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<div class=Section1>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>HGI Seminar <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>"Which Hash Functions
will <span class=GramE>survive ?"</span><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><span
style='mso-spacerun:yes'> </span><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><span
style='mso-spacerun:yes'> </span><span style='mso-spacerun:yes'> </span></span></font><st1:place><st1:City><span
class=SpellE><font size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;mso-ansi-language:EN-GB'>Xiaoyun</span></font></span><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'> Wang</span></font></st1:City><font size=2
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>, </span></font><st1:State><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>Shandong</span></font></st1:State></st1:place><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'> University,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><span
style='mso-spacerun:yes'> </span><span class=SpellE>Xuejia</span> Lai, </span></font><st1:place><st1:PlaceName><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>Shanghai</span></font></st1:PlaceName><font size=2
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'> </span></font><st1:PlaceName><span class=SpellE><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>Jiaotong</span></font></span></st1:PlaceName><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'> </span></font><st1:PlaceType><font size=2
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>University</span></font></st1:PlaceType></st1:place><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><span
style='mso-spacerun:yes'> </span></span></font><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Magnus Daum, Ruhr University Bochum<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Freitag, 5.November 2004, 14.15 Uhr in NA 01/99<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>(Please note the room in the </span></font><st1:place><st1:PlaceName><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>NA-</span></font></st1:PlaceName><font size=2
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'> </span></font><st1:PlaceType><font size=2
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>Building</span></font></st1:PlaceType></st1:place><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
mso-ansi-language:EN-GB'>, not the IC Building)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>Hash functions are an
important primitive in many <span class=SpellE>cryptographical</span>
applications, for example in digital signature schemes, where instead of a
message its short hash value is signed. In practical implementations hash
functions have to be fast and secure. The latter means, that it is impossible
to find so-called "collisions", i.e. pairs of different messages with
the same hash value. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>However, presently no method
is known to prove the security of hash functions. As in case of block ciphers
for instance, their design in practice follows more an <span class=SpellE>adhoc</span>
approach. In reality, with only very few exceptions, hash functions of the MD4
family are applied. Recently there has been great progress in the analysis of
these hash functions. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>At Crypto 2004 rump session
in Santa Barbara, collisions for many hash functions of MD4 type were announced
by <span class=SpellE>Xiaoyun</span> Wang, for example for SHA-0, RIPEMD,
HAVAL-128, MD5. We are proud to present a talk of <span class=SpellE>Xiaoyun</span>
Wang and <span class=SpellE>Xuejia</span> Lai, two cryptographers whose
analysis was the most spectacular news at Crypto 2004.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>A survey of the current
situation in the cryptanalysis of hash functions of the MD4 family will be given.
It starts with a short introduction on some main aspects and properties of
cryptographic hash functions given by Magnus <span class=SpellE>Daum</span>. Then
the techniques used by Dobbertin, <span class=SpellE>Chabaud/Joux</span> and
Biham/Chen in their respective attacks will be roughly sketched. Finally Wang
and Lai will describe ideas and methods they used in their attack.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB;mso-no-proof:yes'>============================================<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB;mso-no-proof:yes'>Prof. Christof Paar<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB;mso-no-proof:yes'>Chair for Communication
Security<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB;mso-no-proof:yes'>Dept. of Electr. Eng.
& Information Sciences<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
mso-no-proof:yes'>Ruhr-University Bochum<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
mso-no-proof:yes'>44780 Bochum, Germany<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
mso-no-proof:yes'><a href="www.crypto.rub.de">www.crypto.rub.de</a><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
mso-no-proof:yes'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
mso-no-proof:yes'>mobile phone: 0170 790 3393<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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