Non-repudiation - CompTIA Security+ SY0-701 - 1.2

Non-repudiation

You can't deny what you've said

- Theres no taking it back

Signing a contract

Adds a different perspective for cryptography

- Proof of integrity

Proof of integrity

Verify data does not change

-The data remains accurate and consistent

In cryptography, we use a hash

-Represent data as a short string of text

-A message digest, a fingerprint

If the data changes, the hash changes

-If the person changes, you get a different fingerprint

Doesn't necessarily associate data with an individual

-Only tells you if the data has changed

Proof of origin

Prove the message was not changes

- Integrity

Prove the source of the message

- Authentication

Make sure the signature isn't fake

- Non-repudiation

Sign with the private key

- The message doesn't need to be encrypted

- Nobody else can sign this (obviously)

- Verify with public key

- Any change to the message will invalidate the signature

Verifying a Digital Signature

Bob decrypts the digital signature to obtain the plaintext hash