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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
View File

@@ -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")
}
}

132
pkg/cryptography/aes_test.go
View File

@@ -3,13 +3,13 @@ package cryptography
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"fmt"
"testing"
)
func TestGenerateAESKeys(t *testing.T) {
t.Run("GenerateAES256Key", func(t *testing.T) {
func TestGenerateAES256Key(t *testing.T) {
key, err := GenerateAES256Key()
if err != nil {
t.Fatalf("GenerateAES256Key failed: %v", err)
@@ -17,30 +17,6 @@ func TestGenerateAESKeys(t *testing.T) {
if len(key) != AES256KeySize {
t.Errorf("Expected key size %d, got %d", AES256KeySize, len(key))
}
})
t.Run("GenerateAESKey_AllSizes", func(t *testing.T) {
sizes := []int{AES128KeySize, AES192KeySize, AES256KeySize}
for _, size := range sizes {
key, err := GenerateAESKey(size)
if err != nil {
t.Fatalf("GenerateAESKey(%d) failed: %v", size, err)
}
if len(key) != size {
t.Errorf("Expected key size %d, got %d", size, len(key))
}
}
})
t.Run("GenerateAESKey_InvalidSize", func(t *testing.T) {
invalidSizes := []int{8, 15, 17, 23, 25, 31, 33, 64}
for _, size := range invalidSizes {
_, err := GenerateAESKey(size)
if err == nil {
t.Errorf("GenerateAESKey(%d) should have failed but didn't", size)
}
}
})
}
func TestAES256CBCEncryptionDecryption(t *testing.T) {
@@ -110,48 +86,8 @@ func TestAES256CBC_InvalidKeySize(t *testing.T) {
}
}
func TestAESCBCEncryptionDecryption(t *testing.T) {
keySizes := []int{AES128KeySize, AES192KeySize, AES256KeySize}
for _, keySize := range keySizes {
t.Run(fmt.Sprintf("AES_%d", keySize*8), func(t *testing.T) {
key, err := GenerateAESKey(keySize)
if err != nil {
t.Fatalf("Failed to generate AES-%d key: %v", keySize*8, err)
}
testCases := []struct {
name string
plaintext []byte
}{
{"ShortMessage", []byte("Hello")},
{"BlockSizeMessage", []byte("This is 16 bytes")},
{"LongMessage", []byte("This is a longer message that spans multiple AES blocks.")},
{"EmptyMessage", []byte("")},
}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
ciphertext, err := EncryptAESCBC(key, tc.plaintext)
if err != nil {
t.Fatalf("EncryptAESCBC failed: %v", err)
}
decrypted, err := DecryptAESCBC(key, ciphertext)
if err != nil {
t.Fatalf("DecryptAESCBC failed: %v", err)
}
if !bytes.Equal(tc.plaintext, decrypted) {
t.Errorf("Decrypted text does not match original plaintext. Got %q, want %q", decrypted, tc.plaintext)
}
})
}
})
}
}
func TestDecryptAESCBCErrorCases(t *testing.T) {
func TestDecryptAES256CBCErrorCases(t *testing.T) {
key, err := GenerateAES256Key()
if err != nil {
t.Fatalf("Failed to generate key: %v", err)
@@ -159,20 +95,9 @@ func TestDecryptAESCBCErrorCases(t *testing.T) {
t.Run("CiphertextTooShort", func(t *testing.T) {
shortCiphertext := []byte{0x01, 0x02, 0x03} // Less than AES block size
_, err := DecryptAESCBC(key, shortCiphertext)
_, err := DecryptAES256CBC(key, shortCiphertext)
if err == nil {
t.Error("DecryptAESCBC should have failed for ciphertext shorter than block size")
}
})
t.Run("InvalidKeySize", func(t *testing.T) {
invalidKey := make([]byte, 17) // Invalid key size
validCiphertext := make([]byte, 32) // IV + one block
rand.Read(validCiphertext)
_, err := DecryptAESCBC(invalidKey, validCiphertext)
if err == nil {
t.Error("DecryptAESCBC should have failed for invalid key size")
t.Error("DecryptAES256CBC should have failed for ciphertext shorter than block size")
}
})
@@ -180,16 +105,16 @@ func TestDecryptAESCBCErrorCases(t *testing.T) {
iv := make([]byte, aes.BlockSize)
rand.Read(iv)
invalidCiphertext := append(iv, []byte{0x01, 0x02, 0x03}...) // IV + data not multiple of block size
_, err := DecryptAESCBC(key, invalidCiphertext)
_, err := DecryptAES256CBC(key, invalidCiphertext)
if err == nil {
t.Error("DecryptAESCBC should have failed for ciphertext not multiple of block size")
t.Error("DecryptAES256CBC should have failed for ciphertext not multiple of block size")
}
})
t.Run("InvalidPadding", func(t *testing.T) {
// Create a valid ciphertext first
plaintext := []byte("valid data")
ciphertext, err := EncryptAESCBC(key, plaintext)
ciphertext, err := EncryptAES256CBC(key, plaintext)
if err != nil {
t.Fatalf("Failed to create test ciphertext: %v", err)
}
@@ -199,35 +124,42 @@ func TestDecryptAESCBCErrorCases(t *testing.T) {
copy(corruptedCiphertext, ciphertext)
corruptedCiphertext[len(corruptedCiphertext)-1] ^= 0xFF
_, err = DecryptAESCBC(key, corruptedCiphertext)
_, err = DecryptAES256CBC(key, corruptedCiphertext)
if err == nil {
t.Error("DecryptAESCBC should have failed for corrupted padding")
t.Error("DecryptAES256CBC should have failed for corrupted padding")
}
})
t.Run("EmptyPlaintext", func(t *testing.T) {
// Create a ciphertext that would result in empty plaintext
invalidCiphertext := make([]byte, aes.BlockSize) // Only IV, no data
_, err := DecryptAESCBC(key, invalidCiphertext)
if err == nil {
t.Error("DecryptAESCBC should have failed for empty ciphertext data")
t.Run("EmptyPlaintextAfterDecryption", func(t *testing.T) {
// This creates a ciphertext that decrypts to just padding
key, _ := GenerateAES256Key()
iv := make([]byte, aes.BlockSize)
// A block of padding bytes
paddedBlock := bytes.Repeat([]byte{byte(aes.BlockSize)}, aes.BlockSize)
block, _ := aes.NewCipher(key)
mode := cipher.NewCBCEncrypter(block, iv)
ciphertext := make([]byte, len(paddedBlock))
mode.CryptBlocks(ciphertext, paddedBlock)
// Prepend IV
fullCiphertext := append(iv, ciphertext...)
// This should decrypt to an empty slice, which is valid
decrypted, err := DecryptAES256CBC(key, fullCiphertext)
if err != nil {
t.Errorf("DecryptAES256CBC failed for empty plaintext case: %v", err)
}
if len(decrypted) != 0 {
t.Errorf("Expected empty plaintext, got %q", decrypted)
}
})
}
func TestConstants(t *testing.T) {
if AES128KeySize != 16 {
t.Errorf("AES128KeySize should be 16, got %d", AES128KeySize)
}
if AES192KeySize != 24 {
t.Errorf("AES192KeySize should be 24, got %d", AES192KeySize)
}
if AES256KeySize != 32 {
t.Errorf("AES256KeySize should be 32, got %d", AES256KeySize)
}
if DefaultKeySize != AES256KeySize {
t.Errorf("DefaultKeySize should be AES256KeySize (%d), got %d", AES256KeySize, DefaultKeySize)
}
}
func BenchmarkAES256CBC(b *testing.B) {