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Diffstat (limited to 'documentation/README.md')
| -rw-r--r-- | documentation/README.md | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/documentation/README.md b/documentation/README.md index ca08eef..f507ecc 100644 --- a/documentation/README.md +++ b/documentation/README.md @@ -206,12 +206,14 @@ can now list the hashes of all registered users. The next step is to find a valid preimage for the hashes obtained previously, to log in as them and query information about their files. -To calculate the preimage we choose a seed for srand at random. Then -we XOR the values encoded in the hex-encoded with calls to rand(). -If the sum of the generated values is greated than the seed we used, -restart. Otherwise, append some characters to make the sum match -the seed like it does in mhash. The value of these 'extra' chars -is irrelevant, since mhash only processes the first 20 chars anyways. +To calculate the preimage we repeatedly choose a seed for srand. For +each seed, we XOR the values encoded in the hex-encoded hash with +calls to rand(). If after generating each character the sum of the +generated values is less than the seed we used, restart. Otherwise, +we append some characters to make the sum of the input characters +match the seed, such that the seed for srand mhash uses matches the +one we chose. The actual value of these 'extra' chars is irrelevant, +since mhash only processes the first 20 chars anyways. See `checker/src/revhash/main.c` for an example implementation in C. |