Mozilla's CA certificate bundle for TLS/SSL validation in command-line tools and libraries.

OpenSSL 3.x: cryptographic library and command-line toolkit for SSL/TLS, hashing, and encryption.

C library implementing TLS, DTLS, and X.509 certificate handling per GNU standards.

GNU implementation of OpenPGP encryption, signing, and key management.

Low-level C cryptographic library providing hash, cipher, and public-key algorithms.

C library to load and enumerate PKCS#11 cryptographic modules and tokens.

Cryptographic library for TLS, certificate validation, and digital signatures used by Firefox and other applications.

Cryptographic library providing symmetric, asymmetric, and hash algorithms for C/C++ applications.

C library providing programmatic access to GnuPG encryption and signing operations.

C library for X.509 certificate and CMS message parsing and validation.

C library implementing modern and legacy password hashing algorithms (bcrypt, scrypt, SHA-crypt, yescrypt, and others).

Portable C library for network communication and cryptography with a modern, audited API.

Passphrase entry dialog for GnuPG using the Assuan protocol.

C++ bindings library for GPGME, providing object-oriented access to GnuPG cryptographic operations.

Python library providing cryptographic recipes and low-level primitives (symmetric/asymmetric encryption, hashing, signatures).

C library implementing BLAKE2, a cryptographic hash function faster than MD5.

Cryptography and SSL/TLS toolkit library (version 4.0.0+), OpenSSL's latest major release with modernized APIs.

C++14 TLS 1.3 implementation from Facebook supporting full handshake modes, PSK resumption, and early data.

Fast cryptographic hash function supporting parallel hashing, streaming, and variable output sizes.

Cryptographic & SSL/TLS library implementing TLS, DTLS, and X.509 certificate handling (version 3.x)

C library implementing FIDO2 and U2F hardware authentication protocols, with USB device support.

OpenSSL 3.5 — cryptography library and command-line toolkit for SSL/TLS, encryption, and digital signatures.

C library for arbitrary-precision integer arithmetic and number theory operations.

Password hashing library and CLI tool implementing the Argon2 memory-hard function (PHC winner).

AWS-backed C library implementation of TLS/SSL protocols with cryptographic agility and formal verification.

C library implementing TLS/DTLS protocols, X.509 certificates, and cryptographic operations via PSA Crypto API.

C99 shared library for AWS client-side authentication, credentials providers, and request signing.

AWS C99 cryptography abstraction layer providing cross-platform wrappers for hash, HMAC, and symmetric encryption.

DNS library in C with DNSSEC support and high-level packet manipulation API.

C library and command-line tool for generating RFC 4122 UUIDs with BSD licensing.

FFI bindings for Rustls, a memory-safe TLS library written in Rust, enabling use from C, C++, Python and other languages.