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For the complete documentation index, see llms.txt.

For the complete documentation index, see llms.txt

SK Mobile-ID signing

Mobile-ID from SK ID Solutions is a SIM card-based digital identity solution available in Estonia and Lithuania. In Sign API v2, this signing method is called SK Mobile-ID.

SK Mobile-ID creates certificate-based electronic signatures through the Sign API v2 PKISIGNING flow. This guide details how to configure and invoke SK Mobile-ID for signing.

Our authentication documentation refers to the same service as Mobiil-ID.

Supported capabilities​

Signature level​

SK Mobile-ID PKISIGNING produces a Qualified Electronic Signature (QES) in PDF Advanced Electronic Signatures (PAdES) BASELINE-LT format. The signed PDF embeds an authoritative signature timestamp and validation material (certificates and revocation data) for long-term (LT) validation.

Signing setup​

To request SK Mobile-ID through the Universal API, set signingSetup[].vendor to SK_MOBILEID and signingFlow to PKISIGNING in your HTTP POST request to the Signing sessions endpoint.

Include this configuration in the request body:

{
  "signingSetup": [
    {
      "vendor": "SK_MOBILEID",
      "signingFlow": "PKISIGNING",
      "requestedAttributes": ["nin"]
    }
  ]
}

For the complete session creation and document upload process, see our Sign API v2 integration guide.

Signer attributes​

The signer name and identity provider name are returned by default. To request the national identity number, include nin in the requestedAttributes array.

Attribute response​

When the session is complete, output.userInfo contains the retrieved attributes:

Restrict signing to a known person​

To require a particular national identity number, request the nin attribute and configure signer validation:

{
  "signer": {
    "nationalIdentificationNumber": "60706225732",
    "prefill": [],
    "validations": ["NATIONAL_IDENTIFICATION_NUMBER"]
  },
  "signingSetup": [
    {
      "vendor": "SK_MOBILEID",
      "signingFlow": "PKISIGNING",
      "requestedAttributes": ["nin"]
    }
  ]
}
Note

The session is rejected if the national identity number returned by SK Mobile-ID differs from the configured value. Setting nationalIdentificationNumber without "validations": ["NATIONAL_IDENTIFICATION_NUMBER"] does not enforce a match.

Pre-authentication with SK Mobile-ID​

To pre-authenticate with SK Mobile-ID, use sk-mobileid as the idpName:

{
  "signingSetup": [
    {
      "vendor": "SK_MOBILEID",
      "signingFlow": "PKISIGNING"
    }
  ],
  "preAuthentication": {
    "enabled": true,
    "identityProviders": [
      { "idpName": "sk-mobileid" }
    ]
  }
}

When preAuthentication.identityProviders is omitted, all identity providers configured on the account are offered.

Note

If national identity number validation is requested, the pre-authentication and signing identity providers must resolve to the same national identity. Otherwise, the session is rejected with a national identity number mismatch.

Signing result​

A completed session contains one PAdES result (PAdES-BASELINE-LT) for each signed input document:

{
  "lifecycle": {
    "state": "SIGNED",
    "stateIsFinal": true
  },
  "output": {
    "signatures": [
      {
        "resultDocumentId": "019ff016-75fc-739e-ab04-5ca7b56d0178",
        "originalDocumentId": "019ff013-ce14-7523-a706-165e3260a5f8",
        "signatureType": "PADES"
      }
    ],
    "packages": [],
    "userInfo": {
      "signingTime": "2026-08-11T12:10:09+03:00",
      "fullName": "Mary Änn O'connež-Šuslik Testnumber",
      "idpName": "sk-mobileid",
      "nin": "60706225732",
      "uniqueId": "PNOEE-60706225732",
      "firstName": "Mary Änn",
      "lastName": "O'connež-Šuslik Testnumber",
      "extra": {
        "client-ip": "203.0.113.42",
        "user-agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 Chrome/148.0.0.0 Safari/537.36"
      }
    },
    "seals": []
  }
}

Use resultDocumentId to retrieve the signed PDF. For multiple documents, match each result to its input using originalDocumentId rather than array order.

Limitations​

  • Only PDF documents are supported.
  • Signer identity prefill is not supported.

Test accounts​

You can test SK Mobile-ID signing using the official SK ID Solutions test numbers:

For the full list of test identities and error scenarios, see the SK Mobile-ID test numbers for automated testing in DEMO.

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