"Guaranteed to be available" isn't the same as "available in practice". Linux's current crypt function provides yescrypt, gost-yescrypt, scrypt, bcrypt, sha512

"Guaranteed to be available" isn't the same as "available in practice". Linux's current crypt function provides yescrypt, gost-yescrypt, scrypt, bcrypt, sha512crypt, sha256crypt, sha1crypt, sunmd5, md5crypt, bsdicrypt, bigcrypt, descrypt and NT (ordered by decreasing strength). https://manpages.debian.org/unstable/libcrypt-dev/crypt.5.en.html https://manpages.debian.org/unstable/libcrypt-dev/crypt.5.en... So, if you're on an ancient unix box (or a Mac, apparently), then you're stuck with the obsolete standard library your OS vendor packaged, but that's true of other things. Presumably, they'll remove SSL support soon too, since, when provided with a sufficiently old version of openssl support, it won't provide modern algorithms either. That means "only obsolete SSL modes are guaranteed to be available".