Because many of the hash-functions implemented by LTC use the length
of the input when padding the input out to a block-length, LTC keeps
track of the input length in a 64-bit integer. However, it did not
previously test for overflow of this value. Since many of the
hash-functions implemented by LTC are defined for inputs of length
2^128 bits or more, this means that LTC was incorrectly implementing
these hash functions for extremely long inputs. Also, this might have
been a minor security problem: A clever attacker might have been able
to take a message with a known hash and find another message (longer
by 2^64 bits) that would be hashed to the same value by LTC.
Fortunately, LTC uses a pre-processor macro to make the actual code
for hashing, and so this problem could be fixed by adding an
overflow-check to that macro.
