Canonical Msgpack

Algorand uses a version of MsgPack to produce canonical encodings of data.

Algorand’s msgpack encodings are valid msgpack encodings, but the encoding function is deterministic to ensure a canonical representation that can be reproduced to verify signatures.

A canonical msgpack encoding in Algorand must follow these rules:

1. Maps MUST contain keys in lexicographic order;

2. Maps MUST omit key-value pairs where the value is a zero-value, unless otherwise specified;

3. Positive integer values MUST be encoded as unsigned in msgpack, regardless of whether the value space is semantically signed or unsigned;

4. Integer values MUST be represented in the shortest possible encoding;

5. Binary arrays MUST be represented using the bin format family (that is, use the most recent version of msgpack rather than the older msgpack version that had no bin family).