Proof Key for Code Exchange
Proof Key for Code Exchange (PKCE) is an OAuth security extension in which a client proves possession of a per-request secret when exchanging an authorization code.
Software Security for Developers
Proof Key for Code Exchange is an OAuth extension in which a client proves possession of a per-request secret when exchanging an authorization code.
- How it is used
- Strengthens the OAuth authorization code flow for public clients that cannot safely store client secrets.
- How deep it goes
- Explains interception risk, verifier and challenge generation, hashing, and token exchange, without detailing implementation code.
- Examples
- Uses an intercepted authorization code, mobile and web clients, and a shopping-list application to illustrate the risk and defense.
- What you can do after
- Apply it via an OAuth authorization flow by generating a verifier, deriving its challenge, and presenting the verifier during token exchange.
Read how Software Security for Developers explains Proof Key for Code Exchange →
ASP.NET Core in Action, 3e
Authorization code with PKCE is an OAuth authorization flow that protects the authorization code exchange with a proof key generated by the client.
- How it is used
- Protects interactive OAuth authorization-code exchanges when a user delegates access to a resource.
- How deep it goes
- Defines PKCE’s protective role and contrasts grant choices, but does not detail proof-key generation or exchange mechanics.
- Examples
- Uses dogphotos.com accessing Facebook photos as an OAuth authorization example.
- What you can do after
- Evaluate/understand when authorization code with PKCE fits interactive OAuth flows instead of machine-only client credentials.
Read how ASP.NET Core in Action, 3e explains Proof Key for Code Exchange →
Secure APIs
Proof Key for Code Exchange (PKCE) is an OAuth security extension in which a client binds an authorization-code request to a proof derived from a secret.
- How it is used
- Protects OAuth authorization-code exchanges from intercepted-code attacks and access-token hijacking.
- How deep it goes
- Explains verifier generation, SHA-256 derivation, base64url encoding, request parameters, and the interception threat.
- Examples
- Uses a complete authorization URL containing code_challenge and code_challenge_method=S256.
- What you can do after
- Implement PKCE by generating a verifier, deriving its S256 challenge, and sending the required authorization parameters.
Spring Security in Action, Second Edition
Proof key for code exchange is an OAuth extension that binds an authorization-code exchange to a client-generated secret to mitigate code interception.
- How it is used
- Protects authorization-code exchanges when client credentials or authorization codes might be intercepted.
- How deep it goes
- Explains verifier generation, challenge hashing, request placement, and authorization-server comparison without framework implementation details.
- Examples
- Uses random verifier and hash-derived challenge pseudocode, plus the two PKCE message steps.
- What you can do after
- Apply it by generating a verifier, sending its challenge during login, and presenting the verifier during token exchange.
Read how Spring Security in Action, Second Edition explains Proof Key for Code Exchange →
Building Distributed Applications that Work
Proof Key for Code Exchange is an OAuth security extension that binds an authorization-code exchange to the client that initiated it.
- How it is used
- Adds an optional security layer to the authorization-code flow, particularly for public clients.
- How deep it goes
- Defines PKCE as an OpenID Connect option but does not explain the authorization-code exchange mechanics.
- Examples
- Names `options.UsePkce` as the configuration switch without showing a PKCE-specific code example.
- What you can do after
- Configure PKCE by setting `options.UsePkce` in OpenID Connect options, particularly for public-client authorization-code flows.
Read how Building Distributed Applications that Work explains Proof Key for Code Exchange →
Related concepts
- authorization code flowuses · The authorization code flow is an OAuth protocol in which a client obtains a short-lived authorization code after user authorization and exchanges it for access or other tokens.
- OAuthuses · OAuth is an authorization framework that enables a client to obtain limited, delegated access to protected resources without receiving the resource owner's credentials.
- public clientaddresses · A public client is an OAuth client that cannot securely keep its credentials confidential, such as an application distributed to users or running in a browser.
- cross-site request forgeryaddresses · Cross-site request forgery is a web attack that induces an authenticated user’s browser to submit an unintended request to a trusted application.
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