Bug #80744 [Com]: password_verify fail to verify bcrypt hashes with cost below 4

Edit report at https://bugs.php.net/bug.php?id=80744&edit=1 ID: 80744 Comment by: php-bugs at allenjb dot me dot uk Reported by: divinity76 at gmail dot com Summary: password_verify fail to verify bcrypt hashes with cost below 4 Status: Open Type: Bug Package: *Encryption and hash functions PHP Version: 8.0.2 Block user comment: N Private report: N New Comment: I would posit that this response is correct: The original OpenBSD implementation[0], which is the closest I believe exists to a specification for bcrypt, specifies a minimum number of 16 (2^4) rounds (BCRYPT_MINROUNDS in the OpenBSD source). I would guess this is because lower values are likely vulnerable to the speed of brute-force cracking even at the time the algorithm was first proposed (and we've had over 2 decades of advances since then). Following this "reference implementation", no library should ever generate a hash with a cost value of less than 4, and any such hashes that exist are therefore invalid. [0] https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/crypt/bcrypt.c?rev=1.1&content-type=text/x-cvsweb-markup Previous Comments: ------------------------------------------------------------------------ [2021-02-13 13:11:08] divinity76 at gmail dot com Description: ------------ password_verify fail to verify bcrypt hashes with cost below 4 Test script: --------------- <?php var_dump(password_verify("",'$2a$03$AAAAAAAAAAAAAAAAAAAAA.TCFhOtNOtk2Oeef1z4xP561tW1AQOMW')); Expected result: ---------------- bool(true) Actual result: -------------- bool(false) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=80744&edit=1