1 files changed, 136 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/signers/GenericSigner.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/signers/GenericSigner.java
new file mode 100644
index 000000000..0df5a8757
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/signers/GenericSigner.java
@@ -0,0 +1,136 @@
+package org.spongycastle.crypto.signers;
+
+import org.spongycastle.crypto.AsymmetricBlockCipher;
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.CryptoException;
+import org.spongycastle.crypto.DataLengthException;
+import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.Signer;
+import org.spongycastle.crypto.params.AsymmetricKeyParameter;
+import org.spongycastle.crypto.params.ParametersWithRandom;
+import org.spongycastle.util.Arrays;
+
+public class GenericSigner
+    implements Signer
+{
+    private final AsymmetricBlockCipher engine;
+    private final Digest digest;
+    private boolean forSigning;
+
+    public GenericSigner(
+        AsymmetricBlockCipher engine,
+        Digest                digest)
+    {
+        this.engine = engine;
+        this.digest = digest;
+    }
+
+    /**
+     * initialise the signer for signing or verification.
+     *
+     * @param forSigning
+     *            true if for signing, false otherwise
+     * @param parameters
+     *            necessary parameters.
+     */
+    public void init(
+        boolean          forSigning,
+        CipherParameters parameters)
+    {
+        this.forSigning = forSigning;
+        AsymmetricKeyParameter k;
+
+        if (parameters instanceof ParametersWithRandom)
+        {
+            k = (AsymmetricKeyParameter)((ParametersWithRandom)parameters).getParameters();
+        }
+        else
+        {
+            k = (AsymmetricKeyParameter)parameters;
+        }
+
+        if (forSigning && !k.isPrivate())
+        {
+            throw new IllegalArgumentException("signing requires private key");
+        }
+
+        if (!forSigning && k.isPrivate())
+        {
+            throw new IllegalArgumentException("verification requires public key");
+        }
+
+        reset();
+
+        engine.init(forSigning, parameters);
+    }
+
+    /**
+     * update the internal digest with the byte b
+     */
+    public void update(
+        byte input)
+    {
+        digest.update(input);
+    }
+
+    /**
+     * update the internal digest with the byte array in
+     */
+    public void update(
+        byte[]  input,
+        int     inOff,
+        int     length)
+    {
+        digest.update(input, inOff, length);
+    }
+
+    /**
+     * Generate a signature for the message we've been loaded with using the key
+     * we were initialised with.
+     */
+    public byte[] generateSignature()
+        throws CryptoException, DataLengthException
+    {
+        if (!forSigning)
+        {
+            throw new IllegalStateException("GenericSigner not initialised for signature generation.");
+        }
+
+        byte[] hash = new byte[digest.getDigestSize()];
+        digest.doFinal(hash, 0);
+
+        return engine.processBlock(hash, 0, hash.length);
+    }
+
+    /**
+     * return true if the internal state represents the signature described in
+     * the passed in array.
+     */
+    public boolean verifySignature(
+        byte[] signature)
+    {
+        if (forSigning)
+        {
+            throw new IllegalStateException("GenericSigner not initialised for verification");
+        }
+
+        byte[] hash = new byte[digest.getDigestSize()];
+        digest.doFinal(hash, 0);
+
+        try
+        {
+            byte[] sig = engine.processBlock(signature, 0, signature.length);
+
+            return Arrays.constantTimeAreEqual(sig, hash);
+        }
+        catch (Exception e)
+        {
+            return false;
+        }
+    }
+
+    public void reset()
+    {
+        digest.reset();
+    }
+}