# Certificate is valid even if we change the additional fields data in blockchain certificate

**URL:** <https://community.blockcerts.org/t/certificate-is-valid-even-if-we-change-the-additional-fields-data-in-blockchain-certificate/3316>\
**Category:** Support\
**Created:** [November 11, 2022, 2:28pm UTC](https://community.blockcerts.org/t/certificate-is-valid-even-if-we-change-the-additional-fields-data-in-blockchain-certificate/3316 "2022-11-11T14:28:45Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![sreenumalae](https://sea2.discourse-cdn.com/flex016/user_avatar/community.blockcerts.org/sreenumalae/32/773_2.png) [@sreenumalae](https://community.blockcerts.org/u/sreenumalae)\
**Post date:** [November 11, 2022, 2:28pm UTC](https://community.blockcerts.org/t/certificate-is-valid-even-if-we-change-the-additional-fields-data-in-blockchain-certificate/3316/1 "2022-11-11T14:28:45Z")

</div>

@lemoustachiste  
I have created the certificate using the cert-tools  
and here is my unsigned certificate

```auto
{"@context": ["https://www.w3.org/2018/credentials/v1", {"alumniOf": {"@id": "http://schema.org/alumniOf", "@type": "http://www.w3.org/1999/02/22-rdf-syntax-ns#HTML"}, "certificate_title": {"@id": "http://schema.org/image", "@type": "@id"}, "certificate_description": {"@id": "http://schema.org/url", "@type": "@id"}, "criteria_narrative": {"@id": "http://schema.org/image", "@type": "@id"}, "validity": {"@id": "http://schema.org/url", "@type": "@id"}}, "https://w3id.org/blockcerts/v3"], "type": ["VerifiableCredential", "BlockcertsCredential"], "issuer": "https://raw.githubusercontent.com/sreenumalae/DataStorage/main/issuer.json", "issuanceDate": "2022-11-11T14:10:00Z", "id": "urn:uuid:ab6bdbfd-9af4-4854-918f-60a1c52553b2", "credentialSubject": {"id": "ecdsa-koblitz-pubkey:mtr98kany9G1XYNU74pRnfBQmaCg2FZLmc", "alumniOf": {"id": "https://www.human-logic.com/"}}, "certificate_description": "this is to certify so and so for falana dimkana", "certificate_title": "Course Completion @ Marketing and sales", "criteria_narrative": "Nibh iriure ei nam, modo ridens neglegentur mel eu. At his cibo mucius.", "validity": "3months"}

```

**using cert-issuer i signed the above certificate using the ethereum\_sepolia**

Signed Certificate

```auto
{"@context": ["https://www.w3.org/2018/credentials/v1", {"alumniOf": {"@id": "http://schema.org/alumniOf", "@type": "http://www.w3.org/1999/02/22-rdf-syntax-ns#HTML"}, "certificate_title": {"@id": "http://schema.org/image", "@type": "@id"}, "certificate_description": {"@id": "http://schema.org/url", "@type": "@id"}, "criteria_narrative": {"@id": "http://schema.org/image", "@type": "@id"}, "validity": {"@id": "http://schema.org/url", "@type": "@id"}}, "https://w3id.org/blockcerts/v3"], "type": ["VerifiableCredential", "BlockcertsCredential"], "issuer": "https://raw.githubusercontent.com/sreenumalae/DataStorage/main/issuer.json", "issuanceDate": "2022-11-11T14:10:00Z", "id": "urn:uuid:ab6bdbfd-9af4-4854-918f-60a1c52553b2", "credentialSubject": {"id": "ecdsa-koblitz-pubkey:mtr98kany9G1XYNU74pRnfBQmaCg2FZLmc", "alumniOf": {"id": "https://www.human-logic.com/"}}, "certificate_description": "this is to certify so and so for falana dimkana", "certificate_title": "Course Completion @ Marketing and sales", "criteria_narrative": "Nibh iriure ei nam, modo ridens neglegentur mel eu. At his cibo mucius.", "validity": "3months", "proof": {"type": "MerkleProof2019", "created": "2022-11-11T14:12:19.302024", "proofValue": "znKD4YGVqA8textxySpp1sELjvYVAyFoEqUaCBtTKrN4UYbf4XtpvqqDoC4H9nzvZKNNkpRfqvZzEsPkFC65JfrpSQXRGPz9euwHAqCEiEYddj96P6XZUkycVR41xRDpKDr9pH71anHSJfPeWMUNvsdKPAQSjhAms1XjkTC2j5skH7Qw4shwsxG6B9TJVWjWDp2ELALBWJiqN52Lo2Kyza4nBSCgEQpP1d7NauFtK27dqw94QS5fNDQY7ZSBEGeifaEMmf1GC7pJ2JatNunsf4PmTe7TJwsmHot9P3fRzfNfxBPKsq79X7jTZSV", "proofPurpose": "assertionMethod", "verificationMethod": "URL"}}

```

The above certificate is valid even if I change the text in the additional fields.

How can we avoid this?

---

<div class="post-metadata">

**Author:** ![lemoustachiste](https://avatars.discourse-cdn.com/v4/letter/l/7c8e57/32.png) [@lemoustachiste](https://community.blockcerts.org/u/lemoustachiste)\
**Post date:** [November 18, 2022, 12:37pm UTC](https://community.blockcerts.org/t/certificate-is-valid-even-if-we-change-the-additional-fields-data-in-blockchain-certificate/3316/2 "2022-11-18T12:37:38Z")

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it might be because the RDF normalization does not pick up correctly your terms.

This tool proved useful for me when I was working on the terms for blockcerts v3: [FHIR JSON-LD Playground](https://fhircat.org/jsonld/playground/). With that you can adjust the values and get to a point where your data is being normalized (and then hashed).

I’m honestly still struggling with JSONLD at times, so I cannot be of much more help.