I am currently implementing the SHA256 hash-algorithm for a "custom-built" embeded-device. Obviously I have a problem with message padding. The routine I wrote does not work with message whose size equals exactly 512 bits.
In that case, how should the message be padded ? i.e.
M = "AABBCCDDEEFFGGHHIIJJKKLLMMNNOOPPAABBCCDDEEFFGGHHIIJJKKLLMMNNOOPP"
I mean, what should be the hexa-decimal representation of the last padded block?