130 lines
3.7 KiB
Java
130 lines
3.7 KiB
Java
package com.cscn.zuc256;
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import com.cscn.Zuc256Core;
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import com.cscn.Zuc256State;
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import java.util.Arrays;
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/**
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* 加密上下文类
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*/
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public final class Zuc256EncryptCtx {
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Zuc256State state;
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byte[] buf;
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int buflen;
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public Zuc256EncryptCtx(Zuc256State state, byte[] buf){
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this.state = state;
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this.buf = buf;
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}
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public Zuc256EncryptCtx(Zuc256State state){
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this.state = state;
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this.buf = new byte[4];
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}
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public Zuc256EncryptCtx(){
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this.state = new Zuc256State();
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this.buf = new byte[4];
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}
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// 初始化加密上下文
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public void init(byte[] key32, byte[] iv) {
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Arrays.fill(this.buf, (byte) 0);
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this.buflen = 0;
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Zuc256Core.initState(this.state, key32, iv);
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}
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// 分阶段处理加密数据
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public void update(byte[] in, int inlen, byte[] out) {
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if (in == null || out == null || inlen == 0) return;
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// 处理缓冲区中剩余的非4字节数据
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if (this.buflen > 0) {
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int need = 4 - this.buflen;
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int copy = Math.min(inlen, need);
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System.arraycopy(in, 0, this.buf, this.buflen, copy);
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this.buflen += copy;
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// 调整输入指针和长度
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byte[] newIn = new byte[inlen - copy];
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if (inlen - copy > 0) {
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System.arraycopy(in, copy, newIn, 0, inlen - copy);
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}
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in = newIn;
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inlen -= copy;
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// 缓冲区已满，处理一个完整的4字节块
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if (this.buflen == 4) {
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int keystream = zuc256GenerateKeyword(this.state);
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int plain = getU32(this.buf, 0);
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putU32(out, 0, plain ^ keystream);
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this.buflen = 0;
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Arrays.fill(this.buf, (byte) 0);
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// 调整输出指针
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byte[] newOut = new byte[out.length - 4];
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if (out.length - 4 > 0) {
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System.arraycopy(out, 4, newOut, 0, out.length - 4);
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}
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out = newOut;
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}
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}
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// 处理完整的4字节块
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int fullBlocks = inlen / 4;
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if (fullBlocks > 0) {
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int[] keystream = new int[fullBlocks];
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zuc256GenerateKeystream(this.state, fullBlocks, keystream);
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// 逐块异或加密
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for (int i = 0; i < fullBlocks; i++) {
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int plain = getU32(in, i * 4);
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putU32(out, i * 4, plain ^ keystream[i]);
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}
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// 调整输入指针和长度
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int processed = fullBlocks * 4;
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byte[] newIn = new byte[inlen - processed];
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if (inlen - processed > 0) {
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System.arraycopy(in, processed, newIn, 0, inlen - processed);
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}
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in = newIn;
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inlen -= processed;
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}
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// 缓存剩余不足4字节的数据
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if (inlen > 0) {
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System.arraycopy(in, 0, this.buf, 0, inlen);
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this.buflen = inlen;
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}
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}
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// 完成加密处理
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public void finish(byte[] out) {
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if (this == null || out == null) return;
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// 处理缓冲区中剩余的不足4字节数据
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if (this.buflen > 0) {
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int keystream = zuc256GenerateKeyword(this.state);
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byte[] keystreamBytes = new byte[4];
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putU32(keystreamBytes, 0, keystream);
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// 逐字节异或
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for (int i = 0; i < this.buflen; i++) {
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out[i] = (byte) (this.buf[i] ^ keystreamBytes[i]);
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}
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}
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// 清理上下文
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Arrays.fill(this.buf, (byte) 0);
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this.buflen = 0;
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Arrays.fill(this.state.LFSR, 0);
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this.state.R1 = 0;
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this.state.R2 = 0;
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}
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}
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