ios - Problema con CCCrypt(CommonCrypt) en Swift

objective-c cryptography

Question

Estoy transfiriendo una categoría Objective-C funcional (NSData + AESCrypt.m) a Swift y he encontrado un problema al trabajar con los punteros. El código para la parte de cifrado en Swift se compila correctamente, pero genera un error EXEC_BAD_ACCES en tiempo de ejecución.

El código que tengo hasta ahora es (intenté diseccionar el código tanto como sea posible):

let key = "123456789012345678901234567890120"
let keyLength = UInt(kCCKeySizeAES256 + 1)
let keyPointer = strdup(key) // Convert key to <UnsafeMutablePointer<Int8>
let message = "Don´t try to read this text. Top Secret Stuff"
let data = (message as NSString).dataUsingEncoding(NSUTF8StringEncoding)
let dataBytes = data?.bytes
let length = data?.length
let dataLength = UInt(length!)
let dataPointer = UnsafePointer<UInt8>(dataBytes!)
let operation: CCOperation = UInt32(kCCEncrypt)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionECBMode + kCCOptionPKCS7Padding)
let cryptBufferSize = UInt(dataLength + kCCBlockSizeAES128)
var cryptBuffer = [UInt8](count: Int(cryptBufferSize), repeatedValue: 0)
var cryptBufferPointer = UnsafeMutablePointer<UInt8>(cryptBuffer)
var numBytesEncrypted = UnsafeMutablePointer<UInt>()
var cryptStatus = CCCrypt(operation, algoritm, options, keyPointer, keyLength, nil, dataPointer, dataLength, cryptBufferPointer, cryptBufferSize, numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
let size = NSInteger(cryptBufferSize)
let encryptedData = NSData(bytes: cryptBufferPointer, length: size)
let encryptedString = NSString(data: encryptedData, encoding: NSUTF8StringEncoding)
println("Encrypted String = /(encryptedString)") // EXEC_BAD_ACCESS error
} else {
println("Error: /(cryptStatus)")
}

El objeto encryptedData muestra la siguiente información:

<279c2d0f d3ce2200 0dc10cc1 9df46e76 cb26f423 7c9bde76 f9d8d0e2 632acef9 74fb0614 4717422b 684d1889 e3ce882c 00000000 00000000 00000000 0000>

Pero encryptedString muestra 0x0000000000 en el depurador, y al intentar println() genera el error EXEC_BAD_ACCESS

¿Alguna idea de lo que falta?

Rgds ....

Answer 1

Swift 2.0

Aquí hay un ejemplo
Si esto no es exactamente lo que se necesita, los métodos deberían ser un buen ejemplo
Nota: la cadena de clave se convierte en datos

Agregue Security.framework al proyecto
Agregue #import <CommonCrypto/CommonCryptor.h> al encabezado de puente.

let keyString = "12345678901234567890123456789012"
let keyData: NSData! = (keyString as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
print("keyLength = /(keyData.length), keyData = /(keyData)")
let message = "Don´t try to read this text. Top Secret Stuff"
let data: NSData! = (message as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
print("data length = /(data.length), data = /(data)")
let cryptData = NSMutableData(length: Int(data.length) + kCCBlockSizeAES128)!
let keyLength = size_t(kCCKeySizeAES256)
let operation: CCOperation = UInt32(kCCEncrypt)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionECBMode + kCCOptionPKCS7Padding)
var numBytesEncrypted :size_t = 0
var cryptStatus = CCCrypt(operation,
algoritm,
options,
keyData.bytes, keyLength,
nil,
data.bytes, data.length,
cryptData.mutableBytes, cryptData.length,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
cryptData.length = Int(numBytesEncrypted)
print("cryptLength = /(numBytesEncrypted), cryptData = /(cryptData)")
// Not all data is a UTF-8 string so Base64 is used
let base64cryptString = cryptData.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
print("base64cryptString = /(base64cryptString)")
} else {
print("Error: /(cryptStatus)")
}

Salida:

keyLength = 32, keyData = <31323334 35363738 39303132 33343536 37383930 31323334 35363738 39303132>
dataLength = 46, data = <446f6ec2 b4742074 72792074 6f207265 61642074 68697320 74657874 2e20546f 70205365 63726574 20537475 6666>
cryptLength = 48, cryptData = <118a32dc c23f7caa 883abc3c 1c7f0770 e200016b 2737acfa 17bb96fb a02b02a7 c147603b 06acd863 94bb8ff2 6cb14515>
base64cryptString = EYoy3MI/fKqIOrw8HH8HcOIAAWsnN6z6F7uW+6ArAqfBR2A7BqzYY5S7j/JssUUV

Swift 3

El iv está prefijado a los datos encriptados

aesCBC128Encrypt creará un IV aleatorio y con el prefijo del código cifrado.
aesCBC128Decrypt usará el IV prefijado durante el descifrado.

