1656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project/* crypto/rsa/rsa_oaep.c */ 2656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project/* Written by Ulf Moeller. This software is distributed on an "AS IS" 3656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */ 4656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 5656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project/* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */ 6656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 7656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project/* See Victor Shoup, "OAEP reconsidered," Nov. 2000, 8656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * <URL: http://www.shoup.net/papers/oaep.ps.Z> 9656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * for problems with the security proof for the 10656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * original OAEP scheme, which EME-OAEP is based on. 11656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * 12656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * A new proof can be found in E. Fujisaki, T. Okamoto, 13656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * D. Pointcheval, J. Stern, "RSA-OEAP is Still Alive!", 14656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * Dec. 2000, <URL: http://eprint.iacr.org/2000/061/>. 15656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * The new proof has stronger requirements for the 16656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * underlying permutation: "partial-one-wayness" instead 17656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * of one-wayness. For the RSA function, this is 18656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project * an equivalent notion. 19656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project */ 20656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 21c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root#include "constant_time_locl.h" 22656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 23656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#if !defined(OPENSSL_NO_SHA) && !defined(OPENSSL_NO_SHA1) 24656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <stdio.h> 25656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include "cryptlib.h" 26656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <openssl/bn.h> 27656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <openssl/rsa.h> 28656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <openssl/evp.h> 29656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <openssl/rand.h> 30656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <openssl/sha.h> 31656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 32221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstromstatic int MGF1(unsigned char *mask, long len, 33656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned char *seed, long seedlen); 34656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 35656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Projectint RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen, 36656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned char *from, int flen, 37656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned char *param, int plen) 38656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 39656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project int i, emlen = tlen - 1; 40656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned char *db, *seed; 41656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH]; 42656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 43656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1) 44656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 45656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, 46656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 47656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project return 0; 48656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 49656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 50656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project if (emlen < 2 * SHA_DIGEST_LENGTH + 1) 51656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 52656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_KEY_SIZE_TOO_SMALL); 53656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project return 0; 54656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 55656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 56656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project to[0] = 0; 57656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project seed = to + 1; 58656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project db = to + SHA_DIGEST_LENGTH + 1; 59656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 60392aa7cc7d2b122614c5393c3e357da07fd07af3Brian Carlstrom if (!EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL)) 61392aa7cc7d2b122614c5393c3e357da07fd07af3Brian Carlstrom return 0; 62656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project memset(db + SHA_DIGEST_LENGTH, 0, 63656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project emlen - flen - 2 * SHA_DIGEST_LENGTH - 1); 64656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01; 65656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen); 66656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 0) 67656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project return 0; 68656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#ifdef PKCS_TESTVECT 69656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project memcpy(seed, 70656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f", 71656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 20); 72656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#endif 73656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 7498d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH); 7598d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom if (dbmask == NULL) 7698d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom { 7798d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE); 7898d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom return 0; 7998d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom } 8098d58bb80c64b02a33662f0ea80351d4a1535267Brian Carlstrom 81221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom if (MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH) < 0) 82221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom return 0; 83656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++) 84656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project db[i] ^= dbmask[i]; 85656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 86221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom if (MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH) < 0) 87221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom return 0; 88656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project for (i = 0; i < SHA_DIGEST_LENGTH; i++) 89656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project seed[i] ^= seedmask[i]; 90656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 91656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project OPENSSL_free(dbmask); 92656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project return 1; 93656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 94656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 95656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Projectint RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen, 96656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned char *from, int flen, int num, 97656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned char *param, int plen) 98656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 99c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root int i, dblen, mlen = -1, one_index = 0, msg_index; 100c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned int good, found_one_byte; 101c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root const unsigned char *maskedseed, *maskeddb; 102c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* |em| is the encoded message, zero-padded to exactly |num| bytes: 103c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * em = Y || maskedSeed || maskedDB */ 104c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned char *db = NULL, *em = NULL, seed[EVP_MAX_MD_SIZE], 105c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root phash[EVP_MAX_MD_SIZE]; 106c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 107c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root if (tlen <= 0 || flen <= 0) 108c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root return -1; 109656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 110c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* 111c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * |num| is the length of the modulus; |flen| is the length of the 112c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * encoded message. Therefore, for any |from| that was obtained by 113c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * decrypting a ciphertext, we must have |flen| <= |num|. Similarly, 114c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * num < 2 * SHA_DIGEST_LENGTH + 2 must hold for the modulus 115c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * irrespective of the ciphertext, see PKCS #1 v2.2, section 7.1.2. 116c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * This does not leak any side-channel information. 117c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root */ 118c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root if (num < flen || num < 2 * SHA_DIGEST_LENGTH + 2) 119c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root goto decoding_err; 120656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 121c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root dblen = num - SHA_DIGEST_LENGTH - 1; 122c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root db = OPENSSL_malloc(dblen); 123c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root em = OPENSSL_malloc(num); 124c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root if (db == NULL || em == NULL) 125656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 126656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, ERR_R_MALLOC_FAILURE); 127c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root goto cleanup; 128656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 129656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 130c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* 131c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * Always do this zero-padding copy (even when num == flen) to avoid 132c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * leaking that information. The copy still leaks some side-channel 133c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * information, but it's impossible to have a fixed memory access 134c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * pattern since we can't read out of the bounds of |from|. 