41 lines
957 B
Go
41 lines
957 B
Go
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package ximalaya
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import (
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_ "embed"
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"encoding/binary"
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)
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var x3mKey = [...]byte{
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'3', '9', '8', '9', 'd', '1', '1', '1',
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'a', 'a', 'd', '5', '6', '1', '3', '9',
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'4', '0', 'f', '4', 'f', 'c', '4', '4',
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'b', '6', '3', '9', 'b', '2', '9', '2',
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}
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const x3mHeaderSize = 1024
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var x3mScrambleTable = [x3mHeaderSize]uint16{}
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//go:embed x3m_scramble_table.bin
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var x3mScrambleTableBytes []byte
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func init() {
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if len(x3mScrambleTableBytes) != 2*x3mHeaderSize {
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panic("invalid x3m scramble table")
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}
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for i := range x3mScrambleTable {
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x3mScrambleTable[i] = binary.LittleEndian.Uint16(x3mScrambleTableBytes[i*2:])
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}
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}
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// decryptX3MHeader decrypts the header of ximalaya .x3m file.
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// make sure input src is 1024 (x3mHeaderSize) bytes long.
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func decryptX3MHeader(src []byte) []byte {
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dst := make([]byte, len(src))
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for dstIdx := range src {
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srcIdx := x3mScrambleTable[dstIdx]
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dst[dstIdx] = src[srcIdx] ^ x3mKey[dstIdx%len(x3mKey)]
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}
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return dst
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}
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