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P ICTORIAL O VERVIEW
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DIGITAL SIGNATURESBy Umair Sadiq
WHAT IS A DIGITAL SIGNATURE? A signature to validate any electronic data.
Its not modified It belongs to signatory Signatory cannot repudiate
PICTORIAL OVERVIEW
VARIOUS ALGORITHMS RSA DSA (US Federal Govt Standard) Elliptic Curve DSA ElGamal (based on computing discrete
logarithm), Pointcheval-Stern (a variant of ElGamal) Note: Unlocking the key requires solution to a
mathematically hard problem like factoring the product of large primes or computing discrete logarithms
A SIMPLIFIED SCENARIO
nmsgcode e mod
msg
nmsg
ncodede
d
)(mod
mod
Encryption, (e,n)
Decryption, (d,n) msg
)(ned
POTENTIAL THREATS AND SOLUTIONS Man-in-the-middle-attack
a person intercepts and modifies messages in both direction and uses its own generated set of keys
digital certificates are used to authenticate keys
Timing attacks with the knowledge of hardware and decipher
time becomes possible to deduce the key it is rectified by combining decryption with a
random computation
CONCLUSION Where digital signature provide a safe way to
authenticate electronic piece of information, it is important to use an algorithm that has been put to rigorous testing and has proven its validity over a period of time.
REFERENCES http://csrc.nist.gov/publications/fips/fips186-
2/fips186-2-change1.pdf http://www.abanet.org/scitech/ec/isc/dsg-
tutorial.html http://gdp.globus.org/gt4-tutorial/
multiplehtml/ch09s03.html