java/org/rivoreo/crypto/ECIES_ChaCha20.java

/*
 * Copyright 2015-2016 Rivoreo
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 */

package org.rivoreo.crypto;

public class ECIES_ChaCha20 extends ECIES implements ECIES.NonceListener {
	public ECIES_ChaCha20(SECTDomainParameters dp, int chacha20_key_size) {
		super(dp);
		if(chacha20_key_size != 16 && chacha20_key_size != 32) {
			throw new IllegalArgumentException("chacha20_key_size can only be 16 or 32");
		}
		key_size = chacha20_key_size;
		nonce = new byte[8];
		set_symmetric_crypt_nonce_listener(this, 8);
	}
	public ECIES_ChaCha20(SECTDomainParameters dp) {
		this(dp, 32);
	}

	private final int key_size;
	private final byte[] nonce;

	public void set_nonce(byte[] nonce) {
		if(nonce.length < 8) throw new IllegalArgumentException("nonce.length < 8");
		for(int i=0; i<8; i++) this.nonce[i] = nonce[i];
	}

	protected int get_symmetric_key_bytes() {
		return key_size;
	}

	protected void ctr_crypt(byte[] data, int len, final byte[] key) {
		System.err.printf("method: org.rivoreo.crypto.ECIES_ChaCha20::ctr_crypt(byte[%d], %d, final byte[%d])\n", data.length, len, key.length);
		ChaCha20 ctx = new ChaCha20(key, key_size, nonce);
		ctx.encrypt(data, len);
	}

	protected void cbc_mac(byte[] mac, final byte[] data, int len, final byte[] key) {
		System.err.printf("method: org.rivoreo.crypto.ECIES_ChaCha20::cbc_mac(byte[%d], final byte[%d], %d, final byte[%d])\n", mac.length, data.length, len, key.length);
		ChaCha20 ctx = new ChaCha20(key, key_size, nonce);
		int blen, i, di = 0;
		int_to_bytes(mac, 0, 0);
		int_to_bytes(mac, 4, len);
		ctx.encrypt(mac, ECIES_CHUNK_OVERHEAD);
		while(len > 0) {
			blen = Math.min(ECIES_CHUNK_OVERHEAD, len);
			i = 0;
			while(i < blen) mac[i++] ^= data[di++];
			ctx.encrypt(mac, ECIES_CHUNK_OVERHEAD);
			len -= blen;
		}
	}

	protected void davies_meyer(byte[] out, final byte[] in, int ilen) {
		System.err.printf("method: org.rivoreo.crypto.ECIES_ChaCha20::davies_meyer(byte[%d], final byte[%d], %d)\n", out.length, in.length, ilen);
		debug_print_bytes(nonce, 8);
		int i, offset = 0;
		byte[] buffer = new byte[key_size / 2];
		ChaCha20 ctx;
		for(i = 0; i < key_size / 2; i++) out[i] = 0;
		while(ilen-- > 0) {
			ctx = new ChaCha20(sub_byte_array(in, offset), key_size, nonce);
			for(i = 0; i < buffer.length; i++) buffer[i] = out[i];
			ctx.encrypt(buffer, buffer.length);
			debug_print_bytes(buffer, buffer.length);
			for(i = 0; i < buffer.length; i++) out[i] ^= buffer[i];
			offset += key_size;
		}
	}

}