Based on the error message you're receiving, it appears that there's an issue with client authentication during the OAuth2 authorization code flow. This error typically occurs when the client credentials (client ID and client secret) are not correctly provided or don't match what's expected by the authorization server. Let's explore some possible reasons and solutions: 1. Client Authentication Method: The error suggests that the client authentication method might be incorrect. Ory Hydra supports different authentication methods for the token endpoint. Make sure you're using the correct method as configured for your client. According to the [Ory Hydra API Reference](https://www.ory.sh/docs/hydra/reference/api), the default authentication method is

client_secret_basic

. However, if you've configured your client to use a different method, such as

client_secret_post

, you need to ensure that you're using the correct method when making the token request. 2. Client Credentials: Double-check that you're using the correct client ID and client secret. These should match exactly what was provided when you created the OAuth2 client in Ory Hydra. 3. Client Configuration: Ensure that your client is properly configured in Ory Hydra. You can check the client configuration using the Ory CLI. Here's an example of how to view a client's configuration:

ory get oauth2-client <your-client-id>

Pay special attention to the

token_endpoint_auth_method

in the client configuration. 4. Redirect URI: Make sure that the redirect URI you're using in your

ory perform authorization-code

command matches exactly with what's configured for your client in Ory Hydra. 5. Proper Encoding: Ensure that your client ID and secret are properly URL-encoded if you're including them in the request URL or body. To help diagnose and resolve the issue, you could try the following: 1. Double-check your client configuration in Ory Hydra. 2. Ensure you're using the correct authentication method (

client_secret_basic

or

client_secret_post

) as configured for your client. 3. Verify that you're using the correct client ID and secret. 4. Check that your redirect URI matches exactly with what's configured. If you're still encountering issues, you might want to enable debug logging in Ory Hydra to get more detailed error information. This can help pinpoint the exact cause of the authentication failure. For more detailed troubleshooting steps, you can refer to the [Ory Hydra OAuth2 First Aid guide](https://www.ory.sh/docs/hydra/debug). If you need further assistance, please provide more details about your client configuration and the exact command you're using with

ory perform authorization-code

.

Thank you for providing that additional information. You're right to question this, as public clients indeed don't use client secrets. Let's clarify this situation based on the information provided in the knowledge sources. For public clients, such as Single Page Applications (SPAs) or mobile apps, the recommended approach is to use the Authorization Code flow with PKCE (Proof Key for Code Exchange). This method doesn't require a client secret, making it suitable for public clients that can't securely store secrets. Here's what you should do: 1. Ensure your OAuth2 client is correctly configured as a public client: When creating the OAuth2 client, you should use the

--token-endpoint-auth-method none

flag. This tells Ory that the client doesn't use any authentication method at the token endpoint. Here's an example command:

ory create oauth2-client --token-endpoint-auth-method none

[Source](https://www.ory.sh/docs/oauth2-oidc/authorization-code-flow#spa-and-public-client-with-pkce) 2. Use PKCE when initiating the authorization flow: Generate a code verifier and code challenge, then include the code challenge in your authorization request. Here's a simplified example:

javascript    const { codeChallenge, codeVerifier } = await generatePKCES256()    const authorizationUrl = `https://$<http://PROJECT_SLUG.projects.oryapis.com/oauth2/auth?response_type=code&client_id=${clientId}&redirect_uri=https://myapp.com/callback&scope=openid&state=12345&code_challenge_method=S256&code_challenge=${codeChallenge}|PROJECT_SLUG.projects.oryapis.com/oauth2/auth?response_type=code&client_id=${clientId}&redirect_uri=https://myapp.com/callback&scope=openid&state=12345&code_challenge_method=S256&code_challenge=${codeChallenge}>`

3. When exchanging the code for a token, include the code verifier:

javascript    const requestBody = `grant_type=authorization_code&client_id=${clientId}&code_verifier=${codeVerifier}&code=${code}`

[Source](https://www.ory.sh/docs/oauth2-oidc/authorization-code-flow#spa-and-public-client-with-pkce) The error message you received about passwords not matching is indeed confusing for a public client. This could indicate that your client might be misconfigured on the server side, possibly still set up as a confidential client instead of a public one. To resolve this: 1. Double-check your client configuration using the Ory CLI:

ory get oauth2-client <your-client-id>

Ensure that

token_endpoint_auth_method

is set to

none

. 2. If the configuration is incorrect, you may need to delete the client and recreate it with the correct settings for a public client. 3. When using the

ory perform authorization-code

command for testing, make sure you're not including any client secret parameters. If you continue to face issues after making these changes, it would be helpful to review the exact command you're using with

ory perform authorization-code

and your client configuration details (excluding any sensitive information). [Source](https://www.ory.sh/docs/hydra/debug/token-endpoint-auth-method)

