Encryption (AQA A-Level Computer Science): Flashcards

Converting plaintext into ciphertext

Data in readable, understandable format

Substitution cipher shifting letters by fixed positions

Exploits predictable letter patterns to crack ciphers

'e' appears ~12.7% of the time

Rearranges letters rather than substituting them

One-time pad method invented ~100 years ago

Key as long as plaintext, used once then destroyed

Combines plaintext & key bits to create ciphertext

Theoretically breakable but impractical with current tech