The getaca package as a whole is distributed under the MIT licence recorded in
the LICENSE file, with the following exception.

src/ed25519.c
-------------

The Curve25519 field arithmetic, the extended-coordinate point addition, the
Montgomery ladder and the scalar reduction modulo the group order are derived
from TweetNaCl version 20140427, by Daniel J. Bernstein, Bernard van Gastel,
Wesley Janssen, Tanja Lange, Peter Schwabe and Sjaak Smetsers.

TweetNaCl is released into the public domain by its authors. See
https://tweetnacl.cr.yp.to/.

The derived work adds detached signature entry points, a canonicality check on
the scalar half of a signature, streaming message input, and an operating
system random source, and is distributed under the licence of the package.