Encryption/Decryption
plaintext -> Encryption -> ciphertext -> Decryption -> plaintext
there is a one-to-one mapping
provides confidentiality protection
Other services:
Integrity checking: no tampering
Authenticity: verified authorship
Authentication: not an imposter
Encryption basics
ancient crypto:
early sings of encryption in Egypt in ~2000 B.C.
letter-based scheme (e.g., Caesar’s cipher) ever since
Symmetric ciphers:
from ancient time to the presence
Asymmetric ciphers:
first by diffie-Hellman-