Las entradas son los datos y la clave son objetos de datos. Si es una forma codificada como Base64 si es necesario, convierta ay desde el método de llamada.

La clave debe tener exactamente 128 bits (16 bytes), 192 bits (24 bytes) o 256 bits (32 bytes) de longitud. Si se utiliza otro tamaño de clave, se generará un error.

El relleno PKCS # 7 está configurado de forma predeterminada.

Este ejemplo requiere criptografía común
Es necesario tener un encabezado de puente para el proyecto:
#import <CommonCrypto/CommonCrypto.h>
Agregue Security.framework al proyecto.

Este es un ejemplo, no un código de producción.

enum AESError: Error {
case KeyError((String, Int))
case IVError((String, Int))
case CryptorError((String, Int))
}
// The iv is prefixed to the encrypted data
func aesCBCEncrypt(data:Data, keyData:Data) throws -> Data {
let keyLength = keyData.count
let validKeyLengths = [kCCKeySizeAES128, kCCKeySizeAES192, kCCKeySizeAES256]
if (validKeyLengths.contains(keyLength) == false) {
throw AESError.KeyError(("Invalid key length", keyLength))
}
let ivSize = kCCBlockSizeAES128;
let cryptLength = size_t(ivSize + data.count + kCCBlockSizeAES128)
var cryptData = Data(count:cryptLength)
let status = cryptData.withUnsafeMutableBytes {ivBytes in
SecRandomCopyBytes(kSecRandomDefault, kCCBlockSizeAES128, ivBytes)
}
if (status != 0) {
throw AESError.IVError(("IV generation failed", Int(status)))
}
var numBytesEncrypted :size_t = 0
let options = CCOptions(kCCOptionPKCS7Padding)
let cryptStatus = cryptData.withUnsafeMutableBytes {cryptBytes in
data.withUnsafeBytes {dataBytes in
keyData.withUnsafeBytes {keyBytes in
CCCrypt(CCOperation(kCCEncrypt),
CCAlgorithm(kCCAlgorithmAES),
options,
keyBytes, keyLength,
cryptBytes,
dataBytes, data.count,
cryptBytes+kCCBlockSizeAES128, cryptLength,
&numBytesEncrypted)
}
}
}
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
cryptData.count = numBytesEncrypted + ivSize
}
else {
throw AESError.CryptorError(("Encryption failed", Int(cryptStatus)))
}
return cryptData;
}
// The iv is prefixed to the encrypted data
func aesCBCDecrypt(data:Data, keyData:Data) throws -> Data? {
let keyLength = keyData.count
let validKeyLengths = [kCCKeySizeAES128, kCCKeySizeAES192, kCCKeySizeAES256]
if (validKeyLengths.contains(keyLength) == false) {
throw AESError.KeyError(("Invalid key length", keyLength))
}
let ivSize = kCCBlockSizeAES128;
let clearLength = size_t(data.count - ivSize)
var clearData = Data(count:clearLength)
var numBytesDecrypted :size_t = 0
let options = CCOptions(kCCOptionPKCS7Padding)
let cryptStatus = clearData.withUnsafeMutableBytes {cryptBytes in
data.withUnsafeBytes {dataBytes in
keyData.withUnsafeBytes {keyBytes in
CCCrypt(CCOperation(kCCDecrypt),
CCAlgorithm(kCCAlgorithmAES128),
options,
keyBytes, keyLength,
dataBytes,
dataBytes+kCCBlockSizeAES128, clearLength,
cryptBytes, clearLength,
&numBytesDecrypted)
}
}
}
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
clearData.count = numBytesDecrypted
}
else {
throw AESError.CryptorError(("Decryption failed", Int(cryptStatus)))
}
return clearData;
}

Ejemplo de uso:

let clearData = "clearData0123456".data(using:String.Encoding.utf8)!
let keyData = "keyData890123456".data(using:String.Encoding.utf8)!
print("clearData: /(clearData as NSData)")
print("keyData: /(keyData as NSData)")
var cryptData :Data?
do {
cryptData = try aesCBCEncrypt(data:clearData, keyData:keyData)
print("cryptData: /(cryptData! as NSData)")
}
catch (let status) {
print("Error aesCBCEncrypt: /(status)")
}
let decryptData :Data?
do {
let decryptData = try aesCBCDecrypt(data:cryptData!, keyData:keyData)
print("decryptData: /(decryptData! as NSData)")
}
catch (let status) {
print("Error aesCBCDecrypt: /(status)")
}

