Encryption.Blowfish

Efficient implementation of Blowfish cipher with minimal memory allocations in ECB, CBC and CTR block modes.
CTR is also available as encryption and decryption stream.
Non-stream variants work by mutating input buffer (Span<byte>).

Implemented using defaults, 16-round with pre-computed subkeys.
Tested against well-known test vectors.

Quickstart

nuget package Encryption.Blowfish

dotnet add package Encryption.Blowfish [ -v 2.0.0 ]

Buffer

using Encryption.Blowfish; using System.Security.Cryptography; var key = "a3bd614b27864e3f854b971f9df1a802"; // cipher key var iv = RandomNumberGenerator.GetBytes(8); // IV byte[] buf = ...; // data you want to encrypt buf = buf.CopyAndPadIfNotAlreadyPadded(); var cbc = new BlowfishCbc(key); var ok = cbc.Encrypt(buf, iv); ok = cbc.Decrypt(buf, iv);

Stream

using Encryption.Blowfish; using System.Security.Cryptography; var codec = new Codec(Convert.FromHexString("df83d31539c244d298ce302036f91edd")); var iv = RandomNumberGenerator.GetBytes(8); // encrypt using var encrypted = new MemoryStream(); using (var bfe = new BlowfishCtrEncryptStream(encrypted, codec, iv)) { bfe.Write(...); bfe.Write(...); // ... } // It is important to dispose or Close the stream as soon as the writing is finished. enc.Position = 0; // decrypt using var decrypted = new MemoryStream(); using var bfd = new BlowfishCtrDecryptStream(encrypted, codec, iv); bfd.CopyTo(decrypted);

Available types

type	mode	usage	works on	thread-safe
BlowfishEcb	ECB	Only when forced to. Lack of diffusion. Require padded original data.	buffer	yes
BlowfishCbc	CBC	Recommended. Require padded original data.	buffer	yes
BlowfishCtr	CTR	Recommended. Works without padding.	buffer	yes
ParallelBlowfishEcb	EBC	Only when forced to. Parallel computation from certain data size. Require padded original data.	buffer	yes
ParallelBlowfishCtr	CTR	Recommended. Parallel computation from certain data size. Works without padding.	buffer	yes
BlowfishCtrEncryptStream	CTR	Only when you need stream-sematics; otherwise you are better off with input buffer variants.	stream	no
BlowfishCtrDecryptStream	CTR	dtto	stream	no