digital signature

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Related to digital signature: Digital certificate, Digital Signature Algorithm

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 ?
The existing implementations of the digital signature systems, most often use the following cryptographic algorithms:
CoSign has the unique ability to seamlessly integrate with organizations' existing user-management systems, thereby streamlining the deployment of digital signatures within the organization.
Its products are optimized for high volume transaction applications intended for digitally signing documents and verifying digital signatures.
Many high profile companies in various industries and governmental organizations using AuthentiDate digital signature solutions for years in Germany, Europe and other countries to substitute paper processing through legally binding, electronic business processes in accordance with international and local legal environments.
A digital signature relies on the mathematically complex world of asymmetric cryptography.
Digital signatures are based on techniques used in cryptology.
As electronic commerce grows and computer-based business becomes the norm, states that have digital signature laws will be prepared for great changes in contract and commercial law.
which produces equipment and software based on a rival, proprietary digital signature and encryption method known as RSA.
ARX (Algorithmic Research) is a leading provider of secure, cost-efficient digital signature solutions for the AEC industry.
Every time Corporation Ideal reviews a record or needs it for court, it can show the digital signature being associated with the transaction record.
SAN FRANCISCO -- ARX (Algorithmic Research), the leader in enterprise digital signature solutions, announced today that its CoSign digital signature solution has passed tests as defined by the Defense Information Systems Agency (DISA) Joint Interoperability Test Command (JITC).
define what constitutes a legitimate, safe, secure digital signature -- matters that will be addressed in future regulations.

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