DIGITAL SIGNATURE

DIGITAL SIGNATURE-:

digital signature or digital signature scheme is a type of a symmetric cryptography. For messages sent through an insecure channel, a properly implemented digital signature gives the receiver reason to believe the message was sent by the claimed sender.

Uses of digital signatures-

Below are some common reasons for applying a digital signature to communications:AA

Authentication-

Digital signatures can be used to authenticate the source of messages. When ownership of a digital signature secret key is bound to a specific user, a valid signature shows that the message was sent by that user.

Integrity-

It confirms that the message has not been altered.

Gnome PGP-

GnomePGP is a PGP frontend/widget for GNOME. GnomePGP uses GNU Privacy Guard (gpg) so GnomePGP is completly Free Software. GnomePGP allows you to browse and edit keyrings, sign and encrypt files, etc. There is a plan to make a complete GUI for PGP. GnomePGP is split into widgets, which you can use it in your applications.

GNOME -

GNOME is a desktop environment—the graphical user interface which runs on top of a computer operating system -composed entirely of free software. It is an international project that includes creating software development frameworks, selecting application software for the desktop, and working on the programs which manage application launching, file handling, and window and task management.GNOME is part of the GProject and can be used with various Unix-like operating systems, most notably those built on top of the Linux-Kernel and the GNU Userland , and as part of Java Desktop system in Solaris.

Widget-

A widget (or control) is an element of a (GUI) that displays an information arrangement changeable by the user, such as a window or a textbox . The defining characteristic of a widget is to provide a single interaction point for the direct manipulation of a given kind of data. Widgets are basic visual building blocks which, combined in an application, hold all the data processed by the application and the available interactions on this data.

GTK+ is an object oriented widget toolkit written in the c programming language ; object orientation is achieved by using the Glib object system.

PGP:

PGP uses a cryptographically strong hash function on the plaintext the user is signing. This generates a fixed-length data item known as a message digest. (Again, any change to the information results in a totally different digest.)Then PGP uses the digest and the private key to create the "signature." PGP transmits the signature and the plaintext together. Upon receipt of the message, the recipient uses PGP to recompute the digest, thus verifying the signature. PGP can encrypt the plaintext or not; signing plaintext is useful if some of the recipients are not interested in or capable of verifying the signature.

At The Sender's End-
Plain Text------------hash function--------------->Message Digest (S=Sender,R=Recepient)
Message Digest-----encrypt(S.private Key)---->Digital Signature

This Digital Signature Is Them Appended With The Document And Sent To Recipient


At The recipient's end-
Plain Text -------decrypt(S.public key)------->Message Digest


If S.Message Digest Is Found To Be Same as R.Message digest Then It Confirms That Message Has Been Sent By That Sender And Has Not Been Altered.