Official Rules

Final Results

The challenge is now over.
A Collision in the full MD5 hash function was found by researchers in China. Wang, Feng, Lai, and Yu published full collisions for:

  • MD4,
  • MD5,
  • HAVAL-128, and
  • RIPEMD-128
    This represents one the the most substantial developments in cryptography in recent years. Using their technique, an MD5 collision can be found in a matter of minutes!!!
    Here are the files you can use to verify their discovery:


    CertainKey will give one award of $10,000 CAD in a lump sum to the individual or group that discovers the first collision in the MD5 hash algorithm as defined by RFC 1321.

    Only one award will be given. CertainKey will verify the validity of all submitted claims and the award will be paid for the first verifiable collision.

    A valid claim must include the following:

    1. A description of the hardware and software used to find the collision.
    2. The date, time and time zone of the discovery.
    3. Provide a single point of contact, including an e-mail address, postal address and phone number where CertainKey can contact the claimant regarding the claim. In the case of a group effort, the group must designate an individual with whom CertainKey will correspond.


    1. Full disclosure is required and as such CertainKey requires that rights be given to freely publish the methods, algorithms, source code and detailed descriptions of hardware without undue restrictions or cost. This disclosure is designed to further cryptographic knowledge, specifically in designing effective hash algorithms.
    2. Claims including the above information must be made via e-mail to with the following subject: MD5 collision claim white list
    3. Efforts to discover a collision may not be carried out in a malicious manner. Any person or persons engaged in activities not in the scientific spirit of the competition will be disqualified and lose any claim to the award.
    CertainKey reserves the right to make changes to these rules for clarification, to remove ambiguity and correct errors.