PAIN Cryptography - Who Would Like To Define?

Privacy Authority Integrity Non-Repudiation I'm trying to get my head around these to understand the core 4 areas of cryptography better. How do you define each? Hiya, You still need this explained further? I saw you started another thread asking about non-repudiation & wasn't sure. Also the 'A' in PAIN is for authenticity, not authority. Privacy - prevent unauthorized disclosure authenticity - verify origin of message. integrity - it refers to protecting information from being modified by unauthorized parties. non-repudiation - binding message and content to individual Thanks Prashant Kumar Dey, i agree with your response, its a good one, that clears things up. Integrity - also protection from data being altered due a medium related problem (some data lost, noise ...). Never called it PAIN but understand what you mean. I was taught CIA which is more about security than cryptography (CIA: Confidentiality, Integrity, Availability). Privacy, or confidentiality is provided by encryption and is intended to prevent unauthorised disclosure of contents. Authenticity is about confirming the identity of a person, or the origin of a message. Identification (iirc) is about picking a person out of a crowd (1 person out of N), while authenticity is about confirming that the person you picked from the crowd has their identity verified. We can think in terms of passports for people, or MACs for data packets. Integrity checks don't prevent nor "protect" anything, but rather they indicate that something has been tampered with. A simple check sum can show transmission errors. A hash will show whether something has been modified in the absence of an active on-path attacker (they could replace the hash with one they calculate). While MAC (message authentication code) will show modification even when there is an active on-path attacker: calculating a MAC requires the secret MACing key. Assuming that key is confidential then a MAC will show modifications against even the most aggressive attackers. Non-repudiation is fairly described as linking a person to the content of a message. The signer cannot refute that the message was signed by them (in theory at least :-) ). This is done by digital signatures. A hash of the entire message is calculated (provides integrity) and is then signed by the signer's (private) signing key.