Table of Contents

Threefish512 Class

Definition

Namespace
Bodu.Security.Cryptography
Assembly
Bodu.Security.Cryptography.dll
Package
Bodu.Security.Cryptography 1.2.0
Source
Threefish.512.cs

Provides a managed implementation of the Threefish-512 tweakable symmetric block cipher, which operates on 512-bit (64-byte) blocks using a 512-bit key and a 128-bit tweak. This class cannot be inherited.

public sealed class Threefish512 : Threefish, IDisposable
Inheritance
Threefish512
Implements
Inherited Members
Extension Methods

Examples

using System.Security.Cryptography;
using Bodu.Security.Cryptography;
using Bodu.Security.Cryptography.Extensions;

using var tf = Threefish512.Create();
tf.Key = RandomNumberGenerator.GetBytes(64); // 512-bit key
tf.IV = RandomNumberGenerator.GetBytes(64); // matches the 512-bit block
tf.Tweak = RandomNumberGenerator.GetBytes(16); // 128-bit tweak
byte[] ciphertext = tf.Encrypt(plaintext);
byte[] roundTrip = tf.Decrypt(ciphertext);

Remarks

Threefish is the tweakable block cipher underlying the Skein hash function. This variant supports a variety of cipher block modes (CBC, CFB, OFB, CTR) via the BlockMode property, and is suitable for scenarios such as disk encryption or format-preserving encryption where a tweak is useful.

For other block sizes, see Threefish256 and Threefish1024.

Parameters at a glance.

  • Block size: 512 bits (64 bytes).
  • Key size: 512 bits (64 bytes).
  • Tweak size: 128 bits (16 bytes).
  • Default mode: CBC; default padding: PKCS7.

When to choose Threefish-512. The most common Threefish width - the wider 512-bit block lifts the birthday bound to ~2256 blocks, removing the SWEET32-style concerns that 64-bit and 128-bit block ciphers run into when re-used heavily under one key. A natural fit when building Skein-style constructions (Skein-512 wraps this engine under the UBI mode). Use Threefish256 when the smaller block matches the surrounding scheme; use Threefish1024 when even more block width is required.

Constructors

Threefish512()

Initializes a new instance of the Threefish512 class using a 512-bit block size, 512-bit key, and 128-bit tweak.

public Threefish512()

Methods

Create()

Creates a new Threefish512 instance with default parameters.

public static Threefish512 Create()

Returns

Threefish512

A new Threefish512 instance.

Remarks

The key, initialization vector, and tweak are generated on demand the first time they are accessed unless assigned explicitly via Key, IV, or Tweak.

CreateCipher(byte[], byte[])

Instantiates the concrete Threefish block cipher with the specified key and tweak.

protected override ThreefishBlockCipher CreateCipher(byte[] key, byte[] tweak)

Parameters

key byte[]

The encryption key.

tweak byte[]

The tweak value.

Returns

ThreefishBlockCipher

A configured IBlockCipher instance for encryption or decryption.

Exceptions

ArgumentNullException

Thrown when key is null.

CryptographicException

Thrown when the underlying cryptographic algorithm fails.

Applies to

ProductVersions
.NET8, 10

See Also

Using Threefish-512 (guide with full encrypt / decrypt examples)
Encryption basics
Cipher block modes
Padding
Threefish
Threefish256
Threefish1024
Threefish512Cipher
Skein512