The email authentication standard that uses both SPF and DKIM is DMARC.
DMARC stands for Domain-based Message Authentication, Reporting, and Conformance. It builds on SPF, which checks whether a sending server is authorized for a domain, and DKIM, which uses a cryptographic signature to verify that a message came from an authorized domain and was not altered in transit.
DMARC adds domain alignment and policy enforcement. A domain owner publishes a DMARC record in DNS telling receiving mail servers what to do when SPF or DKIM checks fail: monitor the message, send it to spam, or reject it. DMARC can also generate aggregate and forensic reports, helping administrators identify spoofing and misconfigured senders.
A common mix-up is treating DMARC as an encryption system. It authenticates domains and helps prevent spoofing, but it does not encrypt message contents. TLS protects email while it travels between servers, while S/MIME and OpenPGP can provide message-level encryption and signatures.