The OAuth 2 specification

There is sometimes a misconception that OAuth 2 is an evolution from OAuth 1, but it is a completely different approach. OAuth1 specification requires signatures, so you would have to use cryptographic algorithms to create generate and validate those signatures that are no longer required for OAuth 2. The OAuth 2 encryption is now handled by TLS, which is required.

OAuth 2 RFC-6749, The OAuth 2.0 Authorization Framework (https://tools.ietf.org/html/rfc6749):
The OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf.

This specification replaces and makes obsolate the OAuth 1.0 protocol described...