最近在看harmony。网络通讯最基础的数据加解密需要封装，以下研究了其写法。其实写法和flutter里 甚至android中代码写法 大同小异，具体算法可自定义修改，只展示原理。
原理：
加密：1.json字符串（待加密原文）通过base64执行decodeSync 2.通过算法转换为byte数组 3.byte转string
解密：1.string json字符串（密文） 转byte 2.通过算法得到新byte数组 3.通过base64的encodeToStringSync 把byte转为string
import util from '@ohos.util';
/**
* 加解密 位移符占位数
*/
static readonly PACKET_HEADER_SIZE: number = 5;
/**
* 加密算法
* @param strBuf
* @returns
*/
public decryption(strBuf: string): string {
var base64 = new util.Base64Helper();
let pBuffer = base64.decodeSync(strBuf);
var strBuffer = "";
var pNewBuffer = new Array(pBuffer.length - CommonConstants.PACKET_HEADER_SIZE);
let iSize = pBuffer.length;
if (pBuffer[0] != 0) {
for (let i = CommonConstants.PACKET_HEADER_SIZE; i < iSize; i++) {
let t1 = ((pBuffer[i] & 0xFF) ^ ((pBuffer[0] & 0xFF) ^ (iSize - i))) % 256;
if (t1 < 0) {
t1 = t1 + 256;
}
pNewBuffer[i - CommonConstants.PACKET_HEADER_SIZE] = t1;
let t2 = ((pNewBuffer[i - CommonConstants.PACKET_HEADER_SIZE] & 0xFF) - ((i - CommonConstants.PACKET_HEADER_SIZE) ^ (pBuffer[0] & 0xFF))) % 256;
// 取余数时 负数 加 256
if (t2 < 0) {
t2 = t2 + 256;
}
// pNewBuffer[i - PACKET_HEADER_SIZE] = Convert.ToByte(t2);
pNewBuffer[i - CommonConstants.PACKET_HEADER_SIZE] = t2;
}
strBuffer = this.byteToString(pNewBuffer);
}
return strBuffer;
}
/**
* 解密算法
* @param strBuf
* @param bEncryption
* @returns
*/
public encryption(strBuf: string, bEncryption: boolean): string {
var base64 = new util.Base64Helper();
var pSndBuf = new Array();
pSndBuf = this.stringToByte(strBuf);
var iSize = pSndBuf.length;
let pTempBuffer = new Uint8Array(pSndBuf.length + CommonConstants.PACKET_HEADER_SIZE);
if (bEncryption) {
var rd = Math.random() * 1000;
pTempBuffer[0] = rd % 128;
} else {
pTempBuffer[0] = 0;
}
var iLength = (iSize + CommonConstants.PACKET_HEADER_SIZE);
var byteLength = new Array(iLength);
pTempBuffer[1] = byteLength[0];
pTempBuffer[2] = byteLength[1];
if (pTempBuffer[0] != 0) {
for (let i = 0; i < iSize; i++) {
pTempBuffer[CommonConstants.PACKET_HEADER_SIZE + i] = (((pSndBuf[i] & 0xFF) + (i ^ ((pTempBuffer[0] & 0xFF)))) % 256);
pTempBuffer[CommonConstants.PACKET_HEADER_SIZE + i] = (((pTempBuffer[CommonConstants.PACKET_HEADER_SIZE + i] & 0xFF) ^ ((pTempBuffer[0] & 0xFF) ^ (iSize - i))) % 256);
}
} else {
for (let i = 0; i < iSize; i++) {
pTempBuffer[CommonConstants.PACKET_HEADER_SIZE + i] = pSndBuf[i];
}
}
return base64.encodeToStringSync(pTempBuffer);
}
/**
* string转byte
* @param str
* @returns
*/
public stringToByte(str) {
var bytes = new Array();
var len, c;
len = str.length;
for (var 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 <= 0x00FFF) {
bytes.push(((c >> 12) & 0x07) | 0xf0);
bytes.push(((c >> 6) & 0x3F) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else if (c >= 0x000800 && c <= 0x0007FF) {
bytes.push(((c >> 6) & 0x3F) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else {
bytes.push(c & 0xFF)
}
}
return bytes;
}
/**
* byte转string
* @param str
* @returns
*/
public byteToString(arr): string {
if (typeof arr === 'string') {
return arr;
}
var str = '',
_arr = arr;
for (var i = 0; i < _arr.length; i++) {
var one = _arr[i].toString(2),
v = one.match(/^1+?(?=0)/);
if (v && one.length == 8) {
var bytesLength = v[0].length;
var store = _arr[i].toString(2).slice(7 - bytesLength);
for (var st = 1; st < bytesLength; st++) {
store += _arr[st + i].toString(2).slice(2);
}
str += String.fromCharCode(parseInt(store, 2));
i += bytesLength - 1;
} else {
str += String.fromCharCode(_arr[i]);
}
}
return str;
}
用法：
CommonUtils.encryption(needEncryption.toString(),true);
CommonUtils.decryption(resultJson.Body.toString());
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