA_decrypt| with
- * |RSA_PKCS1_PADDING| make it impossible to completely avoid Bleichenbacher's
- * attack. */
- if (!RSA_message_index_PKCS1_type_2(from, flen, &msg_index)) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_2,
- RSA_R_PKCS_DECODING_ERROR);
- return -1;
- }
-
- msg_len = flen - msg_index;
- if (msg_len > tlen) {
- /* This shouldn't happen because this function is always called with |tlen|
- * the key size and |flen| is bounded by the key size. */
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_type_2,
- RSA_R_PKCS_DECODING_ERROR);
- return -1;
- }
- memcpy(to, &from[msg_index], msg_len);
- return msg_len;
- }
-
- int RSA_padding_add_none(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) {
- if (flen > tlen) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_none,
- RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
- return 0;
- }
-
- if (flen < tlen) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_none,
- RSA_R_DATA_TOO_SMALL_FOR_KEY_SIZE);
- return 0;
- }
-
- memcpy(to, from, (unsigned int)flen);
- return 1;
- }
-
- int RSA_padding_check_none(uint8_t *to, unsigned tlen, const uint8_t *from,
- unsigned flen) {
- if (flen > tlen) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_none, RSA_R_DATA_TOO_LARGE);
- return -1;
- }
-
- memcpy(to, from, flen);
- return flen;
- }
-
- int PKCS1_MGF1(uint8_t *mask, unsigned len, const uint8_t *seed,
- unsigned seedlen, const EVP_MD *dgst) {
- unsigned outlen = 0;
- uint32_t i;
- uint8_t cnt[4];
- EVP_MD_CTX c;
- uint8_t md[EVP_MAX_MD_SIZE];
- unsigned mdlen;
- int ret = -1;
-
- EVP_MD_CTX_init(&c);
- mdlen = EVP_MD_size(dgst);
-
- for (i = 0; outlen < len; i++) {
- cnt[0] = (uint8_t)((i >> 24) & 255);
- cnt[1] = (uint8_t)((i >> 16) & 255);
- cnt[2] = (uint8_t)((i >> 8)) & 255;
- cnt[3] = (uint8_t)(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;
- }
- }
- ret = 0;
-
- err:
- EVP_MD_CTX_cleanup(&c);
- return ret;
- }
-
- int RSA_padding_add_PKCS1_OAEP_mgf1(uint8_t *to, unsigned tlen,
- const uint8_t *from, unsigned flen,
- const uint8_t *param, unsigned plen,
- const EVP_MD *md, const EVP_MD *mgf1md) {
- unsigned i, emlen, mdlen;
- uint8_t *db, *seed;
- uint8_t *dbmask = NULL, seedmask[EVP_MAX_MD_SIZE];
- int ret = 0;
-
- if (md == NULL) {
- md = EVP_sha1();
- }
- if (mgf1md == NULL) {
- mgf1md = md;
- }
-
- mdlen = EVP_MD_size(md);
-
- if (tlen < 2 * mdlen + 2) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_OAEP_mgf1,
- RSA_R_KEY_SIZE_TOO_SMALL);
- return 0;
- }
-
- emlen = tlen - 1;
- if (flen > emlen - 2 * mdlen - 1) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_OAEP_mgf1,
- RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
- return 0;
- }
-
- if (emlen < 2 * mdlen + 1) {
- OPENSSL_PUT_ERROR(RSA, 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, flen);
- if (!RAND_bytes(seed, mdlen)) {
- return 0;
- }
-
- dbmask = OPENSSL_malloc(emlen - mdlen);
- if (dbmask == NULL) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_OAEP_mgf1,
- ERR_R_MALLOC_FAILURE);
- return 0;
- }
-
- if (PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md) < 0) {
- goto out;
- }
- for (i = 0; i < emlen - mdlen; i++) {
- db[i] ^= dbmask[i];
- }
-
- if (PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md) < 0) {
- goto out;
- }
- for (i = 0; i < mdlen; i++) {
- seed[i] ^= seedmask[i];
- }
- ret = 1;
-
- out:
- if (dbmask != NULL) {
- OPENSSL_free(dbmask);
- }
- return ret;
- }
-
- int RSA_padding_check_PKCS1_OAEP_mgf1(uint8_t *to, unsigned tlen,
- const uint8_t *from, unsigned flen,
- const uint8_t *param, unsigned plen,
- const EVP_MD *md, const EVP_MD *mgf1md) {
- unsigned i, dblen, mlen = -1, mdlen;
- const uint8_t *maskeddb, *maskedseed;
- uint8_t *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