To get the client configuration for an OAuth2 client in Ory Hydra, you can use the

ory get oauth2-client

command. Here's how you can do it:

ory get oauth2-client <your-client-id>

Replace

<your-client-id>

with the actual ID of your OAuth2 client. This command will retrieve and display the details of the specified OAuth2 client. The output will include information such as the client ID, grant types, response types, scopes, redirect URIs, and other configuration details. If you want to format the output in a specific way, you can use the

--format

flag. For example:

ory get oauth2-client <your-client-id> --format json

This will output the client configuration in JSON format. You can also use this command in combination with

jq

to extract specific information. For example, to get just the client name:

ory get oauth2-client <your-client-id> --format json | jq -r '.client_name'

These commands are documented in the [Ory Hydra CLI documentation](https://www.ory.sh/docs/hydra/cli/hydra-get-oauth2-client). Remember that you need to have the appropriate permissions and be authenticated to use these commands. If you're using Ory Network, make sure you're logged in with the correct account and have selected the right project. [Source](https://www.ory.sh/docs/hydra/cli/hydra-get-oauth2-client)

Based on the command you're running and the client configuration you've provided, I can see a few potential issues that might be causing the problem. Let's address them: 1. Client Authentication Method: Your client configuration doesn't explicitly show the

token_endpoint_auth_method

. For public clients, this should be set to

none

. You can check this by running:

ory get oauth2-client 606d01f7-00d0-4817-ae8b-9086735fe929 --format json | jq .token_endpoint_auth_method

If it's not set to

none

, you'll need to update your client configuration. 2. Redirect URI: The

ory perform authorization-code

command by default uses

<http://127.0.0.1:4446/callback>

as the redirect URI. This is included in your client's allowed redirect URIs, so it should work. 3. Missing Client Secret: Your client configuration shows an empty CLIENT SECRET field, which is correct for a public client. However, the

ory perform authorization-code

command you're using doesn't specify that this is a public client. To resolve this issue, try the following: 1. Update your client to be explicitly set as a public client:

ory update oauth2-client 606d01f7-00d0-4817-ae8b-9086735fe929 \      --project 90af1bad-8ee7-447e-bad9-679df15f2460 \      --token-endpoint-auth-method none

2. Then, run the

ory perform authorization-code

command with the

--token-endpoint-auth-method none

flag:

ory perform authorization-code \      --project 90af1bad-8ee7-447e-bad9-679df15f2460 \      --client-id 606d01f7-00d0-4817-ae8b-9086735fe929 \      --token-endpoint-auth-method none

This should correctly indicate to Ory that your client is a public client and doesn't use a client secret for authentication. If you're still encountering issues after making these changes, please provide the new error message or behavior you're seeing. [Source](https://www.ory.sh/docs/oauth2-oidc/authorization-code-flow#spa-and-public-client-with-pkce) [Source](https://www.ory.sh/docs/hydra/debug/token-endpoint-auth-method)

Based on the new error message you're receiving, it appears that there's a mismatch between the redirect URI used in your request and the ones registered for your OAuth2 client. Let's address this issue: The error states: "The 'redirect_uri' parameter does not match any of the OAuth 2.0 Client's pre-registered redirect urls." This typically happens when the redirect URI in your authorization request doesn't exactly match one of the redirect URIs you've registered for your client. Here's how we can troubleshoot and resolve this: 1. Check your registered redirect URIs: From the client configuration you shared earlier, your registered redirect URIs are:

<http://127.0.0.1:8080/login/oauth2/code/messaging-client-oidc>    <http://127.0.0.1:5555/callback>    <http://127.0.0.1:4446/callback>

2. Verify the redirect URI used by `ory perform`: The

ory perform authorization-code

command by default uses

<http://127.0.0.1:4446/callback>

as the redirect URI. This URI is included in your client's allowed redirect URIs, so it should work. 3. Explicitly specify the redirect URI: To ensure you're using a correct redirect URI, you can explicitly specify it in your command:

ory perform authorization-code \      --project 90af1bad-8ee7-447e-bad9-679df15f2460 \      --client-id 606d01f7-00d0-4817-ae8b-9086735fe929 \      --token-endpoint-auth-method none \      --redirect <http://127.0.0.1:4446/callback>

Make sure to use one of the exact URIs from your client configuration. 4. Check for any typos or extra spaces: Ensure that there are no extra spaces or characters in your registered redirect URIs. The comparison is exact, so even a trailing space can cause a mismatch. 5. URL encoding: If your redirect URIs contain any special characters, make sure they are properly URL-encoded both in the client configuration and in your request. If you're still encountering issues after trying these steps, you might want to double-check your client configuration again to ensure all details are correct. You can do this using the command:

ory get oauth2-client 606d01f7-00d0-4817-ae8b-9086735fe929 --project 90af1bad-8ee7-447e-bad9-679df15f2460

Review the output carefully, paying special attention to the

redirect_uris

field. If the problem persists, you might want to consider updating your client's redirect URIs to ensure they match exactly what you're using in your requests. You can update the client configuration using the

ory update oauth2-client

command. [Source](https://www.ory.sh/docs/hydra/debug#wrong-or-misconfigured-oauth-20-client)