SimpleBase

This is my own take for exotic base encodings like Base32, Base58 and Base85. I started to write it in 2013 as coding practice and kept it as a small pet project. I suggest anyone who wants to brush up their coding skills to give those encoding problems a shot. They turned out to be more challenging than I expected. To grasp the algorithms I had to get a pen and paper to see how the math worked.

Features

• Base32: RFC 4648, BECH32, Crockford, z-base-32, Geohash, FileCoin and Extended Hex (BASE32-HEX) flavors with Crockford character substitution, or any other custom flavors.
• Base45: The standard Base45 encoding/decoding in RFC 9285 is supported.
• Base58: Both the standard encoding (Bitcoin (BTC), Ripple (XRP), Flickr, and custom alphabets) and Monero (XMR) Base58 algorithms are supported. Also provides Base58Check and Avalanche CB58 encoding helpers.
• Base62: The standard Base62 encoding/decoding supported along with a custom alphabet.
• Base85: Ascii85, Z85 and custom flavors. IPv6 encoding/decoding support.
• Base16: UpperCase, LowerCase and ModHex flavors. An experimental hexadecimal encoder/decoder just to see how far I can take the optimizations compared to .NET's implementations. It's quite fast now. It could also be used as a replacement for SoapHexBinary.Parse although .NET has Convert.FromHexString() method since .NET 5.
• Multibase support. All formats covered by SimpleBase including a few Base64 variants are supported.
• One-shot memory buffer based APIs for simple use cases.
• Stream-based async APIs for more advanced scenarios.
• Lightweight: No dependencies.
• Support for big-endian CPUs like IBM s390x (zArchitecture).
• Thread-safe.
• Simple to use.

NuGet

To install it from NuGet:

Install-Package SimpleBase

Usage

Base32

Encode a byte array:

using SimpleBase;

byte[] myBuffer;
string result = Base32.Crockford.Encode(myBuffer, padding: true);
// you can also use "ExtendedHex" or "Rfc4648" as encoder flavors

Decode a Base32-encoded string:

using SimpleBase;

string myText = ...
byte[] result = Base32.Crockford.Decode(myText);

Base58

Encode a byte array:

byte[] myBuffer = ...
string result = Base58.Bitcoin.Encode(myBuffer);
// you can also use "Ripple" or "Flickr" as encoder flavors

Decode a Base58-encoded string:

string myText = ...
byte[] result = Base58.Bitcoin.Decode(myText);

Encode a Base58Check address:

byte[] address = ...
byte version = 1; // P2PKH address
string result = Base58.Bitcoin.EncodeCheck(address, version);

Decode a Base58Check address:

string address = ...
Span<byte> buffer = new byte[maxAddressLength];
if (Base58.Bitcoin.TryDecodeCheck(address, buffer, out byte version, out int bytesWritten));
buffer = buffer[..bytesWritten]; // use only the written portion of the buffer

Avalanche CB58 usage is pretty much the same except it doesn't have a separate version field. Just use EncodeCb58 and TryDecodeCb58 methods instead. For encoding:

byte[] address = ...
byte version = 1;
string result = Base58.Bitcoin.EncodeCb58(address);

For decoding:

string address = ...
Span<byte> buffer = new byte[maxAddressLength];
if (Base58.Bitcoin.TryDecodeCb58(address, buffer, out int bytesWritten));
buffer = buffer[..bytesWritten]; // use only the written portion of the buffer

Base85

Encode a byte array to Ascii85 string:

byte[] myBuffer = ...
string result = Base85.Ascii85.Encode(myBuffer);
// you can also use Z85 as a flavor

Decode an encoded Ascii85 string:

string encodedString = ...
byte[] result = Base85.Ascii85.Decode(encodedString);

Both "zero" and "space" shortcuts are supported for Ascii85. Z85 is still vanilla.

