w3c-vcdm-privacy-minimization

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Use when implementing data-minimization and selective disclosure privacy approaches in W3C VCDM. Covers privacy tradeoffs and mitigation patterns in mid-section privacy guidance.

sourcelabbg By sourcelabbg schedule Updated 3/7/2026
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name: "w3c-vcdm-privacy-minimization" description: "Use when implementing data-minimization and selective disclosure privacy approaches in W3C VCDM. Covers privacy tradeoffs and mitigation patterns in mid-section privacy guidance." sections: - "8.8 Favor Abstract ClaimsThis section is non-normative." - "8.9 The Principle of Data MinimizationThis section is non-normative." - "8.10 Bearer CredentialsThis section is non-normative." - "8.11 Correlation During ValidationThis section is non-normative."

8.8 Favor Abstract ClaimsThis section is non-normative.

Issuers are encouraged to limit the information included in a verifiable credential to the smallest set required for the intended purposes, so as to allow recipients to use them in various situations without disclosing more personally identifiable information (PII) than necessary. One way to avoid placing PII in a verifiable credential is to use an abstract property that meets the needs of verifiers without providing overly specific information about a subject.

For example, this document uses the ageOver property instead of a specific birthdate, which would represent more sensitive PII. If retailers in a particular market commonly require purchasers to be older than a certain age, an issuer trusted in that market might choose to offer verifiable credentials that claim that subjects have met that requirement rather than offering verifiable credentials that contain claims about the customers' birthdays. This practice enables individual customers to make purchases without disclosing more PII than necessary.

8.9 The Principle of Data MinimizationThis section is non-normative.

Privacy violations occur when information divulged in one context leaks into another. One accepted best practice for preventing such a violation is for verifiers to limit the information requested and received, to the absolute minimum necessary for a particular transaction. Regulations in multiple jurisdictions, including the Health Insurance Portability and Accountability Act (HIPAA) in the United States and the General Data Protection Regulation (GDPR) in the European Union, mandate this data minimization approach.

With verifiable credentials, data minimization for issuers means limiting the content of a verifiable credential to the minimum required by potential verifiers for expected use. For verifiers, data minimization means restricting the scope of information requested or required for accessing services.

For example, a driver's license containing a driver's ID number, height, weight, birthday, and home address expressed as a verifiable credential contains more information than is necessary to establish that the person is above a certain age.

It is considered best practice for issuers to atomize information or use a securing mechanism that allows for selective disclosure. For example, an issuer of driver's licenses could issue a verifiable credential containing every property that appears on a driver's license, and allow the holder to disclose each property selectively. It could also issue more abstract verifiable credentials (for example, a verifiable credential containing only an ageOver property). One possible adaptation would be for issuers to provide secure HTTP endpoints for retrieving single-use bearer credentials that promote the pseudonymous use of verifiable credentials. Implementers that find this impractical or unsafe might consider using selective disclosure schemes that eliminate dependence on issuers at proving time and reduce the risk of temporal correlation by issuers.

Verifiers are urged to only request information that is strictly necessary for a specific transaction to occur. This is important for at least two reasons:

      -

It reduces the liability on the verifier for handling highly sensitive information that it does not need to handle.

      -

It enhances the subject's and/or holder's privacy by only asking for information that is necessary for a specific transaction.

Implementers of software used by holders are encouraged to disclose the information being requested by a verifier, allowing the holder to decline to share specific information that is unnecessary for the transaction. Implementers of software used by holders are also advised to give holders access to logs of information shared with verifiers, enabling the holders to provide this information to authorities if they believe that they have been subjected to information overreach or coerced to share more information than necessary for a particular transaction.

    Note: Minimum disclosure can still lead to unique identification

While it is possible to practice the principle of minimum disclosure, it might be impossible to avoid the strong identification of an individual for specific use cases during a single session or over multiple sessions. The authors of this document cannot stress how difficult it is to meet this principle in real-world scenarios.

8.10 Bearer CredentialsThis section is non-normative.

A bearer credential is a privacy-enhancing piece of information, such as a concert ticket, that entitles its holder to a specific resource without requiring the holder to divulge sensitive information. In low-risk scenarios, entities often use bearer credentials where multiple holders presenting the same verifiable credential is not a concern or would not result in large economic or reputational losses.

Verifiable credentials that are bearer credentials are made possible by not specifying the subject identifier, expressed using the id property, which is nested in the credentialSubject property. For example, the following verifiable credential is a bearer credential:

[Example 35](https://www.w3.org/TR/vc-data-model-2.0/#example-use-of-issuer-properties): Use of issuer properties

  - Credential- ecdsa- ecdsa-sd- bbs- jose- cose- sd-jwt```

{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "http://university.example/credentials/temporary/28934792387492384", "type": ["VerifiableCredential", "ExampleDegreeCredential"], "issuer": "https://university.example/issuers/14", "validFrom": "2017-10-22T12:23:48Z", "credentialSubject": { // note that the 'id' property is not specified for bearer credentials "degree": { "type": "ExampleBachelorDegree", "name": "Bachelor of Science and Arts" } } }