- int bad, looking_for_one_byte, one_index = 0;
-
- if (md == NULL) {
- md = EVP_sha1();
- }
- if (mgf1md == NULL) {
- mgf1md = md;
- }
-
- mdlen = EVP_MD_size(md);
-
- /* The encoded message is one byte smaller than the modulus to ensure that it
- * doesn't end up greater than the modulus. Thus there's an extra "+1" here
- * compared to https://tools.ietf.org/html/rfc2437#section-9.1.1.2. */
- if (flen < 1 + 2*mdlen + 1) {
- /* 'flen' is the length of the modulus, i.e. does not depend on the
- * particular ciphertext. */
- goto decoding_err;
- }
-
- dblen = flen - mdlen - 1;
- db = OPENSSL_malloc(dblen);
- if (db == NULL) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_OAEP_mgf1,
- ERR_R_MALLOC_FAILURE);
- goto err;
- }
-
- maskedseed = from + 1;
- maskeddb = from + 1 + mdlen;
-
- if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md)) {
- goto err;
- }
- for (i = 0; i < mdlen; i++) {
- seed[i] ^= maskedseed[i];
- }
-
- if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md)) {
- goto err;
- }
- for (i = 0; i < dblen; i++) {
- db[i] ^= maskeddb[i];
- }
-
- if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL)) {
- goto err;
- }
-
- bad = CRYPTO_memcmp(db, phash, mdlen);
- bad |= from[0];
-
- looking_for_one_byte = 1;
- for (i = mdlen; i < dblen; i++) {
- int equals1 = constant_time_byte_eq(db[i], 1);
- int equals0 = constant_time_byte_eq(db[i], 0);
- one_index =
- constant_time_select(looking_for_one_byte & equals1, i, one_index);
- looking_for_one_byte =
- constant_time_select(equals1, 0, looking_for_one_byte);
- bad |= looking_for_one_byte & ~equals0;
- }
-
- bad |= looking_for_one_byte;
-
- if (bad) {
- goto decoding_err;
- }
-
- one_index++;
- mlen = dblen - one_index;
- if (tlen < mlen) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_OAEP_mgf1,
- RSA_R_DATA_TOO_LARGE);
- mlen = -1;
- } else {
- memcpy(to, db + one_index, 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 */
- OPENSSL_PUT_ERROR(RSA, RSA_padding_check_PKCS1_OAEP_mgf1,
- RSA_R_OAEP_DECODING_ERROR);
- err:
- if (db != NULL) {
- OPENSSL_free(db);
- }
- return -1;
- }
-
- static const unsigned char zeroes[] = {0,0,0,0,0,0,0,0};
-
- int RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const uint8_t *mHash,
- const EVP_MD *Hash, const EVP_MD *mgf1Hash,
- const uint8_t *EM, int sLen) {
- int i;
- int ret = 0;
- int maskedDBLen, MSBits, emLen;
- size_t hLen;
- const uint8_t *H;
- uint8_t *DB = NULL;
- EVP_MD_CTX ctx;
- uint8_t H_[EVP_MAX_MD_SIZE];
- EVP_MD_CTX_init(&ctx);
-
- if (mgf1Hash == NULL) {
- mgf1Hash = Hash;
- }
-
- hLen = EVP_MD_size(Hash);
-
- /* Negative sLen has special meanings:
- * -1 sLen == hLen
- * -2 salt length is autorecovered from signature
- * -N reserved */
- if (sLen == -1) {
- sLen = hLen;
- } else if (sLen == -2) {
- sLen = -2;
- } else if (sLen < -2) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1, RSA_R_SLEN_CHECK_FAILED);
- goto err;
- }
-
- MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
- emLen = RSA_size(rsa);
- if (EM[0] & (0xFF << MSBits)) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1,
- RSA_R_FIRST_OCTET_INVALID);
- goto err;
- }
- if (MSBits == 0) {
- EM++;
- emLen--;
- }
- if (emLen < ((int)hLen + sLen + 2)) {
- /* sLen can be small negative */
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1, RSA_R_DATA_TOO_LARGE);
- goto err;
- }
- if (EM[emLen - 1] != 0xbc) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1, RSA_R_LAST_OCTET_INVALID);
- goto err;
- }
- maskedDBLen = emLen - hLen - 1;
- H = EM + maskedDBLen;
- DB = OPENSSL_malloc(maskedDBLen);
- if (!DB) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1, ERR_R_MALLOC_FAILURE);
- goto err;
- }
- if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) {