Base16

Encode a byte array to hex string:

byte[] myBuffer = ...
string result = Base16.EncodeUpper(myBuffer); // encode to uppercase
// or 
string result = Base16.EncodeLower(myBuffer); // encode to lowercase

To decode a valid hex string:

string text = ...
byte[] result = Base16.Decode(text); // decodes both upper and lowercase

Stream Mode

Most encoding classes also support a stream mode that can work on streams, be it a network connection, a file or whatever you want. They are ideal for handling arbitrarily large data as they don't consume memory other than a small buffer when encoding or decoding. Their syntaxes are mostly identical. Text encoding decoding is done through a TextReader/TextWriter and the rest is read through a Stream interface. Here is a simple code that encodes a file to another file using Base85 encoding:

using (var input = File.Open("somefile.bin"))
using (var output = File.Create("somefile.ascii85"))
using (var writer = new TextWriter(output)) // you can specify encoding here
{
  Base85.Ascii85.Encode(input, writer);
}

Decode works similarly. Here is a Base32 file decoder:

using (var input = File.Open("somefile.b32"))
using (var output = File.Create("somefile.bin"))
using (var reader = new TextReader(input)) // specify encoding here
{
	Base32.Crockford.Decode(reader, output);
}

Asynchronous Stream Mode

You can also encode/decode streams in asynchronous fashion:

using (var input = File.Open("somefile.bin"))
using (var output = File.Create("somefile.ascii85"))
using (var writer = new TextWriter(output)) // you can specify encoding here
{
  await Base85.Ascii85.EncodeAsync(input, writer);
}

And the decode:

using (var input = File.Open("somefile.b32"))
using (var output = File.Create("somefile.bin"))
using (var reader = new TextReader(input)) // specify encoding here
{
	await Base32.Crockford.DecodeAsync(reader, output);
}

TryEncode/TryDecode

If you want to use an existing pre-allocated buffer to encode or decode without causing a GC allocation every time, you can make use of TryEncode/TryDecode methods which receive input, output buffers as parameters.

Encoding is like this:

byte[] input = [1, 2, 3, 4, 5];
int outputBufferSize = Base58.Bitcoin.GetSafeCharCountForEncoding(input);
var output = new char[outputBufferSize];

if (Base58.Bitcoin.TryEncode(input, output, out int numCharsWritten))
{
   // there you go
}

and decoding:

string input = "... some bitcoin address ...";
int outputBufferSize = Base58.Bitcoin.GetSafeByteCountForDecoding(output);
var output = new byte[outputBufferSize];

if (Base58.Bitcoin.TryDecode(input, output, out int bytesWritten))
{
    // et voila!
}

Multibase encoding/decoding

In order to encode a Multibase string just specify the encoding you want to use:

byte[] input = [1, 2, 3, 4, 5];
string result = Multibase.Encode(input, MultibaseEncoding.Base32);

When decoding a multibase string, the encoding is automatically detected:

string input = "... some encoded multibase string ...";
byte[] result = Multibase.Decode(input);

If you don't want decoding to raise an exception, use TryDecode() method instead:

string input = "... some encoded multibase string ...";
byte[] output = new byte[outputBufferSize]; // enough the fit the decoded buffer
if (Multibase.TryDecode(input, output, out int bytesWritten))
{
    // et voila!
}

Benchmark Results

Small buffer sizes are used (64 characters). They are closer to real life applications. Base58 performs really bad in decoding of larger buffer sizes, due to polynomial complexity of numeric base conversions.

BenchmarkDotNet v0.14.0, Windows 11 (10.0.26100.3915) AMD Ryzen 9 5950X, 1 CPU, 32 logical and 16 physical cores .NET SDK 9.0.203 [Host] : .NET 8.0.15 (8.0.1525.16413), X64 RyuJIT AVX2 DefaultJob : .NET 8.0.15 (8.0.1525.16413), X64 RyuJIT AVX2

Encoding (64 byte buffer)

Decoding (80 character string, except Base45 which must use an 81 character string)

Notes

I'm sure there are areas for improvement. I didn't want to go further in optimizations which would hurt readability and extensibility. I might experiment on them in the future.

Test suite for Base32 isn't complete, I took most of it from RFC4648. Base58 really lacks a good spec or test vectors needed. I had to resort to using online converters to generate preliminary test vectors.

Base85 tests are also makseshift tests based on what output Cryptii produces. Contribution to missing test cases are greatly appreciated.

It's interesting that I wasn't able to reach .NET Base64's performance with Base16 with a straightforward managed code despite that it's much simpler. I was only able to match it after I converted Base16 to unsafe code with good independent interleaving so CPU pipeline optimizations could take place. Still not satisfied though. Is .NET's Base64 implementation native? Perhaps.

Thanks

Thanks to all contributors (most up to date is on the GitHub sidebar) who provided patches, and reported bugs.

Chatting about this pet project with my friends @detaybey, @vhallac, @alkimake and @Utopians at one of our friend's birthday encouraged me to finish this. Thanks guys.