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Better Way to Detect Mflac Mask

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MengYX 2020-02-09 14:05:40 +08:00
parent 9aab7a7713
commit 27b74ea5dd
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GPG Key ID: E63F9C7303E8F604
1 changed files with 41 additions and 23 deletions
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64
src/decrypt/mflac.js
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@ -29,7 +29,7 @@ async function Decrypt(file, raw_filename, raw_ext) {
// 读取Meta // 读取Meta
let tag = await musicMetadata.parseBlob(musicData); let tag = await musicMetadata.parseBlob(musicData);
const info = util.GetFileInfo(tag.common.artist, tag.common.title, raw_filename); const info = util.GetFileInfo(tag.common.artist, tag.common.title, raw_filename);
reportKeyInfo(new Uint8Array(fileBuffer.slice(-0x170)), seed.mask, reportKeyInfo(new Uint8Array(fileBuffer.slice(-0x170)), seed.mask128,
info.artist, info.title, tag.common.album, raw_filename); info.artist, info.title, tag.common.album, raw_filename);
// 返回 // 返回
@ -51,38 +51,56 @@ class Mask {
constructor() { constructor() {
this.index = -1; this.index = -1;
this.mask_index = -1; this.mask_index = -1;
this.mask = new Uint8Array(128); this.mask128 = new Uint8Array(128);
this.mask58_martix = new Uint8Array(56);
this.mask58_super1 = 0x00;
this.mask58_super2 = 0x00;
} }
DetectMask(data) { DetectMask(data) {
let search_len = data.length - 256, mask; let search_len = Math.min(0x8000, data.length), mask;
for (let block_idx = 0; block_idx < search_len; block_idx += 128) { for (let block_idx = 0; block_idx < search_len; block_idx += 128) {
let flag = true;
mask = data.slice(block_idx, block_idx + 128); mask = data.slice(block_idx, block_idx + 128);
let next_mask = data.slice(block_idx + 128, block_idx + 256); const mask58 = this.Convert128to58(mask);
for (let idx = 0; idx < 128; idx++) { if (mask58 === undefined) continue;
if (mask[idx] !== next_mask[idx]) {
flag = false;
break;
}
}
if (!flag) continue;
for (let test_idx = 0; test_idx < FLAC_HEADER.length; test_idx++) { if (!FLAC_HEADER.every((val, idx) => {
let p = data[test_idx] ^ mask[test_idx]; return val === mask[idx] ^ data[idx];
if (p !== FLAC_HEADER[test_idx]) { })) continue;
flag = false;
//todo: Check this this.mask128 = mask;
break; this.mask58_martix = mask58.matrix;
} this.mask58_super1 = mask58.super_8_1;
} this.mask58_super2 = mask58.super_8_2;
if (!flag) continue;
this.mask = mask;
return true; return true;
} }
return false; return false;
} }
Convert128to58(mask128) {
const super_8_1 = mask128[0], super_8_2 = mask128[8];
let matrix = [];
for (let row_idx = 0; row_idx < 8; row_idx++) {
const len_start = 16 * row_idx;
const len_right_start = 120 - len_start;//16*(8-row_idx-1)+8
if (mask128[len_start] !== super_8_1 || mask128[len_start + 8] !== super_8_2) {
return
}
const row_left = mask128.slice(len_start + 1, len_start + 8);
const row_right = mask128.slice(len_right_start + 1, len_right_start + 8).reverse();
if (row_left.every((val, idx) => {
return row_right[idx] === val
})) {
matrix.push(row_left);
} else {
return
}
}
return {matrix, super_8_1, super_8_2}
}
NextMask() { NextMask() {
this.index++; this.index++;
this.mask_index++; this.mask_index++;
@ -93,7 +111,7 @@ class Mask {
if (this.mask_index >= 128) { if (this.mask_index >= 128) {
this.mask_index -= 128; this.mask_index -= 128;
} }
return this.mask[this.mask_index] return this.mask128[this.mask_index]
} }
} }