const staticCipherBox = new Uint8Array([ 0x77, 0x48, 0x32, 0x73, 0xDE, 0xF2, 0xC0, 0xC8, //0x00 0x95, 0xEC, 0x30, 0xB2, 0x51, 0xC3, 0xE1, 0xA0, //0x08 0x9E, 0xE6, 0x9D, 0xCF, 0xFA, 0x7F, 0x14, 0xD1, //0x10 0xCE, 0xB8, 0xDC, 0xC3, 0x4A, 0x67, 0x93, 0xD6, //0x18 0x28, 0xC2, 0x91, 0x70, 0xCA, 0x8D, 0xA2, 0xA4, //0x20 0xF0, 0x08, 0x61, 0x90, 0x7E, 0x6F, 0xA2, 0xE0, //0x28 0xEB, 0xAE, 0x3E, 0xB6, 0x67, 0xC7, 0x92, 0xF4, //0x30 0x91, 0xB5, 0xF6, 0x6C, 0x5E, 0x84, 0x40, 0xF7, //0x38 0xF3, 0x1B, 0x02, 0x7F, 0xD5, 0xAB, 0x41, 0x89, //0x40 0x28, 0xF4, 0x25, 0xCC, 0x52, 0x11, 0xAD, 0x43, //0x48 0x68, 0xA6, 0x41, 0x8B, 0x84, 0xB5, 0xFF, 0x2C, //0x50 0x92, 0x4A, 0x26, 0xD8, 0x47, 0x6A, 0x7C, 0x95, //0x58 0x61, 0xCC, 0xE6, 0xCB, 0xBB, 0x3F, 0x47, 0x58, //0x60 0x89, 0x75, 0xC3, 0x75, 0xA1, 0xD9, 0xAF, 0xCC, //0x68 0x08, 0x73, 0x17, 0xDC, 0xAA, 0x9A, 0xA2, 0x16, //0x70 0x41, 0xD8, 0xA2, 0x06, 0xC6, 0x8B, 0xFC, 0x66, //0x78 0x34, 0x9F, 0xCF, 0x18, 0x23, 0xA0, 0x0A, 0x74, //0x80 0xE7, 0x2B, 0x27, 0x70, 0x92, 0xE9, 0xAF, 0x37, //0x88 0xE6, 0x8C, 0xA7, 0xBC, 0x62, 0x65, 0x9C, 0xC2, //0x90 0x08, 0xC9, 0x88, 0xB3, 0xF3, 0x43, 0xAC, 0x74, //0x98 0x2C, 0x0F, 0xD4, 0xAF, 0xA1, 0xC3, 0x01, 0x64, //0xA0 0x95, 0x4E, 0x48, 0x9F, 0xF4, 0x35, 0x78, 0x95, //0xA8 0x7A, 0x39, 0xD6, 0x6A, 0xA0, 0x6D, 0x40, 0xE8, //0xB0 0x4F, 0xA8, 0xEF, 0x11, 0x1D, 0xF3, 0x1B, 0x3F, //0xB8 0x3F, 0x07, 0xDD, 0x6F, 0x5B, 0x19, 0x30, 0x19, //0xC0 0xFB, 0xEF, 0x0E, 0x37, 0xF0, 0x0E, 0xCD, 0x16, //0xC8 0x49, 0xFE, 0x53, 0x47, 0x13, 0x1A, 0xBD, 0xA4, //0xD0 0xF1, 0x40, 0x19, 0x60, 0x0E, 0xED, 0x68, 0x09, //0xD8 0x06, 0x5F, 0x4D, 0xCF, 0x3D, 0x1A, 0xFE, 0x20, //0xE0 0x77, 0xE4, 0xD9, 0xDA, 0xF9, 0xA4, 0x2B, 0x76, //0xE8 0x1C, 0x71, 0xDB, 0x00, 0xBC, 0xFD, 0x0C, 0x6C, //0xF0 0xA5, 0x47, 0xF7, 0xF6, 0x00, 0x79, 0x4A, 0x11, //0xF8 ]) export interface StreamCipher { decrypt(buf: Uint8Array, offset: number): void } export class QmcStaticCipher implements StreamCipher { public getMask(offset: number) { if (offset > 0x7FFF) offset %= 0x7FFF return staticCipherBox[(offset * offset + 27) & 0xff] } public decrypt(buf: Uint8Array, offset: number) { for (let i = 0; i < buf.length; i++) { buf[i] ^= this.getMask(offset + i) } } } export class QmcMapCipher implements StreamCipher { key: Uint8Array n: number constructor(key: Uint8Array) { if (key.length == 0) throw Error("qmc/cipher_map: invalid key size") this.key = key this.n = key.length } private static rotate(value: number, bits: number) { let rotate = (bits + 4) % 8; let left = value << rotate; let right = value >> rotate; return (left | right) & 0xff; } decrypt(buf: Uint8Array, offset: number): void { for (let i = 0; i < buf.length; i++) { buf[i] ^= this.getMask(offset + i) } } private getMask(offset: number) { if (offset > 