A rust implementation of the varsig "spec".
This implementation fully supports the varsig spec linked above but it also supports a propsed version 2 of the specification that gives more data to tools even when they don't recognize the key codec. The two versions are detailed below. The main difference is the location of the encoding codec.
Varsig version 2 uses a new codec sigil 0x39 instead of the original 0x34
to distinguish the two formats.
payload encoding
key codec codec
| |
v v
0x34 <varuint> N(<varuint>) <varuint> N(OCTET)
^ ^ ^
| | |
varsig variable number of variable number
v1 sigil signature specific of signature data
values octets
The v1 format unfortunately has a variable number of signature-specific values immediately following the key codec and before the encoding codec. This makes it impossible for a tool to decode the encoding codec when it doesn't recognize the key codec. It is forced to treat everything after the key codec as unparsable data.
variable number of
count of signature specific count of
key codec attributes attributes signature octets
| \ | /
v v v v
0x39 <varuint> <varuint> <varuint> N(<varuint>) <varuint> N(OCTET)
^ ^ ^
| | |
varsig payload encoding variable number
v2 sigil codec of signature octets
The v2 format allows tools that don't recognize the key codec to at least parse the encoding codec for the signed data as well as hold all of the signature- specific information together as the remainder that couldn't be parsed. This is cleaner than the v1 format.