1 files changed, 48 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/paddings/BlockCipherPadding.java b/core/src/main/java/org/spongycastle/crypto/paddings/BlockCipherPadding.java
new file mode 100644
index 00000000..f68915d1
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/paddings/BlockCipherPadding.java
@@ -0,0 +1,48 @@
+package org.spongycastle.crypto.paddings;
+
+import java.security.SecureRandom;
+
+import org.spongycastle.crypto.InvalidCipherTextException;
+
+/**
+ * Block cipher padders are expected to conform to this interface
+ */
+public interface BlockCipherPadding
+{
+    /**
+     * Initialise the padder.
+     *
+     * @param random the source of randomness for the padding, if required.
+     */
+    public void init(SecureRandom random)
+        throws IllegalArgumentException;
+
+    /**
+     * Return the name of the algorithm the cipher implements.
+     *
+     * @return the name of the algorithm the cipher implements.
+     */
+    public String getPaddingName();
+
+    /**
+     * add the pad bytes to the passed in block, returning the
+     * number of bytes added.
+     * <p>
+     * Note: this assumes that the last block of plain text is always 
+     * passed to it inside in. i.e. if inOff is zero, indicating the
+     * entire block is to be overwritten with padding the value of in
+     * should be the same as the last block of plain text. The reason
+     * for this is that some modes such as "trailing bit compliment"
+     * base the padding on the last byte of plain text.
+     * </p>
+     */
+    public int addPadding(byte[] in, int inOff);
+
+    /**
+     * return the number of pad bytes present in the block.
+     * @exception InvalidCipherTextException if the padding is badly formed
+     * or invalid.
+     */
+    public int padCount(byte[] in)
+        throws InvalidCipherTextException;
+}