Computer Evidence Glossary

         A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Hacker: Someone who breaks into computer systems in order to steal, change or destroy information.

Half Duplex: Transmission systems that can send and receive, but not at the same time.

Halftone: See Dithering.

Handshake: A transmission that occurs at the beginning of a communications session between computers to ensure they agree on how the communication will proceed.

Hard Drive: The primary storage unit on PCs, consisting of one or more magnetic media platters on which digital data can be written and erased magnetically. See Platter.

Harvesting: The process of retrieving or collecting ESI from storage media or devices; an e­discovery vendor or specialist “harvests” ESI from computer hard drives, file servers, CDs, and backup tapes for processing and load to storage media or a database management system.

Hash: A mathematical algorithm that represents a unique value for a given set of data, similar to a digital fingerprint. Common hash algorithms include MD5 and SHA.

Hash Coding: To create a digital fingerprint that represents the binary content of a file unique to every electronically­generated document; assists in subsequently ensuring that data has not been modified. See also Data Verification, Digital Fingerprint and File Level Binary Comparison.

Hash Function: A function used to create a hash value from binary input. The hash is substantially smaller than the text itself, and is generated by the hash function in such a way that it is extremely unlikely that some other input will produce the same hash value.

HD (High Density): A 5.25” HD Floppy Disc holds 1.2 MB and a 3.5” holds 1.4 MB.

Head: Each platter on a hard drive contains a head for each side of the platter. The heads are devices which ride very closely to the surface of the platter and allow information to be read from and written to the platter.

Header: In information technology, a header is, in general, something that goes in front of something else and is usually repeated as a standard part of the units of something else. A header can consist of multiple fields, each containing its own value. In email it is the part of the message containing information about the message, such as the sender, date sent and other brief details.

Hexadecimal: A number system with a base of 16. The digits are 0­9 and A­F, where F equals the decimal value of 15.

Hidden Files or Data: Files or data not visible in the file directory; cannot be accessed by unauthorized or unsophisticated users. Some operating system files are hidden, to prevent inexperienced users from inadvertently deleting or changing these essential files. See also Steganography.

Hierarchical Storage Management (HSM): Software that automatically migrates files from on­line to near­line storage media, usually on the basis of the age or frequency of use of the files.

Hold: See Legal Hold.

Holorith: Encoded data on aperture cards or old­style punch cards that contained encoded data.

Horizontal De­duplication: A way to identify ESI duplicated across multiple custodians or other production data sets. See De­Duplication.

Host: In a network, the central computer that controls the remote computers and holds the central databases.

HP­PCL & HPGL: Hewlett­Packard graphics file formats.

HRS: Handwriting recognition software for interpreting handwriting into machine readable form.

HTCIA (High Technology Crime Investigation Association): Computer forensics non­profit association; resources include educational programs and list servs.

HTML: HyperText Markup Language, developed by CERN of Geneva, Switzerland. The document format used on the Internet. (HTML+ adds support for multi­media.) The tag­based ASCII language used to create pages on the World Wide Web ­uses tags to tell a web browser to display text and images. HTML is a markup or “presentation” language, not a programming language. Programming code can be imbedded in an HTML page to make it interactive. See Java.

HTTP (HyperText Transfer Protocol): The underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.

Hub: A network device that connects multiple computers/peripherals together and allows them to share ESI. A central unit that repeats and/or amplifies data signals being sent across a network.

Hyperlink: A link ­usually appearing as an underlined or highlighted word or picture within a hypertext document ­that when clicked changes the active view, possibly to another place within the same document or view, or to another document altogether, usually regardless of the application or environment in which the other document or view exists.

HyperText: Text that includes links or shortcuts to other documents or views, allowing the reader to easily jump from one view to a related view in a non­linear fashion.

Glossary - Courtesy of The Sedona Conference^®