Salida de ejemplo:

clearData: <636c6561 72446174 61303132 33343536>
keyData: <6b657944 61746138 39303132 33343536>
cryptData: <92c57393 f454d959 5a4d158f 6e1cd3e7 77986ee9 b2970f49 2bafcf1a 8ee9d51a bde49c31 d7780256 71837a61 60fa4be0>
decryptData: <636c6561 72446174 61303132 33343536>

Notas:

Un problema típico con el código de ejemplo del modo CBC es que deja la creación y el intercambio del IV aleatorio para el usuario. Este ejemplo incluye la generación del IV, prefija los datos cifrados y usa el IV prefijado durante el descifrado. Esto libera al usuario ocasional de los detalles necesarios para el modo CBC .

Por seguridad, los datos cifrados también deben tener autenticación, este código de ejemplo no proporciona eso para que sea pequeño y permita una mejor interoperabilidad para otras plataformas.

También falta la derivación de la clave de una contraseña, se sugiere que se use PBKDF2 contraseñas de texto se usan como material de claves.

Para obtener un código de cifrado multiplataforma listo para la producción, consulte RNCryptor

Answer 2

Cifrado y descifrado Swift 2.0. Acabo de actualizar la respuesta anterior para admitir Swift 2.0.

static func AES128Encryption()
{
let keyString = "12345678901234567890123456789012"
let keyData: NSData! = (keyString as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let keyBytes = UnsafeMutablePointer<Void>(keyData.bytes)
print("keyLength = /(keyData.length), keyData = /(keyData)")
let message = "Don´t try to read this text. Top Secret Stuff"
let data: NSData! = (message as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let dataLength = size_t(data.length)
let dataBytes = UnsafeMutablePointer<Void>(data.bytes)
print("dataLength = /(dataLength), data = /(data)")
let cryptData = NSMutableData(length: Int(dataLength) + kCCBlockSizeAES128)
let cryptPointer = UnsafeMutablePointer<Void>(cryptData!.mutableBytes)
let cryptLength = size_t(cryptData!.length)
let keyLength = size_t(kCCKeySizeAES256)
let operation: CCOperation = UInt32(kCCEncrypt)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionPKCS7Padding + kCCOptionECBMode)
var numBytesEncrypted :size_t = 0
let cryptStatus = CCCrypt(operation,
algoritm,
options,
keyBytes, keyLength,
nil,
dataBytes, dataLength,
cryptPointer, cryptLength,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
// let x: UInt = numBytesEncrypted
cryptData!.length = Int(numBytesEncrypted)
print("cryptLength = /(numBytesEncrypted), cryptData = /(cryptData)")
// Not all data is a UTF-8 string so Base64 is used
let base64cryptString = cryptData!.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
print("base64cryptString = /(base64cryptString)")
} else {
print("Error: /(cryptStatus)")
}
}
static func AES128Decryption(data:NSData) //data = cryptData
{
let keyString = "12345678901234567890123456789012"
let keyData: NSData! = (keyString as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let keyBytes = UnsafeMutablePointer<Void>(keyData.bytes)
print("keyLength = /(keyData.length), keyData = /(keyData)")
//let message = "Don´t try to read this text. Top Secret Stuff"
// let data: NSData! = (message as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let dataLength = size_t(data.length)
let dataBytes = UnsafeMutablePointer<Void>(data.bytes)
print("dataLength = /(dataLength), data = /(data)")
let cryptData = NSMutableData(length: Int(dataLength) + kCCBlockSizeAES128)
let cryptPointer = UnsafeMutablePointer<Void>(cryptData!.mutableBytes)
let cryptLength = size_t(cryptData!.length)
let keyLength = size_t(kCCKeySizeAES256)
let operation: CCOperation = UInt32(kCCDecrypt)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionPKCS7Padding + kCCOptionECBMode)
var numBytesEncrypted :size_t = 0
let cryptStatus = CCCrypt(operation,
algoritm,
options,
keyBytes, keyLength,
nil,
dataBytes, dataLength,
cryptPointer, cryptLength,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
// let x: UInt = numBytesEncrypted
cryptData!.length = Int(numBytesEncrypted)
print("DecryptcryptLength = /(numBytesEncrypted), Decrypt = /(cryptData)")
// Not all data is a UTF-8 string so Base64 is used
let base64cryptString = cryptData!.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
print("base64DecryptString = /(base64cryptString)")
print( "utf8 actual string = /(NSString(data: cryptData!, encoding: NSUTF8StringEncoding))");
} else {
print("Error: /(cryptStatus)")
}
}