CSharp-Ascon

Managed C# (CSharp) implementation of Ascon (Ascon-128 and Ascon-128a)

Build status

Nuget

LibAscon128

Why

I needed a weekend project for myself

How to use

Currently the basic API is similar to C based one. There is also a fancy API for easier operations.

Both Ascon-128 (Ascon128v12.cs) and Ascon-128a (Ascon128av12.cs) are standalone files, so you can copy either one of them to your project and just use it.

❗ Do NOT reuse same key + nonce combination. Always change at least the nonce when you create a new encrypted message ❗

C style API example

With Ascon-128 you can do the following

using CSAscon;

// Message that will be encrypted 
byte[] message = System.Text.Encoding.UTF8.GetBytes("This message should be encrypted");

// Associated data
byte[] associatedData = System.Text.Encoding.UTF8.GetBytes("Associated data");

// Nonce (MUST be 16 bytes)
byte[] nonce = new byte[] { 206, 74, 86, 166, 217, 45, 90, 73, 240, 65, 165, 45, 215, 47, 94, 73 };

// Key (MUST be 16 bytes)
byte[] key = new byte[] { 101, 101, 174, 222, 224, 97, 156, 94, 123, 183, 109, 219, 208, 135, 104, 122 };

// Preallocate storage for encrypted data
byte[] encryptedMessage = new byte[message.Length + 16];

// Encrypt
int func_ret = Ascon128v12.crypto_aead_encrypt(encryptedMessage, out int clen, message, message.Length, associatedData, associatedData.Length, null, nonce, key);

// Decrypt
byte[] decryptedMessage = new byte[message.Length];
func_ret = Ascon128v12.crypto_aead_decrypt(decryptedMessage, out mlen2, null, encryptedMessage, clen, associatedData, associatedData.Length, nonce, key);

with Ascon-128a you can do the following

using CSAscon;

// Message that will be encrypted 
byte[] message = System.Text.Encoding.UTF8.GetBytes("This message should be encrypted");

// Associated data
byte[] associatedData = System.Text.Encoding.UTF8.GetBytes("Associated data");

// Nonce (MUST be 16 bytes)
byte[] nonce = new byte[] { 6, 74, 86, 166, 217, 45, 90, 73, 241, 65, 165, 45, 215, 47, 94, 73 };

// Key (MUST be 16 bytes)
byte[] key = new byte[] { 11, 101, 174, 222, 224, 97, 156, 94, 123, 13, 109, 219, 208, 15, 14, 122 };

// Preallocate storage for encrypted data
byte[] encryptedMessage = new byte[message.Length + 16];

// Encrypt
int func_ret = Ascon128av12.crypto_aead_encrypt(encryptedMessage, out int clen, message, message.Length, associatedData, associatedData.Length, null, nonce, key);

// Decrypt
byte[] decryptedMessage = new byte[message.Length];
func_ret = Ascon128av12.crypto_aead_decrypt(decryptedMessage, out mlen2, null, encryptedMessage, clen, associatedData, associatedData.Length, nonce, key);

Fancy API example

With Ascon-128 you can do the following, test it out in .NET Fiddle

using CSAscon;

ReadOnlySpan<byte> message = "This is a very long and boring text for testing purposes 😀 !"u8;
ReadOnlySpan<byte> associatedData = "My associated data"u8;

ReadOnlySpan<byte> nonce = "MY_CAT_IS_NOT_IT"u8;
ReadOnlySpan<byte> key = "DO_NOT_USE_IN_PR"u8; // Use better key in real life

// Encrypt
byte[] encryptedMessage = Ascon128v12.Encrypt(message, associatedData, nonce, key);

// Decrypt
byte[] decryptedMessage = Ascon128v12.Decrypt(encryptedMessage, associatedData, nonce, key);

With Ascon-128a you can do the following

using CSAscon;

ReadOnlySpan<byte> message = "This is a very long and boring text for testing purposes 😀 !"u8;
ReadOnlySpan<byte> associatedData = "My associated data"u8;

ReadOnlySpan<byte> nonce = "MY_CAT_IS_NOT_IT"u8;
ReadOnlySpan<byte> key = "DO_NOT_USE_IN_PR"u8; // Use better key in real life

// Encrypt
byte[] encryptedMessage = Ascon128av12.Encrypt(message, associatedData, nonce, key);

// Decrypt
byte[] decryptedMessage = Ascon128av12.Decrypt(encryptedMessage, associatedData, nonce, key);

Porting story

Code is ported from opt64 version of the C code version. So it operates 8 bytes (64 bits) at time.

Limitations

Only little-endian (LE) systems (x86, x64, ARM etc.) are supported, because there aren't that many big-endian .NET environments.

Benchmarks

You can run benchmarks by moving to benchmarks folder and running following command

dotnet run -c Release

there are four different input sizes (64 bytes, 1024 bytes, 65536 bytes and 1 MiB) and comparisons are done between Ascon-128 and Ascon-128a

Below is one run of the benchmark

BenchmarkDotNet v0.13.10, Windows 11 (10.0.22621.2715/22H2/2022Update/SunValley2)
AMD Ryzen 5 7600, 1 CPU, 12 logical and 6 physical cores
.NET SDK 8.0.100
  [Host]     : .NET 8.0.0 (8.0.23.53103), X64 RyuJIT AVX2
  DefaultJob : .NET 8.0.0 (8.0.23.53103), X64 RyuJIT AVX2

Method	Mean	Error	StdDev	Gen0	Allocated
Encrypt_64bytes_Ascon128	1,025.6 ns	9.76 ns	7.62 ns	0.3452	5.66 KB
Encrypt_64bytes_Ascon128a	809.6 ns	3.04 ns	2.38 ns	0.2699	4.41 KB
Encrypt_1024bytes_Ascon128	9,500.1 ns	22.50 ns	18.79 ns	3.3264	54.41 KB
Encrypt_1024bytes_Ascon128a	6,934.8 ns	41.65 ns	36.92 ns	2.3346	38.16 KB
Encrypt_65536bytes_Ascon128	589,978.5 ns	6,926.59 ns	6,140.25 ns	203.1250	3330.41 KB
Encrypt_65536bytes_Ascon128a	414,536.1 ns	698.43 ns	545.29 ns	141.1133	2306.16 KB
Encrypt_1048576bytes_Ascon128	9,306,042.2 ns	59,106.82 ns	49,356.87 ns	3250.0000	53250.42 KB
Encrypt_1048576bytes_Ascon128a	6,665,449.5 ns	10,829.38 ns	9,043.03 ns	2250.0000	36866.17 KB

License

CC0 1.0 Universal because original C implementation uses that license

Original genkat uses NIST license, so tests in this project are modified from it.

The tests vector files (LWC_AEAD_KAT_128_128.txt and LWC_AEAD_KAT_128_128_a.txt) are also generated with genkat tool.