From the course: ISC2 Certified Information Systems Security Professional (CISSP) (2024) Cert Prep

Unlock this course with a free trial

Join today to access over 24,000 courses taught by industry experts.

Knowledge-based attacks

Knowledge-based attacks

From the course: ISC2 Certified Information Systems Security Professional (CISSP) (2024) Cert Prep

Start my 1-month free trial Buy for my team

Knowledge-based attacks

“

- [Instructor] Knowledge-based attacks go beyond the simplicity of brute force attacks and combine other information available to the attacker with cryptanalytic techniques to break the security of encrypted data. The first knowledge-based attack is the frequency analysis attack. In this attack, the person trying to break the code does some statistical analysis of the ciphertext to try to detect patterns. The analyst might use many of the common characteristics of the English language to help with this analysis. For example, you may know that the most common letters in the English language are E, T, O, A,-I, and N. If you suspect that a simple substitution cipher was used and see the letter X coming up repeatedly in the ciphertext, there's a good chance that X was substituted for E. There are also lesser known rules that can assist with frequency analysis. For example, researchers can also use pairs of letters that often appear together, known as digraphs. If they see the same two…

Contents