D

Data Encryption Standard (DES):

A widely-used method of data encryption using a private (secret) key. There are 72,000,000,000,000,000 (72 quadrillion) or more possible encryption keys that can be used. For each given message, the key is chosen at random from among this enormous number of keys. Like other private key cryptographic methods , both the sender and the receiver must know and use the same private key. Block size is 64 bits, key strength is 56 bits.

Decryption:

Transferring data from a secure, encrypted form to plain data.

De-identified Data:

Truly anonymous information that cannot be related back to a specific person.

Denial of Service:

The prevention of authorized access to a system resource or the delaying of system operations and functions.

Dictionary Attack:

An attack that uses a brute-force technique of successively trying all the words in some large, exhaustive list. For example, an attack on an authentication service by trying all possible passwords; or an attack on encryption by encrypting some known plaintext phrase with all possible keys so that the key for any given encrypted message containing that phrase may be obtained by lookup.

Digital Certificate:

A digital certificate is an electronic 'credit card' that establishes your credentials when doing business or other transactions on the Web. It is issued by a certification authority. It contains your name , a serial number, expiration dates, a copy of the certificate holder's public key (used for encrypting messages and digital signatures), and the digital signature of the certificate-issuing authority so that a recipient can verify that the certificate is real.

Digital Signature Algorithm (DSA):

An asymmetric cryptographic algorithm that produces a digital signature in the form of a pair of large numbers . The signature is computed using rules and parameters such that the identity of the signer and the integrity of the signed data can be verified .

Digital Signature Standard (DSS):

The U.S. Government standard that specifies the Digital Signature Algorithm (DSA), which involves asymmetric cryptography.

Disaster Recovery Plan:

A part of the required contingency plans that covers how the organization will restore any lost data due to natural disasters, vandalism, or system failures.

Disclosure:

The release, transfer, provision of, access to, or divulging in any other manner of information outside the entity holding the information. [45 C.F.R. § 160.103]

Disruption:

A circumstance or event that interrupts or prevents the correct operation of system services and functions.

Domain:

A sphere of knowledge, or a collection of facts about some program entities or a number of network points or addresses, identified by a name. On the Internet, a domain consists of a set of network addresses. In the Internet's domain name system, a domain is a name with which name server records are associated that describe sub-domains or host. In Windows NT and Windows 2000, a domain is a set of network resources (applications, printers, and so forth) for a group of users. The user need only to log in to the domain to gain access to the resources, which may be located on a number of different servers in the network.

Domain Name:

A domain name locates an organization or other entity on the Internet. For example, the domain name 'www.sans.org' locates an Internet address for 'sans.org' at Internet point 199.0.0.2 and a particular host server named 'www' ^. The 'org' part of the domain name reflects the purpose of the organization or entity (in this example, 'organization') and is called the top-level domain name. The 'sans' part of the domain name defines the organization or entity and together with the top-level is called the second-level domain name.

Domain Name System (DNS):

The domain name system (DNS) is the way that Internet domain names are located and translated into Internet Protocol addresses. A domain name is a meaningful and easy-to-remember 'handle' for an Internet address.