[RFC] Replace glibc's libcrypt with libxcrypt for Fedora 29/30

Hello everyone, since there has been some discussion in the last time about removing libcrypt from glibc in some time [1,2,3,4] and splitting it out into a separate project which can evolve quicker, I'd like to hear your oppinion about replacing glibc's libcrypt with libxcrypt [5] for Fedora 29 (or 30). libxcrypt will be fully binary compatible with software linked against glibc's libcrypt and does not require any rebuilds. However, the converse is not true: programs linked against libxcrypt will not work with glibc's libcrypt. It comes with a set of extended interfaces pioneered by Openwall Linux, crypt_rn, crypt_ra, crypt_gensalt, crypt_gensalt_rn, and crypt_gensalt_ra. Also, programs that use certain legacy APIs supplied by glibc's libcrypt (encrypt, encrypt_r, setkey, setkey_r, and fcrypt) cannot be compiled against libxcrypt. The crypt and gensalt functions are supporting all (except for Crypt16, which was used on Ultrix and Tru64, only) widely used password hashing algorithms [6], which before were specific to just some operating system's implementations of libcrypt [7]. There are preperations to add password hashing with PBKDF2 using HMAC- SHA3-512 to libxcrypt as well. Anyways, before this can happen, there is still some work to be done with libxcrypt, like adding a FIPS mode or FIPS compliance in a different way. Cheers, Björn [1] https://sourceware.org/ml/libc-alpha/2017-06/msg00055.html [2] https://sourceware.org/ml/libc-alpha/2017-06/msg00079.html [3] https://sourceware.org/ml/libc-alpha/2017-08/msg01257.html [4] https://sourceware.org/ml/libc-alpha/2017-08/msg01408.html [5] https://github.com/besser82/libxcrypt [6] https://en.wikipedia.org/wiki/Crypt_(C)#Key_derivation_functions_s upported_by_crypt [7] https://en.wikipedia.org/wiki/Crypt_(C)#Support_in_operating_syste ms