Introduction to Modern Cryptography(Recap Day1)

Recap:

Cryptography evolves from an art form into a science.

It is the scientific study of techniques for securing digital information, transactions, and distributed computations.

The setting of private key Encryption, a.k.a symmetrical encryption

more formally defined, an encryption scheme is:

Key generation algorithm: Gen

encryption algorithm: Enc

Decryption algorithm: Dec

plaintext space M

key space K

Dec(Enc(M))=M(with K)

Kerckhoff's principle: not the algorithm needed secret but the key

Attack scenarios:

Ciphertext-only attack

Known-plaintext attack

Chosen-plaintext attack

Chosen-ciphertext attack