Table of Contents

Class Sm4

Namespace
CryptoHives.Foundation.Security.Cryptography.Cipher
Assembly
CryptoHives.Foundation.Security.Cryptography.dll

SM4 symmetric cipher implementation (GB/T 32907-2016).

public sealed class Sm4 : SymmetricCipher, IDisposable
Inheritance
Sm4
Implements
Inherited Members

Remarks

SM4 is a 128-bit block cipher with a 128-bit key, standardized by the Chinese national standard GB/T 32907-2016. It uses 32 rounds of a Feistel-like nonlinear transformation.

Security level: 128 bits (quantum: 64 bits with Grover's algorithm)

Example usage: 

using var sm4 = Sm4.Create();
sm4.GenerateKey();
sm4.GenerateIV();

byte[] ciphertext = sm4.Encrypt(plaintext);
byte[] decrypted = sm4.Decrypt(ciphertext);

Fields

KeySizeBits

Key size in bits for SM4.

public const int KeySizeBits = 128

Field Value

int

KeySizeBytes

Key size in bytes for SM4.

public const int KeySizeBytes = 16

Field Value

int

Properties

AlgorithmName

Gets the name of the cipher algorithm.

public override string AlgorithmName { get; }

Property Value

string

Examples

"AES-256", "ChaCha20", "AES-256-GCM"

IVSize

Gets the required IV/nonce size in bytes for the current mode.

public override int IVSize { get; }

Property Value

int

Methods

Create()

Creates a new instance of the Sm4 cipher.

public static Sm4 Create()

Returns

Sm4

A new SM4 cipher instance.

CreateCipherDecryptor(ReadOnlySpan<byte>, ReadOnlySpan<byte>)

Creates a decryptor transform using the specified key and IV.

protected override ICipherTransform CreateCipherDecryptor(ReadOnlySpan<byte> key, ReadOnlySpan<byte> iv)

Parameters

key ReadOnlySpan<byte>

The secret key.

iv ReadOnlySpan<byte>

The initialization vector or nonce.

Returns

ICipherTransform

A new cipher decryptor transform.

CreateCipherEncryptor(ReadOnlySpan<byte>, ReadOnlySpan<byte>)

Creates an encryptor transform using the specified key and IV.

protected override ICipherTransform CreateCipherEncryptor(ReadOnlySpan<byte> key, ReadOnlySpan<byte> iv)

Parameters

key ReadOnlySpan<byte>

The secret key.

iv ReadOnlySpan<byte>

The initialization vector or nonce.

Returns

ICipherTransform

A new cipher encryptor transform.

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