---
title: "Certificate, Key, and Trust Services"
framework: security
role: collectionGroup
path: security/certificate-key-and-trust-services
---

# Certificate, Key, and Trust Services

Establish trust using certificates and cryptographic keys.

## Overview

Overview The certificate, key, and trust services API is a collection of functions and data structures that you use to conduct secure and authenticated data transactions. Specifically, you use this API to manage and use: Certificates and identities. A certificate is a collection of data that identifies its owner in a tamper-evident way. When you use a certificate to distribute a public key, a receiver can be confident of its origin. You can also package a certificate together with its corresponding private key in an identity object that you keep secret. Policies and trust services. When you receive a certificate, before you can use the embedded public key, you have to answer the question, “Can I trust this certificate?” You conduct an evaluation of trust according to a set of criteria, or a trust policy. Cryptographic keys. After you have a key whose origin you trust, you can begin to conduct cryptographic operations, such as encryption or data signing and verification. These operations in turn typically serve a larger purpose, such as authenticating a user, transmitting data securely, or verifying that a block of data is unaltered since being sealed with a signature. note: Rely on the classes of the Security Interface framework to ensure a consistent experience when displaying certificates and trust settings to the user and when the user chooses among identities or modifies keychain settings.

## Topics

### API Components

- [Certificates](security/certificates.md)
- [Keys](security/keys.md)
- [Identities](security/identities.md)
- [Policies](security/policies.md)
- [Trust](security/trust.md)

### Thread Safety

- [Working with Concurrency](security/working-with-concurrency.md)

## See Also

### Related Documentation

- [Cryptographic Services Guide](apple-archive/documentation/Security/Conceptual/cryptoservices/Introduction.md)
- [Security Interface](securityinterface.md)