D.Aruna individual only. II. DIGITAL SIGNATURE The authenticity of


of computer application,

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Saraswathi College Of Arts & science,Theni,

Nadu, India

[email protected]


ABSTRACT: Digital signature methodology
provides cryptographic services like entity authentication, authenticated  key transmission and authenticated key
agreement. A Digital Signature is used to provide authentication,
non-repudiation & integrity over the digital data in data exchanged and to
validate the recipient for the authorized identity over open network. The goal
of a Digital signature algorithm is to provide security for message or data.


Keywords : Digital signature, Authentication, Non-repudiation, Integrity


             The information is
highly secret which requires a great security, thus, an extensive security
measures have to be adopted. Many algorithms and techniques can be used to
secure our data or information from threats. These kinds of technologies and
algorithms are collectively known as Cryptography.

            Cryptography system can be widely
categorized into two parts first one is symmetric key cryptography (single key
system) which is possessed by both the sender and receiver and another one is public key system
(asymmetric key cryptography) in which uses of two keys are provided, first is
public key which is common for both the sender and receiver and other one is
private key which is known to the individual only.



authenticity of many legal, financial, and other documents is done by the presence
or absence of an authorized handwritten signature.”Digital Signature” is the best
solution for
authenticity in various fields. A. Digital Signature is an authentication
mechanism that enables the creator of a message to attach a code that acts as a
signature. The signature is formed by taking the hash of the message and
encrypting the message with the creator’s private key. The signature guarantees
the source and integrity of the message.


It must have the following


must verify the author and the date and time of the signature

must to authenticate the  contents at the
time of the  signature

must be verifiable by third parties to resolve disputes




Out of all cryptographic primitives, the digital
signature using public key cryptography is considered as very important and
useful tool to achieve information security.

Apart from ability to provide non-repudiation of message, the
digital signature also provides message authentication and data integrity. Let
us briefly see how this is achieved by the digital signature ?

Message authentication ? When the verifier validates the digital
signature using public key of a sender, he is assured that signature has been
created only by sender who possess the corresponding secret private key and no
one else.

Data Integrity ? In case an attacker has access to the data and modifies
it, the digital signature verification at receiver end fails. The hash of
modified data and the output provided by the verification algorithm will not
match. Hence, receiver can safely deny the message assuming that data integrity
has been breached.

Non-repudiation ? Since it is assumed that only the signer
has the knowledge of the signature key, he can only create unique signature on
a given data. Thus the receiver can present data and the digital signature to a
third party as evidence if any dispute arises in the future.





signature algorithm (DSA) is the part of Digital Signature Standard (DSS)
approach, which is developed by the U.S. National Security Agency (NSA).DSA is
a Federal Information Processing Standard for digital signatures. In August
1991 DSA is developed by the National Institute of Standards and Technology
(NIST).There are two different approaches to the Digital Signature

The RSA Approach.

The DSS Approach.

The RSA Approach

the RSA approach, the message to be signed is input to a hash function that
produces a secure hash code of fixed length. This hash code is then encrypted
using the sender’s private key to form the signature. Both the message and the
signature are then transmitted. The recipient takes the message and produces a
hash code. The recipient also decrypts the signature using the sender’s public
key. If the calculated hash code matches the decrypted signature, the signature
is accepted as valid. Because only the sender knows the private key, only the
sender could have produced a valid signature.

The DSS Approach

The DSS approach also makes use of hash function.
The hash code is provided as input  to a
signature function along with a random number k generated for this particular
signature. The signature function also depends on the sender’s private key and
a set of parameters known to a group of communication principals. We can
consider this set to constitute a global public key. The result is a signature
consisting of two components, labeled s and r.





With the use of digital
signature we can remove the chance of committing scam because the digital
signature cannot be changed. Moreover the forging Signature is impossible.

By having a digital
signature we are proving the Document to be legal We are assuring the receiver
that The document is free from fake or false information.

Increases the speed and correctness
of transactions.


Cost-you must have the essential
software to instruct The signatures, and if you’re using hardware so that
Customers can sign physically, then the cost goes up Even further. Digital
signatures are an extra cost That should be weighed against their possible security

Preparation and
troubleshooting -if your employees aren’t Sure how to use a digital signature,
then  you’ll have to Spend time training
them about how the signature Process works. Additionally, as with all computer
digital Signature 118 Related applications, sooner or later there will be a
Hiccups in the system and you’ll need someone to Troubleshoot.







             The Digital Signature which is based on RSA and DSA approach has been
done. Digital signatures will be championed by many players that the public
distrusts, including national security agencies. New variant    of
algorithms of digital signature that are based on many hard problems like the
elliptic curve, disconnected logarithm and prime factorization has also been
discussed. Based on the relative analysis, we show the performances based on
many characteristics.




1.Wiptogrlliam stalling, a
book of “cryptography and network security principles and practices”,fourth

2..D. Boneh   and 
H.  Shacham  Fast  
variants of   RSA. CryptoBytes
(RSA  Laboratories )

Cryptography and Network Security, 3rd ed.

   EnglewoodCliffs, NJ: Prentice-Hall, 2002.

4.Ashish Vijay, Priyanka
Trikha , Kapil Madhur,” A New Variant of RSA Digital








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