krb5-1.8-beta2 is available
tlyu at MIT.EDU
Fri Feb 26 11:18:06 EST 2010
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[The release has been available for download since last night. The
delay in this announcement is due to a remarkable confluence of
infrastructure problems that occurred recently.]
MIT krb5-1.8-beta2 is now available for download from
The main MIT Kerberos web page is
This is the code freeze for the krb5-1.8 release, which will probably
have a final release early next week. We would appreciate feedback on
documentation, particularly about the DES transition and
The README file contains a more extensive list of changes.
The krb5-1.8 release disables single-DES cryptosystems by default. As
a result, you may need to add the libdefaults setting
"allow_weak_crypto = true" to communicate with existing Kerberos
infrastructures if they do not support stronger ciphers.
The Data Encryption Standard (DES) is widely recognized as weak. The
krb5-1.7 release contains measures to encourage sites to migrate away
- From using single-DES cryptosystems. Among these is a configuration
variable that enables "weak" enctypes, which now defaults to "false"
beginning with krb5-1.8. The krb5-1.8 release includes additional
measures to ease the transition away from single-DES.
Major changes in 1.8
The krb5-1.8 release contains a large number of changes, featuring
improvements in the following broad areas:
* Code quality
* Developer experience
* End-user experience
* Administrator experience
* Protocol evolution
* Move toward test-driven development -- new features have test code,
or at least written testing procedures.
* Remove applications to a separate distribution to simplify
* Increase conformance to coding style
+ "The great reindent"
+ Selective refactoring
* Crypto modularity -- vendors can more easily substitute their own
crypto implementations, which might be hardware-accelerated or
validated to FIPS 140, for the builtin crypto implementation that
has historically shipped as part of MIT Kerberos. Currently, only
an OpenSSL provider is included, but others are planned for the
* Move toward improved KDB interface
* Improved API for verifying and interrogating authorization data
* Investigate and remedy repeatedly-reported performance bottlenecks.
* Encryption performance -- new crypto API with opaque key structures,
to allow for optimizations such as caching of derived keys
* Reduce DNS dependence by implementing an interface that allows
client library to track whether a KDC supports service principal
* Disable DES by default -- this reduces security exposure from using
an increasingly insecure cipher.
* More versatile crypto configuration, to simplify migration away from
DES -- new configuration syntax to allow inclusion and exclusion of
specific algorithms relative to a default set.
* Account lockout for repeated login failures -- mitigates online
password guessing attacks, and helps with some enterprise regulatory
* Bridge layer to allow Heimdal HDB modules to act as KDB backend
modules. This provides a migration path from a Heimdal to an MIT
* FAST enhancements -- preauthentication framework enhancements to
allow a client to securely negotiate the use of FAST with a KDC of
* Microsoft Services for User (S4U) compatibility: S4U2Self, also
known as "protocol transition", allows for service to ask a KDC for
a ticket to themselves on behalf of a client authenticated via a
different means; S4U2Proxy allows a service to ask a KDC for a
ticket to another service on behalf of a client.
* Anonymous PKINIT -- allows the use of public-key cryptography to
anonymously authenticate to a realm
* Support doing constrained delegation similar to Microsoft's
S4U2Proxy without the use of the Windows PAC. This functionality
uses a protocol compatible with Heimdal.
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