Tooling

OpenSSL is an open-source cryptographic library and command-line toolkit, originally derived from SSLeay in 1998 and now governed by the OpenSSL Software Foundation under an Apache 2.0 licence (since version 3.0). It is the default cryptographic substrate for the majority of Linux server software: Apache httpd, nginx, curl, wget, PostgreSQL, MySQL, Postfix, OpenLDAP, and hundreds of other projects link against libssl and libcrypto by default. It implements TLS (all versions from 1.2 through 1.3), X.509 certificate parsing and validation, PKI operations (CSR generation, certificate signing, CRL and OCSP processing), and the full range of cryptographic primitives — symmetric ciphers (AES-GCM, ChaCha20-Poly1305), hash functions (SHA-2, SHA-3, SHAKE), RSA, ECC (ECDSA, ECDH, Ed25519, X25519), HMAC, HKDF, and key derivation functions. The library has two primary components: libcrypto, the algorithm library, and libssl, the TLS protocol layer built on top of it. The openssl command-line tool exposes both as a single swiss-army interface for certificate management, key generation, encryption, hashing, benchmarking, and protocol testing.