Add error handling for encryption routines

agent/bitwarden/crypto/crypto.go

@@ -9,6 +9,7 @@ import (
 	"crypto/sha256"
 	"crypto/x509"
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -170,7 +171,7 @@ func isMacValid(message, messageMAC, key []byte) bool {
 	return hmac.Equal(messageMAC, expectedMAC)
 }
 
-func encryptAESCBC256(data, key []byte) (iv, ciphertext []byte, _ error) {
+func encryptAESCBC256(data, key []byte) (iv, ciphertext []byte, err error) {
 	data = padPKCS7(data, aes.BlockSize)
 	block, err := aes.NewCipher(key)
 	if err != nil {
@@ -182,12 +183,28 @@ func encryptAESCBC256(data, key []byte) (iv, ciphertext []byte, _ error) {
 	if _, err := io.ReadFull(cryptorand.Reader, iv); err != nil {
 		return nil, nil, err
 	}
+
+	defer func() {
+		if r := recover(); r != nil {
+			var ok bool
+			err, ok = r.(error)
+			if !ok {
+				iv = nil
+				ciphertext = nil
+				err = errors.New("error encrypting AES CBC 256 data")
+			}
+		}
+	}()
+
 	mode := cipher.NewCBCEncrypter(block, iv)
 	mode.CryptBlocks(ciphertext, data)
 	return iv, ciphertext, nil
 }
 
-func decryptAESCBC256(iv, ciphertext, key []byte) ([]byte, error) {
+func decryptAESCBC256(iv, ciphertext, key []byte) (decryptedData []byte, err error) {
+	ciphertextCopy := make([]byte, len(ciphertext))
+	copy(ciphertextCopy, ciphertext)
+
 	block, err := aes.NewCipher(key)
 	if err != nil {
 		return nil, err
@@ -195,28 +212,50 @@ func decryptAESCBC256(iv, ciphertext, key []byte) ([]byte, error) {
 	if len(iv) != aes.BlockSize {
 		return nil, fmt.Errorf("iv length does not match AES block size")
 	}
-	if len(ciphertext)%aes.BlockSize != 0 {
+	if len(ciphertextCopy)%aes.BlockSize != 0 {
 		return nil, fmt.Errorf("ciphertext is not a multiple of AES block size")
 	}
+
+	defer func() {
+		if r := recover(); r != nil {
+			var ok bool
+			err, ok = r.(error)
+			if !ok {
+				decryptedData = nil
+				err = errors.New("error decrypting AES CBC 256 data")
+			}
+		}
+	}()
+
 	mode := cipher.NewCBCDecrypter(block, iv)
-	mode.CryptBlocks(ciphertext, ciphertext) // decrypt in-place
+	mode.CryptBlocks(ciphertextCopy, ciphertextCopy) // decrypt in-place
-	data, err := unpadPKCS7(ciphertext, aes.BlockSize)
+	data, err := unpadPKCS7(ciphertextCopy, aes.BlockSize)
 	if err != nil {
 		return nil, err
 	}
-	return data, nil
+
+	resultBuffer := make([]byte, len(data))
+	copy(resultBuffer, data)
+	return resultBuffer, nil
 }
 
 func unpadPKCS7(src []byte, size int) ([]byte, error) {
-	n := src[len(src)-1]
+	srcCopy := make([]byte, len(src))
-	if len(src)%size != 0 {
+	copy(srcCopy, src)
-		return nil, fmt.Errorf("expected PKCS7 padding for block size %d, but have %d bytes", size, len(src))
+
+	n := srcCopy[len(srcCopy)-1]
+	if len(srcCopy)%size != 0 {
+		return nil, fmt.Errorf("expected PKCS7 padding for block size %d, but have %d bytes", size, len(srcCopy))
 	}
-	if len(src) <= int(n) {
+	if len(srcCopy) <= int(n) {
-		return nil, fmt.Errorf("cannot unpad %d bytes out of a total of %d", n, len(src))
+		return nil, fmt.Errorf("cannot unpad %d bytes out of a total of %d", n, len(srcCopy))
 	}
-	src = src[:len(src)-int(n)]
+	srcCopy = srcCopy[:len(srcCopy)-int(n)]
-	return src, nil
+
+	resultCopy := make([]byte, len(srcCopy))
+	copy(resultCopy, srcCopy)
+
+	return resultCopy, nil
 }
 
 func padPKCS7(src []byte, size int) []byte {

agent/bitwarden/crypto/encstring.go

@@ -2,8 +2,6 @@ package crypto
 
 import (
 	"bytes"
-	"crypto/aes"
-	"crypto/cipher"
 	"crypto/hmac"
 	"crypto/rand"
 	"crypto/rsa"
@@ -12,12 +10,14 @@ import (
 	"crypto/x509"
 	"errors"
 	"fmt"
-	"io"
 	"strconv"
 
 	"github.com/awnumar/memguard"
+	"github.com/quexten/goldwarden/logging"
 )
 
+var cryptoLog = logging.GetLogger("Goldwarden", "Crypto")
+
 type EncString struct {
 	Type        EncStringType
 	IV, CT, MAC []byte
@@ -131,11 +131,6 @@ func DecryptWith(s EncString, key SymmetricEncryptionKey) ([]byte, error) {
 		return nil, err
 	}
 
-	block, err := aes.NewCipher(encKeyData)
-	if err != nil {
-		return nil, err
-	}
-
 	switch s.Type {
 	case AesCbc256_B64, AesCbc256_HmacSha256_B64:
 		break
@@ -161,13 +156,11 @@ func DecryptWith(s EncString, key SymmetricEncryptionKey) ([]byte, error) {
 		return nil, fmt.Errorf("decrypt: invalid IV length, expected %d, got %d", block.BlockSize(), len(s.IV))
 	}
 
-	mode := cipher.NewCBCDecrypter(block, s.IV)
+	dst, err := decryptAESCBC256(s.IV, s.CT, encKeyData)
-	dst := make([]byte, len(s.CT))
-	mode.CryptBlocks(dst, s.CT)
-	dst, err = unpadPKCS7(dst, aes.BlockSize)
 	if err != nil {
 		return nil, err
 	}
+
 	return dst, nil
 }
 
@@ -188,19 +181,13 @@ func EncryptWith(data []byte, encType EncStringType, key SymmetricEncryptionKey)
 		return s, fmt.Errorf("encrypt: unsupported cipher type %q", s.Type)
 	}
 	s.Type = encType
-	data = padPKCS7(data, aes.BlockSize)
 
-	block, err := aes.NewCipher(encKeyData)
+	iv, ciphertext, err := encryptAESCBC256(data, encKeyData)
 	if err != nil {
 		return s, err
 	}
-	s.IV = make([]byte, aes.BlockSize)
+	s.CT = ciphertext
-	if _, err := io.ReadFull(rand.Reader, s.IV); err != nil {
+	s.IV = iv
-		return s, err
-	}
-	s.CT = make([]byte, len(data))
-	mode := cipher.NewCBCEncrypter(block, s.IV)
-	mode.CryptBlocks(s.CT, data)
 
 	if encType == AesCbc256_HmacSha256_B64 {
 		if len(macKeyData) == 0 {