AES encryption in swift
Based on @zaph great answer, I create this Playground for:
Swift 5
import Foundation
import CommonCrypto
protocol Cryptable {
func encrypt(_ string: String) throws -> Data
func decrypt(_ data: Data) throws -> String
}
struct AES {
private let key: Data
private let ivSize: Int = kCCBlockSizeAES128
private let options: CCOptions = CCOptions(kCCOptionPKCS7Padding)
init(keyString: String) throws {
guard keyString.count == kCCKeySizeAES256 else {
throw Error.invalidKeySize
}
self.key = Data(keyString.utf8)
}
}
extension AES {
enum Error: Swift.Error {
case invalidKeySize
case generateRandomIVFailed
case encryptionFailed
case decryptionFailed
case dataToStringFailed
}
}
private extension AES {
func generateRandomIV(for data: inout Data) throws {
try data.withUnsafeMutableBytes { dataBytes in
guard let dataBytesBaseAddress = dataBytes.baseAddress else {
throw Error.generateRandomIVFailed
}
let status: Int32 = SecRandomCopyBytes(
kSecRandomDefault,
kCCBlockSizeAES128,
dataBytesBaseAddress
)
guard status == 0 else {
throw Error.generateRandomIVFailed
}
}
}
}
extension AES: Cryptable {
func encrypt(_ string: String) throws -> Data {
let dataToEncrypt = Data(string.utf8)
let bufferSize: Int = ivSize + dataToEncrypt.count + kCCBlockSizeAES128
var buffer = Data(count: bufferSize)
try generateRandomIV(for: &buffer)
var numberBytesEncrypted: Int = 0
do {
try key.withUnsafeBytes { keyBytes in
try dataToEncrypt.withUnsafeBytes { dataToEncryptBytes in
try buffer.withUnsafeMutableBytes { bufferBytes in
guard let keyBytesBaseAddress = keyBytes.baseAddress,
let dataToEncryptBytesBaseAddress = dataToEncryptBytes.baseAddress,
let bufferBytesBaseAddress = bufferBytes.baseAddress else {
throw Error.encryptionFailed
}
let cryptStatus: CCCryptorStatus = CCCrypt( // Stateless, one-shot encrypt operation
CCOperation(kCCEncrypt), // op: CCOperation
CCAlgorithm(kCCAlgorithmAES), // alg: CCAlgorithm
options, // options: CCOptions
keyBytesBaseAddress, // key: the "password"
key.count, // keyLength: the "password" size
bufferBytesBaseAddress, // iv: Initialization Vector
dataToEncryptBytesBaseAddress, // dataIn: Data to encrypt bytes
dataToEncryptBytes.count, // dataInLength: Data to encrypt size
bufferBytesBaseAddress + ivSize, // dataOut: encrypted Data buffer
bufferSize, // dataOutAvailable: encrypted Data buffer size
&numberBytesEncrypted // dataOutMoved: the number of bytes written
)
guard cryptStatus == CCCryptorStatus(kCCSuccess) else {
throw Error.encryptionFailed
}
}
}
}
} catch {
throw Error.encryptionFailed
}
let encryptedData: Data = buffer[..<(numberBytesEncrypted + ivSize)]
return encryptedData
}
func decrypt(_ data: Data) throws -> String {
let bufferSize: Int = data.count - ivSize
var buffer = Data(count: bufferSize)
var numberBytesDecrypted: Int = 0
do {
try key.withUnsafeBytes { keyBytes in
try data.withUnsafeBytes { dataToDecryptBytes in
try buffer.withUnsafeMutableBytes { bufferBytes in
guard let keyBytesBaseAddress = keyBytes.baseAddress,
let dataToDecryptBytesBaseAddress = dataToDecryptBytes.baseAddress,
let bufferBytesBaseAddress = bufferBytes.baseAddress else {
throw Error.encryptionFailed
}
let cryptStatus: CCCryptorStatus = CCCrypt( // Stateless, one-shot encrypt operation
CCOperation(kCCDecrypt), // op: CCOperation
CCAlgorithm(kCCAlgorithmAES128), // alg: CCAlgorithm
