Z85

This is a C# implementation of the Z85 specification found at: https://rfc.zeromq.org/spec:32/Z85/

Why use Z85?

Z85 is a derivative of existing Ascii85 encoding mechanisms, modified for better usability, particularly for use in source code.

The Z85 encoded string is string-safe, so can be used cleanly in source code, XML, JSON, and so on. This is achieved because the character set does not include the single quote, double quote, or backslash characters.

The benefits of Base85 over Base64

Base85 uses 5 ASCII characters to represent 4 bytes of binary data, whereas Base64 uses 4 ASCII characters to represent 3 bytes of binary data.

This makes Base85 only 25% larger than the original data as compared to Base64 being 33% larger.

Getting Started

Installation via NuGet

Using NuGet search for Cromulent.Encoding.Z85 or run the following command in the Package Manager Console:

PM> Install-Package Cromulent.Encoding.Z85

Usage

By default the ToZ85String() method matches the formal Z85 specification and the input binary frame must be divisible by 4, otherwise it will throw an ArgumentException. This ensures that it is interoperable with other implementations of the formal Z85 specification.

ToZ85String() takes an optional parameter autoPad which when set to true will pad the input bytes if required and append a padding character to the end of the output string. Use of autoPad is not interoperable with other implementations of Z85.

Encoding (without padding)

var bytes = new byte[] { 0x86, 0x4F, 0xD2, 0x6F, 0xB5, 0x59, 0xF7, 0x5B };
var output = Z85.ToZ85String(bytes);
// output == "HelloWorld"

Decoding

var encodedString = "HelloWorld";
var output = Z85.FromZ85String(encodedString);
// output == [0x86, 0x4F, 0xD2, 0x6F, 0xB5, 0x59, 0xF7, 0x5B]

Encoding (with padding)

var input = "HelloWorld"; // 10 bytes - NOT divisible by 4 with no remainder
var inputBytes = System.Text.Encoding.Default.GetBytes(input);
var output = Z85.ToZ85String(inputBytes, autoPad: true);
// output == "nm=QNz=Z<$y?9IC2"

License

This project is licensed under the MIT License - see the LICENSE file for details