55 lines
949 B
Go
55 lines
949 B
Go
//From https://play.golang.org/p/LTbId4b6M2
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package CFB8
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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, tmp []byte
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de bool
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}
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func NewCFB8Decrypt(c cipher.Block, iv []byte) *CFB8 {
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cp := make([]byte, len(iv))
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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,
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tmp: make([]byte, c.BlockSize()),
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de: true,
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}
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}
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func NewCFB8Encrypt(c cipher.Block, iv []byte) *CFB8 {
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cp := make([]byte, len(iv))
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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,
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tmp: make([]byte, c.BlockSize()),
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de: false,
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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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copy(cf.tmp, cf.iv)
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cf.c.Encrypt(cf.iv, cf.iv)
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val = val ^ cf.iv[0]
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copy(cf.iv, cf.tmp[1:])
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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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