Predefined Constants

The constants below are always available as part of the PHP core.

PASSWORD_BCRYPT (string)

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 (int) - 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 (string)

PASSWORD_ARGON2I is used to create new password hashes using the Argon2i algorithm.

Supported Options:

  • memory_cost (int) - Maximum memory (in kibibytes) that may be used to compute the Argon2 hash. Defaults to PASSWORD_ARGON2_DEFAULT_MEMORY_COST.

  • time_cost (int) - Maximum amount of time it may take to compute the Argon2 hash. Defaults to PASSWORD_ARGON2_DEFAULT_TIME_COST.

  • threads (int) - Number of threads to use for computing the Argon2 hash. Defaults to PASSWORD_ARGON2_DEFAULT_THREADS. Only available with libargon2, not with libsodium implementation.

Available as of PHP 7.2.0.

PASSWORD_ARGON2ID (string)

PASSWORD_ARGON2ID is used to create new password hashes using the Argon2id algorithm. It supports the same options as PASSWORD_ARGON2I.

Available as of PHP 7.3.0.

PASSWORD_ARGON2_DEFAULT_MEMORY_COST (int)

Default amount of memory in bytes that will be used while trying to compute a hash.

Available as of PHP 7.2.0.

PASSWORD_ARGON2_DEFAULT_TIME_COST (int)

Default amount of time that will be spent trying to compute a hash.

Available as of PHP 7.2.0.

PASSWORD_ARGON2_DEFAULT_THREADS (int)

Default number of threads that Argon2lib will use. Not available with libsodium implementation.

Available as of PHP 7.2.0.

PASSWORD_DEFAULT (mixed)

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 recommended width).

Values for this constant:

  • PHP 5.5.0 - PASSWORD_BCRYPT

Changelog

Version Description
7.4.0 The values of the password algo IDs (PASSWORD_BCRYPT, PASSWORD_ARGON2I, PASSWORD_ARGON2ID and PASSWORD_DEFAULT) are now strings. Previously, they have been ints.