Paper 2010/643

Construct MD5 Collisions Using Just A Single Block Of Message

Tao Xie and Dengguo Feng


So far, all the differential attacks on MD5 were constructed through multi-block collision method. Can collisions for MD5 be found using just a single block of message (i.e. 512-bit)? This has been an open problem since the first 2-block collision attack was given. Today, in the last month (Dec,) of 2010, we have to make public a result of our 1-block collision attacks on MD5 in Table 1 as below, which was actually obtained at the beginning of 2010, but for security reasons, the techniques are not allowed to be disclosed at the moment. Here, we are calling for a challenge to the cryptology community that, any one who first gives a new different 1-block collision attack on MD5 will win 10,000 US dollars (about 50,000 RMB in Chinese Yuan) as a reward for his (her) excellent work. This call for challenge will be ended on Jan 1st, 2013. This announcement’s first affiliated unit will be responsible for this amount of reward when a new different 1-block collision attack is received and verified.

Note: Important Revision!!! This is a replacement of the previous paper.

Available format(s)
Publication info
Published elsewhere. No Publication
1-Block MD5 Collision AttackChallendgeReward
Contact author(s)
hamishxie @ vip sina com
2010-12-25: revised
2010-12-21: received
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      author = {Tao Xie and Dengguo Feng},
      title = {Construct MD5 Collisions Using Just A Single Block Of Message},
      howpublished = {Cryptology ePrint Archive, Paper 2010/643},
      year = {2010},
      note = {\url{}},
      url = {}
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