Line data    Source code

       1             : // Copyright (c) 2014 The Bitcoin developers
       2             : // Distributed under the MIT software license, see the accompanying
       3             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4             : 
       5             : #include "crypto/rfc6979_hmac_sha256.h"
       6             : 
       7             : #include <string.h>
       8             : 
       9             : #include <algorithm>
      10             : 
      11             : static const unsigned char zero[1] = {0x00};
      12             : static const unsigned char one[1] = {0x01};
      13             : 
      14           2 : RFC6979_HMAC_SHA256::RFC6979_HMAC_SHA256(const unsigned char* key, size_t keylen, const unsigned char* msg, size_t msglen) : retry(false)
      15             : {
      16           2 :     memset(V, 0x01, sizeof(V));
      17           2 :     memset(K, 0x00, sizeof(K));
      18             : 
      19           2 :     CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Write(zero, sizeof(zero)).Write(key, keylen).Write(msg, msglen).Finalize(K);
      20           2 :     CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Finalize(V);
      21           2 :     CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Write(one, sizeof(one)).Write(key, keylen).Write(msg, msglen).Finalize(K);
      22           2 :     CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Finalize(V);
      23           2 : }
      24             : 
      25           2 : RFC6979_HMAC_SHA256::~RFC6979_HMAC_SHA256()
      26             : {
      27           2 :     memset(V, 0x01, sizeof(V));
      28           2 :     memset(K, 0x00, sizeof(K));
      29           2 : }
      30             : 
      31           6 : void RFC6979_HMAC_SHA256::Generate(unsigned char* output, size_t outputlen)
      32             : {
      33           6 :     if (retry) {
      34           4 :         CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Write(zero, sizeof(zero)).Finalize(K);
      35           4 :         CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Finalize(V);
      36             :     }
      37             : 
      38          12 :     while (outputlen > 0) {
      39           6 :         CHMAC_SHA256(K, sizeof(K)).Write(V, sizeof(V)).Finalize(V);
      40           6 :         size_t len = std::min(outputlen, sizeof(V));
      41           6 :         memcpy(output, V, len);
      42           6 :         output += len;
      43           6 :         outputlen -= len;
      44             :     }
      45             : 
      46           6 :     retry = true;
      47           6 : }