Stunnel

Stunnel acts as an SSL encryption layer for network services, allowing protocols like POP3, IMAP, and HTTP to gain SSL capabilities without changes. Based on OpenSSL, it supports all its cryptographic features and can meet FIPS 140-2 standards when built accordingly. Available on all major platforms, it provides a simple way to secure communications, with the Windows installer including pre-validated OpenSSL FIPS Provider for assured security in sensitive environments.