John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types commonly found on Unix systems, as well as Windows LM hashes. On top of this, lots of other hashes and ciphers are added in the community-enhanced version (-jumbo), and some are added in John the Ripper Pro.
GnuTLS is a secure communications library implementing the SSL, TLS, and DTLS protocols and technologies around them. It provides a simple C language application programming interface (API) to access the secure communications protocols, as well as APIs to parse and write X.509, PKCS #12, OpenPGP, and other required structures. It is intended to be portable and efficient with a focus on security and interoperability.
libdvdcss is a cross-platform library for transparent DVD device access with on-the-fly CSS decryption. It currently runs under Linux, FreeBSD, NetBSD, OpenBSD, BSD/OS, Solaris, BeOS, Win95/Win98, Win2k/WinXP, MacOS X, HP-UX, QNX, and OS/2. It is used by libdvdread and most DVD players such as VLC because of its portability and because, unlike similar libraries, it does not require your DVD drive to be region locked.
GNUnet is a peer-to-peer framework with focus on providing security. All peer-to-peer messages in the network are confidential and authenticated. The framework provides a transport abstraction layer and can currently encapsulate the network traffic in UDP, TCP, HTTP, HTTPS, or direct 802.11 (WLAN). GNUnet supports accounting to provide contributing nodes with better service. The services built on top of the framework include anonymous file sharing and a virtual network providing IPv4-IPv6 transition via protocol translation over the P2P network.
The Mandos system allows computers to have encrypted root file systems and at the same time be capable of remote or unattended reboots. The computers run a small client program in the initial RAM disk environment which will communicate with a server over a network. All network communication is encrypted using TLS. The clients are identified by the server using an OpenPGP key that is unique to each client. The server sends the clients an encrypted password. The encrypted password is decrypted by the clients using the same OpenPGP key, and the password is then used to unlock the root file system.
The stunnel program is designed to work as an SSL encryption wrapper between remote client and local (inetd-startable) or remote server. It can be used to add SSL functionality to commonly used inetd daemons like POP2, POP3, and IMAP servers without any changes in the programs' code. It will negotiate an SSL connection using the OpenSSL or SSLeay libraries. It calls the underlying crypto libraries, so stunnel supports whatever cryptographic algorithms you compiled into your crypto package.
The CyaSSL embedded SSL library is a lightweight SSL library written in ANSI C and targeted for embedded and RTOS environments, primarily because of its small size, speed, and feature set. It is commonly used in standard operating environments and cloud services as well because of its royalty-free pricing and excellent cross platform support. CyaSSL supports industry standards up to the current TLS 1.2 and DTLS 1.2 levels, is up to 20 times smaller than OpenSSL, and offers progressive ciphers such as HC-128, RABBIT, and NTRU.
MatrixSSL is an embedded SSL and TLS implementation designed for small footprint devices and applications requiring low overhead per connection. The library is less than 50Kb on disk with cipher suites. It includes client and server support through TLS 1.2, mutual authentication, session resumption, and implementations of RSA, ECC, AES, 3DES, ARC4, SHA2, SHA1, and MD5. The source is well documented and contains portability layers for additional operating systems, cipher suites, and cryptography providers.
ipt_pkd is an iptables extension implementing port knock detection with SPA (single packet authorization). This project provides 3 parts: the kernel module ipt_pkd, the iptables user space module libipt_pkd.so, and a user space client knock program. For the knock packet, it uses a UDP packet sent to a random port that contains a SHA-256 of a timestamp, small header, random bytes, and a shared key. ipt_pkd checks the time window of the packet and does the SHA-256 to verify the packet. The shared key is never sent.
cryptmount is a utility for creating and managing secure filing systems on GNU/Linux systems. After initial setup, it allows any user to mount or unmount filesystems on demand, solely by providing the decryption password, with any system devices needed to access the filing system being configured automatically. A wide variety of encryption schemes (provided by the kernel dm-crypt system and the libgcrypt library) can be used to protect both the filesystem and the access key. The protected filing systems can reside in either ordinary files or disk partitions. The package also supports encrypted swap partitions, and automatic configuration on system boot-up.