Added library names

[asdcplib.git] / src / KM_prng.cpp

diff --git a/src/KM_prng.cpp b/src/KM_prng.cpp
index 65c46561a600b21193c170ecddc94aead165da61..d11a330d56f049f233eb478cb6b2d6bcee6d01f0 100755 (executable)
--- a/src/KM_prng.cpp
+++ b/src/KM_prng.cpp
@@ -1,5 +1,5 @@
 /*
-Copyright (c) 2006, John Hurst
+Copyright (c) 2006-2009, John Hurst
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
@@ -163,6 +163,7 @@ Kumu::FortunaRNG::FillRandom(byte_t* buf, ui32_t len)
 {
   assert(buf);
   assert(s_RNG);
+  const byte_t* front_of_buffer = buf;
 
   while ( len )
     {
@@ -179,7 +180,7 @@ Kumu::FortunaRNG::FillRandom(byte_t* buf, ui32_t len)
       s_RNG->set_key(rng_key);
   }
   
-  return buf;
+  return front_of_buffer;
 }
 
 //
@@ -199,28 +200,41 @@ void
 Kumu::Gen_FIPS_186_Value(const byte_t* key, ui32_t key_size, byte_t* out_buf, ui32_t out_buf_len)
 {
   byte_t sha_buf[SHA_DIGEST_LENGTH];
-  const ui32_t key_buf_len = 64;
-  byte_t key_buf[key_buf_len];
-  SHA_CTX SHA;
+  ui32_t const xkey_len = 64; // 512/8
+  byte_t xkey[xkey_len];
   BN_CTX* ctx1 = BN_CTX_new(); // used by BN_* functions
   assert(ctx1);
 
+  if ( key_size > xkey_len )
+    DefaultLogSink().Warn("Key too large for FIPS 186 seed, truncating to 64 bytes.\n");
+
   // init key
-  memset(key_buf, 0, key_buf_len);
-  memcpy(key_buf, key, xmin<ui32_t>(key_buf_len, key_size));
+  memset(xkey, 0, xkey_len);
+  memcpy(xkey, key, xmin<ui32_t>(key_size, xkey_len));
+
+  if ( key_size < SHA_DIGEST_LENGTH )
+    key_size = SHA_DIGEST_LENGTH; // pad short key ( b < 160 )
 
-  // create the 2^160 constant
-  BIGNUM c_2powb, c_2, c_160;
-  BN_init(&c_2powb);  BN_init(&c_2);  BN_init(&c_160);
-  BN_set_word(&c_2, 2);
-  BN_set_word(&c_160, 160);
-  BN_exp(&c_2powb, &c_2, &c_160, ctx1);
+  // create the 2^b constant
+  BIGNUM *c_2powb = BN_new();
+  BIGNUM * c_2 = BN_new();
+  BIGNUM * c_b = BN_new();
+  assert(c_2powb);
+  assert(c_2);
+  assert(c_b);
+
+  BN_set_word(c_2, 2);
+  BN_set_word(c_b, key_size * 8);
+  BN_exp(c_2powb, c_2, c_b, ctx1);
 
   for (;;)
     {
+      SHA_CTX SHA;
+
       // step c -- x = G(t,xkey)
-      SHA1_Init(&SHA);
-      SHA1_Update(&SHA, key_buf, key_buf_len);
+      SHA1_Init(&SHA); // set t
+      SHA1_Update(&SHA, xkey, xkey_len);
+
       ui32_t* buf_p = (ui32_t*)sha_buf;
       *buf_p++ = KM_i32_BE(SHA.h0);
       *buf_p++ = KM_i32_BE(SHA.h1);
@@ -235,22 +249,32 @@ Kumu::Gen_FIPS_186_Value(const byte_t* key, ui32_t key_size, byte_t* out_buf, ui
       out_buf_len -= SHA_DIGEST_LENGTH;
       out_buf += SHA_DIGEST_LENGTH;
 
-      // step d ...
-      BIGNUM xkey1, xkey_buf, x0;
-      BN_init(&xkey1);  BN_init(&xkey_buf);    BN_init(&x0);
-
-      BN_bin2bn(key_buf, SHA_DIGEST_LENGTH, &xkey1);
-      BN_bin2bn(sha_buf, SHA_DIGEST_LENGTH, &x0);
-      BN_add_word(&xkey1, 1);            // xkey += 1
-      BN_add(&xkey_buf, &xkey1, &x0);       // xkey += x
-      BN_mod(&xkey1, &xkey_buf, &c_2powb, ctx1);  // xkey = xkey mod (2^160)
-
-      ui32_t bn_buf_len = BN_num_bytes(&xkey1);
-      assert(bn_buf_len < SHA_DIGEST_LENGTH+1);
-      memset(key_buf, 0, key_buf_len);
-      BN_bn2bin(&xkey1, key_buf);
+      // step d -- XKEY = (1 + XKEY + x) mod 2^b
+      BIGNUM *bn_tmp = BN_new();
+      BIGNUM *bn_xkey = BN_new();
+      BIGNUM *bn_x_n = BN_new();
+      assert(bn_tmp);
+      assert(bn_xkey);
+      assert(bn_x_n);
+
+      BN_bin2bn(xkey, key_size, bn_xkey);
+      BN_bin2bn(sha_buf, SHA_DIGEST_LENGTH, bn_x_n);
+      BN_add_word(bn_xkey, 1);            // xkey += 1
+      BN_add(bn_tmp, bn_xkey, bn_x_n);       // xkey += x
+      BN_mod(bn_xkey, bn_tmp, c_2powb, ctx1);  // xkey = xkey mod (2^b)
+
+      memset(xkey, 0, xkey_len);
+      ui32_t bn_buf_len = BN_num_bytes(bn_xkey);
+      ui32_t idx = ( bn_buf_len < key_size ) ? key_size - bn_buf_len : 0;
+      BN_bn2bin(bn_xkey, &xkey[idx]);
+      BN_free(bn_tmp);
+      BN_free(bn_xkey);
+      BN_free(bn_x_n);
     }
 
+  BN_free(c_2powb);
+  BN_free(c_2);
+  BN_free(c_b);
   BN_CTX_free(ctx1);
 }