MD4 collision reproduced

David Shaw dshaw at jabberwocky.com
Tue Aug 17 01:10:16 EDT 2004


I have reproduced both MD4 collisions from the recent paper.  The
example given had endian problems similar to those noted by Eric
Rescorla for the sorta-MD5 collision.  Also similar to Eric's results,
the hash value (while a collision) does not match what the authors
give in the paper.

Example one:

$ od -tx1 file1.bin 
0000000 83 9c 7a 4d 7a 92 cb 56 78 a5 d5 b9 ee a5 a7 57
0000020 3c 8a 74 de b3 66 c3 dc 20 a0 83 b6 9f 5d 2a 3b
0000040 b3 71 9d c6 98 91 e9 f9 5e 80 9f d7 e8 b2 3b a6
0000060 31 8e dd 45 e5 1f e3 97 08 bf 94 27 e9 c3 e8 b9
0000100
$ od -tx1 file2.bin
0000000 83 9c 7a 4d 7a 92 cb d6 78 a5 d5 29 ee a5 a7 57
0000020 3c 8a 74 de b3 66 c3 dc 20 a0 83 b6 9f 5d 2a 3b
0000040 b3 71 9d c6 98 91 e9 f9 5e 80 9f d7 e8 b2 3b a6
0000060 31 8e dc 45 e5 1f e3 97 08 bf 94 27 e9 c3 e8 b9
0000100
$ cmp file1.bin file2.bin
file1.bin file2.bin differ: char 8, line 1
$ openssl md4 file1.bin file2.bin
MD4(file1.bin)= 4d7e6a1defa93d2dde05b45d864c429b
MD4(file2.bin)= 4d7e6a1defa93d2dde05b45d864c429b

Example two:

$ od -tx1 file1.bin 
0000000 83 9c 7a 4d 7a 92 cb 56 78 a5 d5 b9 ee a5 a7 57
0000020 3c 8a 74 de b3 66 c3 dc 20 a0 83 b6 9f 5d 2a 3b
0000040 b3 71 9d c6 98 91 e9 f9 5e 80 9f d7 e8 b2 3b a6
0000060 31 8e dd 45 e5 1f e3 97 40 c2 13 f7 69 cf b8 a7
0000100
$ od -tx1 file2.bin 
0000000 83 9c 7a 4d 7a 92 cb d6 78 a5 d5 29 ee a5 a7 57
0000020 3c 8a 74 de b3 66 c3 dc 20 a0 83 b6 9f 5d 2a 3b
0000040 b3 71 9d c6 98 91 e9 f9 5e 80 9f d7 e8 b2 3b a6
0000060 31 8e dc 45 e5 1f e3 97 40 c2 13 f7 69 cf b8 a7
0000100
$ cmp file1.bin file2.bin 
file1.bin file2.bin differ: char 8, line 1
$ openssl md4 file1.bin file2.bin 
MD4(file1.bin)= c6f3b3fe1f4833e0697340fb214fb9ea
MD4(file2.bin)= c6f3b3fe1f4833e0697340fb214fb9ea

David

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