CECID (The CEnsorship CIrcumvention Device) is a PHP script designed to anonymize and filter HTTP requests, especially for users behind restrictive firewalls (e.g. workplaces, schools, etc.). It remotely loads a page that a user specifies, and filters it for words on its 'weighted phrase list', a list of words commonly blocked by network administrators. It alters these words to avoid detection, and displays the page requested. It can also be used for anonymizing HTTP requests, for situations where cloaking and security are required.
CERTivity is a powerful multi-platform visual tool for creating, managing, and handling different key store types (such as JKS, JCEKS, PKCS12, the Bouncy Castle types BKS and UBER, and Windows Native), public, private and secret keys in different formats (PKCS, OpenSSL, RSA/DSA, etc.), certificates (version 1 and 3), and certificates chains. It allows you to import and export keys, key pairs and certificates, manage certificate extensions, extend the validity period for self-signed certificates, test certificates, obtain revocation status, convert from one key store type to another, and much more.
chownat allows two peers behind two separate NATs and firewalls to establish a direct connection with each other. No port forwarding, DMZ, third party, proxy, spoofing, elevated user privileges, or DNS tricks are required. More importantly, it opens up a tunnel between the two machines so one peer can access a service, such as SSH or a Web server, on the other machine which is also behind a NAT.
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.
CIRCLean aims to be used by someone receiving a USB key from an untrusted source who wants to see the content without opening the original and potentially malicious files. The code runs on a Raspberry Pi, which means it is never required to plug the original USB key into a computer.
CLNoFault is a tool to protect your files or plain text. Using XOR encryption, it can quickly encrypt data using either a username and a password of your choice, or an external file that will serve as a key. Encrypted files can't be recovered in any way besides re-encrypting them with CLNoFault with the correct user/pass combination or keyfile. CLNoFault is the console-based interface for the NoFault library (like KNoFault for KDE), so it is useful in scripts.
CODEX (the Cornell Data Exchange) is a key distribution system. It is designed for applications with a moderate number of clients (tens or hundreds) requesting keys that change often but not continuously (on the scale of minutes to hours). It employs the RSA and ElGamal encryption schemes, as well as techniques such as threshold cryptography and proactive secret sharing.