diff options
Diffstat (limited to 'crypto/rsa/rsa_oaep.c')
| -rw-r--r-- | crypto/rsa/rsa_oaep.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/crypto/rsa/rsa_oaep.c b/crypto/rsa/rsa_oaep.c new file mode 100644 index 000000000000..45d6f6ef8a5e --- /dev/null +++ b/crypto/rsa/rsa_oaep.c @@ -0,0 +1,213 @@ +/* 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. + */ + + +#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 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; + } + + dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH); + if (dbmask == NULL) + { + RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE); + return 0; + } + + to[0] = 0; + seed = to + 1; + db = to + SHA_DIGEST_LENGTH + 1; + + EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL); + 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, (unsigned int) flen); + if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 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 + + MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH); + for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++) + db[i] ^= dbmask[i]; + + MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH); + for (i = 0; i < SHA_DIGEST_LENGTH; 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) + { + int i, dblen, mlen = -1; + const unsigned char *maskeddb; + int lzero; + unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH]; + 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) + { + /* lzero == -1 */ + + /* 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; + } + maskeddb = from - lzero + SHA_DIGEST_LENGTH; + + dblen = num - SHA_DIGEST_LENGTH; + db = OPENSSL_malloc(dblen); + if (db == NULL) + { + RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, ERR_R_MALLOC_FAILURE); + return -1; + } + + MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen); + for (i = lzero; i < SHA_DIGEST_LENGTH; i++) + seed[i] ^= from[i - lzero]; + + MGF1(db, dblen, seed, SHA_DIGEST_LENGTH); + for (i = 0; i < dblen; i++) + db[i] ^= maskeddb[i]; + + EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL); + + if (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 (db[i] != 0x01 || i++ >= dblen) + 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); + } + } + 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, 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; + + EVP_MD_CTX_init(&c); + mdlen = EVP_MD_size(dgst); + 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); + EVP_DigestInit_ex(&c,dgst, NULL); + EVP_DigestUpdate(&c, seed, seedlen); + EVP_DigestUpdate(&c, cnt, 4); + if (outlen + mdlen <= len) + { + EVP_DigestFinal_ex(&c, mask + outlen, NULL); + outlen += mdlen; + } + else + { + EVP_DigestFinal_ex(&c, md, NULL); + memcpy(mask + outlen, md, len - outlen); + outlen = len; + } + } + EVP_MD_CTX_cleanup(&c); + return 0; + } + +int MGF1(unsigned char *mask, long len, const unsigned char *seed, long seedlen) + { + return PKCS1_MGF1(mask, len, seed, seedlen, EVP_sha1()); + } +#endif |