portainer/pkg/libcrypto/decrypt.go

49 lines
1.0 KiB
Go

package libcrypto
import (
"crypto/aes"
"crypto/cipher"
"errors"
"github.com/portainer/portainer/pkg/fips"
)
// Decrypt decrypts data using 256-bit AES-GCM. This both hides the content of
// the data and provides a check that it hasn't been altered. Expects input
// form nonce|ciphertext|tag where '|' indicates concatenation.
// Creates a 32bit hash of the key before decrypting the data.
func Decrypt(data []byte, key []byte) ([]byte, error) {
return decrypt(data, key, fips.FIPSMode())
}
func decrypt(data []byte, key []byte, fips bool) ([]byte, error) {
var hashKey []byte
if fips {
// sha256 hash 32 bytes
hashKey = HashFromBytes(key)
} else {
// 16 byte hash, hex encoded is 32 bytes
hashKey = InsecureHash32Bytes(key)
}
block, err := aes.NewCipher(hashKey)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCMWithRandomNonce(block)
if err != nil {
return nil, err
}
if len(data) < gcm.NonceSize() {
return nil, errors.New("malformed ciphertext")
}
return gcm.Open(nil,
nil,
data,
nil,
)
}