Rijndael256

AES cryptographic library for .NET Framework and .NET Core

About

Rijndael256 makes encrypting data and files a breeze with the AES symmetric-key cipher Rijndael.

Features

• Advanced Encryption Standard (AES)
• Rijndael symmetric-key cipher:
  • Encrypt data or files
  • AES key sizes:
    • 128-bit
    • 192-bit
    • 256-bit
  • CBC Mode
• Authenticated Encryption (AE)
  • Encrypt-then-MAC (EtM)
• Cryptographic hashes:
  • SHA-512
  • PBKDF2

Quick Start

Encrypt a string using Rijndael AES 256-bit

string password = "sKzvYk#1Pn33!YN";  // The password to encrypt the data with
string plaintext = "Top secret data"; // The string to encrypt

// Encrypt the string
string ciphertext = Rijndael.Encrypt(plaintext, password, KeySize.Aes256);

// Decrypt the string
plaintext = Rijndael.Decrypt(ciphertext, password, KeySize.Aes256);

Encrypt a string using Authenticated Encryption (AE)

string password = "KQpc@HuQ66b$z37";  // The password to encrypt the data with
string plaintext = "Top secret data"; // The string to encrypt

// Encrypt the string
string aeCiphertext = RijndaelEtM.Encrypt(plaintext, password, KeySize.Aes256);

// Decrypt the string
plaintext = RijndaelEtM.Decrypt(aeCiphertext, password, KeySize.Aes256);

Encrypt a file using Rijndael AES 256-bit

string password = "2zj9cV!50BwJ$A1";            // The password to encrypt the file with
string plaintextFile = @"C:\TopSecretFile.png"; // The file to encrypt
string ciphertextFile = @"C:\SecureFile";       // The encrypted file (extension unnecessary)

// Encrypt the file
Rijndael.Encrypt(plaintextFile, ciphertextFile, password, KeySize.Aes256);

// Decrypt the file
Rijndael.Decrypt(ciphertextFile, plaintextFile, password, KeySize.Aes256);

Settings

The Settings object is a collection of mutable defaults used throughout the library. Modification of these defaults is not necessary, but is made available for developers who want finer control of Rijndael256.

Example

// The HashIterations setting is used in several places throughout the lib,
// with Rijndael.Encrypt being just one of them. After making this change,
// any future calls to Rijndael.Encrypt will make use of this new value
Settings.HashIterations = 25000;

// To reset all the settings to their default values
Settings.Reset();

Appendix

Authenticated Encryption (AE)

AE adds an integrity check to the resulting ciphertext, so we can authenticate the ciphertext before decrypting it. Whereas encryption provides confidentiality, AE adds authenticity.

Encrypt-then-MAC (EtM)

Rijndael256 offers AE via the EtM encryption mode, which was standardized in ISO/IEC 19772:2009.

EtM Workflow

1. Encryption:
   1. The plaintext is encrypted.
   2. A MAC is calculated from the resulting ciphertext.
   3. The MAC is appended to the ciphertext.
2. Decryption:
   1. The MAC is extracted from the ciphertext (M_o).
   2. A MAC is calculated from the ciphertext (M_n).
   3. The MACs are compared for equality (M_o == M_n)
      1. Equal: The ciphertext is decrypted.
      2. Not Equal: Authentication has failed -- the decryption process is aborted, with no attempt being made to decrypt the unauthentic ciphertext.