PHP Password Hashing

This extension provides some constants & functions to secure the passwords in secure manner.

Requirements

No external libraries are needed to build this extension.

Installation

There is no installation needed to use these functions;

they are part of the PHP core.

To enable Argon2 password hashing, however, PHP must be build with libargon2 support using the --with-password-argon2[=DIR] configure option.

Run-time Configuration

This extension has no configuration directives defined in php.ini.

Resource Types

This extension has no resource types defined.

Predefined Constants

Constants of this extension below are always available as part of the PHP core.

• PASSWORD_BCRYPT (integer)
• PASSWORD_BCRYPT is used to create new password hashes using the CRYPT_BLOWFISH algorithm.
  • This will always result in a hash using the "$2y$" crypt format, which is always 60 characters wide.
  • Supported Options:
    • salt (string) - to manually provide a salt to use when hashing the password.
    • Note that this will override and prevent a salt from being automatically generated.
    • If omitted, a random salt will be generated by password_hash() for each password hashed.
    • This is the intended mode of operation and as of PHP 7.0.0 the salt option has been deprecated.
    • cost (integer) - which denotes the algorithmic cost that should be used.
    • Examples of these values can be found on the crypt() page.
    • If omitted, a default value of 10 will be used.
    • This is a good baseline cost, but you may want to consider increasing it depending on your hardware.
• PASSWORD_ARGON2I (integer)
• PASSWORD_ARGON2I is used to create new password hashes using the Argon2 algorithm.
  • Supported Options:
    • memory_cost (integer) - Maximum memory (in bytes) that may be used to compute the Argon2 hash.
    • Defaults to PASSWORD_ARGON2_DEFAULT_MEMORY_COST.
    • time_cost (integer) - Maximum amount of time it may take to compute the Argon2 hash. Defaults to PASSWORD_ARGON2_DEFAULT_TIME_COST.
    • threads (integer) - Number of threads to use for computing the Argon2 hash. Defaults to PASSWORD_ARGON2_DEFAULT_THREADS.
    • Available as of PHP 7.2.0.
• PASSWORD_ARGON2_DEFAULT_MEMORY_COST (integer)
  • Default amount of memory in bytes that Argon2lib will use while trying to compute a hash.
  • Available as of PHP 7.2.0.
• PASSWORD_ARGON2_DEFAULT_TIME_COST (integer)
  • Default amount of time that Argon2lib will spend trying to compute a hash.
  • Available as of PHP 7.2.0.
• PASSWORD_ARGON2_DEFAULT_THREADS (integer)
  • Default number of threads that Argon2lib will use.
  • Available as of PHP 7.2.0.
• PASSWORD_DEFAULT (integer)
  • The default algorithm to use for hashing if no algorithm is provided.
  • This may change in newer PHP releases when newer, stronger hashing algorithms are supported.
  • It is worth noting that over time this constant can (and likely will) change.
  • Therefore you should be aware that the length of the resulting hash can change.
  • Therefore, if you use PASSWORD_DEFAULT you should store the resulting hash in a way that can store more than 60 characters (255 is the recomended width).
  • Values for this constant:
  • PHP 5.5.0 – PASSWORD_BCRYPT

Password Hashing Functions

• password_get_info — Returns information about the given hash

• password_hash — Creates a password hash

• password_needs_rehash — Checks if the given hash matches the given options

• password_verify — Verifies that a password matches a hash