D.ArunaDepartmentof computer application,NadarSaraswathi College Of Arts & science,Theni,TamilNadu, [email protected] ABSTRACT: Digital signature methodologyprovides cryptographic services like entity authentication, authenticated key transmission and authenticated keyagreement.

A Digital Signature is used to provide authentication,non-repudiation & integrity over the digital data in data exchanged and tovalidate the recipient for the authorized identity over open network. The goalof a Digital signature algorithm is to provide security for message or data. Keywords : Digital signature, Authentication, Non-repudiation, IntegrityI. INTRODUCTION The information ishighly secret which requires a great security, thus, an extensive securitymeasures have to be adopted. Many algorithms and techniques can be used tosecure our data or information from threats. These kinds of technologies andalgorithms are collectively known as Cryptography.

Cryptography system can be widelycategorized into two parts first one is symmetric key cryptography (single keysystem) 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 ispublic key which is common for both the sender and receiver and other one isprivate key which is known to the individual only. II. DIGITAL SIGNATURE Theauthenticity of many legal, financial, and other documents is done by the presenceor absence of an authorized handwritten signature.”Digital Signature” is the bestsolution forauthenticity in various fields.

A. Digital Signature is an authenticationmechanism that enables the creator of a message to attach a code that acts as asignature. The signature is formed by taking the hash of the message andencrypting the message with the creator’s private key.

The signature guaranteesthe source and integrity of the message. It must have the followingproperties: · Itmust verify the author and the date and time of the signature· Itmust to authenticate the contents at thetime of the signature· Itmust be verifiable by third parties to resolve disputes III. IMPORTANCEOF DIGITAL SIGNATURE Out of all cryptographic primitives, the digitalsignature using public key cryptography is considered as very important anduseful tool to achieve information security.Apart from ability to provide non-repudiation of message, thedigital signature also provides message authentication and data integrity. Letus briefly see how this is achieved by the digital signature ?· Message authentication ? When the verifier validates the digitalsignature using public key of a sender, he is assured that signature has beencreated only by sender who possess the corresponding secret private key and noone else.· Data Integrity ? In case an attacker has access to the data and modifiesit, the digital signature verification at receiver end fails.

The hash ofmodified data and the output provided by the verification algorithm will notmatch. Hence, receiver can safely deny the message assuming that data integrityhas been breached.· Non-repudiation ? Since it is assumed that only the signerhas the knowledge of the signature key, he can only create unique signature ona given data. Thus the receiver can present data and the digital signature to athird party as evidence if any dispute arises in the future. IV.

APPROACHESDigitalsignature algorithm (DSA) is the part of Digital Signature Standard (DSS)approach, which is developed by the U.S. National Security Agency (NSA).DSA isa Federal Information Processing Standard for digital signatures. In August1991 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 Inthe RSA approach, the message to be signed is input to a hash function thatproduces a secure hash code of fixed length. This hash code is then encryptedusing the sender’s private key to form the signature. Both the message and thesignature are then transmitted. The recipient takes the message and produces ahash code. The recipient also decrypts the signature using the sender’s publickey.

If the calculated hash code matches the decrypted signature, the signatureis accepted as valid. Because only the sender knows the private key, only thesender could have produced a valid signature.The DSS ApproachThe DSS approach also makes use of hash function.The hash code is provided as input to asignature function along with a random number k generated for this particularsignature. The signature function also depends on the sender’s private key anda set of parameters known to a group of communication principals. We canconsider this set to constitute a global public key.

The result is a signatureconsisting of two components, labeled s and r. V.ADVANTAGESAND DISADVANTAGES OF DIGITAL SIGNATURE Advantages· With the use of digitalsignature we can remove the chance of committing scam because the digitalsignature cannot be changed. Moreover the forging Signature is impossible.· By having a digitalsignature we are proving the Document to be legal We are assuring the receiverthat The document is free from fake or false information.· Increases the speed and correctnessof transactions.

Disadvantages· Cost-you must have the essentialsoftware to instruct The signatures, and if you’re using hardware so thatCustomers can sign physically, then the cost goes up Even further. Digitalsignatures are an extra cost That should be weighed against their possible securityBenefits.· Preparation andtroubleshooting -if your employees aren’t Sure how to use a digital signature,then you’ll have to Spend time trainingthem about how the signature Process works. Additionally, as with all computerdigital Signature 118 Related applications, sooner or later there will be aHiccups in the system and you’ll need someone to Troubleshoot. VI.

CONCLUSION The Digital Signature which is based on RSA and DSA approach has beendone. Digital signatures will be championed by many players that the publicdistrusts, including national security agencies. New variant ofalgorithms of digital signature that are based on many hard problems like theelliptic curve, disconnected logarithm and prime factorization has also beendiscussed. Based on the relative analysis, we show the performances based onmany characteristics.

REFERENCES 1.Wiptogrlliam stalling, abook of “cryptography and network security principles and practices”,fourthedition.2..D. Boneh and H. Shacham Fast variants of RSA. CryptoBytes(RSA Laboratories )3.

StallingsW.,Cryptography and Network Security, 3rd ed. EnglewoodCliffs, NJ: Prentice-Hall, 2002.4.

Ashish Vijay, PriyankaTrikha , Kapil Madhur,” A New Variant of RSA Digital Signature”https://www.ijarcsse.com/docs/papers.