Comments on ionous: HMAC vs. raw SHA-1

you're right that the hash includes includes t...

2010-06-24T11:12:50.461-07:00

you're right that the hash includes includes the length. my explanation definitely glosses over the way the actual extension attack works.

many hashing algorithms, SHA included, consist of two discrete stages.

in the first stage, the algorithm splits the message into fixed size blocks. as it does so, it pads the message to make sure the final block is of the right

Good explanation, but I have a question about it. ...

2010-06-21T05:00:48.231-07:00

Good explanation, but I have a question about it.
SHA-1 uses padding that incorporates the length of the original message.
Suppose the original length of the message is 10 bytes and the modified one is 15 bytes.
When the hash is calculated, the first block will be different at the sender and the receiver side (since the messages have a different length).
How can this result in

exactly what I was looking for, thank you.

2010-02-11T16:39:07.074-08:00

exactly what I was looking for, thank you.

Thanks for the explanation.

2009-03-09T07:45:00.000-07:00

Thanks for the explanation.