Table of Contents

Class AesCryptor

Namespace
Cuemon.Security.Cryptography
Assembly
Cuemon.Security.Cryptography.dll

Provides an implementation of the Advanced Encryption Standard (AES) symmetric algorithm.

public class AesCryptor
Inheritance
AesCryptor

Examples

AesCryptor provides AES encryption and decryption with configurable key size, cipher mode, and padding. This example generates a 256-bit key and 128-bit IV using AesCryptor.GenerateKey() and GenerateInitializationVector(), encrypts "This is a sensitive message that needs encryption.", decrypts the ciphertext, and verifies the round-trip matches the original. It also demonstrates explicit CBC mode with PKCS7 padding via an options delegate, custom key sizes (AesSize.Aes128 and AesSize.Aes192), and the default constructor that generates random credentials automatically. Console output confirms key and IV lengths, base64 ciphertext, round-trip success, and explicit options round-trip verification.

using System;
using System.Security.Cryptography;
using System.Text;
using Cuemon.Security.Cryptography;

namespace MyApp.Security
{
    public class AesCryptorExamples
    {
        public static void Demonstrate()
        {
            // Generate a 256-bit key and 128-bit initialization vector.
            byte[] key = AesCryptor.GenerateKey();
            byte[] iv = AesCryptor.GenerateInitializationVector();

            Console.WriteLine("Key length: {0} bytes ({1} bits)", key.Length, key.Length * 8);
            Console.WriteLine("IV length: {0} bytes ({1} bits)", iv.Length, iv.Length * 8);

            // Create an AesCryptor instance with the generated key and IV.
            var cryptor = new AesCryptor(key, iv);

            // Encrypt a secret message.
            byte[] plaintext = Encoding.UTF8.GetBytes("This is a sensitive message that needs encryption.");
            byte[] ciphertext = cryptor.Encrypt(plaintext);

            Console.WriteLine("Plaintext bytes: {0}", plaintext.Length);
            Console.WriteLine("Ciphertext (base64): {0}", Convert.ToBase64String(ciphertext));

            // Decrypt the ciphertext back to the original message.
            byte[] decrypted = cryptor.Decrypt(ciphertext);
            string roundtrip = Encoding.UTF8.GetString(decrypted);

            Console.WriteLine("Decrypted message: {0}", roundtrip); // matches original

            // Use explicit AES options (CBC mode, PKCS7 padding).
            byte[] ciphertextExplicit = cryptor.Encrypt(plaintext, o =>
            {
                o.Mode = CipherMode.CBC;
                o.Padding = PaddingMode.PKCS7;
            });

            byte[] decryptedExplicit = cryptor.Decrypt(ciphertextExplicit, o =>
            {
                o.Mode = CipherMode.CBC;
                o.Padding = PaddingMode.PKCS7;
            });

            Console.WriteLine("Explicit options roundtrip: {0}",
                Encoding.UTF8.GetString(decryptedExplicit) == roundtrip); // true
        }

        public static void GenerateKeysWithCustomSize()
        {
            // Generate a 128-bit key explicitly.
            byte[] key128 = AesCryptor.GenerateKey(o => o.Size = AesSize.Aes128);
            Console.WriteLine("128-bit key length: {0} bytes", key128.Length); // 16

            // Generate a 192-bit key.
            byte[] key192 = AesCryptor.GenerateKey(o => o.Size = AesSize.Aes192);
            Console.WriteLine("192-bit key length: {0} bytes", key192.Length); // 24

            // Default is 256-bit.
            byte[] key256 = AesCryptor.GenerateKey();
            Console.WriteLine("256-bit key length: {0} bytes", key256.Length); // 32
        }

        public static void UseDefaultConstructor()
        {
            // Default constructor generates a random key and IV.
            var cryptor = new AesCryptor();

            byte[] data = Encoding.UTF8.GetBytes("Hello, world!");
            byte[] encrypted = cryptor.Encrypt(data);
            byte[] decrypted = cryptor.Decrypt(encrypted);

            Console.WriteLine("Default constructor roundtrip: {0}",
                Encoding.UTF8.GetString(decrypted)); // Hello, world!
        }
    }
}

Constructors

AesCryptor()

Initializes a new instance of the AesCryptor class.

public AesCryptor()

AesCryptor(byte[], byte[])

Initializes a new instance of the AesCryptor class.

public AesCryptor(byte[] key, byte[] initializationVector)

Parameters

key byte[]

The secret key of this instance.

initializationVector byte[]

The initialization vector (IV) of this instance.

Exceptions

ArgumentNullException

key cannot be null -or- initializationVector cannot be null.

CryptographicException

key does not meet the required fixed size of either 128 bits, 192 bits or 256 bits -or- initializationVector does not meet the required fixed size of 128 bits.

Fields

BlockSize

Gets the block size (bits) for the Advanced Encryption Standard (AES) symmetric algorithm.

public const byte BlockSize = 128

Field Value

byte

Properties

InitializationVector

Gets the initialization vector (IV) of this instance.

public byte[] InitializationVector { get; }

Property Value

byte[]

The initialization vector (IV) of this instance.

Key

Gets the secret key of this instance.

public byte[] Key { get; }

Property Value

byte[]

The secret key of this instance.

Methods

Decrypt(byte[], Action<AesCryptorOptions>)

Decrypts the specified value.

public byte[] Decrypt(byte[] value, Action<AesCryptorOptions> setup = null)

Parameters

value byte[]

The encrypted value that needs to be decrypted.

setup Action<AesCryptorOptions>

The AesCryptorOptions which may be configured.

Returns

byte[]

The decrypted value.

Encrypt(byte[], Action<AesCryptorOptions>)

Encrypts the specified value.

public byte[] Encrypt(byte[] value, Action<AesCryptorOptions> setup = null)

Parameters

value byte[]

The value to encrypt.

setup Action<AesCryptorOptions>

The AesCryptorOptions which may be configured.

Returns

byte[]

The encrypted value.

GenerateInitializationVector()

Generates a random 128 bit initialization vector (IV).

public static byte[] GenerateInitializationVector()

Returns

byte[]

A random 128 bit generated initialization vector (IV).

GenerateKey(Action<AesKeyOptions>)

Generates a secret key from the options defined in setup.

public static byte[] GenerateKey(Action<AesKeyOptions> setup = null)

Parameters

setup Action<AesKeyOptions>

The AesKeyOptions which may be configured.

Returns

byte[]

A secret key from the options defined in setup.

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