在做游戏或应用的时候，一些本地数据为了安全需要加密。最简单的加密方式当然是异或加密了，但异或之后输出的是数据块，并非字符串，有效且省空间的做法是装数据块转成Base64了，Base64之后的空间占用约为原数据的133%左右.
字符串与数据块转换
因为在使用过种中，会用到数据块，这里用字节数组Uint8Array来存储数据块,并需要Uint8Array与String UTF8的互转.
// 字符串转uint字节数组
// 由于字符串中可能包含utf8不定长度字节的编码
private str2bytes(str: string):Array<any> {
let bytes = new Array();
let len, c;
len = str.length;
for (let i = 0; i < len; i++) {
c = str.charCodeAt(i);
if (c >= 0x010000 && c <= 0x10FFFF) {
bytes.push(((c >> 18) & 0x07) | 0xF0);
bytes.push(((c >> 12) & 0x3F) | 0x80);
bytes.push(((c >> 6) & 0x3F) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else if (c >= 0x000800 && c <= 0x00FFFF) {
bytes.push(((c >> 12) & 0x0F) | 0xE0);
bytes.push(((c >> 6) & 0x3F) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else if (c >= 0x000080 && c <= 0x0007FF) {
bytes.push(((c >> 6) & 0x1F) | 0xC0);
bytes.push((c & 0x3F) | 0x80);
} else {
bytes.push(c & 0xFF);
}
}
return bytes;
}
// uint8字节数组转string utf8
private bytes2str(uintArray: any): string {
let encodedString = String.fromCharCode.apply(null, uintArray),
decodedString = decodeURIComponent(escape(encodedString));
return decodedString;
}
// 测试
let base = "guoke3915";
var tmp = this.str2bytes(base);
console.log(tmp); // 输出: 103,117,111,107,101,51,57,49,53
var out = this.bytes2str(tmp);
console.log(out ) // 输出: guoke3915
异或加密
网上也有很多异或的算法，很多都是用charCodeAt和fromCharCode来对字符串直接操作的,这样的操作在ts中很不错也不会出问题.但我还是比较喜欢转成用字节数组来操作,在种在网络通讯中,跨平台跨语言时不容易出错.
/**
* encrypto 加密程序
* @param {strng} str 待加密字符串
* @param {number} xor 异或值
* @return {Uint8Array} 加密后的字符串
*/
private xor_encrypto(str: string, xor: number): Uint8Array {
let buf = this.str2bytes(str)
let bufView = new Uint8Array(buf.length);
for (let i = 0; i < buf.length; i++) {
// 进行异或加密
bufView[i] = buf[i] ^ xor;
}
return bufView;
}
/**
* decrypto 解密程序
* @param {strng} str 待加密字符串
* @param {number} xor 异或值
* @return {strng} 解密后的字符串
*/
private xor_decrypto(data: any, xor: number): string {
let bytes = new Uint8Array(data)
let resultList = new Uint8Array(bytes.length);
// 分割出加密字符串的加密后的每个字符
for (let i = 0; i < bytes.length; i++) {
// 异或解密出原字符的ascll码
resultList[i] = bytes[i] ^ xor;
}
return this.bytes2str(resultList);
}
// 测试
let base = "guoke3915";
var tmp = this.xor_encrypto(base);
console.log(tmp); // 输出: 80,66,88,92,82,4,14,6,2
var out = this.xor_decrypto(tmp);
console.log(out ) // 输出: guoke3915
Base64算法
Base64算法在js原生平台有库,使用Buffer类就能实现. Base64的算法也挺简单的,这里为了配合异或加密还是自己写一个.
// base64 编码
private base64_encode(input:string):string{
const _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
var output = "";
var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
var i = 0;
let data = this.str2bytes(input);
while (i < data.length)
{
chr1 = data[i++];
chr2 = data[i++];
chr3 = data[i++];
enc1 = chr1 >> 2;
enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
enc4 = chr3 & 63;
if (isNaN(chr2))
{
enc3 = enc4 = 64;
}
else if (isNaN(chr3))
{
enc4 = 64;
}
output = output +
_keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
_keyStr.charAt(enc3) + _keyStr.charAt(enc4);
}
return output;
}
// base64 解码
private base64_decode(input:string):string{
const _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
var output = new Uint8Array(input.length);
var chr1, chr2, chr3;
var enc1, enc2, enc3, enc4;
var i = 0, index = 0;
input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
while (i < input.length)
{
enc1 = _keyStr.indexOf(input.charAt(i++));
enc2 = _keyStr.indexOf(input.charAt(i++));
enc3 = _keyStr.indexOf(input.charAt(i++));
enc4 = _keyStr.indexOf(input.charAt(i++));
chr1 = (enc1 << 2) | (enc2 >> 4);
chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
chr3 = ((enc3 & 3) << 6) | enc4;
output[index++] = chr1;
if (enc3 != 64)
{
output[index++] = chr2;
}
if (enc4 != 64)
{
output[index++] = chr3;
}
}
return this.bytes2str(output.subarray(0,index));
}
// 测试
let base = "guoke3915";
var tmp = this.base64_encode(base);
console.log(tmp); // 输出: Z3Vva2UzOTE1
var out = this.base64_decode(tmp);
console.log(out ) // 输出: guoke3915
异或加密并输出Base64字符串
回到主题,从上面异或加密和Base64编码的方法中,很容易就能找出规律,要合并二个算法,只要在Base64编码的时候对编码时的字节做一个异或操作就可以了.
/**
* encrypto 加密程序
* @param {strng} str 待加密字符串
* @param {number} xor 异或值
* @return {string} 加密后并base64编码的字符串
*/
private base64_xor_encode(input:string, xor: number):string{
const _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
var output = "";
var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
var i = 0;
let data = this.str2bytes(input);
while (i < data.length)
{
chr1 = data[i++]^xor;
chr2 = i < data.length?(data[i++]^xor):undefined;
chr3 = i < data.length?(data[i++]^xor):undefined;
enc1 = chr1 >> 2;
enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
enc4 = chr3 & 63;
if (isNaN(chr2))
{
enc3 = enc4 = 64;
}
else if (isNaN(chr3))
{
enc4 = 64;
}
output = output +
_keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
_keyStr.charAt(enc3) + _keyStr.charAt(enc4);
}
return output;
}
/**
* decrypto 解密程序
* @param {strng} str 待加密字符串
* @param {number} xor 异或值
* @return {strng} 解密后的字符串
*/
private base64_xor_decode(input:string,xor: number):string{
const _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
var output = new Uint8Array(input.length);
var chr1, chr2, chr3;
var enc1, enc2, enc3, enc4;
var i = 0, index = 0;
input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
while (i < input.length)
{
enc1 = _keyStr.indexOf(input.charAt(i++));
enc2 = _keyStr.indexOf(input.charAt(i++));
enc3 = _keyStr.indexOf(input.charAt(i++));
enc4 = _keyStr.indexOf(input.charAt(i++));
chr1 = ((enc1 << 2) | (enc2 >> 4));
chr2 = (((enc2 & 15) << 4) | (enc3 >> 2));
chr3 = (((enc3 & 3) << 6) | enc4);
output[index++] = chr1^xor;
if (enc3 != 64)
{
output[index++] = chr2^xor;
}
if (enc4 != 64)
{
output[index++] = chr3^xor;
}
}
return this.bytes2str(output.subarray(0,index));
}
// 测试
let base = "guoke3915";
var tmp = this.base64_xor_encode(base);
console.log(tmp); // 输出: UEJYXFIEDgYC
var out = this.base64_xor_decode(tmp);
console.log(out ) // 输出: guoke3915
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