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aes_key.go
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aes_key.go
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package codec
import "bytes"
const (
KeyAES128 = `AES-128`
KeyAES192 = `AES-192`
KeyAES256 = `AES-256`
)
const (
aes128KeyLen = 128 / 8 // 16
aes192KeyLen = 192 / 8 // 24
aes256KeyLen = 256 / 8 // 32
)
// AESKeyTypes AES Key类型
var AESKeyTypes = map[string]int{
KeyAES128: aes128KeyLen,
KeyAES192: aes192KeyLen,
KeyAES256: aes256KeyLen,
}
type KeyFixer func(keyLen int, key []byte) []byte
func newAESKey(keyTypes ...string) *aesKey {
var keyType string
if len(keyTypes) > 0 {
keyType = keyTypes[0]
}
return &aesKey{key: NewSafeKeys(), keyType: keyType, keyFixer: FixedAESKey}
}
type aesKey struct {
key *SafeKeys
keyType string
keyFixer KeyFixer
}
func (a *aesKey) SetKeyFixer(fixer KeyFixer) {
a.keyFixer = fixer
}
func (a *aesKey) GetKey(key []byte) []byte {
ckey := string(key)
k, ok := a.key.Get(ckey)
if !ok {
k = a.GenKey(key, a.keyType)
a.key.Set(ckey, k)
}
return k
}
func (a *aesKey) GenKey(key []byte, typ ...string) []byte {
var keyType string
if len(typ) > 0 {
keyType = typ[0]
}
keyLen, ok := AESKeyTypes[keyType]
if !ok {
keyLen = aes128KeyLen
}
if a.keyFixer == nil {
return FixedAESKey(keyLen, key)
}
return a.keyFixer(keyLen, key)
}
var FixedAESKey = FixedKeyDefault
func FixedKeyDefault(keyLen int, key []byte) []byte {
if len(key) == keyLen {
return key
}
k := make([]byte, keyLen)
copy(k, key)
for i := keyLen; i < len(key); {
for j := 0; j < keyLen && i < len(key); j, i = j+1, i+1 {
k[j] ^= key[i]
}
}
return k
}
func FixedKeyByWhitespacePrefix(keyLen int, key []byte) []byte {
if len(key) == keyLen {
return key
}
k := make([]byte, keyLen)
if len(key) < keyLen {
remains := keyLen - len(key)
copy(k, bytes.Repeat([]byte(` `), remains))
copy(k[remains:], key)
} else {
copy(k, key)
}
return k
}