The pkcs11key package implements a crypto.Signer interface for a PKCS#11 private key.
If you are using Go modules, you should import this with the module-compatible path github.com/letsencrypt/pkcs11key/v4
Some of this code is Copyright (c) 2014 CloudFlare Inc., some is Copyright (c) 2015 Internet Security Research Group.
The code is licensed under the BSD 2-clause license. See the LICENSE file for more details.