Bcrypt

Bcrypt is a password hashing function published by Niels Provos and David Mazières in 1999. It applies a modified Blowfish key schedule repeatedly, controlled by a cost factor (typically 10 to 14) where each step doubles the work. A bcrypt hash like `$2b$12$...` encodes the version, cost, salt, and digest in one string, so verification needs only the hash itself. Bcrypt remains a safe choice for password storage when Argon2 or scrypt are not available, but its 72-byte password truncation and lack of memory-hardness make Argon2id the preferred default for new systems today.