1 files changed, 114 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/tls/SSL3Mac.java b/core/src/main/java/org/spongycastle/crypto/tls/SSL3Mac.java
new file mode 100644
index 00000000..6b3f2faf
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/tls/SSL3Mac.java
@@ -0,0 +1,114 @@
+package org.spongycastle.crypto.tls;
+
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.Mac;
+import org.spongycastle.crypto.params.KeyParameter;
+import org.spongycastle.util.Arrays;
+
+/**
+ * HMAC implementation based on original internet draft for HMAC (RFC 2104)
+ * <p>
+ * The difference is that padding is concatenated versus XORed with the key
+ * <p>
+ * H(K + opad, H(K + ipad, text))
+ */
+public class SSL3Mac
+    implements Mac
+{
+    private final static byte IPAD_BYTE = (byte)0x36;
+    private final static byte OPAD_BYTE = (byte)0x5C;
+
+    static final byte[] IPAD = genPad(IPAD_BYTE, 48);
+    static final byte[] OPAD = genPad(OPAD_BYTE, 48);
+
+    private Digest digest;
+
+    private byte[] secret;
+    private int padLength;
+
+    /**
+     * Base constructor for one of the standard digest algorithms that the byteLength of
+     * the algorithm is know for. Behaviour is undefined for digests other than MD5 or SHA1.
+     *
+     * @param digest the digest.
+     */
+    public SSL3Mac(Digest digest)
+    {
+        this.digest = digest;
+
+        if (digest.getDigestSize() == 20)
+        {
+            this.padLength = 40;
+        }
+        else
+        {
+            this.padLength = 48;
+        }
+    }
+
+    public String getAlgorithmName()
+    {
+        return digest.getAlgorithmName() + "/SSL3MAC";
+    }
+
+    public Digest getUnderlyingDigest()
+    {
+        return digest;
+    }
+
+    public void init(CipherParameters params)
+    {
+        secret = Arrays.clone(((KeyParameter)params).getKey());
+
+        reset();
+    }
+
+    public int getMacSize()
+    {
+        return digest.getDigestSize();
+    }
+
+    public void update(byte in)
+    {
+        digest.update(in);
+    }
+
+    public void update(byte[] in, int inOff, int len)
+    {
+        digest.update(in, inOff, len);
+    }
+
+    public int doFinal(byte[] out, int outOff)
+    {
+        byte[] tmp = new byte[digest.getDigestSize()];
+        digest.doFinal(tmp, 0);
+
+        digest.update(secret, 0, secret.length);
+        digest.update(OPAD, 0, padLength);
+        digest.update(tmp, 0, tmp.length);
+
+        int len = digest.doFinal(out, outOff);
+
+        reset();
+
+        return len;
+    }
+
+    /**
+     * Reset the mac generator.
+     */
+    public void reset()
+    {
+        digest.reset();
+        digest.update(secret, 0, secret.length);
+        digest.update(IPAD, 0, padLength);
+    }
+
+    private static byte[] genPad(byte b, int count)
+    {
+        byte[] padding = new byte[count];
+        Arrays.fill(padding, b);
+        return padding;
+    }
+}