Lecture_8

Attacks on Communications across Network
Disclosure: encryption2. Traffic analysis: encryption3. Masquerade: message authentication4. Content modification: message authentication
5. Sequence modification: message authentication
6. Timing modification: message authentication
7. Source repudiation: digital signatures8. Destination repudiation: digital signatures
Authentication
Receiver wants to verify:
Contents of the message have not been modified (data authentication)
Source of message is who they claim to be (source authentication)
Different approaches available:
Symmetric Key Encryption
Message Authentication Codes (MACs)
Hash Functions
Public Key Encryption (i.e. Digital Signatures)
Symmetric Key Encryption for Authentication
Confidentiality: only B (and A) can recover plaintext
Source Authentication: A is only other user with key; must have come from A
Data Authentication: successfully decrypted; data has not been modified
Assumption: decryptor can recognize correct plaintext