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SHA-2 OpenLDAP support
----------------------
slapd-sha2.c provides support for SSHA-512, SSHA-384, SSHA-256,
SHA-512, SHA-384 and SHA-256 hashed passwords in OpenLDAP. For
instance, one could have the LDAP attribute:
userPassword: {SHA512}vSsar3708Jvp9Szi2NWZZ02Bqp1qRCFpbcTZPdBhnWgs5WtNZKnvCXdhztmeD2cmW192CF5bDufKRpayrW/isg==
or:
userPassword: {SHA384}WKd1ukESvjAFrkQHznV9iP2nHUBJe7gCbsrFTU4//HIyzo3jq1rLMK45dg/ufFPt
or:
userPassword: {SHA256}K7gNU3sdo+OL0wNhqoVWhr3g6s1xYv72ol/pe/Unols=
all of which encode the password 'secret'.
Building
--------
1) Customize the OPENLDAP variable in Makefile to point to the OpenLDAP
source root.
For initial testing you might also want to edit DEFS to define
SLAPD_SHA2_DEBUG, which enables logging to stderr (don't leave this on
in production, as it prints passwords in cleartext).
2) Run 'make' to produce slapd-sha2.so
3) Copy slapd-sha2.so somewhere permanent.
4) Edit your slapd.conf (eg. /etc/ldap/slapd.conf), and add:
moduleload ...path/to/slapd-sha2.so
5) Restart slapd.
Configuring
-----------
The {SSHA256}, {SSHA384}, {SSHA512}, {SSHA256}, {SHA384} and {SHA512}
password schemes should now be recognised.
You can also tell OpenLDAP to use one of these new schemes when processing LDAP
Password Modify Extended Operations, thanks to the password-hash option in
slapd.conf. For example:
password-hash {SSHA512}
Testing
-------
A quick way to test whether it's working is to customize the rootdn and
rootpw in slapd.conf, eg:
rootdn "cn=admin,dc=example,dc=com"
# This encrypts the string 'secret'
rootpw {SHA256}K7gNU3sdo+OL0wNhqoVWhr3g6s1xYv72ol/pe/Unols=
Then to test, run something like:
ldapsearch -b "dc=example,dc=com" -D "cn=admin,dc=example,dc=com" -x -w secret
-- Test hashes:
Test hashes can be generated with openssl:
$ echo -n "secret" | openssl dgst -sha256 -binary | openssl enc -base64
K7gNU3sdo+OL0wNhqoVWhr3g6s1xYv72ol/pe/Unols=
$ echo -n "secret" | openssl dgst -sha384 -binary | openssl enc -base64
WKd1ukESvjAFrkQHznV9iP2nHUBJe7gCbsrFTU4//HIyzo3jq1rLMK45dg/ufFPt
$ echo -n "secret" | openssl dgst -sha512 -binary | openssl enc -base64
vSsar3708Jvp9Szi2NWZZ02Bqp1qRCFpbcTZPdBhnWgs5WtNZKnvCXdhztmeD2cm
W192CF5bDufKRpayrW/isg==
(join those lines up to form the full hash)
Alternatively we could modify an existing user's password with
ldappasswd, and then test binding as that user:
$ ldappasswd -D "cn=admin,dc=example,dc=com" -x -W -S uid=jturner,ou=People,dc=example,dc=com
New password: secret
Re-enter new password: secret
Enter LDAP Password: <cn=admin's password>
$ ldapsearch -b "dc=example,dc=com" -D "uid=jturner,ou=People,dc=example,dc=com" -x -w secret
Debugging (SHA-512, SHA-384 and SHA-256 only)
---------------------------------------------
To see what's going on, recompile with SLAPD_SHA2_DEBUG (use the
commented-out DEFS in Makefile), and then run slapd from the console
to see stderr:
$ sudo /etc/init.d/slapd stop
Stopping OpenLDAP: slapd.
$ sudo /usr/sbin/slapd -f /etc/ldap/slapd.conf -h ldap://localhost:389 -d stats
@(#) $OpenLDAP$
buildd@palmer:/build/buildd/openldap2.3-2.4.9/debian/build/servers/slapd
slapd starting
...
Validating password
Hash scheme: {SHA256}
Password to validate: secret
Password hash: K7gNU3sdo+OL0wNhqoVWhr3g6s1xYv72ol/pe/Unols=
Stored password hash: K7gNU3sdo+OL0wNhqoVWhr3g6s1xYv72ol/pe/Unols=
Result: match
conn=0 op=0 BIND dn="cn=admin,dc=example,dc=com" mech=SIMPLE ssf=0
conn=0 op=0 RESULT tag=97 err=0 text=
conn=0 op=1 SRCH base="dc=example,dc=com" scope=2 deref=0 filter="(objectClass=*)"
conn=0 fd=12 closed (connection lost)
---
This work is part of OpenLDAP Software <http://www.openldap.org/>.
Copyright 2009-2021 The OpenLDAP Foundation.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted only as authorized by the OpenLDAP
Public License.
A copy of this license is available in the file LICENSE in the
top-level directory of the distribution or, alternatively, at
<http://www.OpenLDAP.org/license.html>.
---
ACKNOWLEDGEMENT:
This work was initially developed by Jeff Turner for inclusion in
OpenLDAP Software, based upon the SHA-2 implementation independently
developed by Aaron Gifford.
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