The FREE Cybersecurity Glossary by Thor Pedersen!

Birthday Attack: A type of cryptographic attack that exploits the mathematics behind the birthday problem in probability theory. It takes advantage of the fact that in a set of randomly chosen people, there's a high probability that two of them will share the same birthday. Similarly, in cryptography, the attack uses this principle to find collisions in hash functions, which occur when two different inputs produce the same hash output. This can compromise cryptographic systems that rely on the uniqueness of hash values. The attacker generates multiple variants of input data and computes their hash values until a collision is found. This is significantly faster than a brute force search for two inputs with the same hash value due to the birthday paradox's counterintuitive probability curves. It's particularly a concern for digital signatures and data integrity checks that rely on hashing algorithms.

Bit Error Rate: The number of incorrect bits transmitted in a message, usually expressed as a ratio or percentage. It measures the reliability of communication systems, with a lower bit error rate indicating higher reliability. For example, a bit error rate of 10^-6 means that, on average, one bit error occurs for every one million bits transmitted.

Bit Splitting: A data security technique where data bits are divided and distributed across different locations or paths to enhance security by making it difficult for unauthorized parties to reconstruct the original data.

Black Box Testing: A method of evaluating system functionality without any knowledge of its internal workings or structure. This approach views the system as a "black box," focusing solely on input and output without concerning itself with internal behavior. It can be applied in various scenarios, including functional testing, integration testing, and system testing. In a security context, it is used in penetration testing to identify vulnerabilities or potential entry points for attacks, mimicking the approach of a potential external attacker.

Blind FTP: A form of FTP that allows file transfers without user login or credentials. These servers are configured for anonymous access, commonly used to distribute publicly available files.

Blockchain: A distributed database that maintains a continuously growing list of records (blocks) secured by cryptography. It is used in digital currencies and distributed systems to provide a secure and transparent way of storing and verifying data. For example, a blockchain network can be used to record and verify transactions in a decentralized manner without the need for a central authority.