digital signature

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digital signature

[′dij·əd·əl ′sig·nə·chər]
(communications)
A set of alphabetic or numeric characters used to authenticate a cryptographic message by ensuring that the sender cannot later disavow the message, the receiver cannot forge the message or signature, and the receiver can prove to others that the contents of the message are genuine and originated with the sender.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

digital signature

(cryptography)
Extra data appended to a message which identifies and authenticates the sender and message data using public-key encryption.

The sender uses a one-way hash function to generate a hash-code of about 32 bits from the message data. He then encrypts the hash-code with his private key. The receiver recomputes the hash-code from the data and decrypts the received hash with the sender's public key. If the two hash-codes are equal, the receiver can be sure that data has not been corrupted and that it came from the given sender.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

digital signature

A digital signature is the electronic equivalent of a person's physical signature. It is also a guarantee that information has not been modified, as if it were protected by a tamper-proof seal that is broken if the contents were altered.

Signed Certificates
Digitally signed certificates verify the identity of an organization or individual. Signed certificates are widely used to authenticate a website and establish an encrypted connection for credit cards and confidential data (see digital certificate, SSL and TLS).

Signed Files
Files of any kind can be signed; however, a common application is "code signing," which verifies the integrity of executables downloaded from the Internet. Code signing also uses certificates (see code signing and digital certificate).

An Encrypted Digest
A digital signature is actually an encrypted digest of the data being signed. The digest is computed from the contents of the file by a one-way hash function (see below) and then encrypted with the private key of the signer's public/private key pair. To prove that the file was not tampered with, the recipient uses the public key of the signer to decrypt the signature back into the original digest, recomputes a new digest from the transmitted file and compares the two to see if they match. If they do, the file has not been altered in transit by an attacker. See RSA, MD5, SHA, public key cryptography and electronic signature.


An Encrypted Digest
A digital signature is an encrypted digest of a file. The digest was created with a one-way hash function from the file's contents.







With and Without Privacy


The following two diagrams show how digital signatures are used for data integrity in both non-private and private transmissions.


Message Integrity Without Privacy
The woman makes her message tamper proof by encrypting the digest into a "digital signature," which accompanies the message. At the receiving side, the man uses her public key to verify the signature. However, the message text is sent "in the clear" and could be read by an eavesdropper.








Message Integrity With Privacy
In this example, the message is both signed and transmitted in secret. The woman signs the message first and then entirely encrypts it before sending. The man decrypts the message first and then verifies the signature.
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References in periodicals archive ?
After that authentication is carried out for signature using Digital Signature Scheme (DSS) Algorithm.
Digital signature schemes are based on symmetric-key or asymmetric-key systems and offer effective mechanisms for facilitating content authenticity, integrity, and data-secrecy during transmission.
It is considered the simplest digital signature scheme to be provably secure in a random oracle model.
Reyzin, "A New Forward-Secure Digital Signature Scheme," in Proc.
A digital signature scheme is secure if it is correct and existentially unforgeable under adaptive chosen-message attack (EUF-CMA).
Cypherpunks Mailing List 2 Practical Forward Secure Group Signatures 3 Forward Secure Digital Signature Scheme 4 Forward Secure Signatures with Optimal Signing and Verifying 5 Forward Secure Signatures with Fast Key Update 6 Forward-Secure Threshold Signature Schemes 7 Forward Secure Sequential Aggregate Authenticatio n 8 Universally Composable And Forward-Secure RFID Authenticatio n and Authenticated Key Exchange 9 An Experimental Study Of Transport Layer Security (TLS) Forward Secrecy Deployments.
A digital signature scheme is a mathematical scheme for demonstrating the authenticity of a digital message or document.
A proxy blind signature is a digital signature scheme that performs the functions of both proxy signature and blind signature schemes.
Sendrier, "How to achieve a McEliece-based digital signature scheme," in Advances in Cryptology--ASIACRYPT 2001, vol.
(2000) A new forward secure digital signature scheme. In ASIACRYPT, Springer-Verlag, pp.
Since it was proposed in 1976, the digital signature scheme has more than 40 years' history.
Recently, Tseng[8] et al proposed a new digital signature scheme with message recovery and two variants based on the self-certified public system above.

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