Known Ciphertext Attack
Example:
- Eve steals a bunch of ciphertexts from Alice's handbag, but has no idea what they mean.
Known Plaintext Attack
Example:
- Eve overhears an encrypted communication from Bob to Alice, and later observes them meeting at Baker Street - Eve can now guess that the communication contained the word "baker street" somewhere, a form of known plaintext attack.
Chosen Plaintext Attack
Example:
- A poorly designed file storage system uses the same key to encrypt everyone's files, and lets anyone see anyone's files (in encrypted form). Eve knows Bob uses the service, she registers as well and starts encrypting arbitrary files (which she can choose) and looks at the resulting ciphertext. From this she obtains the service's encryption key, and decrypts Bob's stuff.
Chosen Ciphertext Attack
Example:
- Eve breaks into Bob's house while he is sleeping, and replaces the ciphertext he was going to send to Alice tomorrow with a new one of her choosing. She then eavesdrops on their communications (encrypted or not) the next day to try and work out what Alice read when she decrypted the fake ciphertext (variants of this involve Eve not just creating a new ciphertext, but modifying the existing one slightly).
No comments:
Post a Comment