Self-contained write-ups of the pairing-based cryptography used inside Fedimint. Each page derives the scheme directly from its implementing crate, in the language of linear algebra over the BLS12-381 pairing groups.
fedimint-tbs — the blind BLS signature behind Chaumian e-cash. The
federation blindly signs a note so no guardian learns which note it signed, and any
holder verifies it against one aggregate public key. Covers blinding, the pairing
verification, and the $t$-of-$n$ threshold construction.
fedimint-tpe — committed Diffie–Hellman encryption of a Lightning preimage
to the federation. Covers the ephemeral-key encryption, the embedded BLS signature that
binds the ciphertext to a contract commitment, and threshold decryption via
Lagrange-in-the-exponent.
fedimint-server — the dealer-free Pedersen DKG ceremony that sets up a
federation's threshold keys at creation time, producing exactly the Shamir-shared key
the two schemes above assume. Covers the Feldman commitments, the hash-commit and
share-verification rounds, and what the ceremony outputs.