Password Formats
Notes about the password encryption formats generated and understood by Apache.
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 random 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(1, b);
String s = bi.toString(16);
while (s.length() < 32)
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')