1 files changed, 78 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/engines/RSAEngine.java b/core/src/main/java/org/spongycastle/crypto/engines/RSAEngine.java
new file mode 100644
index 00000000..5ffe2ace
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/engines/RSAEngine.java
@@ -0,0 +1,78 @@
+package org.spongycastle.crypto.engines;
+
+import org.spongycastle.crypto.AsymmetricBlockCipher;
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.DataLengthException;
+
+/**
+ * this does your basic RSA algorithm.
+ */
+public class RSAEngine
+    implements AsymmetricBlockCipher
+{
+    private RSACoreEngine core;
+
+    /**
+     * initialise the RSA engine.
+     *
+     * @param forEncryption true if we are encrypting, false otherwise.
+     * @param param the necessary RSA key parameters.
+     */
+    public void init(
+        boolean             forEncryption,
+        CipherParameters    param)
+    {
+        if (core == null)
+        {
+            core = new RSACoreEngine();
+        }
+
+        core.init(forEncryption, param);
+    }
+
+    /**
+     * Return the maximum size for an input block to this engine.
+     * For RSA this is always one byte less than the key size on
+     * encryption, and the same length as the key size on decryption.
+     *
+     * @return maximum size for an input block.
+     */
+    public int getInputBlockSize()
+    {
+        return core.getInputBlockSize();
+    }
+
+    /**
+     * Return the maximum size for an output block to this engine.
+     * For RSA this is always one byte less than the key size on
+     * decryption, and the same length as the key size on encryption.
+     *
+     * @return maximum size for an output block.
+     */
+    public int getOutputBlockSize()
+    {
+        return core.getOutputBlockSize();
+    }
+
+    /**
+     * Process a single block using the basic RSA algorithm.
+     *
+     * @param in the input array.
+     * @param inOff the offset into the input buffer where the data starts.
+     * @param inLen the length of the data to be processed.
+     * @return the result of the RSA process.
+     * @exception DataLengthException the input block is too large.
+     */
+    public byte[] processBlock(
+        byte[]  in,
+        int     inOff,
+        int     inLen)
+    {
+        if (core == null)
+        {
+            throw new IllegalStateException("RSA engine not initialised");
+        }
+
+        return core.convertOutput(core.processBlock(core.convertInput(in, inOff, inLen)));
+    }
+}