Definition

SubjectId is the unique identifier of the person who owns a wallet.
It is derived from the digital signature returned by the authentication provider (e.g., BankID, ItsMe).

Uniqueness Rules

• Per person + per Wallet Provider: Same person always receives the same SubjectId with the same Wallet Provider.
• Across Wallet Providers: Same person receives a different SubjectId when onboarding with a different Wallet Provider.
• Re-onboarding: SubjectId does not change, even if the wallet is deleted and re-created.
• Multiple devices: All devices onboarded under the same person and Wallet Provider share the same SubjectId.

Lifecycle

• Created: Generated at successful onboarding via the authentication provider.
• Persistent: Remains the same across reinstallations, re-onboarding, and multiple devices (within one Wallet Provider).
• Reissued: If a wallet is deleted and re-onboarded with the same Wallet Provider, the same SubjectId is reissued.

Relationship to Other Identifiers

• SubjectId vs. FixedSDKId

  • SubjectId = identity of the person within one Wallet Provider.
  • FixedSDKId = identity of a specific device onboarding instance.
  • One SubjectId may have many FixedSDKIds.

• SubjectId vs. PaymentInstrumentId

  • SubjectId = identifies the person/wallet owner.
  • PaymentInstrumentId = identifies a specific card, account, or voucher stored in that wallet.

Typical Use Cases

• User lookup: Wallet Providers use SubjectId to manage all wallets/devices for one person.
• Event handling: Included in wallet events for correct user association.
• Multi-device support: Same SubjectId across devices ensures one user identity with multiple devices.
• Fraud protection: SubjectId is unique per Wallet Provider, preventing cross-provider identity correlation.

Key Rules to Remember

1. SubjectId is derived from the authentication provider signature.
2. It is stable across re-onboardings for the same person and Wallet Provider.
3. It changes when the same person onboards with a different Wallet Provider.
4. It is the used identity of a wallet owner in all APIs and events.