108 lines
2.5 KiB
TypeScript
108 lines
2.5 KiB
TypeScript
import {TeaCipher} from "@/utils/tea";
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const SALT_LEN = 2
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const ZERO_LEN = 7
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export function QmcDeriveKey(raw: Uint8Array): Uint8Array {
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const textDec = new TextDecoder()
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const rawDec = Buffer.from(textDec.decode(raw), 'base64')
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let n = rawDec.length;
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if (n < 16) {
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throw Error("key length is too short")
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}
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const simpleKey = simpleMakeKey(106, 8)
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let teaKey = new Uint8Array(16);
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for (let i = 0; i < 8; i++) {
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teaKey[i << 1] = simpleKey[i];
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teaKey[(i << 1) + 1] = rawDec[i];
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}
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const sub = decryptTencentTea(rawDec.subarray(8), teaKey)
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rawDec.set(sub, 8)
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return rawDec.subarray(0, 8 + sub.length)
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}
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// simpleMakeKey exported only for unit test
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export function simpleMakeKey(salt: number, length: number): number[] {
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const keyBuf: number[] = []
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for (let i = 0; i < length; i++) {
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const tmp = Math.tan(salt + i * 0.1)
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keyBuf[i] = 0xff & (Math.abs(tmp) * 100.0)
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}
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return keyBuf
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}
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function decryptTencentTea(inBuf: Uint8Array, key: Uint8Array): Uint8Array {
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if (inBuf.length % 8 != 0) {
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throw Error("inBuf size not a multiple of the block size")
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}
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if (inBuf.length < 16) {
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throw Error("inBuf size too small")
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}
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const blk = new TeaCipher(key, 32)
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const tmpBuf = new Uint8Array(8);
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const tmpView = new DataView(tmpBuf.buffer);
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blk.decrypt(tmpView, new DataView(inBuf.buffer, inBuf.byteOffset, 8))
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const nPadLen = tmpBuf[0] & 0x7;//只要最低三位
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/*密文格式:PadLen(1byte)+Padding(var,0-7byte)+Salt(2byte)+Body(var byte)+Zero(7byte)*/
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const outLen = inBuf.length - 1 /*PadLen*/ - nPadLen - SALT_LEN - ZERO_LEN;
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const outBuf = new Uint8Array(outLen)
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let ivPrev = new Uint8Array(8);
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let ivCur = inBuf.slice(0, 8); // init iv
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let inBufPos = 8;
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// 跳过 Padding Len 和 Padding
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let tmpIdx = 1 + nPadLen;
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// CBC IV 处理
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const cryptBlock = () => {
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ivPrev = ivCur;
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ivCur = inBuf.slice(inBufPos, inBufPos + 8)
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for (let j = 0; j < 8; j++) {
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tmpBuf[j] ^= ivCur[j]
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}
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blk.decrypt(tmpView, tmpView)
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inBufPos += 8;
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tmpIdx = 0;
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}
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// 跳过 Salt
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for (let i = 1; i <= SALT_LEN;) {
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if (tmpIdx < 8) {
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tmpIdx++;
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i++;
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} else {
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cryptBlock()
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}
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}
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// 还原明文
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let outBufPos = 0;
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while (outBufPos < outLen) {
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if (tmpIdx < 8) {
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outBuf[outBufPos] = tmpBuf[tmpIdx] ^ ivPrev[tmpIdx];
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outBufPos++
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tmpIdx++;
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} else {
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cryptBlock()
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}
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}
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// 校验Zero
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for (let i = 1; i <= ZERO_LEN; i++) {
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if (tmpBuf[tmpIdx] != ivPrev[tmpIdx]) {
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throw Error("zero check failed")
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}
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}
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return outBuf
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}
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