Cybersecurity Glossary

Non-repudiation refers to the ability of a system to prove that a specific user and only that specific user sent a message and that it hasn’t been modified. On the internet, a digital signature is used not only to ensure that a message or document has been electronically signed by the person, but also, since a digital signature can only be created by one person, to ensure that a person cannot later deny that they furnished the signature.

A non-printable character is a character that doesn’t have a corresponding character letter to its corresponding ascii code. Examples would be the linefeed, which is ASCII character code 10 decimal, the carriage return, which is 13 decimal, or the bell sound, which is decimal 7. On a pc, you can often add non-printable characters by holding down the alt key, and typing in the decimal value (i.e., alt-007 gets you a bell). There are other character encoding schemes, but ascii is the most prevalent.

OSI (open system interconnection) is an ISO standard for worldwide communications. OSI defines a networking framework for implementing protocols in seven layers. OSI defines seven layers of functions that take place at each end of a communication. Although OSI is not always strictly adhered to in terms of keeping related functions together in a well-defined layer, many products involved in telecommunication attempt to describe themselves in relation to the OSI model.

A one-way function is any function that is easy to compute on every input, but hard to invert given the image of a random input.

An open shortest path first (OSPF) is a routing protocol for IP networks and uses a link-state routing algorithm. It falls into the group of interior routing protocols, operating within a single autonomous system (AS). OSPF is the most commonly used interior gateway protocol (IGP) in large enterprise networks.

Overload is defined as the limitation of system operation by excessive burden on the performance capabilities of a system component.

An octet is a unit of digital information that consists of eight bits. Octets are generally displayed using a variety of representations, for example in the hexadecimal, decimal, or octal number systems. The binary value of all 8 bits set (or turned on) is 11111111, equal to the hexadecimal value ff, the decimal value 255, and the octal value 377. One octet can be used to represent decimal values ranging from 0 to 255.

The open system interconnection (OSI) model defines a networking framework to implement protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. The OSI model takes the task of internetworking and divides that up into what is referred to as a vertical stack that consists of the following layers.1. Physical (layer 1) – this layer conveys the bit stream, electrical impulse, light, or radio signal through the network at the electrical and mechanical level. Fast ethernet, rs232, and ATM are protocols with physical layer components.2. Data link (layer 2) – at this layer, data packets are encoded and decoded into bits. The data link layer is divided into two sub layers: the media access control (MAC) layer and the logical link control (LLC) layer.3. Network (layer 3) – this layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node.4. Transport (layer 4) – this layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.5. Session (layer 5) – this layer establishes, manages and terminates connections between applications.6. Presentation (layer 6) – this layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa.7. Application (layer 7) – this layer supports application and end-user processes. This layer provides application services for file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist entirely at the application level.

One-way encryption or one-way hash function is designed in a manner that it is hard to reverse the process, that is, to find a string that hashes to a given value (hence the name one-way). A good hash function makes it hard to find two strings that would produce the same hash value.

Patching is the process of updating software to a different version. It is also referred to as updating the software to the latest version available and is key in removing bugs of the previous version.