[HN Gopher] MD5 Collision with CRC32 Preimage
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       MD5 Collision with CRC32 Preimage
        
       Author : Retr0id
       Score  : 27 points
       Date   : 2022-09-23 19:46 UTC (3 hours ago)
        
 (HTM) web link (gist.github.com)
 (TXT) w3m dump (gist.github.com)
        
       | hkopp wrote:
       | Note that hashquines, i.e., programs that print their own hash
       | when executed do not depend on the hash function being broken. In
       | fact, they are a fun little exercise.
        
         | smegsicle wrote:
         | #!/bin/sh         md5sum $0
        
         | acchow wrote:
         | I have no idea where to even begin if the digest does not leak
         | _something_ about the data
        
           | adastra22 wrote:
           | Any cryptographic digest is not supposed to leak anything
           | about the data that went in. That's a core property.
           | 
           | In this case the hash doesn't depend on the data at all. Do
           | you see how that helps?
        
       | eimrine wrote:
       | MD5 is broken so badly that this hash starts and ends with 1337.
       | Next step is to generate that type of quine when image has two
       | pieces of string data: one is hash of image with no quine and
       | another is exactly same image with two hashes.
        
         | pxx wrote:
         | 0x1337 is only two bytes. 2^32, for four bytes, is not a
         | particularly large number.
        
         | londons_explore wrote:
         | What are you talking about?? The hash _does not_ start 1337...
         | The hash of the example files is
         | f54e7363d9c72ebf81605e2b38fa2be5. The crc32 is deadbeef.
        
           | Retr0id wrote:
           | They're describing the PNG hashquine, which is referenced
           | near the start of the article.
        
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       (page generated 2022-09-23 23:02 UTC)