3 ms·
If you trust a signer, does this attack do anything to invalidate their SHA-1-based signatures? Or is the scenario strictly an attacker generating both versions
by 0xcde4c3db 10y ago
If you trust a signer, does this attack do anything to invalidate their SHA-1-based signatures? Or is the scenario strictly an attacker generating both versions of the message?
- sp332 10y agoThis only works if the attacker controls both sides, or at least a piece of both sides. That's a collision attack, and it's much easier than a pre-image or second pre-image attack which tries to match an existing hash.
- Ajedi32 10y agoAs I understand it the attacker would have to generate both versions of the message. If an attacker could generate a second message with a hash that matches that of an existing message from a third party, that would be a second-preimage attack, not merely a collision attack. Even MD5 is still considered to be second-preimage resistant: http://crypto.stackexchange.com/q/3441/21238 http://crypto.stackexchange.com/q/3441/21238