4 Cryptography Basics Free Online FlashCards

What are three common goals of cryptography?

Confidentiality keeps data secret, integrity helps detect changes, and authentication establishes who or what is communicating.

What do encryption and decryption do?

Encryption transforms readable plaintext into ciphertext using an algorithm and a key; decryption uses the appropriate key to recover the plaintext.

What key arrangement defines symmetric cryptography?

Symmetric cryptography uses the same secret key, or closely related key material, for encryption and decryption. It is efficient for protecting large amounts of data.

What key pair does asymmetric cryptography use?

Asymmetric cryptography uses a mathematically related public key and private key. The public key can be shared; the private key must be protected.

Which keys encrypt and decrypt a public-key message to Bob?

To send Bob an encrypted message, the sender encrypts it with Bob’s public key, and Bob decrypts it with his private key.

Why do secure connections often combine public-key and symmetric methods?

Public-key methods can help establish shared key material, then efficient symmetric encryption protects bulk data. TLS 1.3 is one example of this combined design.

What does a cryptographic hash function produce?

A cryptographic hash function maps data of any length to a fixed-length value called a hash or digest.

What security properties should a cryptographic hash provide?

A small input change should produce a different digest, and it should be computationally infeasible to find an input matching a chosen digest or two inputs with the same digest.

Why is an unkeyed hash not proof of a message’s origin?

A hash is not designed to be decrypted. An unkeyed hash alone also does not prove who created data, because an attacker can calculate a new hash after changing a message.

What kind of hashing should be used to store passwords?

Password storage should use a password-hashing scheme designed to be slow and salted, rather than plain passwords or a fast general-purpose hash alone.

How do digital signatures support integrity and origin authentication?

A digital signature is created with a signer’s private key and checked with the corresponding public key. Verification can provide evidence of data integrity and that the signature used the corresponding private key.

Do digital signatures keep signed data secret?

A digital signature does not encrypt data, so it does not provide confidentiality.