diff options
Diffstat (limited to 'crypto/userspace/libtomcrypt/pk/pkcs1/pkcs_1_oaep_encode.c')
| -rw-r--r-- | crypto/userspace/libtomcrypt/pk/pkcs1/pkcs_1_oaep_encode.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/crypto/userspace/libtomcrypt/pk/pkcs1/pkcs_1_oaep_encode.c b/crypto/userspace/libtomcrypt/pk/pkcs1/pkcs_1_oaep_encode.c new file mode 100644 index 00000000000..ccee5cfb7b4 --- /dev/null +++ b/crypto/userspace/libtomcrypt/pk/pkcs1/pkcs_1_oaep_encode.c @@ -0,0 +1,163 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtom.org + */ +#include "tomcrypt.h" +#include <ncr_int.h> + +/** + @file pkcs_1_oaep_encode.c + OAEP Padding for LTC_PKCS #1, Tom St Denis +*/ + +#ifdef LTC_PKCS_1 + +/** + LTC_PKCS #1 v2.00 OAEP encode + @param msg The data to encode + @param msglen The length of the data to encode (octets) + @param lparam A session or system parameter (can be NULL) + @param lparamlen The length of the lparam data + @param modulus_bitlen The bit length of the RSA modulus + @param hash_idx The index of the hash desired + @param out [out] The destination for the encoded data + @param outlen [in/out] The max size and resulting size of the encoded data + @return CRYPT_OK if successful +*/ +int pkcs_1_oaep_encode(const unsigned char *msg, unsigned long msglen, + const unsigned char *lparam, unsigned long lparamlen, + unsigned long modulus_bitlen, int hash_idx, + unsigned char *out, unsigned long *outlen) +{ + unsigned char *DB, *seed, *mask; + unsigned long hLen, x, y, modulus_len; + int err; + + LTC_ARGCHK(msg != NULL); + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + + /* test valid hash */ + if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { + return err; + } + + hLen = _ncr_algo_digest_size(hash_idx); + modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0); + + /* test message size */ + if ((2*hLen >= (modulus_len - 2)) || (msglen > (modulus_len - 2*hLen - 2))) { + return CRYPT_PK_INVALID_SIZE; + } + + /* allocate ram for DB/mask/salt of size modulus_len */ + DB = XMALLOC(modulus_len); + mask = XMALLOC(modulus_len); + seed = XMALLOC(hLen); + if (DB == NULL || mask == NULL || seed == NULL) { + if (DB != NULL) { + XFREE(DB); + } + if (mask != NULL) { + XFREE(mask); + } + if (seed != NULL) { + XFREE(seed); + } + return CRYPT_MEM; + } + + /* get lhash */ + /* DB == lhash || PS || 0x01 || M, PS == k - mlen - 2hlen - 2 zeroes */ + x = modulus_len; + if (lparam != NULL) { + if ((err = hash_memory(hash_idx, lparam, lparamlen, DB, &x)) != CRYPT_OK) { + goto LBL_ERR; + } + } else { + /* can't pass hash_memory a NULL so use DB with zero length */ + if ((err = hash_memory(hash_idx, DB, 0, DB, &x)) != CRYPT_OK) { + goto LBL_ERR; + } + } + + /* append PS then 0x01 (to lhash) */ + x = hLen; + y = modulus_len - msglen - 2*hLen - 2; + XMEMSET(DB+x, 0, y); + x += y; + + /* 0x01 byte */ + DB[x++] = 0x01; + + /* message (length = msglen) */ + XMEMCPY(DB+x, msg, msglen); + x += msglen; + + /* now choose a random seed */ + get_random_bytes(seed, hLen); + + /* compute MGF1 of seed (k - hlen - 1) */ + if ((err = pkcs_1_mgf1(hash_idx, seed, hLen, mask, modulus_len - hLen - 1)) != CRYPT_OK) { + goto LBL_ERR; + } + + /* xor against DB */ + for (y = 0; y < (modulus_len - hLen - 1); y++) { + DB[y] ^= mask[y]; + } + + /* compute MGF1 of maskedDB (hLen) */ + if ((err = pkcs_1_mgf1(hash_idx, DB, modulus_len - hLen - 1, mask, hLen)) != CRYPT_OK) { + goto LBL_ERR; + } + + /* XOR against seed */ + for (y = 0; y < hLen; y++) { + seed[y] ^= mask[y]; + } + + /* create string of length modulus_len */ + if (*outlen < modulus_len) { + *outlen = modulus_len; + err = CRYPT_BUFFER_OVERFLOW; + goto LBL_ERR; + } + + /* start output which is 0x00 || maskedSeed || maskedDB */ + x = 0; + out[x++] = 0x00; + XMEMCPY(out+x, seed, hLen); + x += hLen; + XMEMCPY(out+x, DB, modulus_len - hLen - 1); + x += modulus_len - hLen - 1; + + *outlen = x; + + err = CRYPT_OK; +LBL_ERR: +#ifdef LTC_CLEAN_STACK + zeromem(DB, modulus_len); + zeromem(seed, hLen); + zeromem(mask, modulus_len); +#endif + + XFREE(seed); + XFREE(mask); + XFREE(DB); + + return err; +} + +#endif /* LTC_PKCS_1 */ + + +/* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_oaep_encode.c,v $ */ +/* $Revision: 1.9 $ */ +/* $Date: 2007/05/12 14:32:35 $ */ |