options, // options: CCOptions
keyBytesBaseAddress, // key: the "password"
key.count, // keyLength: the "password" size
dataToDecryptBytesBaseAddress, // iv: Initialization Vector
dataToDecryptBytesBaseAddress + ivSize, // dataIn: Data to decrypt bytes
bufferSize, // dataInLength: Data to decrypt size
bufferBytesBaseAddress, // dataOut: decrypted Data buffer
bufferSize, // dataOutAvailable: decrypted Data buffer size
&numberBytesDecrypted // dataOutMoved: the number of bytes written
)
guard cryptStatus == CCCryptorStatus(kCCSuccess) else {
throw Error.decryptionFailed
}
}
}
}
} catch {
throw Error.encryptionFailed
}
let decryptedData: Data = buffer[..<numberBytesDecrypted]
guard let decryptedString = String(data: decryptedData, encoding: .utf8) else {
throw Error.dataToStringFailed
}
return decryptedString
}
}
do {
let aes = try AES(keyString: "FiugQTgPNwCWUY,VhfmM4cKXTLVFvHFe")
let stringToEncrypt: String = "please encrypt meeee"
print("String to encrypt:\t\t\t\(stringToEncrypt)")
let encryptedData: Data = try aes.encrypt(stringToEncrypt)
print("String encrypted (base64):\t\(encryptedData.base64EncodedString())")
let decryptedData: String = try aes.decrypt(encryptedData)
print("String decrypted:\t\t\t\(decryptedData)")
} catch {
print("Something went wrong: \(error)")
}
Output:
I also created a Swift Package based on it:
https://github.com/backslash-f/aescryptable ✌ð»
Be sure to use the same parameters which seem to be AES with CBC mode with iv, PKCS5Padding (actually PKCS#7) padding and a 16-byte (128-bit) key.
PKCS#5 padding and PKCS#7 padding are essentially the same, sometimes for historic reasons PKCS#5 padding is specified for use with AES but the actual padding is PKCS#7.
Make sure the encodings of the key, iv and encrypted data all match. Hex dump them on both platforms to ensure they are identical. Encryption functions are not difficult to use, if all the input parameters are correct the output will be correct.
To make this more secure the iv should be random bytes and prepended to the encrypted data for use during decryption.
The Cross platform AES encryption uses a 256-bit key so will not work as-is.
Example:
Swift 2
// operation: kCCEncrypt or kCCDecrypt
func testCrypt(data data:[UInt8], keyData:[UInt8], ivData:[UInt8], operation:Int) -> [UInt8]? {
let cryptLength = size_t(data.count+kCCBlockSizeAES128)
var cryptData = [UInt8](count:cryptLength, repeatedValue:0)
let keyLength = size_t(kCCKeySizeAES128)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionPKCS7Padding)
var numBytesEncrypted :size_t = 0
let cryptStatus = CCCrypt(CCOperation(operation),
algoritm,
options,
keyData, keyLength,
ivData,
data, data.count,
&cryptData, cryptLength,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
cryptData.removeRange(numBytesEncrypted..<cryptData.count)
} else {
print("Error: \(cryptStatus)")
}
return cryptData;
}
let message = "Don´t try to read this text. Top Secret Stuff"
let messageData = Array(message.utf8)
let keyData = Array("12345678901234567890123456789012".utf8)
let ivData = Array("abcdefghijklmnop".utf8)
let encryptedData = testCrypt(data:messageData, keyData:keyData, ivData:ivData, operation:kCCEncrypt)!
let decryptedData = testCrypt(data:encryptedData, keyData:keyData, ivData:ivData, operation:kCCDecrypt)!
var decrypted = String(bytes:decryptedData, encoding:NSUTF8StringEncoding)!
