--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/trilead/ssh2/crypto/digest/MAC.java	Thu May 22 10:41:19 2014 -0700
@@ -0,0 +1,154 @@
+
+package com.trilead.ssh2.crypto.digest;
+
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+
+import javax.crypto.Mac;
+import javax.crypto.ShortBufferException;
+import javax.crypto.spec.SecretKeySpec;
+
+/**
+ * MAC.
+ *
+ * @author Christian Plattner, plattner@trilead.com
+ * @version $Id: MAC.java,v 1.1 2007/10/15 12:49:57 cplattne Exp $
+ */
+public final class MAC {
+    /**
+     * From http://tools.ietf.org/html/rfc4253
+     */
+    private static final String HMAC_MD5 = "hmac-md5";
+
+    /**
+     * From http://tools.ietf.org/html/rfc4253
+     */
+    private static final String HMAC_MD5_96 = "hmac-md5-96";
+
+    /**
+     * From http://tools.ietf.org/html/rfc4253
+     */
+    private static final String HMAC_SHA1 = "hmac-sha1";
+
+    /**
+     * From http://tools.ietf.org/html/rfc4253
+     */
+    private static final String HMAC_SHA1_96 = "hmac-sha1-96";
+
+    /**
+     * From http://tools.ietf.org/html/rfc6668
+     */
+    private static final String HMAC_SHA2_256 = "hmac-sha2-256";
+
+    /**
+     * From http://tools.ietf.org/html/rfc6668
+     */
+    private static final String HMAC_SHA2_512 = "hmac-sha2-512";
+
+    Mac mac;
+    int outSize;
+    int macSize;
+    byte[] buffer;
+
+    /* Higher Priority First */
+    private static final String[] MAC_LIST = {
+        HMAC_SHA2_256, HMAC_SHA2_512,
+        HMAC_SHA1_96, HMAC_SHA1, HMAC_MD5_96, HMAC_MD5
+    };
+
+    public final static String[] getMacList() {
+        return MAC_LIST;
+    }
+
+    public final static void checkMacList(String[] macs) {
+        for (int i = 0; i < macs.length; i++)
+            getKeyLen(macs[i]);
+    }
+
+    public final static int getKeyLen(String type) {
+        if (HMAC_SHA1.equals(type) || HMAC_SHA1_96.equals(type))
+            return 20;
+
+        if (HMAC_MD5.equals(type) || HMAC_MD5_96.equals(type))
+            return 16;
+
+        if (HMAC_SHA2_256.equals(type))
+            return 32;
+
+        if (HMAC_SHA2_512.equals(type))
+            return 64;
+
+        throw new IllegalArgumentException("Unkown algorithm " + type);
+    }
+
+    public MAC(String type, byte[] key) {
+        try {
+            if (HMAC_SHA1.equals(type) || HMAC_SHA1_96.equals(type)) {
+                mac = Mac.getInstance("HmacSHA1");
+            }
+            else if (HMAC_MD5.equals(type) || HMAC_MD5_96.equals(type)) {
+                mac = Mac.getInstance("HmacMD5");
+            }
+            else if (HMAC_SHA2_256.equals(type)) {
+                mac = Mac.getInstance("HmacSHA256");
+            }
+            else if (HMAC_SHA2_512.equals(type)) {
+                mac = Mac.getInstance("HmacSHA512");
+            }
+            else
+                throw new IllegalArgumentException("Unkown algorithm " + type);
+        }
+        catch (NoSuchAlgorithmException e) {
+            throw new IllegalArgumentException("Unknown algorithm " + type, e);
+        }
+
+        macSize = mac.getMacLength();
+
+        if (type.endsWith("-96")) {
+            outSize = 12;
+            buffer = new byte[macSize];
+        }
+        else {
+            outSize = macSize;
+            buffer = null;
+        }
+
+        try {
+            mac.init(new SecretKeySpec(key, type));
+        }
+        catch (InvalidKeyException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    public final void initMac(int seq) {
+        mac.reset();
+        mac.update((byte)(seq >> 24));
+        mac.update((byte)(seq >> 16));
+        mac.update((byte)(seq >> 8));
+        mac.update((byte)(seq));
+    }
+
+    public final void update(byte[] packetdata, int off, int len) {
+        mac.update(packetdata, off, len);
+    }
+
+    public final void getMac(byte[] out, int off) {
+        try {
+            if (buffer != null) {
+                mac.doFinal(buffer, 0);
+                System.arraycopy(buffer, 0, out, off, out.length - off);
+            }
+            else {
+                mac.doFinal(out, off);
+            }
+        }
+        catch (ShortBufferException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    public final int size() {
+        return outSize;
+    }
+}