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cipher.go
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cipher.go
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package sharedsecret
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"io"
)
// CipherAESTransform .
func CipherAESTransform(key []byte) TransformFunc {
keyHash := sha256.Sum256(key)
return func(data []byte, isBackwardDir bool) ([]byte, error) {
c, err := aes.NewCipher(keyHash[:])
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(c)
if err != nil {
return data, nil
}
if isBackwardDir {
// decrypt
nonceSize := gcm.NonceSize()
if len(data) < nonceSize {
return nil, ErrInvlidArgument
}
nonce, ciphertext := data[:nonceSize], data[nonceSize:]
return gcm.Open(nil, nonce, ciphertext, nil)
}
// encrypt
nonce := make([]byte, gcm.NonceSize())
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
return gcm.Seal(nonce, nonce, data, nil), nil
}
}