digital signature

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digital signature

[′dij·əd·əl ′sig·nə·chər]
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.

digital signature

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.

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.
References in periodicals archive ?
It was latter decided to supplement e-Gov Identity with a function of the e-signature, with which the platform of mobile identification became even more functional.
The first step in fostering adoption is getting the right e-signature solution.
The fifth, an E-Signature Ambassador Award, recognizes an individual's contribution in helping advance e-signature adoption through education, innovation and participation in industry associations.
An e-signature session is created where the signatory's details and documents are submitted and ID verification is undertaken.
60% OF INSURANCE COMPANIES that sell their products through financial professionals use e-signatures and an additional 20% plan to add this tool within a year.
SignDoc Enterprise enables organizations to design, deploy and manage custom e-signing workflows and embed advanced e-signature capabilities within a host of enterprise applications.
Nearly two-thirds of carriers, he said, now use some type of e-signature and offer them to their distribution channels "for everything from sales, onboarding new producers, vendor agreements, claims payments, new employees .
The legal groundwork for a cross-border e-signature law was established by a directive issued in 1999.
The E-App to E-Signature solution framework reinforces our intent to innovate by using latest technology as well as improve and enhance existing processes,: says Faisal Husain, CEO of Synechron.
After the successful activation and execution of e-signature system in government internal correspondences, it can be applied for all types of public services,' Abdullah said.
With an e-signature and Web contracting solution, schools can stop worrying about their seemingly endless paperwork and focus on more important tasks.
We get more calls from apartment communities who show interest in our E-Signature Module than any other feature," says Javier Gonzalez, President, Blue Moon.