135c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * 136c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL. 137c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root */ 138c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root memset(em, 0, num); 139c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root memcpy(em + num - flen, from, flen); 140c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 141c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* 142c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * The first byte must be zero, however we must not leak if this is 143c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * true. See James H. Manger, "A Chosen Ciphertext Attack on RSA 144c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * Optimal Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001). 145c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root */ 146c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root good = constant_time_is_zero(em[0]); 147c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 148c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root maskedseed = em + 1; 149c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root maskeddb = em + 1 + SHA_DIGEST_LENGTH; 150656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 151221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom if (MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen)) 152c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root goto cleanup; 153656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project for (i = 0; i < SHA_DIGEST_LENGTH; i++) 154c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root seed[i] ^= maskedseed[i]; 155c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 156221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom if (MGF1(db, dblen, seed, SHA_DIGEST_LENGTH)) 157c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root goto cleanup; 158656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project for (i = 0; i < dblen; i++) 159656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project db[i] ^= maskeddb[i]; 160656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 161392aa7cc7d2b122614c5393c3e357da07fd07af3Brian Carlstrom if (!EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL)) 162c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root goto cleanup; 163656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 164c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root good &= constant_time_is_zero(CRYPTO_memcmp(db, phash, SHA_DIGEST_LENGTH)); 165c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 166c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root found_one_byte = 0; 167c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root for (i = SHA_DIGEST_LENGTH; i < dblen; i++) 168c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root { 169c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* Padding consists of a number of 0-bytes, followed by a 1. */ 170c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned int equals1 = constant_time_eq(db[i], 1); 171c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned int equals0 = constant_time_is_zero(db[i]); 172c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root one_index = constant_time_select_int(~found_one_byte & equals1, 173c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root i, one_index); 174c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root found_one_byte |= equals1; 175c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root good &= (found_one_byte | equals0); 176c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root } 177c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 178c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root good &= found_one_byte; 179c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 180c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* 181c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * At this point |good| is zero unless the plaintext was valid, 182c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * so plaintext-awareness ensures timing side-channels are no longer a 183c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * concern. 184c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root */ 185c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root if (!good) 186656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project goto decoding_err; 187c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 188c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root msg_index = one_index + 1; 189c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root mlen = dblen - msg_index; 190c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root 191c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root if (tlen < mlen) 192c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root { 193c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE); 194c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root mlen = -1; 195c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root } 196656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project else 197656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 198c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root memcpy(to, db + msg_index, mlen); 199c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root goto cleanup; 200656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 201656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 202656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Projectdecoding_err: 203c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root /* To avoid chosen ciphertext attacks, the error message should not reveal 204c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * which kind of decoding error happened. */ 205656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR); 206c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Rootcleanup: 207656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project if (db != NULL) OPENSSL_free(db); 208c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root if (em != NULL) OPENSSL_free(em); 209c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root return mlen; 210656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 211656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 212656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Projectint PKCS1_MGF1(unsigned char *mask, long len, 213656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned char *seed, long seedlen, const EVP_MD *dgst) 214656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 215656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project long i, outlen = 0; 216656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned char cnt[4]; 217656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project EVP_MD_CTX c; 218656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned char md[EVP_MAX_MD_SIZE]; 219656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project int mdlen; 220ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom int rv = -1; 221656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 222656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project EVP_MD_CTX_init(&c); 223221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom mdlen = EVP_MD_size(dgst); 224221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom if (mdlen < 0) 225ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom goto err; 226656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project for (i = 0; outlen < len; i++) 227656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 228656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project cnt[0] = (unsigned char)((i >> 24) & 255); 229656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project cnt[1] = (unsigned char)((i >> 16) & 255); 230656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project cnt[2] = (unsigned char)((i >> 8)) & 255; 231656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project cnt[3] = (unsigned char)(i & 255); 232ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom if (!EVP_DigestInit_ex(&c,dgst, NULL) 233ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom || !EVP_DigestUpdate(&c, seed, seedlen) 234ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom || !EVP_DigestUpdate(&c, cnt, 4)) 235ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom goto err; 236656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project if (outlen + mdlen <= len) 237656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 238ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL)) 239ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom goto err; 240656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project outlen += mdlen; 241656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 242656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project else 243656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 244ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom if (!EVP_DigestFinal_ex(&c, md, NULL)) 245ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom goto err; 246656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project memcpy(mask + outlen, md, len - outlen); 247656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project outlen = len; 248656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 249656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 250ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom rv = 0; 251ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom err: 252656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project EVP_MD_CTX_cleanup(&c); 253ee7afb3c942c4eefef6ed06201eafaf8ec58e2e3Brian Carlstrom return rv; 254656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 255656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 256221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstromstatic int MGF1(unsigned char *mask, long len, const unsigned char *seed, 257221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom long seedlen) 258656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project { 259656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project return PKCS1_MGF1(mask, len, seed, seedlen, EVP_sha1()); 260656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project } 261656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#endif 262