So I'm reading this question to learn more about length extension attack, and I want to make sure I understand the basics of padding.
It says in the post that given the hash and the length of the message, I can easily compute the padding.
Now, from what I understand, each block will always be 512 bits, or 64 bytes.
So does this mean if I have a message that says "LengthExtensionIsSuchAnInterestingConcept", which has a length of 41, it occupies 41 bytes. (Looked at some other posts, ASCII character is 1 byte per character. please correct me if I'm wrong.)
64 - 41 = 23 bytes, so the padding will be 23 bytes. And the entire MD5 in this case will only consists of one block.
Am I correct in my understanding above?