Difference between revisions of "SHA-256/224"
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=== Collision Attacks === | === Collision Attacks === | ||
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| + | <bibtex> | ||
| + | @inproceedings{acispSanadhyaS08, | ||
| + | author = {Somitra Kumar Sanadhya and Palash Sarkar}, | ||
| + | title = {Non-linear Reduced Round Attacks against SHA-2 Hash Family}, | ||
| + | booktitle = {ACISP}, | ||
| + | year = {2008}, | ||
| + | pages = {254-266}, | ||
| + | abstract = {Most of the attacks against (reduced) SHA-2 family in literature have used local collisions which are valid for linearized version of SHA-2 hash functions. Recently, at FSE 2008, an attack against reduced round SHA-256 was presented by Nikolic and Biryukov which used a local collision which is valid for the actual SHA-256 function. It is a 9-step local collision which starts by introducing a modular difference of 1 in the two messages. It succeeds with probability roughly 1/3. We build on the work of Nikolic and Biryukov and provide a generalized nonlinear local collision which accepts an arbitrary initial message difference. This local collision succeeds with probability 1. Using this local collision we present attacks against 18-step SHA-256 and 18-step SHA-512 with arbitrary initial difference. Both of these attacks succeed with probability 1. We then present special cases of our local collision and show two different differential paths for attacking 20-step SHA-256 and 20-step SHA-512. One of these paths is the same as presented by Nikolic and Biryukov while the other one is a new differential path. Messages following both these differential paths can be found with probability 1. This improves on the previous result where the success probability of 20-step attack was 1/3. Finally, we present two differential paths for 21-step collisions for SHA-256 and SHA-512, one of which is a new path. The success probabilities of these paths for SHA-256 are roughly 2-^15 and 2^-17 which improve on the 21-step attack having probability 2^-19 reported earlier. We show examples of message pairs following all the presented differential paths for up to 21-step collisions in SHA-256. We also show first real examples of colliding message pairs for up to 20-step reduced SHA-512. }, | ||
| + | url = {http://dx.doi.org/10.1007/978-3-540-70500-0_19}, | ||
| + | editor = {Yi Mu and Willy Susilo and Jennifer Seberry}, | ||
| + | publisher = {Springer}, | ||
| + | series = {LNCS}, | ||
| + | volume = {5107}, | ||
| + | isbn = {978-3-540-69971-2}, | ||
| + | } | ||
| + | </bibtex> | ||
<bibtex> | <bibtex> | ||
Revision as of 13:57, 10 November 2008
Contents
1 Specification
- digest size: 256 bits
- max. message length: < 264 bits
- compression function: 512-bit message block, 256-bit chaining variable
- Specification: FIPS 180-2 Secure Hash Standard
2 Cryptanalysis
2.1 Best Known Results
Collision attacks up to 21 out of 64 steps. Other non random behavior up to 25 steps. Both results are due to Nicolic and Biryukov.
2.2 Generic Attacks
2.3 Collision Attacks
Somitra Kumar Sanadhya, Palash Sarkar - Non-linear Reduced Round Attacks against SHA-2 Hash Family
- ACISP 5107:254-266,2008
- http://dx.doi.org/10.1007/978-3-540-70500-0_19
BibtexAuthor : Somitra Kumar Sanadhya, Palash Sarkar
Title : Non-linear Reduced Round Attacks against SHA-2 Hash Family
In : ACISP -
Address :
Date : 2008
Ivica Nikolic, Alex Biryukov - Collisions for Step-Reduced SHA-256
- FSE 5086:1-15,2008
- http://dx.doi.org/10.1007/978-3-540-71039-4_1
BibtexAuthor : Ivica Nikolic, Alex Biryukov
Title : Collisions for Step-Reduced SHA-256
In : FSE -
Address :
Date : 2008
Somitra Kumar Sanadhya, Palash Sarkar - New Local Collisions for the SHA-2 Hash Family
- ICISC 4817:193-205,2007
- http://dx.doi.org/10.1007/978-3-540-76788-6_16
BibtexAuthor : Somitra Kumar Sanadhya, Palash Sarkar
Title : New Local Collisions for the SHA-2 Hash Family
In : ICISC -
Address :
Date : 2007
Florian Mendel, Norbert Pramstaller, Christian Rechberger, Vincent Rijmen - Analysis of Step-Reduced SHA-256
- FSE 4047:126-143,2006
- http://dx.doi.org/10.1007/11799313_9
BibtexAuthor : Florian Mendel, Norbert Pramstaller, Christian Rechberger, Vincent Rijmen
Title : Analysis of Step-Reduced SHA-256
In : FSE -
Address :
Date : 2006
Hirotaka Yoshida, Alex Biryukov - Analysis of a SHA-256 Variant
- Selected Areas in Cryptography 3897:245-260,2005
- http://dx.doi.org/10.1007/11693383_17
BibtexAuthor : Hirotaka Yoshida, Alex Biryukov
Title : Analysis of a SHA-256 Variant
In : Selected Areas in Cryptography -
Address :
Date : 2005
Henri Gilbert, Helena Handschuh - Security Analysis of SHA-256 and Sisters
- Selected Areas in Cryptography 3006:175-193,2003
- http://springerlink.metapress.com/openurl.asp?genre=article{\&}issn=0302-9743{\&}volume=3006{\&}spage=175
BibtexAuthor : Henri Gilbert, Helena Handschuh
Title : Security Analysis of SHA-256 and Sisters
In : Selected Areas in Cryptography -
Address :
Date : 2003