0x7fff) offset %= 0x7fff; const idx = (offset * offset + 71214) % this.n; return QmcMapCipher.rotate(this.key[idx], idx & 0x7) } } const FIRST_SEGMENT_SIZE = 0x80; const SEGMENT_SIZE = 5120 export class QmcRC4Cipher implements StreamCipher { S: Uint8Array N: number key: Uint8Array hash: number constructor(key: Uint8Array) { if (key.length == 0) { throw Error("invalid key size") } this.key = key this.N = key.length // init seed box this.S = new Uint8Array(this.N); for (let i = 0; i < this.N; ++i) { this.S[i] = i & 0xff; } let j = 0; for (let i = 0; i < this.N; ++i) { j = (this.S[i] + j + this.key[i % this.N]) % this.N; [this.S[i], this.S[j]] = [this.S[j], this.S[i]] } // init hash base this.hash = 1; for (let i = 0; i < this.N; i++) { let value = this.key[i]; // ignore if key char is '\x00' if (!value) continue; const next_hash = (this.hash * value) & 0xffffffff; if (next_hash == 0 || next_hash <= this.hash) break; this.hash = next_hash; } } decrypt(buf: Uint8Array, offset: number): void { let toProcess = buf.length; let processed = 0; const postProcess = (len: number): boolean => { toProcess -= len; processed += len offset += len return toProcess == 0 } // Initial segment if (offset < FIRST_SEGMENT_SIZE) { const len_segment = Math.min(buf.length, FIRST_SEGMENT_SIZE - offset); this.encFirstSegment(buf.subarray(0, len_segment), offset); if (postProcess(len_segment)) return } // align segment if (offset % SEGMENT_SIZE != 0) { const len_segment = Math.min(SEGMENT_SIZE - (offset % SEGMENT_SIZE), toProcess); this.encASegment(buf.subarray(processed, processed + len_segment), offset); if (postProcess(len_segment)) return } // Batch process segments while (toProcess > SEGMENT_SIZE) { this.encASegment(buf.subarray(processed, processed + SEGMENT_SIZE), offset); postProcess(SEGMENT_SIZE) } // Last segment (incomplete segment) if (toProcess > 0) { this.encASegment(buf.subarray(processed), offset); } } private encFirstSegment(buf: Uint8Array, offset: number) { for (let i = 0; i < buf.length; i++) { buf[i] ^= this.key[this.getSegmentSkip(offset + i)]; } } private encASegment(buf: Uint8Array, offset: number) { // Initialise a new seed box const S = this.S.slice(0) // Calculate the number of bytes to skip. // The initial "key" derived from segment id, plus the current offset. const skipLen = (offset % SEGMENT_SIZE) + this.getSegmentSkip(offset / SEGMENT_SIZE) // decrypt the block let j = 0; let k = 0; for (let i = -skipLen; i < buf.length; i++) { j = (j + 1) % this.N; k = (S[j] + k) % this.N; [S[k], S[j]] = [S[j], S[k]] if (i >= 0) { buf[i] ^= S[(S[j] + S[k]) % this.N]; } } } private getSegmentSkip(id: number): number { const seed = this.key[id % this.N] const idx = (this.hash / ((id + 1) * seed) * 100.0) | 0; return idx % this.N } }