MD5 is an algorithm that is used to verify data integrity through the creation of a 128-bit message digest from data input (which may be a message of any length) that is claimed to be as unique to that specific data as a fingerprint is to the specific individual. MD5 was developed by Professor Ronald L. Rivest of MIT. Test md5 online.

string md5 ( string $str [, bool $raw_output = false ] )

PHP Documentation by the PHP Documentation Group


(PHP 4, PHP 5, PHP 7)

md5Calculate the md5 hash of a string


It is not recommended to use this function to secure passwords, due to the fast nature of this hashing algorithm. See the Password Hashing FAQ for details and best practices.


string md5 ( string $str [, bool $raw_output = false ] )

Calculates the MD5 hash of str using the » RSA Data Security, Inc. MD5 Message-Digest Algorithm, and returns that hash.



The string.


If the optional raw_output is set to TRUE, then the md5 digest is instead returned in raw binary format with a length of 16.

Return Values

Returns the hash as a 32-character hexadecimal number.


Example #1 A md5() example


if (
md5($str) === '1f3870be274f6c49b3e31a0c6728957f') {
"Would you like a green or red apple?";

See Also

  • md5_file() - Calculates the md5 hash of a given file
  • sha1_file() - Calculate the sha1 hash of a file
  • crc32() - Calculates the crc32 polynomial of a string
  • sha1() - Calculate the sha1 hash of a string
  • hash() - Generate a hash value (message digest)
  • crypt() - One-way string hashing
  • password_hash() - Creates a password hash

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