49 lines
834 B
Go
49 lines
834 B
Go
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package server
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import "crypto/cipher"
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type cfb8 struct {
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c cipher.Block
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blockSize int
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iv, ivReal, tmp []byte
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de bool
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}
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func newCFB8(c cipher.Block, iv []byte, decrypt bool) cipher.Stream {
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if len(iv) != 16 {
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panic("bad iv length!")
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}
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cp := make([]byte, 256)
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copy(cp, iv)
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return &cfb8{
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c: c,
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blockSize: c.BlockSize(),
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iv: cp[:16],
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ivReal: cp,
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tmp: make([]byte, 16),
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de: decrypt,
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}
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}
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func (cf *cfb8) XORKeyStream(dst, src []byte) {
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for i := 0; i < len(src); i++ {
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val := src[i]
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cf.c.Encrypt(cf.tmp, cf.iv)
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val = val ^ cf.tmp[0]
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if cap(cf.iv) >= 17 {
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cf.iv = cf.iv[1:17]
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} else {
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copy(cf.ivReal, cf.iv[1:])
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cf.iv = cf.ivReal[:16]
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}
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if cf.de {
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cf.iv[15] = src[i]
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} else {
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cf.iv[15] = val
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}
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dst[i] = val
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}
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}
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