            ```
{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "id": "http://university.example/credentials/temporary/28934792387492384",
  "type": [
    "VerifiableCredential",
    "ExampleDegreeCredential"
  ],
  "issuer": "https://university.example/issuers/14",
  "validFrom": "2017-10-22T12:23:48Z",
  "credentialSubject": {
    "degree": {
      "type": "ExampleBachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  },
  "proof": {
    "type": "DataIntegrityProof",
    "created": "2025-04-27T17:58:34Z",
    "verificationMethod": "did:key:zDnaebSRtPnW6YCpxAhR5JPxJqt9UunCsBPhLEtUokUvp87nQ",
    "cryptosuite": "ecdsa-rdfc-2019",
    "proofPurpose": "assertionMethod",
    "proofValue": "z5gCBzvpHbsJoeuuy5Z54rKQwkGzBZkmapRZZAKKW4ervhBGGTaygnh4sBG6vV8MHGD8eKhXEmkXr487JwVhZ2WHQ"
  }
}
```**application/vc**
            ```
{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "id": "http://university.example/credentials/temporary/28934792387492384",
  "type": [
    "VerifiableCredential",
    "ExampleDegreeCredential"
  ],
  "issuer": "https://university.example/issuers/14",
  "validFrom": "2017-10-22T12:23:48Z",
  "credentialSubject": {
    "degree": {
      "type": "ExampleBachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  },
  "proof": {
    "type": "DataIntegrityProof",
    "created": "2025-04-27T17:58:34Z",
    "verificationMethod": "did:key:zDnaerJh8WwyBVVGcZKKkqRKK9iezje8ut6t9bnNChtxcWwNv",
    "cryptosuite": "ecdsa-sd-2023",
    "proofPurpose": "assertionMethod",
    "proofValue": "u2V0AhVhAOEMucTcwHIY19VxghifeZjhZGFI9buw5OmEiWzSpbStoG5arWcYX6NB2-ftSiNc_CMh-CemG3peCu8ZOrSCHVFgjgCQC1zlBPjThDb-LSIbpc3uzcrjmKdC3xyuQAM8DoT5zv3FYIP13m1SOplZJx47EsonA19WEGnwABCA4hlMlQS96LIQMhVhADxlyJM3iqf_jn__vvJ0KgjL5uKLmVSsOxTFUsIHJ82mS8DAo_WZUmDxMnCAjrrxPQXLaNdfcmqehQOLT4_oiiVhA74UxSBi3EedkNnN5F2WV_Hd1Pr1vPWA_Qx52meKAa0_FhKu-Gm8uk2fFxK28flIbUv5HVQgGT0nrSuSprE4JslhAGl8hwCBGr5KxrUVAcMZE3vW26KrrI6jMTDLPGb81b9-ILrXLIJKb_ZOcmLggwzgbyxE_hUDLL9b88aZ7tE4dOVhACerSusVIq25s-hjms5Ws4Uw3wmgRQp1lp228deojpcavN-n3FNe3AIBgHFbpK2SzdOzvraj-HVkMpQptXrGEhVhAujmfdq6faQbfYn4LUQCy_sDUr1WNbklcyg2XTDQKscMF0VAUU38d50UrmprSKbhrnZpgWMBFg4ibUco_HO4UToFnL2lzc3Vlcg"
  }
}
```**application/vc**
            ```
{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "id": "http://university.example/credentials/temporary/28934792387492384",
  "type": [
    "VerifiableCredential",
    "ExampleDegreeCredential"
  ],
  "issuer": "https://university.example/issuers/14",
  "validFrom": "2017-10-22T12:23:48Z",
  "credentialSubject": {
    "degree": {
      "type": "ExampleBachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  },
  "proof": {
    "type": "DataIntegrityProof",
    "verificationMethod": "did:key:zUC78GzFRA4TWh2mqRiKro1wwRb5KDaMJ3M1AD3qGtgEbFrwWGvWbnCzArkeTZCyzBz4Panr2hLaZxsXHiBQCwBc3fRPH6xY4u5v8ZAd3dPW1aw89Rra86CVwXr3DczANggYbMD",
    "cryptosuite": "bbs-2023",
    "proofPurpose": "assertionMethod",
    "proofValue": "u2V0ChVhQhlm-IXSzQAaXH0xW-NU1t3ikH2xt--sFY-DtoL44DiWf3qv-nuhCc36deovk3t1GLy9JeN-vdeth8XWKMGUcyA4eWD21lxYdvK5Qdzw07ytYQGd_DaMQQsoaryttl5TvxnFT-Vm4SkVx03K9qNJ4jhArdrHmhnEXifHmmlKM3zCnc0pq4l3ZkBkIESZ4DrQomVNYYJVTGbTfcflzyx41E-f9kSqmf10xYzxJrGfC7b7GPY8X7VjMT__ZKSuwdH-5jak-5gkjocsHI6oxIKlLrhW1Wh5yrDCH-QC823TS8NE9VGBzIFAfUt5qazGEcJ8CxeSPxFggOkuR5x7VvZAB-RbcqkcwxkQ7or0tsVOUTPlebfxRUQCBZy9pc3N1ZXI"
  }
}

