NaCl (pronounced "salt") is a new, easy to use high-speed software library for network communication, encryption, decryption, signatures, etc. It uses elliptic curve cryptography. libsodium is a portable fork of NaCl. Crypto-Nacl is a Pharo/Squeak interface to libsodium. It uses FFI. As is, the library should be named liblibsodium.dylib when used with Crypto-Nacl on OSX.

SqueakSSL is a plugin to the platform-native SSL/TLS facility. The plugin is bundled with the Cog VM. Zodiac is an open source, cross-Smalltalk implementation of regular and secure socket streams. Zodiac uses SqueakSSL. Webclient also uses SqueakSSL to support HTTPS.

The Cryptography package has been around for a while. It now lives on SmalltalkHub. It has plugins for DES, DSA, MD5 and SHA256. At this time, this package doesn't look viable for real-world use.