Authenticity and Integrity

Authenticity and Integrity come together

Authenticity

Sign your data so that others can see that it is really you that sent it. It is clearly nice to know that documents are not forged.

Integrity

Guarantee that the data does not get changed in transit.
If you are on a line carrying invoicing data you probably want to know that the amounts and account numbers are correct and have not been modified by a third party.