# P521.KeyAgreement.PublicKey A P-521 public key used for key agreement. ``` struct PublicKey ``` ## Topics ### Creating a public key [`init(rawRepresentation: D) throws`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/init(rawRepresentation:)) Creates a P-521 public key for key agreement from a collection of bytes. [`init(compactRepresentation: Bytes) throws`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/init(compactRepresentation:)) Creates a P-521 public key for key agreement from a compact representation of the key. [`init(derRepresentation: Bytes) throws`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/init(derRepresentation:)) Creates a P-521 public key for key agreement from a Distinguished Encoding Rules (DER) encoded representation. [`init(pemRepresentation: String) throws`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/init(pemRepresentation:)) Creates a P-521 public key for key agreement from a Privacy-Enhanced Mail (PEM) representation. [`init(x963Representation: Bytes) throws`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/init(x963Representation:)) Creates a P-521 public key for key agreement from an ANSI x9.63 representation. [`init(compressedRepresentation: Bytes) throws`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/init(compressedRepresentation:)) Creates a P-521 public key for key agreement from a compressed representation of the key. ### Representing the key [`var rawRepresentation: Data`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/rawRepresentation) A full representation of the public key. [`var compactRepresentation: Data?`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/compactRepresentation) A compact representation of the public key. [`var derRepresentation: Data`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/derRepresentation) A Distinguished Encoding Rules (DER) encoded representation of the public key. [`var pemRepresentation: String`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/pemRepresentation) A Privacy-Enhanced Mail (PEM) representation of the public key. [`var x963Representation: Data`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/x963Representation) An ANSI x9.63 representation of the public key. [`var compressedRepresentation: Data`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/compressedRepresentation) A compressed representation of the public key. ### Type Aliases [`typealias HPKEEphemeralPrivateKey`](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/HPKEEphemeralPrivateKey) The type of the ephemeral private key associated with this public key. ### Default Implementations [HPKEDiffieHellmanPublicKey Implementations](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/HPKEDiffieHellmanPublicKey-Implementations) [HPKEPublicKeySerialization Implementations](/documentation/CryptoKit/P521/KeyAgreement/PublicKey/HPKEPublicKeySerialization-Implementations) ## Relationships ### Conforms To [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`HPKEPublicKeySerialization`](/documentation/CryptoKit/HPKEPublicKeySerialization) [`Copyable`](/documentation/Swift/Copyable) [`HPKEDiffieHellmanPublicKey`](/documentation/CryptoKit/HPKEDiffieHellmanPublicKey) [`Escapable`](/documentation/Swift/Escapable) [`Sendable`](/documentation/Swift/Sendable) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)