For example, I have:
- Unknown: A secret variable, lets call it
secret, that is unknown to me
- Known: The length of
secret, (lets say 128 bytes)
- Known: The hash of
secret, in hash1 (lets say hash1 is sha512, this is an important part of the question since hash1 isn't hash2)
My objective here is to get hash2(secret || data_that_I_know), but hash2 being different than hash1, (lets say hash2 is sha1).
With my current understanding of the length extension attack I believe I can obtain the digest of hash1(secret || data_that_I_know), but, is it possible to get the digest from another hash type (like sha256, md5 etc.)?