I am trying to understand MD5 hash algorithm from the link http://www.ietf.org/rfc/rfc1321.txt
At first I was not able to understand padding of MD5. Then I asked a question in this link: To understand a fact related to padding in MD5
From this answer I can understand padding. Now I have faced another problem: to understand the second step of MD5.
I am trying to understand the second step from the same link: http://www.ietf.org/rfc/rfc1321.txt
But I have failed to understand a sentence and a phrase as before. Here is the phrase:
A 64-bit representation of b
what does 64-bit representation stand for?
Here is the next sentence:
In the unlikely event that b is greater than 2^64, then only the low-order 64 bits of b are used.
what does lower-order bits mean?
Can anyone explain the above phrase and sentence with better clarity?