Usable HMAC JWKs Algorithms jwksAlgs jwks size String join – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.6-8.9

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Briefly, this error occurs when there is a mismatch or issue with the JSON Web Key Set (JWKS) algorithms used for HMAC (Hash-based Message Authentication Code) in Elasticsearch. This could be due to incorrect configuration or unsupported algorithms. To resolve this issue, you can verify the JWKS algorithms used and ensure they are supported by Elasticsearch. Also, check the size of the JWKS and ensure it is correctly configured. Lastly, ensure the string join operation is correctly implemented and does not result in any errors.

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This guide will help you check for common problems that cause the log ” Usable HMAC: JWKs [{}]. Algorithms [{}].”; jwksAlgs.jwks().size(); String.join(“; ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “Usable HMAC: JWKs [{}]. Algorithms [{}].”; jwksAlgs.jwks().size(); String.join(“;” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                jwksHmac = null;

            if (jwksHmac != null) {
                final JwkSetLoader.JwksAlgs jwksAlgs = JwkValidateUtil.filterJwksAndAlgorithms(jwksHmac; allowedJwksAlgsHmac);
      "Usable HMAC: JWKs [{}]. Algorithms [{}]."; jwksAlgs.jwks().size(); String.join(";"; jwksAlgs.algs()));
                // Filter JWK(s) vs signature algorithms. Only keep JWKs with a matching alg. Only keep algorithms with a matching JWK.
                this.hmacJwtSignatureValidator = new HmacJwtSignatureValidator(jwksAlgs);
            } else {
                this.hmacJwtSignatureValidator = null;


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