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use AES-256-CBC only

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ivan
2025-07-15 13:31:19 -05:00
parent b9aebc8406
commit 12f487d937
2 changed files with 69 additions and 161 deletions
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84
pkg/cryptography/aes.go
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@@ -9,54 +9,24 @@ import (
)
const (
// AES key sizes in bytes
AES128KeySize = 16 // 128 bits
AES192KeySize = 24 // 192 bits
// AES256KeySize is the size of an AES-256 key in bytes.
AES256KeySize = 32 // 256 bits
// Default to AES-256
DefaultKeySize = AES256KeySize
)
// GenerateAESKey generates a random AES key of the specified size
func GenerateAESKey(keySize int) ([]byte, error) {
if keySize != AES128KeySize && keySize != AES192KeySize && keySize != AES256KeySize {
return nil, errors.New("invalid key size: must be 16, 24, or 32 bytes")
}
key := make([]byte, keySize)
// GenerateAES256Key generates a random AES-256 key.
func GenerateAES256Key() ([]byte, error) {
key := make([]byte, AES256KeySize)
if _, err := io.ReadFull(rand.Reader, key); err != nil {
return nil, err
}
return key, nil
}
// GenerateAES256Key generates a random AES-256 key (default)
func GenerateAES256Key() ([]byte, error) {
return GenerateAESKey(AES256KeySize)
}
// EncryptAES256CBC encrypts data using AES-256 in CBC mode
// EncryptAES256CBC encrypts data using AES-256 in CBC mode.
// The IV is prepended to the ciphertext.
func EncryptAES256CBC(key, plaintext []byte) ([]byte, error) {
if len(key) != AES256KeySize {
return nil, errors.New("key must be 32 bytes for AES-256")
}
return EncryptAESCBC(key, plaintext)
}
// DecryptAES256CBC decrypts data using AES-256 in CBC mode
func DecryptAES256CBC(key, ciphertext []byte) ([]byte, error) {
if len(key) != AES256KeySize {
return nil, errors.New("key must be 32 bytes for AES-256")
}
return DecryptAESCBC(key, ciphertext)
}
// EncryptAESCBC encrypts data using AES in CBC mode (accepts any valid AES key size)
func EncryptAESCBC(key, plaintext []byte) ([]byte, error) {
// Validate key size
if len(key) != AES128KeySize && len(key) != AES192KeySize && len(key) != AES256KeySize {
return nil, errors.New("invalid key size: must be 16, 24, or 32 bytes")
return nil, errors.New("invalid key size: must be 32 bytes for AES-256")
}
block, err := aes.NewCipher(key)
@@ -64,13 +34,13 @@ func EncryptAESCBC(key, plaintext []byte) ([]byte, error) {
return nil, err
}
// Generate IV
// Generate a random IV.
iv := make([]byte, aes.BlockSize)
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
// Add PKCS7 padding
// Add PKCS7 padding.
padding := aes.BlockSize - len(plaintext)%aes.BlockSize
padtext := make([]byte, len(plaintext)+padding)
copy(padtext, plaintext)
@@ -78,19 +48,20 @@ func EncryptAESCBC(key, plaintext []byte) ([]byte, error) {
padtext[i] = byte(padding)
}
// Encrypt
mode := cipher.NewCBCEncrypter(block, iv) // #nosec G407
// Encrypt the data.
mode := cipher.NewCBCEncrypter(block, iv)
ciphertext := make([]byte, len(padtext))
mode.CryptBlocks(ciphertext, padtext)
// Prepend the IV to the ciphertext.
return append(iv, ciphertext...), nil
}
// DecryptAESCBC decrypts data using AES in CBC mode (accepts any valid AES key size)
func DecryptAESCBC(key, ciphertext []byte) ([]byte, error) {
// Validate key size
if len(key) != AES128KeySize && len(key) != AES192KeySize && len(key) != AES256KeySize {
return nil, errors.New("invalid key size: must be 16, 24, or 32 bytes")
// DecryptAES256CBC decrypts data using AES-256 in CBC mode.
// It assumes the IV is prepended to the ciphertext.
func DecryptAES256CBC(key, ciphertext []byte) ([]byte, error) {
if len(key) != AES256KeySize {
return nil, errors.New("invalid key size: must be 32 bytes for AES-256")
}
block, err := aes.NewCipher(key)
@@ -99,34 +70,39 @@ func DecryptAESCBC(key, ciphertext []byte) ([]byte, error) {
}
if len(ciphertext) < aes.BlockSize {
return nil, errors.New("ciphertext too short")
return nil, errors.New("ciphertext is too short")
}
// Extract the IV from the beginning of the ciphertext.
iv := ciphertext[:aes.BlockSize]
ciphertext = ciphertext[aes.BlockSize:]
if len(ciphertext)%aes.BlockSize != 0 {
return nil, errors.New("ciphertext is not a multiple of block size")
return nil, errors.New("ciphertext is not a multiple of the block size")
}
// Decrypt the data.
mode := cipher.NewCBCDecrypter(block, iv)
plaintext := make([]byte, len(ciphertext))
mode.CryptBlocks(plaintext, ciphertext)
// Remove PKCS7 padding
// Remove PKCS7 padding.
if len(plaintext) == 0 {
return nil, errors.New("invalid padding: empty plaintext")
return nil, errors.New("invalid padding: plaintext is empty")
}
padding := int(plaintext[len(plaintext)-1])
if padding == 0 || padding > aes.BlockSize || padding > len(plaintext) {
return nil, errors.New("invalid PKCS7 padding")
if padding > aes.BlockSize || padding == 0 {
return nil, errors.New("invalid padding size")
}
if len(plaintext) < padding {
return nil, errors.New("invalid padding: padding size is larger than plaintext")
}
// Verify all padding bytes are correct
// Verify the padding bytes.
for i := len(plaintext) - padding; i < len(plaintext); i++ {
if plaintext[i] != byte(padding) {
return nil, errors.New("invalid PKCS7 padding")
return nil, errors.New("invalid padding bytes")
}
}