refactor to mautrix 0.17.x; update deps

vendor/maunium.net/go/mautrix/crypto/goolm/cipher/pickle.go

@@ -0,0 +1,58 @@
+package cipher
+
+import (
+	"fmt"
+
+	"maunium.net/go/mautrix/crypto/goolm"
+)
+
+const (
+	kdfPickle       = "Pickle" //used to derive the keys for encryption
+	pickleMACLength = 8
+)
+
+// PickleBlockSize returns the blocksize of the used cipher.
+func PickleBlockSize() int {
+	return AESSha512BlockSize()
+}
+
+// Pickle encrypts the input with the key and the cipher AESSHA256. The result is then encoded in base64.
+func Pickle(key, input []byte) ([]byte, error) {
+	pickleCipher := NewAESSHA256([]byte(kdfPickle))
+	ciphertext, err := pickleCipher.Encrypt(key, input)
+	if err != nil {
+		return nil, err
+	}
+	mac, err := pickleCipher.MAC(key, ciphertext)
+	if err != nil {
+		return nil, err
+	}
+	ciphertext = append(ciphertext, mac[:pickleMACLength]...)
+	encoded := goolm.Base64Encode(ciphertext)
+	return encoded, nil
+}
+
+// Unpickle decodes the input from base64 and decrypts the decoded input with the key and the cipher AESSHA256.
+func Unpickle(key, input []byte) ([]byte, error) {
+	pickleCipher := NewAESSHA256([]byte(kdfPickle))
+	ciphertext, err := goolm.Base64Decode(input)
+	if err != nil {
+		return nil, err
+	}
+	//remove mac and check
+	verified, err := pickleCipher.Verify(key, ciphertext[:len(ciphertext)-pickleMACLength], ciphertext[len(ciphertext)-pickleMACLength:])
+	if err != nil {
+		return nil, err
+	}
+	if !verified {
+		return nil, fmt.Errorf("decrypt pickle: %w", goolm.ErrBadMAC)
+	}
+	//Set to next block size
+	targetCipherText := make([]byte, int(len(ciphertext)/PickleBlockSize())*PickleBlockSize())
+	copy(targetCipherText, ciphertext)
+	plaintext, err := pickleCipher.Decrypt(key, targetCipherText)
+	if err != nil {
+		return nil, err
+	}
+	return plaintext, nil
+}