print("message: \(message)");
print("messageData: \(NSData(bytes:messageData, length:messageData.count))");
print("keyData: \(NSData(bytes:keyData, length:keyData.count))");
print("ivData: \(NSData(bytes:ivData, length:ivData.count))");
print("encryptedData: \(NSData(bytes:encryptedData, length:encryptedData.count))");
print("decryptedData: \(NSData(bytes:decryptedData, length:decryptedData.count))");
print("decrypted: \(String(bytes:decryptedData,encoding:NSUTF8StringEncoding)!)");
Output:
message: Don´t try to read this text. Top Secret Stuff messageData: 446f6ec2 b4742074 72792074 6f207265 61642074 68697320 74657874 2e20546f 70205365 63726574 20537475 6666 keyData: 31323334 35363738 39303132 33343536 37383930 31323334 35363738 39303132 ivData: 61626364 65666768 696a6b6c 6d6e6f70 encryptedData: b1b6dc17 62eaf3f8 baa1cb87 21ddc35c dee803ed fb320020 85794848 21206943 a85feb5b c8ee58fc d6fb664b 96b81114 decryptedData: 446f6ec2 b4742074 72792074 6f207265 61642074 68697320 74657874 2e20546f 70205365 63726574 20537475 6666 decrypted: Don´t try to read this text. Top Secret Stuff
Swift 3 with
[UInt8]type
func testCrypt(data:[UInt8], keyData:[UInt8], ivData:[UInt8], operation:Int) -> [UInt8]? {
let cryptLength = size_t(data.count+kCCBlockSizeAES128)
var cryptData = [UInt8](repeating:0, count:cryptLength)
let keyLength = size_t(kCCKeySizeAES128)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionPKCS7Padding)
var numBytesEncrypted :size_t = 0
let cryptStatus = CCCrypt(CCOperation(operation),
algoritm,
options,
keyData, keyLength,
ivData,
data, data.count,
&cryptData, cryptLength,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
cryptData.removeSubrange(numBytesEncrypted..<cryptData.count)
} else {
print("Error: \(cryptStatus)")
}
return cryptData;
}
Swift 3 & 4 with
Datatype
func testCrypt(data:Data, keyData:Data, ivData:Data, operation:Int) -> Data {
let cryptLength = size_t(data.count + kCCBlockSizeAES128)
var cryptData = Data(count:cryptLength)
let keyLength = size_t(kCCKeySizeAES128)
let options = CCOptions(kCCOptionPKCS7Padding)
var numBytesEncrypted :size_t = 0
let cryptStatus = cryptData.withUnsafeMutableBytes {cryptBytes in
data.withUnsafeBytes {dataBytes in
ivData.withUnsafeBytes {ivBytes in
keyData.withUnsafeBytes {keyBytes in
CCCrypt(CCOperation(operation),
CCAlgorithm(kCCAlgorithmAES),
options,
keyBytes, keyLength,
ivBytes,
dataBytes, data.count,
cryptBytes, cryptLength,
&numBytesEncrypted)
}
}
}
}
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
cryptData.removeSubrange(numBytesEncrypted..<cryptData.count)
} else {
print("Error: \(cryptStatus)")
}
return cryptData;
}
let message = "Don´t try to read this text. Top Secret Stuff"
let messageData = message.data(using:String.Encoding.utf8)!
let keyData = "12345678901234567890123456789012".data(using:String.Encoding.utf8)!
let ivData = "abcdefghijklmnop".data(using:String.Encoding.utf8)!
let encryptedData = testCrypt(data:messageData, keyData:keyData, ivData:ivData, operation:kCCEncrypt)
let decryptedData = testCrypt(data:encryptedData, keyData:keyData, ivData:ivData, operation:kCCDecrypt)
var decrypted = String(bytes:decryptedData, encoding:String.Encoding.utf8)!
