I have forked pem as crypton-pem. Kazu Yamamoto has kindly agreed to be a co-maintainer. For people who have not seen my recent and similar posts, Kazu stepped up to maintain the crypton* (and other) packages after cryptonite* became unmaintained. pem is not a cryptographic package but the crypton-* prefix is intended to signal that it is part of a family of maintained equivalents.
The sole maintainer of pem is Vincent Hanquez who, for his reasons published elsewhere, does not wish to further develop his packages or introduce new maintainers.
crypton-pem-0.2.4 is a carbon copy of pem-0.2.4. crypton-pem-0.2.5 (EDIT: now released) will then bring things up to date. My medium term plan includes to eliminate dependency on the unmaintained basement package (EDIT: done in crypton-pem-0.3.0, now released).
EDIT: crypton-pem-0.3.0 is included in Stackage snapshot nightly-2025-07-12.