- goto err;
- }
- for (i = 0; i < maskedDBLen; i++) {
- DB[i] ^= EM[i];
- }
- if (MSBits) {
- DB[0] &= 0xFF >> (8 - MSBits);
- }
- for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) {
- ;
- }
- if (DB[i++] != 0x1) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1,
- RSA_R_SLEN_RECOVERY_FAILED);
- goto err;
- }
- if (sLen >= 0 && (maskedDBLen - i) != sLen) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1, RSA_R_SLEN_CHECK_FAILED);
- goto err;
- }
- if (!EVP_DigestInit_ex(&ctx, Hash, NULL) ||
- !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) ||
- !EVP_DigestUpdate(&ctx, mHash, hLen)) {
- goto err;
- }
- if (maskedDBLen - i) {
- if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) {
- goto err;
- }
- }
- if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) {
- goto err;
- }
- if (memcmp(H_, H, hLen)) {
- OPENSSL_PUT_ERROR(RSA, RSA_verify_PKCS1_PSS_mgf1, RSA_R_BAD_SIGNATURE);
- ret = 0;
- } else {
- ret = 1;
- }
-
- err:
- if (DB) {
- OPENSSL_free(DB);
- }
- EVP_MD_CTX_cleanup(&ctx);
-
- return ret;
- }
-
- int RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM,
- const unsigned char *mHash,
- const EVP_MD *Hash, const EVP_MD *mgf1Hash,
- int sLen) {
- int i;
- int ret = 0;
- size_t maskedDBLen, MSBits, emLen;
- size_t hLen;
- unsigned char *H, *salt = NULL, *p;
- EVP_MD_CTX ctx;
-
- if (mgf1Hash == NULL) {
- mgf1Hash = Hash;
- }
-
- hLen = EVP_MD_size(Hash);
-
- /* Negative sLen has special meanings:
- * -1 sLen == hLen
- * -2 salt length is maximized
- * -N reserved */
- if (sLen == -1) {
- sLen = hLen;
- } else if (sLen == -2) {
- sLen = -2;
- } else if (sLen < -2) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_PSS_mgf1,
- RSA_R_SLEN_CHECK_FAILED);
- goto err;
- }
-
- if (BN_is_zero(rsa->n)) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_PSS_mgf1,
- RSA_R_EMPTY_PUBLIC_KEY);
- goto err;
- }
-
- MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
- emLen = RSA_size(rsa);
- if (MSBits == 0) {
- assert(emLen >= 1);
- *EM++ = 0;
- emLen--;
- }
- if (sLen == -2) {
- if (emLen < hLen + 2) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_PSS_mgf1,
- RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
- goto err;
- }
- sLen = emLen - hLen - 2;
- } else if (emLen < hLen + sLen + 2) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_PSS_mgf1,
- RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
- goto err;
- }
- if (sLen > 0) {
- salt = OPENSSL_malloc(sLen);
- if (!salt) {
- OPENSSL_PUT_ERROR(RSA, RSA_padding_add_PKCS1_PSS_mgf1,
- ERR_R_MALLOC_FAILURE);
- goto err;
- }
- if (!RAND_bytes(salt, sLen)) {
- goto err;
- }
- }
- maskedDBLen = emLen - hLen - 1;
- H = EM + maskedDBLen;
- EVP_MD_CTX_init(&ctx);
- if (!EVP_DigestInit_ex(&ctx, Hash, NULL) ||
- !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) ||
- !EVP_DigestUpdate(&ctx, mHash, hLen)) {
- goto err;
- }
- if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) {
- goto err;
- }
- if (!EVP_DigestFinal_ex(&ctx, H, NULL)) {
- goto err;
- }
- EVP_MD_CTX_cleanup(&ctx);
-
- /* Generate dbMask in place then perform XOR on it */
- if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) {
- goto err;
- }
-
- p = EM;
-
- /* Initial PS XORs with all zeroes which is a NOP so just update
- * pointer. Note from a test above this value is guaranteed to
- * be non-negative. */
- p += emLen - sLen - hLen - 2;
- *p++ ^= 0x1;
- if (sLen > 0) {
- for (i = 0; i < sLen; i++) {
- *p++ ^= salt[i];
- }
- }
- if (MSBits) {
- EM[0] &= 0xFF >> (8 - MSBits);
- }
-
- /* H is already in place so just set final 0xbc */
-
- EM[emLen - 1] = 0xbc;
-
- ret = 1;
-
- err:
- if (salt) {
- OPENSSL_free(salt);
- }
-
- return ret;
- }
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