Example from sunsetted documentation section:
AES encryption in CBC mode with a random IV (Swift 3+)
The iv is prefixed to the encrypted data
aesCBC128Encrypt will create a random IV and prefixed to the encrypted code.aesCBC128Decrypt will use the prefixed IV during decryption.
Inputs are the data and key are Data objects. If an encoded form such as Base64 if required convert to and/or from in the calling method.
The key should be exactly 128-bits (16-bytes), 192-bits (24-bytes) or 256-bits (32-bytes) in length. If another key size is used an error will be thrown.
PKCS#7 padding is set by default.
This example requires Common Crypto
It is necessary to have a bridging header to the project:#import <CommonCrypto/CommonCrypto.h>
Add the Security.framework to the project.
This is example, not production code.
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;
}
Example usage:
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)")
}
Example Output:
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>
Notes:
One typical problem with CBC mode example code is that it leaves the creation and sharing of the random IV to the user. This example includes generation of the IV, prefixed the encrypted data and uses the prefixed IV during decryption. This frees the casual user from the details that are necessary for CBC mode.
For security the encrypted data also should have authentication, this example code does not provide that in order to be small and allow better interoperability for other platforms.
Also missing is key derivation of the key from a password, it is suggested that PBKDF2 be used is text passwords are used as keying material.
For robust production ready multi-platform encryption code see RNCryptor.
Swift 5
I refactored @ingconti 's code.
import Foundation
import CommonCrypto
struct AES {
// MARK: - Value
// MARK: Private
private let key: Data
private let iv: Data
// MARK: - Initialzier
init?(key: String, iv: String) {
guard key.count == kCCKeySizeAES128 || key.count == kCCKeySizeAES256, let keyData = key.data(using: .utf8) else {
debugPrint("Error: Failed to set a key.")
return nil
}
guard iv.count == kCCBlockSizeAES128, let ivData = iv.data(using: .utf8) else {
debugPrint("Error: Failed to set an initial vector.")
return nil
}
self.key = keyData
self.iv = ivData
}
// MARK: - Function
// MARK: Public
func encrypt(string: String) -> Data? {
return crypt(data: string.data(using: .utf8), option: CCOperation(kCCEncrypt))
}
func decrypt(data: Data?) -> String? {
guard let decryptedData = crypt(data: data, option: CCOperation(kCCDecrypt)) else { return nil }
return String(bytes: decryptedData, encoding: .utf8)
}
func crypt(data: Data?, option: CCOperation) -> Data? {
guard let data = data else { return nil }
let cryptLength = data.count + key.count
var cryptData = Data(count: cryptLength)
var bytesLength = Int(0)
let status = cryptData.withUnsafeMutableBytes { cryptBytes in
data.withUnsafeBytes { dataBytes in
iv.withUnsafeBytes { ivBytes in
key.withUnsafeBytes { keyBytes in
CCCrypt(option, CCAlgorithm(kCCAlgorithmAES), CCOptions(kCCOptionPKCS7Padding), keyBytes.baseAddress, key.count, ivBytes.baseAddress, dataBytes.baseAddress, data.count, cryptBytes.baseAddress, cryptLength, &bytesLength)
}
}
}
}
guard Int32(status) == Int32(kCCSuccess) else {
debugPrint("Error: Failed to crypt data. Status \(status)")
return nil
}
cryptData.removeSubrange(bytesLength..<cryptData.count)
return cryptData
}
}
Use like this
let password = "UserPassword1!"
let key128 = "1234567890123456" // 16 bytes for AES128
let key256 = "12345678901234561234567890123456" // 32 bytes for AES256
let iv = "abcdefghijklmnop" // 16 bytes for AES128
let aes128 = AES(key: key128, iv: iv)
let aes256 = AES(key: key256, iv: iv)
let encryptedPassword128 = aes128?.encrypt(string: password)
aes128?.decrypt(data: encryptedPassword128)
let encryptedPassword256 = aes256?.encrypt(string: password)
aes256?.decrypt(data: encryptedPassword256)
Results
