# Technical Report CS0884

 TR#: CS0884 Class: CS Title: How to Forge DES-Encrypted Messages in $2^{28}$ Steps Authors: Eli Biham PDF CS0884.pdf Abstract: In this paper we suggest {\it key-collision attacks}, and show that the theoretic strength of a cipher cannot exceed the square root of the size of the key space. As a result, in some circumstances, some DES keys can be recovered while they are still in use, and these keys can then be used to forge messages: in particular, one key of DES can be recovered with complexity $2^{28}$, and one key of (three-key) triple-DES can be recovered with complexity $2^{84}$. Copyright The above paper is copyright by the Technion, Author(s), or others. Please contact the author(s) for more information

Remark: Any link to this technical report should be to this page (http://www.cs.technion.ac.il/users/wwwb/cgi-bin/tr-info.cgi/1996/CS/CS0884), rather than to the URL of the PDF files directly. The latter URLs may change without notice.