35 lines
808 B
Go
35 lines
808 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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const x2mHeaderSize = 1024
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var x2mKey = [...]byte{'x', 'm', 'l', 'y'}
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var x2mScrambleTable = [x2mHeaderSize]uint16{}
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//go:embed x2m_scramble_table.bin
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var x2mScrambleTableBytes []byte
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func init() {
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if len(x2mScrambleTableBytes) != 2*x2mHeaderSize {
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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(x2mScrambleTableBytes[i*2:])
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}
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}
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// decryptX2MHeader decrypts the header of ximalaya .x2m file.
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// make sure input src is 1024(x2mHeaderSize) bytes long.
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func decryptX2MHeader(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 := x2mScrambleTable[dstIdx]
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dst[dstIdx] = src[srcIdx] ^ x2mKey[dstIdx%len(x2mKey)]
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}
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return dst
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}
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