The password-hashing algorithm designed by Niels Provos and David Mazières in 1999 was bcrypt.
bcrypt was created for OpenBSD and is based on the Blowfish symmetric-key cipher. Unlike ordinary fast hashes, it was designed to make password guessing expensive by using a configurable cost factor. As computers become faster, systems can increase that factor to require more computation for each password attempt.
bcrypt’s design also uses a deliberately small memory requirement and a 128-bit salt. Salting ensures that identical passwords do not produce identical stored hash values, while the work factor slows large-scale brute-force attacks and makes precomputed rainbow tables less useful.
bcrypt is often confused with encryption because both involve cryptography, but bcrypt is a one-way password-hashing function, not a method for recovering plaintext passwords. Modern password-storage guidance also discusses memory-hard alternatives such as scrypt and Argon2, especially for new systems.