Add HMAC-SHA256

src/crypto/hmac_sha256.cpp

@@ -0,0 +1,34 @@
+// Copyright (c) 2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "crypto/hmac_sha256.h"
+
+#include <string.h>
+
+CHMAC_SHA256::CHMAC_SHA256(const unsigned char* key, size_t keylen)
+{
+    unsigned char rkey[64];
+    if (keylen <= 64) {
+        memcpy(rkey, key, keylen);
+        memset(rkey + keylen, 0, 64 - keylen);
+    } else {
+        CSHA256().Write(key, keylen).Finalize(rkey);
+        memset(rkey + 32, 0, 32);
+    }
+
+    for (int n = 0; n < 64; n++)
+        rkey[n] ^= 0x5c;
+    outer.Write(rkey, 64);
+
+    for (int n = 0; n < 64; n++)
+        rkey[n] ^= 0x5c ^ 0x36;
+    inner.Write(rkey, 64);
+}
+
+void CHMAC_SHA256::Finalize(unsigned char hash[OUTPUT_SIZE])
+{
+    unsigned char temp[32];
+    inner.Finalize(temp);
+    outer.Write(temp, 32).Finalize(hash);
+}

src/crypto/hmac_sha256.h

@@ -0,0 +1,32 @@
+// Copyright (c) 2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_HMAC_SHA256_H
+#define BITCOIN_HMAC_SHA256_H
+
+#include "crypto/sha256.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+/** A hasher class for HMAC-SHA-512. */
+class CHMAC_SHA256
+{
+private:
+    CSHA256 outer;
+    CSHA256 inner;
+
+public:
+    static const size_t OUTPUT_SIZE = 32;
+
+    CHMAC_SHA256(const unsigned char* key, size_t keylen);
+    CHMAC_SHA256& Write(const unsigned char* data, size_t len)
+    {
+        inner.Write(data, len);
+        return *this;
+    }
+    void Finalize(unsigned char hash[OUTPUT_SIZE]);
+};
+
+#endif // BITCOIN_SHA256_H