06-07-2012, 02:28 PM
FPGA IMPLEMENTATION OF COST EFFICIENT SECURE HASH ALGORITHM
FPGA IMPLEMENTATION .ppt (Size: 1.5 MB / Downloads: 38)
Cryptography
Cryptography is an effective way of protecting sensitive information as it is stored on media or transmitted through network communication paths.
The word cryptography refers to the science of keeping secrecy of message exchanged between a sender and a receiver over an insecure channel
Cryptography is used to implement security services
INTRODUCTION
The SHA-1 was approved by national institute of standards and technology (NIST) in 1995.
SHA is a one-way hash function designed by Ron Rivest.
SHA is similar to message digest(MD-4). It has some extra mathematical functions and produces a160-bit hash instead of 128-bit, which makes it more security.
Secure hash algorithm follows some standard values that are :-
Non- linear function
Constant values
Initial hash values
Secure hash algorithm
Secure hash algorithm (SHA-1) requires the operation of 80 rounds which can be grouped into 4 groups, 20 rounds each.
Each round operates on five 32 bits hashing words (H0 to H4) which have A to E as their temporary versions.
Functions and constants are basic operation of each round. Those constants are round constants ( Kt ) and message word computations (Wt ).
The SHA-1 takes an input of 512-bits variable length string and produces an output of fixed length 160- bits message digest.
MESSAGE DIGEST
The message digest function operates on message schedule to form a 160-bits digest image of a each data block.
The message digest is initialized with five 32-bits words that are A,B,C,D,E, to form the initial digest.
The message digest sequentially processes each message schedule with set of operators , by mixing each words , forming intermediate hash value.
The word computation wt of 32-bits is an input for message digest single round.