To be useful for a message authentication, the hash functions must have the following properties –
• H can be applied to a block of data of any size
• H produces a fixed-length output
• H(x) is easy to compute for any given x, making both hardware and software implementations practical.
• For any given code h, it is computationally infeasible to find x such that H(x) = h. A hash function with this property is referred to as one-way or pre-image resistant.
• For any given block x, it is computationally infeasible to find y ≠ x with H(y) = H(x). A hash function with this property is referred to as second pre-image resistant. This is sometimes referred to as weak collision resistant.
• It is computationally infeasible to find any pair (x, y) such that H(x) = H(y). A hash function with this property is referred to as collision resistant. This is sometimes referred to as strong collision resistant.
it is creating new useful software
Yes, although it might not be a very useful function. However, there are times when you are studing properties of a set of functions and it is quite possible that a member of a set of functions has a null domain.
Their properties
Characteristic properties.
CFC's are useful to man. They act as coolants.
theyre not
No
radio useful the message so radio that is interast the new message
as it is costlier . Less useful than what?
eggs are useful
make it into something useful
Constituents, appearance, shape, and taste are used to classifying materials. This is useful because materials with similar properties can be placed in the same category.