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Full Discussion: Hash Funtion properties
Special Forums Cybersecurity Hash Funtion properties Post 302072426 by newkidintown on Tuesday 2nd of May 2006 07:01:40 PM
Old 05-02-2006
Hash Funtion properties
Here are some desirable properties for cryptographic hash functions:

These properties below are generally considered prerequisites:

* Preimage resistant: given h it should be hard to find any m such that h = hash(m).
* Second preimage resistant: given an input m1, it should be hard to find another input, m2 (not equal to m1) such that hash(m1) = hash(m2).
* Collision-resistant: it should be hard to find two different messages m1 and m2 such that hash(m1) = hash(m2).

For each of the following applications of hash functions, explain which of these three properties are needed and which are not.


(a) Cryptographic signatures are produced by computing a hash of a message, then applying a signature function to the hash of the message. Suppose Eve has a list of messages m1,...mn, and their signatures computed using Bob's signing key, but does not have Bob's signing key. Assuming that the signature function is not susceptible to attack, it should not be possible for Eve to present Bob's signature on any message other than m1,...mn.

(b) Suppose that Eve works for a Certificate Authority. She does not have access to the special harware that computes digital signatures, but she knows the hash function. In addition, Eve can get messages signed, but every message that is signed automatically goes into a log file that Eve cannot change. Eve should not be able to produce a certificate signed by the Certificate Authority that does not appear in the log file.

Anybody can explain these to me?

thanks
Akhil
 

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LEARN ABOUT OPENSOLARIS

nautilus-file-management-properties

nautilus-file-management-properties(1)				   User Commands			    nautilus-file-management-properties(1)

NAME

       nautilus-file-management-properties - configure nautilus file manager behavior

SYNOPSIS

       nautilus-file-management-properties [gnome-std-options]

DESCRIPTION

       nautilus-file-management-properties enables you to customize the behavior of nautilus(1), the desktop file manager.

OPTIONS

       The following options are supported:

       gnome-std-options       Standard options available for use with most GNOME applications.  See gnome-std-options(5) for more information.

EXAMPLES

       Example 1: Launching the nautilus-file-management-properties tool

       example% nautilus-file-management-properties

ENVIRONMENT VARIABLES

       See environ(5) for descriptions of the following environment variables: NLSPATH.

EXIT STATUS

       The exit value 0 is returned regardless of success or failure.

FILES

       The following files are used by this application:

       /usr/bin/nautilus-file-management-properties

	   Executable to edit file manager options

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWgnome-file-mgr	   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |Volatile			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Latest version of the GNOME Desktop User Guide for your platform.

       gnome-control-center(1), nautilus(1), attributes(5), environ(5), gnome-std-options(5)

NOTES

       Written by Stephen Browne, Sun Microsystems Inc., 2004, 2006, 2007.

SunOS 5.11							    09 Nov 2007 			    nautilus-file-management-properties(1)
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