Protected Headers

{
  "kid": "ExHkBMW9fmbkvV266mRpuP2sUY_N_EWIN1lapUzO8ro",
  "alg": "ES256"
}

application/vc

{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "id": "http://university.example/credentials/temporary/28934792387492384",
  "type": [
    "VerifiableCredential",
    "ExampleDegreeCredential"
  ],
  "issuer": "https://university.example/issuers/14",
  "validFrom": "2017-10-22T12:23:48Z",
  "credentialSubject": {
    "degree": {
      "type": "ExampleBachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  }
}

application/vc+jwt

eyJraWQiOiJFeEhrQk1XOWZtYmt2VjI2Nm1ScHVQMnNVWV9OX0VXSU4xbGFwVXpPOHJvIiwiYWxnIjoiRVMyNTYifQ .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 .6xC1cZL-ht0EvN7nz2Zs81htECRBp_87csS2IRyRG41wp-4zW0US8rth2KZjQMhsuPy7s0yjVIRWFGb6TQRCdg

application/vc

{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "id": "http://university.example/credentials/temporary/28934792387492384",
  "type": [
    "VerifiableCredential",
    "ExampleDegreeCredential"
  ],
  "issuer": "https://university.example/issuers/14",
  "validFrom": "2017-10-22T12:23:48Z",
  "credentialSubject": {
    "degree": {
      "type": "ExampleBachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  }
}

application/vc+cose

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

  - 
    Encoded
  
  - 
    Decoded
  
  - 
    Issuer Disclosures

eyJraWQiOiJFeEhrQk1XOWZtYmt2VjI2Nm1ScHVQMnNVWV9OX0VXSU4xbGFwVXpPOHJvIiwiYWxnIjoiRVMyNTYifQ .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 .71495BlH0xrBlHTp-Y2JqwvTx1u3nu8dS8eiXwxSF-TukGYmbZ0y74RxVQCZ046h7YK2OZ-FZjlVUAcTN0vLvQ WyJqVThiaS1zWHk1dzVKNUYtdlhNaUZ3IiwgImlkIiwgImh0dHA6Ly91bml2ZXJzaXR5LmV4YW1wbGUvY3JlZGVudGlhbHMvdGVtcG9yYXJ5LzI4OTM0NzkyMzg3NDkyMzg0Il0WyJlbXBLOFdGNDhHcW56ekVudTJNblV3IiwgInR5cGUiLCBbIlZlcmlmaWFibGVDcmVkZW50aWFsIiwgIkV4YW1wbGVEZWdyZWVDcmVkZW50aWFsIl1dWyJnTnRsVmhfeVZyWm5aeEVXQUpyaFhRIiwgInR5cGUiLCAiRXhhbXBsZUJhY2hlbG9yRGVncmVlIl0

  ```

{  "kid": "ExHkBMW9fmbkvV266mRpuP2sUY_N_EWIN1lapUzO8ro",  "alg": "ES256"}

      ```
{  "iat": 1745776714,  "exp": 1746986314,  "_sd_alg": "sha-256",  "@context": [    "https://www.w3.org/ns/credentials/v2",    "https://www.w3.org/ns/credentials/examples/v2"  ],  "issuer": "https://university.example/issuers/14",  "validFrom": "2017-10-22T12:23:48Z",  "credentialSubject": {    "degree": {      "name": "Bachelor of Science and Arts",      "_sd": [        "_AOV6RD0Jaho5ZiH1ILMwJWJQ7q-nyeoyXHAj2yWmRY"      ]    }  },  "_sd": [    "PoZyPSPkswP287lENY02Gw85Ccs262YN_VFKHAi8fwo",    "V4cI8h49UKzznTtjLA_MgxAnQhydt0N99eUv0Serbl4"  ]}

8.11 Correlation During ValidationThis section is non-normative.

When processing verifiable credentials, verifiers evaluate relevant claims before relying upon them. This evaluation might be done in any manner desired as long as it satisfies the requirements of the verifier doing the validation. Many verifiers will perform the checks listed in Appendix A. Validation as well as a variety of specific business process checks such as:

      -

The professional licensure status of the holder.

      -

A date of license renewal or revocation.

      -

The sub-qualifications of an individual.

      -

If a relationship exists between the holder and the entity with whom the holder is attempting to interact.

      -

The geolocation information associated with the holder.

The process of performing these checks might result in information leakage that leads to a privacy violation of the holder. For example, a simple operation, such as checking an improperly configured revocation list, can notify the issuer that a specific business is likely interacting with the holder. This could enable issuers to collude to correlate individuals without their knowledge.

Issuers are urged to not use mechanisms, such as credential revocation lists that are unique per credential, during the verification process, which could lead to privacy violations. Organizations providing software to holders ought to warn when credentials include information that could lead to privacy violations during the verification process. Verifiers are urged to consider rejecting credentials that produce privacy violations or that enable substandard privacy practices.

Install via CLI
npx skills add https://github.com/sourcelabbg/eudi-knowledge --skill w3c-vcdm-privacy-minimization
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