Open Transactions is a solid, easy-to-use, financial crypto and digital cash library, including an API, server, and test client. It features anonymous numbered accounts, untraceable digital cash, triple-signed receipts, basket currencies, and signed XML contracts. It also supports cheques, invoices, payment plans, markets with trades, and other instruments. It uses OpenSSL and Lucre blinded tokens.
Lasso (Liberty Alliance Single Sign On) is an implementation of the Liberty Alliance specifications. These specifications define protocols for federated identities, single sign-on, etc. Lasso supports ID-FF 1.2, SAML 2.0, and parts of ID-WSF. It provides both a C library and bindings for several languages (Python, Java, Perl, PHP 4, and PHP 5).
PyCryptoPlus is a cryptographic module similar to PyCrypto, with which it shares the API. But PyCryptoPlus is written 100% in Python, so its primary interest is educational and scientific; if you want real speed, you're better checking out PyCrypto. It was not completely written from scratch, but integrates other cipher codes when available in Python and under appropriate licenses. It contains, among other things: Block cipher algorithms (Serpent, Blowfish, Twofish, DES, 3DES, AES, Rijndael, and PRESENT); modes of operation (CMAC, ECB, CBC, CTR, and XTS); paddings (bit padding, zeros, PKCS7, PKCS12, ISO 10126, and ANSI X.923); and one-way functions (MD5, SHA1/SHA2, Whirlpool, RipeMD, RadioGatun, HMAC, and PBKDF2).
TnFOX is a modern secure, robust, multithreaded, exception aware, internationalizable, portable GUI toolkit library designed for mission-critical work in C++ and Python, forked from the FOX library. It replicates the Qt API in many places, comes with a full set of Python bindings, and has been designed primarily for Tn, the port of Tornado to FOX.
PyKCS11 is a PKCS#11 wrapper for Python. It lets you access almost all PKCS#11 functions and data types using any PKCS#11 library, such as the various modules supplied by smartcard vendors. It comes with two interfaces: a low level and very thin interface over the original PKCS#11 API, generated using the SWIG compiler (designed for library tests), and a high level interface that offers simpler access (with few limits) to the PKCS#11 APIs.