diff --git a/briar-core/src/org/briarproject/crypto/AuthenticatedCipher.java b/briar-core/src/org/briarproject/crypto/AuthenticatedCipher.java
index 3225b65e49d04b9dfa7179748719fb37ed013f4c..5ee21e3e4ca1047f67f40a2b427d1e37ae7005ce 100644
--- a/briar-core/src/org/briarproject/crypto/AuthenticatedCipher.java
+++ b/briar-core/src/org/briarproject/crypto/AuthenticatedCipher.java
@@ -1,19 +1,41 @@
 package org.briarproject.crypto;
 
-import java.security.GeneralSecurityException;
-
 import org.briarproject.api.crypto.SecretKey;
 
+import java.security.GeneralSecurityException;
+
 interface AuthenticatedCipher {
 
 	/**
 	 * Initializes this cipher for encryption or decryption with a key and an
 	 * initialisation vector (IV).
+	 *
+	 * @param encrypt whether we are encrypting or decrypting.
+	 * @param key the key material to use.
+	 * @param iv the IV.
+	 * @throws GeneralSecurityException on invalid input.
 	 */
 	void init(boolean encrypt, SecretKey key, byte[] iv)
 			throws GeneralSecurityException;
 
-	/** Encrypts or decrypts data in a single-part operation. */
+	/**
+	 * Encrypts or decrypts data in a single-part operation.
+	 *
+	 * @param input the input byte array. If encrypting, the plaintext to be
+	 *              encrypted. If decrypting, the ciphertext to be decrypted
+	 *              including the MAC.
+	 * @param inputOff the offset into the input array where the data to be
+	 *                 processed starts.
+	 * @param len the number of bytes to be processed. If decrypting, includes
+	 *            the MAC length.
+	 * @param output the output buffer the processed bytes go into. If
+	 *               encrypting, the ciphertext including the MAC. If
+	 *               decrypting, the plaintext.
+	 * @param outputOff the offset into the output byte array the processed
+	 *                  data starts at.
+	 * @return  the number of bytes processed.
+	 * @throws GeneralSecurityException on invalid input.
+	 */
 	int process(byte[] input, int inputOff, int len, byte[] output,
 			int outputOff) throws GeneralSecurityException;