Add DTLS 1.3 record protection to TlsAEADCipher via a new TlsDTLS13Cipher interface, relates to github #1468.

Author: mondain

tls/src/main/java/org/bouncycastle/tls/crypto/TlsDTLS13Cipher.java

@@ -0,0 +1,57 @@
+package org.bouncycastle.tls.crypto;
+
+import java.io.IOException;
+
+/**
+ * The optional DTLS 1.3 (RFC 9147) record protection extension to {@link TlsCipher}, implemented by ciphers
+ * that can protect DTLS 1.3 records.
+ */
+public interface TlsDTLS13Cipher
+{
+    /**
+     * Encode the passed in plaintext as a DTLS 1.3 protected record (RFC 9147 4). The supplied unified header is
+     * the AEAD additional data; when its L bit is set the (zeroed) length field is filled in by this method. The
+     * returned record holds the header, with record number encryption (RFC 9147 4.2.3) applied to its sequence
+     * number bytes, followed by the encrypted record.
+     *
+     * @param seqNo the 64-bit record sequence number (the epoch is not included, unlike DTLS 1.2).
+     * @param contentType the true content type, written into the DTLSInnerPlaintext.
+     * @param header array holding the unified header with the sequence number in the clear.
+     * @param headerOff offset of the header in the array.
+     * @param headerLen length of the header.
+     * @param plaintext array holding input plaintext to the cipher.
+     * @param offset offset into input array the plaintext starts at.
+     * @param len length of the plaintext in the array.
+     * @return A {@link TlsEncodeResult} whose buffer holds the complete record (header followed by ciphertext),
+     *         with 'recordType' set to the first byte of the unified header.
+     * @throws IOException
+     */
+    TlsEncodeResult encodeDTLS13Plaintext(long seqNo, short contentType, byte[] header, int headerOff, int headerLen,
+        byte[] plaintext, int offset, int len) throws IOException;
+
+    /**
+     * Decrypt (in place) the record number of a received DTLS 1.3 protected record (RFC 9147 4.2.3). The record
+     * starts with its unified header; at least 16 bytes of ciphertext must follow the header.
+     *
+     * @param record array holding the received record.
+     * @param recordOff offset of the record (its unified header) in the array.
+     * @param recordLen length of the record.
+     * @throws IOException
+     */
+    void decryptDTLS13RecordNumber(byte[] record, int recordOff, int recordLen) throws IOException;
+
+    /**
+     * Decode a received DTLS 1.3 protected record. The unified header (with the sequence number already decrypted)
+     * at 'recordOff' is the AEAD additional data, and the ciphertext immediately follows it.
+     *
+     * @param seqNo the 64-bit record sequence number reconstructed by the caller (the epoch is not included).
+     * @param record array holding the received record.
+     * @param recordOff offset of the record (its unified header) in the array.
+     * @param headerLen length of the unified header.
+     * @param ciphertextLen length of the ciphertext following the header.
+     * @return A {@link TlsDecodeResult} containing the result of decoding.
+     * @throws IOException
+     */
+    TlsDecodeResult decodeDTLS13Ciphertext(long seqNo, byte[] record, int recordOff, int headerLen, int ciphertextLen)
+        throws IOException;
+}