HsOpenSSL is an OpenSSL binding for Haskell. It can generate RSA and DSA keys, read and write PEM files, generate message digests, sign and verify messages, encrypt and decrypt messages.

Please note that this project has started at the time when there were no pure-Haskell implementations of TLS. Now there is tls package (http://hackage.haskell.org/package/tls), which looks pretty saner than HsOpenSSL especially for initialisation and error handlings. So PHO (the initial author of HsOpenSSL) wants to encourage you to use and improve the tls package instead as long as possible. The only problem is that the tls package has not received as much review as OpenSSL from cryptography specialists yet, thus we can't assume it's secure enough.

Features that aren't (yet) supported:

SSL network connection

ssl(3) functionalities aren't fully covered yet. See OpenSSL.Session.

Complete coverage of Low-level API to symmetric ciphers

Only high-level APIs (EVP and BIO) are fully available. But I believe no one will be lost without functions like DES_set_odd_parity.

Low-level API to asymmetric ciphers

Only a high-level API (EVP) is available. But I believe no one will complain about the absence of functions like RSA_public_encrypt.

X.509 v3 extension handling

It should be supported in the future.

Low-level API to message digest functions

Just use EVP instead of something like MD5_Update.

API to PKCS#12 functionality

It should be covered someday.

BIO

BIO isn't needed because we are Haskell hackers. Though HsOpenSSL itself uses BIO internally.

ENGINE cryptographic module

The default implementations work very well, don't they?