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Diffstat (limited to 'imap/src/c-client/hmac.c')
| -rw-r--r-- | imap/src/c-client/hmac.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/imap/src/c-client/hmac.c b/imap/src/c-client/hmac.c new file mode 100644 index 00000000..431026db --- /dev/null +++ b/imap/src/c-client/hmac.c @@ -0,0 +1,228 @@ +/**************************** hmac.c ****************************/ +/******************** See RFC 4634 for details ******************/ +/* + * Description: + * This file implements the HMAC algorithm (Keyed-Hashing for + * Message Authentication, RFC2104), expressed in terms of the + * various SHA algorithms. + */ + +#include "sha.h" + +/* + * hmac + * + * Description: + * This function will compute an HMAC message digest. + * + * Parameters: + * whichSha: [in] + * One of SHA1, SHA224, SHA256, SHA384, SHA512 + * key: [in] + * The secret shared key. + * key_len: [in] + * The length of the secret shared key. + * message_array: [in] + * An array of characters representing the message. + * length: [in] + * The length of the message in message_array + * digest: [out] + * Where the digest is returned. + * NOTE: The length of the digest is determined by + * the value of whichSha. + * + * Returns: + * sha Error Code. + * + */ +int hmac(SHAversion whichSha, const unsigned char *text, int text_len, + const unsigned char *key, int key_len, + uint8_t digest[USHAMaxHashSize]) +{ + HMACContext ctx; + return hmacReset(&ctx, whichSha, key, key_len) || + hmacInput(&ctx, text, text_len) || + hmacResult(&ctx, digest); +} + +/* + * hmacReset + * + * Description: + * This function will initialize the hmacContext in preparation + * for computing a new HMAC message digest. + * + * Parameters: + * context: [in/out] + * The context to reset. + * whichSha: [in] + * One of SHA1, SHA224, SHA256, SHA384, SHA512 + * key: [in] + * The secret shared key. + * key_len: [in] + * The length of the secret shared key. + * + * Returns: + * sha Error Code. + * + */ +int hmacReset(HMACContext *ctx, enum SHAversion whichSha, + const unsigned char *key, int key_len) +{ + int i, blocksize, hashsize; + + /* inner padding - key XORd with ipad */ + unsigned char k_ipad[USHA_Max_Message_Block_Size]; + + /* temporary buffer when keylen > blocksize */ + unsigned char tempkey[USHAMaxHashSize]; + + if (!ctx) return shaNull; + + blocksize = ctx->blockSize = USHABlockSize(whichSha); + hashsize = ctx->hashSize = USHAHashSize(whichSha); + + ctx->whichSha = whichSha; + + /* + * If key is longer than the hash blocksize, + * reset it to key = HASH(key). + */ + if (key_len > blocksize) { + USHAContext tctx; + int err = USHAReset(&tctx, whichSha) || + USHAInput(&tctx, key, key_len) || + USHAResult(&tctx, tempkey); + if (err != shaSuccess) return err; + + key = tempkey; + key_len = hashsize; + } + + /* + * The HMAC transform looks like: + * + * SHA(K XOR opad, SHA(K XOR ipad, text)) + * + * where K is an n byte key. + * ipad is the byte 0x36 repeated blocksize times + * opad is the byte 0x5c repeated blocksize times + * and text is the data being protected. + */ + + /* store key into the pads, XOR'd with ipad and opad values */ + for (i = 0; i < key_len; i++) { + k_ipad[i] = key[i] ^ 0x36; + ctx->k_opad[i] = key[i] ^ 0x5c; + } + /* remaining pad bytes are '\0' XOR'd with ipad and opad values */ + for ( ; i < blocksize; i++) { + k_ipad[i] = 0x36; + ctx->k_opad[i] = 0x5c; + } + + /* perform inner hash */ + /* init context for 1st pass */ + return USHAReset(&ctx->shaContext, whichSha) || + /* and start with inner pad */ + USHAInput(&ctx->shaContext, k_ipad, blocksize); +} + +/* + * hmacInput + * + * Description: + * This function accepts an array of octets as the next portion + * of the message. + * + * Parameters: + * context: [in/out] + * The HMAC context to update + * message_array: [in] + * An array of characters representing the next portion of + * the message. + * length: [in] + * The length of the message in message_array + * + * Returns: + * sha Error Code. + * + */ +int hmacInput(HMACContext *ctx, const unsigned char *text, + int text_len) +{ + if (!ctx) return shaNull; + /* then text of datagram */ + return USHAInput(&ctx->shaContext, text, text_len); +} + +/* + * HMACFinalBits + * + * Description: + * This function will add in any final bits of the message. + * + * Parameters: + * context: [in/out] + * The HMAC context to update + * message_bits: [in] + * The final bits of the message, in the upper portion of the + * byte. (Use 0b###00000 instead of 0b00000### to input the + * three bits ###.) + * length: [in] + * The number of bits in message_bits, between 1 and 7. + * + * Returns: + * sha Error Code. + */ +int hmacFinalBits(HMACContext *ctx, + const uint8_t bits, + unsigned int bitcount) +{ + if (!ctx) return shaNull; + /* then final bits of datagram */ + return USHAFinalBits(&ctx->shaContext, bits, bitcount); +} + +/* + * HMACResult + * + * Description: + * This function will return the N-byte message digest into the + * Message_Digest array provided by the caller. + * NOTE: The first octet of hash is stored in the 0th element, + * the last octet of hash in the Nth element. + * + * Parameters: + * context: [in/out] + * The context to use to calculate the HMAC hash. + * digest: [out] + * Where the digest is returned. + * NOTE 2: The length of the hash is determined by the value of + * whichSha that was passed to hmacReset(). + * + * Returns: + * sha Error Code. + * + */ +int hmacResult(HMACContext *ctx, uint8_t *digest) +{ + if (!ctx) return shaNull; + + /* finish up 1st pass */ + /* (Use digest here as a temporary buffer.) */ + return USHAResult(&ctx->shaContext, digest) || + + /* perform outer SHA */ + /* init context for 2nd pass */ + USHAReset(&ctx->shaContext, ctx->whichSha) || + + /* start with outer pad */ + USHAInput(&ctx->shaContext, ctx->k_opad, ctx->blockSize) || + + /* then results of 1st hash */ + USHAInput(&ctx->shaContext, digest, ctx->hashSize) || + + /* finish up 2nd pass */ + USHAResult(&ctx->shaContext, digest); +} |