Swift AES Extensions

NSData+AES.swift

import Foundation

extension NSData {

    func encryptAES128(key: NSString, iv: NSString) -> NSData? {
        return aes128(method: CCOperation(kCCEncrypt), key: key, iv: iv)
    }

    func decryptAES128(key: NSString, iv: NSString) -> NSData? {
        return aes128(method: CCOperation(kCCDecrypt), key: key, iv: iv)
    }

    private func aes128(method: CCOperation, key: NSString, iv: NSString) -> NSData? {
        let keyPtr = UnsafeMutablePointer<CChar>.allocate(capacity: Int(kCCKeySizeAES128) + 1)

        defer {
            keyPtr.deallocate()
        }

        let ivPtr = iv.utf8String
        bzero(keyPtr, 0)
        key.getCString(keyPtr, maxLength: Int(kCCKeySizeAES128) + 1, encoding: String.Encoding.utf8.rawValue)

        let bufferSize = self.length + kCCBlockSizeAES128
        let buffer = UnsafeMutableRawPointer.allocate(byteCount: bufferSize, alignment: MemoryLayout.alignment(ofValue: CChar.self))

        var numBytesEncrypted = 0

        let cryptStatus = CCCrypt(method, CCAlgorithm(kCCAlgorithmAES128), CCOptions(kCCOptionPKCS7Padding), keyPtr, kCCKeySizeAES128, ivPtr, self.bytes, self.length, buffer, bufferSize, &numBytesEncrypted)

        if cryptStatus == kCCSuccess {
            return NSData(bytesNoCopy: buffer, length: numBytesEncrypted, freeWhenDone: true)
        }

        buffer.deallocate()
        return nil
    }

}

String+AES.swift

import Foundation

extension String {
    
    func encryptAES128(key: String, iv: String) -> String? {
        return aes128(method: CCOperation(kCCEncrypt), key: key, iv: iv)
    }
    
    func decryptAES128(key: String, iv: String) -> String? {
        return aes128(method: CCOperation(kCCDecrypt), key: key, iv: iv)
    }
    
    private func aes128(method: CCOperation, key: String, iv: String) -> String? {
        if let keyData = key.data(using: String.Encoding.utf8),
            let data = NSData(base64Encoded: self, options: .ignoreUnknownCharacters),
            let cryptData = NSMutableData(length: Int((data.length)) + kCCBlockSizeAES128) {
            
            let keyLength = size_t(kCCKeySizeAES128)
            
            let algoritm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
            var numBytesEncrypted :size_t = 0
            
            let cryptStatus = CCCrypt(method,
                                      algoritm,
                                      CCOptions(kCCOptionPKCS7Padding),
                                      (keyData as NSData).bytes, keyLength,
                                      iv,
                                      data.bytes, data.length,
                                      cryptData.mutableBytes, cryptData.length,
                                      &numBytesEncrypted)
            
            if UInt32(cryptStatus) == UInt32(kCCSuccess) {
                cryptData.length = Int(numBytesEncrypted)
                let unencryptedMessage = String(data: cryptData as Data, encoding:String.Encoding.utf8)
                return unencryptedMessage
            }
        }
        return nil
    }
}

Swift 5 version

extension Data {

    func encryptAES128(key: String, iv: String) -> Data? {
        aes128(method: CCOperation(kCCEncrypt), key: key, iv: iv)
    }

    func decryptAES128(key: String, iv: String) -> Data? {
        aes128(method: CCOperation(kCCDecrypt), key: key, iv: iv)
    }

    private func aes128(method: CCOperation, key: String, iv: String) -> Data? {
        let keyData = key.data(using: .utf8)!
        let ivData = iv.data(using: .utf8)!

        let bufferSize = count + kCCBlockSizeAES128
        var buffer = [UInt8](repeating: 0, count: bufferSize)

        var numBytesEncrypted = 0

        let cryptStatus = keyData.withUnsafeBytes { keyBytes in
            ivData.withUnsafeBytes { ivBytes in
                withUnsafeBytes { dataBytes in
                    CCCrypt(
                        method,
                        CCAlgorithm(kCCAlgorithmAES128),
                        CCOptions(kCCOptionPKCS7Padding),
                        keyBytes.baseAddress,
                        kCCKeySizeAES128,
                        ivBytes.baseAddress,
                        dataBytes.baseAddress,
                        count,
                        &buffer,
                        bufferSize,
                        &numBytesEncrypted
                    )
                }
            }
        }

        if cryptStatus == kCCSuccess {
            return Data(bytes: buffer, count: numBytesEncrypted)
        }

        return nil
    }
    
}