Password Formats

Notes about the password encryption formats generated and understood by Apache.

Basic Authentication
Digest Authentication

Basic Authentication

There are four formats that Apache recognizes for basic-authentication passwords. Note that not all formats work on every platform:

PLAIN TEXT (i.e. unencrypted): Windows, BEOS, & Netware only.
CRYPT: Unix only. Uses the traditional Unix crypt(3) function with a randomly-generated 32-bit salt (only 12 bits used) and the first 8 characters of the password.
SHA1: "{SHA}" + Base64-encoded SHA-1 digest of the password.
MD5: "$apr1$" + the result of an Apache-specific algorithm using an iterated (1,000 times) MD5 digest of various combinations of a randoml 32-bit salt and the password. See the APR source file apr_md5.c for the details of the algorithm.

Generating values with htpasswd

MD5

$ htpasswd -nbm myName myPassword myName:$apr1$r31.....$HqJZimcKQFAMYayBlzkrA/

SHA1

$ htpasswd -nbs myName myPassword myName:{SHA}VBPuJHI7uixaa6LQGWx4s+5GKNE=

CRYPT

$ htpasswd -nbd myName myPassword myName:rqXexS6ZhobKA

Generating CRYPT and MD5 values with the OpenSSL command-line program

OpenSSL knows the Apache-specific MD5 algorithm.

MD5

$ openssl passwd -apr1 myPassword $apr1$qHDFfhPC$nITSVHgYbDAK1Y0acGRnY0

CRYPT

openssl passwd -crypt myPassword qQ5vTYO3c8dsU

Validating CRYPT or MD5 passwords with the OpenSSL command line program

The salt for a CRYPT password is the first two characters (converted to a binary value). To validate myPassword against rqXexS6ZhobKA

CRYPT

$ openssl passwd -crypt -salt rq myPassword Warning: truncating password to 8 characters rqXexS6ZhobKA

Note that using myPasswo instead of myPassword will produce the same result because only the first 8 characters of CRYPT passwords are considered.

The salt for an MD5 password is between $apr1$ and the following $ (as a Base64-encoded binary value - max 8 chars) To validate myPassword against $apr1$r31.....$HqJZimcKQFAMYayBlzkrA/

MD5

$ openssl passwd -apr1 -salt r31..... myPassword $apr1$r31.....$HqJZimcKQFAMYayBlzkrA/

Database password fields for mod_dbd

The SHA1 variant is probably the most useful format for DBD authentication. Since the SHA1 and Base64 functions are commonly available, other software can populate a database with encrypted passwords that are usable by Apache basic authentication.

To create Apache SHA1-variant basic-authentication passwords in various languages:

PHP

'{SHA}' . base64_encode(sha1($password, TRUE))

Java

"{SHA}" + new sun.misc.BASE64Encoder().encode(java.security.MessageDigest.getInstance("SHA1").digest(password.getBytes()))

ColdFusion

"{SHA}" & ToBase64(BinaryDecode(Hash(password, "SHA1"), "Hex"))

Ruby

require 'digest/sha1' require 'base64' '{SHA}' + Base64.encode64(Digest::SHA1.digest(password))

C or C++

Use the APR function: apr_sha1_base64

PostgreSQL (with the contrib/pgcrypto functions installed)

'{SHA}'||encode(digest(password,'sha1'),'base64')

Digest Authentication

Apache recognizes one format for digest-authentication passwords - the MD5 hash of the string user:realm:password as a 32-character string of hexadecimal digits. realm is the Authorization Realm argument to the AuthName directive in httpd.conf.

Database password fields for mod_dbd

Since the MD5 function is commonly available, other software can populate a database with encrypted passwords that are usable by Apache digest authentication.

To create Apache digest-authentication passwords in various languages:

PHP

md5($user . ':' . $realm . ':' .$password)

Java

byte b[] = java.security.MessageDigest.getInstance("MD5").digest( (user + ":" + realm + ":" + password ).getBytes()); java.math.BigInteger bi = new java.math.BigInteger(b); String s = bi.toString(16); if (s.length() % 2 != 0) s = "0" + s; // String s is the encrypted password

ColdFusion

LCase(Hash( (user & ":" & realm & ":" & password) , "MD5"))

Ruby

require 'digest/md5' Digest::MD5.hexdigest(user + ':' + realm + ':' + password)

PostgreSQL (with the contrib/pgcrypto functions installed)

encode(digest( user || ':' || realm || ':' || password , 'md5'), 'hex')