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moby--moby/vendor/github.com/fernet/fernet-go/key.go

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package fernet
import (
"crypto/rand"
"encoding/base64"
"encoding/hex"
"errors"
"io"
)
var (
errKeyLen = errors.New("fernet: key decodes to wrong size")
errNoKeys = errors.New("fernet: no keys provided")
)
// Key represents a key.
type Key [32]byte
func (k *Key) cryptBytes() []byte {
return k[len(k)/2:]
}
func (k *Key) signBytes() []byte {
return k[:len(k)/2]
}
// Generate initializes k with pseudorandom data from package crypto/rand.
func (k *Key) Generate() error {
_, err := io.ReadFull(rand.Reader, k[:])
return err
}
// Encode returns the URL-safe base64 encoding of k.
func (k *Key) Encode() string {
return encoding.EncodeToString(k[:])
}
// DecodeKey decodes a key from s and returns it. The key can be in
// hexadecimal, standard base64, or URL-safe base64.
func DecodeKey(s string) (*Key, error) {
var b []byte
var err error
if s == "" {
return nil, errors.New("empty key")
}
if len(s) == hex.EncodedLen(len(Key{})) {
b, err = hex.DecodeString(s)
} else {
b, err = base64.StdEncoding.DecodeString(s)
if err != nil {
b, err = base64.URLEncoding.DecodeString(s)
}
}
if err != nil {
return nil, err
}
if len(b) != len(Key{}) {
return nil, errKeyLen
}
k := new(Key)
copy(k[:], b)
return k, nil
}
// DecodeKeys decodes each element of a using DecodeKey and returns the
// resulting keys. Requires at least one key.
func DecodeKeys(a ...string) ([]*Key, error) {
if len(a) == 0 {
return nil, errNoKeys
}
var err error
ks := make([]*Key, len(a))
for i, s := range a {
ks[i], err = DecodeKey(s)
if err != nil {
return nil, err
}
}
return ks, nil
}
// MustDecodeKeys is like DecodeKeys, but panics if an error occurs.
// It simplifies safe initialization of global variables holding
// keys.
func MustDecodeKeys(a ...string) []*Key {
k, err := DecodeKeys(a...)
if err != nil {
panic(err)
}
return k
}