Which of these techniques will ensure the property of 'non-repudiation'?

Non-repudiation provides proof of the origin and integrity of data, ensuring that a party cannot deny having sent or received a message. Digital signatures are the primary cryptographic technique used to achieve this. By signing a message with a private key that only the sender possesses, the sender creates a unique, verifiable link to the message. Anyone with the corresponding public key can verify the signature, thus confirming the sender's identity and preventing them from later denying their involvement (repudiating the action).

A. Passwords: These are used for authentication to prove an identity but can be compromised or shared, making it possible to deny an action performed with them.

C. Encryption: This primarily provides confidentiality by making data unreadable to unauthorized parties. It does not inherently prove the origin of the data.

D. Using a VPN: A VPN (Virtual Private Network) encrypts a communication channel for confidentiality and privacy but does not provide non-repudiation for specific actions or messages.

1. National Institute of Standards and Technology (NIST). (2023). FIPS PUB 186-5: Digital Signature Standard (DSS). U.S. Department of Commerce. In Section 1

"Introduction

" it states

"Digital signatures are used to detect unauthorized modifications to data and to authenticate the identity of the signatory. In addition

the recipient of signed data can use a digital signature as evidence in demonstrating to a third party that the signature was

in fact

generated by the claimed signatory. This is known as non-repudiation..."

2. Kaufman

C.

Perlman

R.

& Speciner

M. (2002). Network Security: Private Communication in a Public World (2nd ed.). Prentice Hall. In Chapter 15

"Digital Signatures

" the text explains that a key purpose of digital signatures is to create a binding that "can be demonstrated to a third party

" which is the essence of non-repudiation.

3. MIT OpenCourseWare. (2017). 6.857 Computer and Network Security

Lecture 10: Public Key Cryptography. Massachusetts Institute of Technology. The lecture notes explicitly state that digital signatures provide non-repudiation

defining it as the property where the "sender can't later deny sending message."