Extended crypt library for descrypt, md5crypt, bcrypt, and others

libxcrypt is a modern library for one-way hashing of passwords. It supports a wide variety of both modern and historical hashing methods: yescrypt, gost-yescrypt, scrypt, bcrypt, sha512crypt, sha256crypt, md5crypt, SunMD5, sha1crypt, NT, bsdicrypt, bigcrypt, and descrypt. It provides the traditional Unix crypt and crypt_r interfaces, as well as a set of extended interfaces pioneered by Openwall Linux, crypt_rn, crypt_ra, crypt_gensalt, crypt_gensalt_rn, and crypt_gensalt_ra. libxcrypt is intended to be used by login(1), passwd(1), and other similar programs; that is, to hash a small number of passwords during an interactive authentication dialogue with a human. It is not suitable for use in bulk password-cracking applications, or in any other situation where speed is more important than careful handling of sensitive data. However, it is intended to be fast and lightweight enough for use in servers that must field thousands of login attempts per minute. This version of the library does not provide the legacy API functions that have been provided by glibc's libcrypt.so.1.