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/*
* Minio Go Library for Amazon S3 Compatible Cloud Storage (C) 2017 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package encrypt
import (
"crypto/aes"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"errors"
)
// Key - generic interface to encrypt/decrypt a key.
// We use it to encrypt/decrypt content key which is the key
// that encrypt/decrypt object data.
type Key interface {
// Encrypt data using to the set encryption key
Encrypt([]byte) ([]byte, error)
// Decrypt data using to the set encryption key
Decrypt([]byte) ([]byte, error)
}
// SymmetricKey - encrypts data with a symmetric master key
type SymmetricKey struct {
masterKey []byte
}
// Encrypt passed bytes
func (s *SymmetricKey) Encrypt(plain []byte) ([]byte, error) {
// Initialize an AES encryptor using a master key
keyBlock, err := aes.NewCipher(s.masterKey)
if err != nil {
return []byte{}, err
}
// Pad the key before encryption
plain, _ = pkcs5Pad(plain, aes.BlockSize)
encKey := []byte{}
encPart := make([]byte, aes.BlockSize)
// Encrypt the passed key by block
for {
if len(plain) < aes.BlockSize {
break
}
// Encrypt the passed key
keyBlock.Encrypt(encPart, plain[:aes.BlockSize])
// Add the encrypted block to the total encrypted key
encKey = append(encKey, encPart...)
// Pass to the next plain block
plain = plain[aes.BlockSize:]
}
return encKey, nil
}
// Decrypt passed bytes
func (s *SymmetricKey) Decrypt(cipher []byte) ([]byte, error) {
// Initialize AES decrypter
keyBlock, err := aes.NewCipher(s.masterKey)
if err != nil {
return nil, err
}
var plain []byte
plainPart := make([]byte, aes.BlockSize)
// Decrypt the encrypted data block by block
for {
if len(cipher) < aes.BlockSize {
break
}
keyBlock.Decrypt(plainPart, cipher[:aes.BlockSize])
// Add the decrypted block to the total result
plain = append(plain, plainPart...)
// Pass to the next cipher block
cipher = cipher[aes.BlockSize:]
}
// Unpad the resulted plain data
plain, err = pkcs5Unpad(plain, aes.BlockSize)
if err != nil {
return nil, err
}
return plain, nil
}
// NewSymmetricKey generates a new encrypt/decrypt crypto using
// an AES master key password
func NewSymmetricKey(b []byte) *SymmetricKey {
return &SymmetricKey{masterKey: b}
}
// AsymmetricKey - struct which encrypts/decrypts data
// using RSA public/private certificates
type AsymmetricKey struct {
publicKey *rsa.PublicKey
privateKey *rsa.PrivateKey
}
// Encrypt data using public key
func (a *AsymmetricKey) Encrypt(plain []byte) ([]byte, error) {
cipher, err := rsa.EncryptPKCS1v15(rand.Reader, a.publicKey, plain)
if err != nil {
return nil, err
}
return cipher, nil
}
// Decrypt data using public key
func (a *AsymmetricKey) Decrypt(cipher []byte) ([]byte, error) {
cipher, err := rsa.DecryptPKCS1v15(rand.Reader, a.privateKey, cipher)
if err != nil {
return nil, err
}
return cipher, nil
}
// NewAsymmetricKey - generates a crypto module able to encrypt/decrypt
// data using a pair for private and public key
func NewAsymmetricKey(privData []byte, pubData []byte) (*AsymmetricKey, error) {
// Parse private key from passed data
priv, err := x509.ParsePKCS8PrivateKey(privData)
if err != nil {
return nil, err
}
privKey, ok := priv.(*rsa.PrivateKey)
if !ok {
return nil, errors.New("not a valid private key")
}
// Parse public key from passed data
pub, err := x509.ParsePKIXPublicKey(pubData)
if err != nil {
return nil, err
}
pubKey, ok := pub.(*rsa.PublicKey)
if !ok {
return nil, errors.New("not a valid public key")
}
// Associate the private key with the passed public key
privKey.PublicKey = *pubKey
return &AsymmetricKey{
publicKey: pubKey,
privateKey: privKey,
}, nil
}
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