1 files changed, 58 insertions, 0 deletions

diff --git a/core/src/main/java/org/spongycastle/crypto/StreamBlockCipher.java b/core/src/main/java/org/spongycastle/crypto/StreamBlockCipher.java
new file mode 100644
index 00000000..58410183
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/StreamBlockCipher.java
@@ -0,0 +1,58 @@
+package org.spongycastle.crypto;
+
+/**
+ * A parent class for block cipher modes that do not require block aligned data to be processed, but can function in
+ * a streaming mode.
+ */
+public abstract class StreamBlockCipher
+    implements BlockCipher, StreamCipher
+{
+    private final BlockCipher cipher;
+
+    protected StreamBlockCipher(BlockCipher cipher)
+    {
+        this.cipher = cipher;
+    }
+
+    /**
+     * return the underlying block cipher that we are wrapping.
+     *
+     * @return the underlying block cipher that we are wrapping.
+     */
+    public BlockCipher getUnderlyingCipher()
+    {
+        return cipher;
+    }
+
+    public final byte returnByte(byte in)
+    {
+        return calculateByte(in);
+    }
+
+    public int processBytes(byte[] in, int inOff, int len, byte[] out, int outOff)
+        throws DataLengthException
+    {
+        if (outOff + len > out.length)
+        {
+            throw new DataLengthException("output buffer too short");
+        }
+
+        if (inOff + len > in.length)
+        {
+            throw new DataLengthException("input buffer too small");
+        }
+
+        int inStart = inOff;
+        int inEnd = inOff + len;
+        int outStart = outOff;
+
+        while (inStart < inEnd)
+        {
+             out[outStart++] = calculateByte(in[inStart++]);
+        }
+
+        return len;
+    }
+
+    protected abstract byte calculateByte(byte b);
+}
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