Add MessageSignerAdapter

Author: peterdettman

core/src/main/java/org/bouncycastle/pqc/crypto/MessageSignerAdapter.java

@@ -0,0 +1,76 @@
+package org.bouncycastle.pqc.crypto;
+
+import java.io.ByteArrayOutputStream;
+
+import org.bouncycastle.crypto.CipherParameters;
+import org.bouncycastle.crypto.Signer;
+import org.bouncycastle.util.Arrays;
+
+public final class MessageSignerAdapter
+    implements Signer
+{
+    private final Buffer buffer = new Buffer();
+
+    private final MessageSigner messageSigner;
+
+    public MessageSignerAdapter(MessageSigner messageSigner)
+    {
+        if (messageSigner == null)
+        {
+            throw new NullPointerException("'messageSigner' cannot be null");
+        }
+
+        this.messageSigner = messageSigner;
+    }
+
+    public void init(boolean forSigning, CipherParameters param)
+    {
+        messageSigner.init(forSigning, param);
+    }
+
+    public void update(byte b)
+    {
+        buffer.write(b);
+    }
+
+    public void update(byte[] in, int off, int len)
+    {
+        buffer.write(in, off, len);
+    }
+
+    public byte[] generateSignature()
+    {
+        return messageSigner.generateSignature(getMessage());
+    }
+
+    public boolean verifySignature(byte[] signature)
+    {
+        return messageSigner.verifySignature(getMessage(), signature);
+    }
+
+    public void reset()
+    {
+        buffer.reset();
+    }
+
+    private byte[] getMessage()
+    {
+        try
+        {
+            return buffer.toByteArray();
+        }
+        finally
+        {
+            reset();
+        }
+    }
+
+    private static final class Buffer extends ByteArrayOutputStream
+    {
+        public synchronized void reset()
+        {
+            Arrays.fill(buf, 0, count, (byte)0);
+            this.count = 0;
+        }
+    }
+}