ACL2 is a mathematical logic, programming language, and mechanical theorem prover based on the applicative subset of Common Lisp. It is an "industrial-strength" version of the NQTHM or Boyer/Moore theorem prover, and has been used for the formal verification of commercial microprocessors, the Java Virtual Machine, interesting algorithms, and so forth.
Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.
CACKey provides a standard interface (PKCS#11) for smartcards connected to a PC/SC compliant reader. It performs a similar function to "CoolKey", but only supports Government Smartcards. It supports all Government Smartcards that implement the Government Smartcard Interoperability Specification (GSC-IS) v2.1 or newer.
CAKE (Key Addressed Crypto Encapsulation) is a bunch of Python and C++ for implementing the CAKE protocol. The CAKE protocol is a protocol in which all messages have source and destination addresses that are public keys. This is in the same way that IP packets have a source and destination address that is an IP address.
CDSA stands for Common Data Security Architecture. It provides a security framework that includes cryptographically signed modules to present an abstracted unified API to the application developer to perform cryptographic and security related operations. It also includes hardware support for cryptographic tokens and biometric devices, such as thumbprint scanners. Intel has implemented the CDSA 2 specification and released it as open source.
CIPE (Crypto IP Encapsulation) is an ongoing project to build encrypting IP routers. The protocol used is as lightweight as possible. It is designed for passing encrypted packets between prearranged routers in the form of UDP packets. This is not as flexible as IPSEC but it is enough for the original intended purpose: securely connecting subnets over an insecure transit network.
Charon simplifies reselling Internet access via WiFi access points. It installs onto Linksys, ASUS, and other common WiFi access points and manages automatic price and access negotiation with local wireless customers, charging them via the mikolaj.cx micropayment system. Deposits are accepted via either cash or credit card. It will ultimately provide secure and fraud-resistant access by utilizing cash-like settlement, reputation tracking, and PKI-based non-repudiable contracts, to protect both the end-user and the access provider.