To aid in the implementation of Biscuit tokens in various languages, this repository contains an example implementation of its cryptographic algorithms using libsodium.
Biscuit uses Aggregated Gamma Signatures ("Aggregation of Gamma-Signatures and Applications to Bitcoin, Yunlei Zhao") for its attenuation scheme, and this algorithm is implemented over the Ristretto group ("Ristretto: prime order elliptic curve groups with non-malleable encodings"), of which libsodium proposes an implementation.
The libsodium implementation is available in src/sodium.rs.