- `inputS3Url` – A presigned URL that the Lambda function can use to download the original object. By using a presigned URL, the Lambda function doesn't need to have MinIO credentials to retrieve the original object. This allows Lambda function to focus on transformation of the object instead of securing the credentials.

import javax.security.auth.login.LoginException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import jcifs.CIFSException;

/**
 * JAAS kerberos authenticator
 *
 * Either configure JAAS for credential caching or reuse a single instance of this authenticator -otherwise you won't
 * get proper ticket caching.
 *
 * Be advised that short/NetBIOS name usage is not supported with this authenticator. Always specify full FQDNs/Realm.

}
```

These credentials can now be used to perform MinIO API operations, these credentials automatically expire in 1hr. To understand more about credential expiry duration and client grants STS API read further [here](https://github.com/minio/minio/blob/master/docs/sts/client-grants.md).

## Explore Further

	// Get credential.
	credentials := globalActiveCred
	if !globalReplicationPool.IsSet() {
		globalReplicationPool.Set(nil)
	}
	testServer.Obj = objLayer
	testServer.rawDiskPaths = disks
	testServer.Disks = mustGetPoolEndpoints(0, disks...)
	testServer.AccessKey = credentials.AccessKey
	testServer.SecretKey = credentials.SecretKey

    server.enqueue(
      MockResponse(code = 401),
    )
    server.enqueue(MockResponse())
    val credential = basic("jesse", "secret")
    client =
      client
        .newBuilder()
        .authenticator(RecordingOkAuthenticator(credential, null))
        .build()
    val response =
      getResponse(
        Request(
          url = server.url("/"),

	// Not allowed to add a user with same access key as root credential
	if accessKey == globalActiveCred.AccessKey {
		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrAddUserInvalidArgument), r.URL)
		return
	}

	user, exists := globalIAMSys.GetUser(ctx, accessKey)
	if exists && (user.Credentials.IsTemp() || user.Credentials.IsServiceAccount()) {
		// Updating STS credential is not allowed, and this API does not

		isDerived := false
		if v.Credentials.IsServiceAccount() || v.Credentials.IsTemp() {
			isDerived = true
		}

		if !isDerived && v.Credentials.AccessKey == accessKey {
			userExists = true
		} else if isDerived && v.Credentials.ParentUser == accessKey {
			userExists = true
			if v.Credentials.IsTemp() {
				// Hide secret key & session key here
				v.Credentials.SecretKey = ""

        }

        return new String(out, 0, j);
    }

    /**
     * Check if the given mechanism is preferred for this credential
     *
     * @param mechanism the mechanism to check
     * @return whether the given mechanism is the preferred one for this credential
     */
    public boolean isPreferredMech(ASN1ObjectIdentifier mechanism) {
        return NtlmContext.NTLMSSP_OID.equals(mechanism);
    }

    private String user = null;
    /** The Kerberos realm */
    private String realm = null;
    /** The service principal name */
    private String service = DEFAULT_SERVICE;
    /** The user credential lifetime */
    private int userLifetime = GSSCredential.DEFAULT_LIFETIME;
    /** The security context lifetime */
    private int contextLifetime = GSSContext.DEFAULT_LIFETIME;

}

func validateAdminSignature(ctx context.Context, r *http.Request, region string) (auth.Credentials, bool, APIErrorCode) {
	var cred auth.Credentials
	var owner bool
	s3Err := ErrAccessDenied
	if _, ok := r.Header[xhttp.AmzContentSha256]; ok &&
		getRequestAuthType(r) == authTypeSigned {
		// Get credential information from the request.
		cred, owner, s3Err = getReqAccessKeyV4(r, region, serviceS3)