The Multibase Data Format

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Table of Contents

1. Introduction

This specification describes a forward-compatible data model for expressing raw binary data in a variety of base-encoding formats such as base32, base58. and base64.¶

When text is encoded as bytes, we can usually use a one-size-fits-all encoding (UTF-8) because we're always encoding to the same set of 256 bytes. When that doesn't work, usually for historical or performance reasons, we can usually infer the encoding from the context.¶

However, when bytes are encoded as text (using a base encoding), the choice of base encoding is often restricted by the context. Worse, these restrictions can change based on where the data appears in the text. In some cases, we can only use [a-z0-9]. In others, we can use a larger set of characters but need a compact encoding. This has lead to a large set of "base encodings", one for every use-case. Unlike when encoding text to bytes, we can't just standardize around a single base encoding because there is no optimal encoding for all cases.¶

Unfortunately, it's not always clear what base encoding is used; that's where this specification comes in. It answers the question:¶

Given data 'd' encoded into text 's', what base is it encoded with?¶

2. The Multibase Format

A multibase-encoded value follows a simple format:¶

base-encoding-character base-encoded-data

The encoding algorithm is a single character value that is always the first byte of the data. The possible values for this field are provided in The Multibase Algorithm Registry.¶

z2NEpo7TZRRrLZSi2U

Appendix A. Security Considerations

There are a number of security considerations to take into account when implementing or utilizing this specification. TBD¶

Appendix B. Test Values

The multibase examples are chosen to show different encoding algorithms and different output lengths at play. The input test data for all of the examples in this section is:¶

Multibase is awesome! \o/

F4D756C74696261736520697320617765736F6D6521205C6F2F

BJV2WY5DJMJQXGZJANFZSAYLXMVZW63LFEEQFY3ZP

zYAjKoNbau5KiqmHPmSxYCvn66dA1vLmwbt

MTXVsdGliYXNlIGlzIGF3ZXNvbWUhIFxvLw==

Appendix C. Acknowledgements

The editors would like to thank the following individuals for feedback on and implementations of the specification (in alphabetical order):¶

Appendix D. IANA Considerations

Authors' Addresses