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seed.go
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seed.go
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package seed
import (
"crypto/cipher"
"errors"
"strconv"
)
type seed128Cipher struct {
pdwRoundKey []uint32
}
// KeySizeError is Invalid Key Size Error.
type KeySizeError int
func (k KeySizeError) Error() string {
return "github.com/geeksbaek/seed128: Invalid key size " + strconv.Itoa(int(k))
}
// NewCipher creates and returns a new cipher.Block.
// The key argument should be 16 bytes.
func NewCipher(key []byte) (cipher.Block, error) {
k := len(key)
switch k {
case 16:
break
case 32:
return nil, errors.New("github.com/geeksbaek/seed128: Unsupported key size 32")
default:
return nil, KeySizeError(k)
}
return newCipherGeneric(key)
}
func newCipherGeneric(key []byte) (cipher.Block, error) {
n := len(key) + 28
c := seed128Cipher{make([]uint32, n)}
c.pdwRoundKey = seedRoundKey(key)
return &c, nil
}
func (c *seed128Cipher) BlockSize() int { return BlockSize }
func (c *seed128Cipher) Encrypt(dst, src []byte) {
if len(src) < BlockSize {
panic("github.com/geeksbaek/seed128: input not full block")
}
if len(dst) < BlockSize {
panic("github.com/geeksbaek/seed128: output not full block")
}
// if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
// panic("github.com/geeksbaek/seed128: invalid buffer overlap")
// }
seedEncrypt(c.pdwRoundKey, dst, src)
}
func (c *seed128Cipher) Decrypt(dst, src []byte) {
if len(src) < BlockSize {
panic("github.com/geeksbaek/seed128: input not full block")
}
if len(dst) < BlockSize {
panic("github.com/geeksbaek/seed128: output not full block")
}
// if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
// panic("github.com/geeksbaek/seed128: invalid buffer overlap")
// }
seedDecrypt(c.pdwRoundKey, dst, src)
}