ISA-L is a collection of optimized low-level functions targeting storage applications. ISA-L includes:
   Erasure codes - Fast block Reed-Solomon type erasure codes for any encode/decode matrix in GF(2^8).
   CRC - Fast implementations of cyclic redundancy check. Six different polynomials supported.
       iscsi32, ieee32, t10dif, ecma64, iso64, jones64.
   Raid - calculate and operate on XOR and P+Q parity found in common RAID implementations.
   Compression - Fast deflate-compatible data compression.
   De-compression - Fast inflate-compatible data compression.
BSD 3-Clause "New" or "Revised" License.
According to https://github.com/catid/cm256, ISA-L uses a O(N^3) Gaussian elimination solver for decoding. The CM256 decoder solves the linear system using a fast O(N^2) LDU-decomposition algorithm from "Pivoting and Backward Stability of Fast Algorithms for Solving Cauchy Linear Equations" (T. Boros, T. Kailath, V. Olshevsky), which was hand-optimized for memory accesses.
See also https://github.com/catid/leopard for a fast O(N log(N)) RS erasure decoder.

This package provides a library and a command-line tool named wormhole, which makes it possible to get arbitrary-sized files and directories (or short pieces of text) from one computer to another. The two endpoints are identified by using identical “wormhole codes”: in general, the sending machine generates and displays the code, which must then be typed into the receiving machine.

The codes are short and human-pronounceable, using a phonetically-distinct wordlist. The receiving side offers tab-completion on the codewords, so usually only a few characters must be typed. Wormhole codes are single-use and do not need to be memorized.

Here's a list of protocols and software that use or support the superfast, super secure Ed25519 public-key signature system from Daniel J. Bernstein, Niels Duif, Tanja Lange, Peter Schwabe, and Bo-Yin Yang.

Encrypted, deduplicated backup tool, runs on Linux, *BSD, OS X and Windows.

These steps describe a full disk (including /boot) encrypted setup on a non coreboot enabled system using the great grml live distro.

Sequoia is a cool new OpenPGP implementation.  It consists of several
crates, providing both a low-level and a high-level API for dealing
with OpenPGP data.
It is written in Rust

NeoPG is a modern replacement for GnuPG 2
NeoPG starts as an opinonated fork of GnuPG 2 to clean up the code and make it easier to develop.
We want to provide a stable and extensible API for application developers, too.
Eventually, we will add new ways to use OpenPGP that make it accessible and usable.

Abstract.
ElsieFour (LC4) is a low-tech cipher that can be computed by hand;
but unlike many historical ciphers, LC4 is designed to be hard to break. LC4 is intended for encrypted communication between humans only, and therefore it encrypts and decrypts plaintexts and ciphertexts consisting only of the English letters A through Z plus a few other characters. LC4 uses a nonce in addition to the secret key, and requires that different messages use unique nonces. LC4 performs authenticated encryption, and optional header data can be included in the authentication. This paper defines the LC4 encryption and decryption algorithms, analyzes LC4’s security, and describes a simple appliance for computing LC4 by hand.

An extended version called LS47 can be found on https://github.com/exaexa/ls47, which includes a 3D-printable model of the tiles.

Monocypher is an easy to use crypto library inspired by libsodium and TweetNaCl.

Cryptocat is free software with a simple mission: everyone should be able to chat with their friends in privacy.

   Open source. All Cryptocat software is published transparently.
   Encrypted by default. Every message is encrypted, always.
   Forward secure. Chats are safe even if your keys are stolen.
   Multiple devices. Devices receive messages even when offline.
   File sharing. Securely share files with friends.

Available for Windows, Linux and Mac.