1 files changed, 128 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/tls/DeferredHash.java b/core/src/main/java/org/bouncycastle/crypto/tls/DeferredHash.java
new file mode 100644
index 00000000..e8c76e65
--- /dev/null
+++ b/core/src/main/java/org/bouncycastle/crypto/tls/DeferredHash.java
@@ -0,0 +1,128 @@
+package org.bouncycastle.crypto.tls;
+
+import java.io.ByteArrayOutputStream;
+
+import org.bouncycastle.crypto.Digest;
+
+/**
+ * Buffers input until the hash algorithm is determined.
+ */
+class DeferredHash
+    implements TlsHandshakeHash
+{
+
+    protected TlsContext context;
+
+    private ByteArrayOutputStream buf = new ByteArrayOutputStream();
+    private int prfAlgorithm = -1;
+    private Digest hash = null;
+
+    DeferredHash()
+    {
+        this.buf = new ByteArrayOutputStream();
+        this.hash = null;
+    }
+
+    private DeferredHash(Digest hash)
+    {
+        this.buf = null;
+        this.hash = hash;
+    }
+
+    public void init(TlsContext context)
+    {
+        this.context = context;
+    }
+
+    public TlsHandshakeHash commit()
+    {
+
+        int prfAlgorithm = context.getSecurityParameters().getPrfAlgorithm();
+
+        Digest prfHash = TlsUtils.createPRFHash(prfAlgorithm);
+
+        byte[] data = buf.toByteArray();
+        prfHash.update(data, 0, data.length);
+
+        if (prfHash instanceof TlsHandshakeHash)
+        {
+            TlsHandshakeHash tlsPRFHash = (TlsHandshakeHash)prfHash;
+            tlsPRFHash.init(context);
+            return tlsPRFHash.commit();
+        }
+
+        this.prfAlgorithm = prfAlgorithm;
+        this.hash = prfHash;
+        this.buf = null;
+
+        return this;
+    }
+
+    public TlsHandshakeHash fork()
+    {
+        checkHash();
+        return new DeferredHash(TlsUtils.clonePRFHash(prfAlgorithm, hash));
+    }
+
+    public String getAlgorithmName()
+    {
+        checkHash();
+        return hash.getAlgorithmName();
+    }
+
+    public int getDigestSize()
+    {
+        checkHash();
+        return hash.getDigestSize();
+    }
+
+    public void update(byte input)
+    {
+        if (hash == null)
+        {
+            buf.write(input);
+        }
+        else
+        {
+            hash.update(input);
+        }
+    }
+
+    public void update(byte[] input, int inOff, int len)
+    {
+        if (hash == null)
+        {
+            buf.write(input, inOff, len);
+        }
+        else
+        {
+            hash.update(input, inOff, len);
+        }
+    }
+
+    public int doFinal(byte[] output, int outOff)
+    {
+        checkHash();
+        return hash.doFinal(output, outOff);
+    }
+
+    public void reset()
+    {
+        if (hash == null)
+        {
+            buf.reset();
+        }
+        else
+        {
+            hash.reset();
+        }
+    }
+
+    protected void checkHash()
+    {
+        if (hash == null)
+        {
+            throw new IllegalStateException("No hash algorithm has been set");
+        }
+    }
+}