Cyrus SASL is an open-source implementation of the Simple Authentication and Security Layer (SASL) API specified in RFC 4422, providing authentication and authorization services for both client and server applications. The library supports multiple authentication mechanisms including ANONYMOUS, CRAM-MD5, GSSAPI, Kerberos, NTLM, PLAIN, SCRAM, and SRP, and can store user credentials in hash databases (Berkeley DB, gdbm, ndbm), LDAP, or SQL databases. The project is maintained by the Cyrus team and is written in C, with additional components including a password checking daemon (pwcheck), an LDAP auxiliary property plugin contributed by the OpenLDAP Project, and support for various platforms including Unix, macOS, and Windows. The codebase includes optional Kerberos integration (supporting MIT Kerberos 5 and Heimdal) and relies on OpenSSL for certain authentication mechanisms.