ChaCha20Poly1305 Class

Namespace: Rebex.Security.Cryptography
Assembly: Rebex.Security.dll (version 7.0.9119)

Represents an authenticated encryption with associated data (AEAD) ChaCha20/Poly1305 cipher.

Syntax
public sealed class ChaCha20Poly1305 : IDisposable
Inheritance
Object
ChaCha20Poly1305
Implements
Inherited Members
Examples
public void EncryptAndDecryptData()
{
   //Prepare plain text.
   byte[] plainText = GetMyPlainText();

   //Create the  array for the resulting cipher text.
   byte[] cipherText = new byte[plainText.Length];

   byte[] key;
   byte[] nonce;
   using (var randomGenerator = RandomNumberGenerator.Create())
   {
       //Generate random key.
       key = new byte[ChaCha20Poly1305.KeySize];
       randomGenerator.GetBytes(key);

       //Generate random nonce.
       nonce = new byte[ChaCha20Poly1305.NonceSize];
       randomGenerator.GetBytes(nonce);
   }

   //Prepare additional authentication data. Can be null.
   byte[] aaaData = GetMyAadData();

   //Prepare the array in which will be stored authentication tag.
   var authTag = new byte[ChaCha20Poly1305.AuthenticationTagSize];

   //Create the instance of the ChaCha20Poly1305 class.
   using (var chacha20Poly1305 = new ChaCha20Poly1305(key))
   {
       //Encrypt data.
       chacha20Poly1305.Encrypt(nonce, plainText, cipherText, authTag, aaaData);
       //After a successful call cipherText contains encrypted data and authTag contains authentication tag.

   }

   //Later decrypt data.

   //Prepare an array in which decrypted data will be stored.
   byte[] decryptedData = new byte[cipherText.Length];

   //Create the instance of the ChaCha20Poly1305 class and use the same key.
   using (var chacha20Poly1305 = new ChaCha20Poly1305(key))
   {
       //Decrypt data. Use the same nonce, same additional authentication data, and use the authTag from the previous encrypt operation.
       chacha20Poly1305.Decrypt(nonce, cipherText, authTag, decryptedData, aaaData);
       //After a successful call decryptedData contains decrypted data.

   }
}

Constructors

Name Description
ChaCha20Poly1305(Byte[])

Initializes a new ChaCha20Poly1305 instance with the provided key.

Fields

Name Description
AuthenticationTagSize

ChaCha20Poly1305 authentication tag size (in bytes). The value of the constant is 16.
KeySize

Required ChaCha20Poly1305 key size (in bytes). The value of the constant is 32.
NonceSize

Required ChaCha20Poly1305 nonce size (in bytes). The value of the constant is 12.

Methods

Name Description
Decrypt(Byte[], Byte[], Byte[], Byte[], Byte[])

Decrypts ciphertext using the secret key and nonce, stores the result to the ciphertext and validates authTag.
Dispose()

Releases the resources used by the current instance.
Encrypt(Byte[], Byte[], Byte[], Byte[], Byte[])

Encrypts plaintext using the secret key and nonce, stores the result to the ciphertext and authenticates resulting ciphertext with optional additionalAuthData and stores the authentication tag to the authTag.