https://docbox.etsi.org/workshop/201...oves_Annex.pdf

Soliloquy was a public key scheme based on ideal and lattice cryptography proposed by GCHQ, and it was abandoned after cryptanalysts there developed a quantum attack in polynomial time. Still, it's a good read for those getting into modern cryptography.

Pre-requisites: Some algebraic number theory, primarily the study of cyclotomic fields.