70 lines
2.2 KiB
JavaScript
70 lines
2.2 KiB
JavaScript
const crypto = require('crypto');
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module.exports = class EncryptionService {
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getSongFileName(trackInfos, trackQuality) {
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const step1 = [trackInfos.MD5_ORIGIN, trackQuality, trackInfos.SNG_ID, trackInfos.MEDIA_VERSION].join('¤');
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let step2 = crypto.createHash('md5').update(step1, 'ascii').digest('hex') + '¤' + step1 + '¤';
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while (step2.length % 16 > 0) step2 += ' ';
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return crypto.createCipheriv('aes-128-ecb', 'jo6aey6haid2Teih', '').update(step2, 'ascii', 'hex');
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}
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/**
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* Calculate the blowfish key to decrypt the track
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*
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* @param {Object} trackInfos
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*/
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getBlowfishKey(trackInfos) {
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const SECRET = 'g4el58wc0zvf9na1';
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const idMd5 = crypto.createHash('md5').update(trackInfos.SNG_ID.toString(), 'ascii').digest('hex');
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let bfKey = '';
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for (let i = 0; i < 16; i++) {
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bfKey += String.fromCharCode(idMd5.charCodeAt(i) ^ idMd5.charCodeAt(i + 16) ^ SECRET.charCodeAt(i));
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}
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return bfKey;
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}
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/**
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* Decrypt a deezer track.
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*
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* @param {Buffer} trackBuffer
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* @param {Object} trackInfos
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*
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* @return {Buffer}
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*/
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decryptTrack(trackBuffer, trackInfos) {
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const blowFishKey = this.getBlowfishKey(trackInfos);
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let decryptedBuffer = Buffer.alloc(trackBuffer.length);
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let chunkSize = 2048;
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let progress = 0;
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while (progress < trackBuffer.length) {
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if ((trackBuffer.length - progress) < 2048) {
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chunkSize = trackBuffer.length - progress;
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}
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let encryptedChunk = trackBuffer.slice(progress, progress + chunkSize);
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// Only decrypt every third chunk and only if not at the end
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if (progress % (chunkSize * 3) === 0 && chunkSize === 2048) {
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let cipher = crypto.createDecipheriv('bf-cbc', blowFishKey, Buffer.from([0, 1, 2, 3, 4, 5, 6, 7]));
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cipher.setAutoPadding(false);
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encryptedChunk = Buffer.concat([cipher.update(encryptedChunk), cipher.final()]);
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}
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decryptedBuffer.write(encryptedChunk.toString('binary'), progress, encryptedChunk.length, 'binary');
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progress += chunkSize;
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}
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return decryptedBuffer;
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}
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}; |