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ChainHash Definitions
chain variable
A chain variable is a variable taking value in the
set of all bit strings of a specified length.
block
A block is a bit string of a specified length.
compression function
A compression function is a function from the product
space of the domains of a specified set of
chain variables and the
Set of all blocks of some fixed length to
the product space of the domains of the chain variables.
initial value
An initial value is a explicitly specified point
in the product space of the domains of a set of
chain variables.
padding algorithm
A padding algorithm is an algorithm which appends
bits to a bit string giving a new bit string whose length
has some desired propery.
chain hash function
A chain hash function is a function constructed from
a compression function, padding algorithm and
initial value in such a manner as to have the following properties:
- Its domain is either all bits string up to some specified
length, or arbitrary length bit strings.
- Its range is the equal to the range of the
compression function.
- The value of the function at a bit string is determined
as follows:
- The bit string is padded by using the
padding algorithm to
increase its length to a multiple of the size
of the blocks of the compression function.
- The chain variables are set equal to the
initial value.
- For each block in the padded message, the
chain variables' values are updated to the
value of the compression function at the point
specified by the chain variable and the
block.
- The value of the chain hash function is equal to the
concatenation of the final values of the
chain variables.
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