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.
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.
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.
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).
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 numBytesWritten));
buffer = buffer[..numBytesWritten]; // 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 numBytesWritten));
buffer = buffer[..numBytesWritten]; // 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 = new byte[] { 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 numBytesWritten))
{
// 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.
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.
