For Fedora 35, a transition to the yescrypt password hashing scheme is planned. This change has not yet been reviewed by the FESCo (Fedora Engineering Steering Committee), which is responsible for the technical aspects of the Fedora distribution's development. If approved, starting with Fedora 35, passwords for new users in /etc/shadow will be hashed by default using yescrypt. Support for older hashes created with the previously used sha512crypt algorithm will be preserved and available as an option. Notable distributions that have already switched to yescrypt include ALT Linux, Debian Testing, and Kali Linux.
Yescrypt expands the capabilities of classic scrypt by supporting schemes with a higher memory usage and decreases the effectiveness of attacks using GPU, FPGA, and specialized chips. The security of Yescrypt is ensured through the use of already proven cryptographic primitives SHA-256, HMAC, and PBKDF2.
Among the drawbacks of the sha512crypt algorithm used in Fedora is its effectiveness only when the salt size exceeds 90 bits (at least 128 bits is recommended); vulnerability to DoS attacks through the creation of parasitic CPU load while hashing long passwords; susceptibility to attacks that determine password size based on passive analysis of hash processing time; functioning without using a cryptographic key derivation function (KDF).
Kilde: opennet.ru
