Verifiable Credentials Use Cases

1.1 Importance of this work

Entities (people, organizations, devices) need to make many kinds of claims as part of their everyday activities. As more and more of these important activities move to the Internet, entities need to be able to transmit instantly verifiable claims (e.g., about their location, accomplishments, value, what-have-you). From educational records to payment account access, the next generation of web applications will authorize entities to perform actions based on rich sets of credentials issued by trusted parties. Human- and machine-mediated decisions about job applications, account access, collaboration, and professional development will depend on filtering and analyzing growing amounts of data. It is essential that data be verifiable.

Standardization of digital claim technologies makes it possible for many stakeholders to issue, earn, and trust these essential records about their counterparties, without being locked into proprietary platforms.

1.2 Use case model

This document presents an aggregate use case model, comprised of Needs, Roles, Tasks, and Sequences. Taken together, these models define the use cases that the Verifiable Claims Working Group has addressed.

User needs define the problem space addressed by verifiable credentials. User Roles specify the roles different entities play when interacting with verifiable credentials. Tasks define the functions users can accomplish, and sequences demonstrate how tasks might be realized, by interactions between entities over time.

As with all models, this use case model is neither exhaustive nor complete. The listed uses cannot capture all possible use cases. Similarly, the models do not completely characterize the use cases represented. However, the combined model is intended to provide specific, coherent guidance for the work ahead.

3.1 Education

The education domain includes all levels of the educational experience; from primary through professional continuing education.

E.1 Digital transcript

Joleen is the registrar of Mega University and, by virtue of her office, is responsible for the integrity, accuracy, and security of academic records. Joleen has been a pioneering registrar in advocating an "extended transcript" that includes not only the standard set of course grades but also adds supplementary information on learner competencies. These might include work experiences and non-educational but marketable skills. Upon the request of her students, Joleen issues a digital credential that includes an extended transcript.

E.2 Taking a test

Eunice is about to take her ACT (a test used to evaluate her readiness for college). When she arrives at the testing center, she is required to present identification. Her government-issued identity certificate is acceptable, as the verifiable credentials contained in it reflect all of the required attributes and it is difficult to counterfeit.

E.3 Transferring schools

Rocky is an undergraduate student at Wossamotta U. His school provides a credential repository service to all students and alumni, so he chooses to use it. In his third year, Rocky decides to transfer to Moosylvania Tech. They do not offer a service, but he does not want to continue to use the service of his old (and now rival school) so he moves his claims to the service offered by his bank without needing to have them reissued.

E.4 Online classes

In MOOC and other online learning systems, being able to reliably identify participants is vital to ensure the individual evaluation and certification. Nick is participating in a course online and takes a test. He is required to provide his credentials to prove his identity before the test, and then to allow the system to issue a verifiable credential regarding the results of his test.

3.2 Retail

The retail domain encompasses all things where there is an exchange of value on an individual level. This includes brick-and-mortar store fronts, web-only venues, and even person-to-person sales.

R.1 Address verification

Francis has found the perfect pair of shoes. When processing orders, Giant Shoe Company wants to be certain that his shipping address is accurate (inaccurate addresses are very expensive in terms of customer service). They offer a discount for customers who make verifiable addresses available as part of the checkout process. Francis offers his certificate and gets the perfect shoes for even less than he expected.

R.2 Adult beverages

June goes to her local beer and wine store to buy a bottle of wine. She submits her identity credential that lets the liquor store owner know that she is over 21 without having to reveal her actual date of birth, her address, or her state ID number.

R.3 Fraud detection

On a bright Sunday, Oskar remembers that he still needs to buy his wife a precious gift for their wedding anniversary. However, he is acutely aware that it is precisely in weekends that gangs set up fraudulent web shops that claim to sell such gifts, while in fact they only take the cash, and disappear on Mondays. So before actually purchasing a gift from the web shop of his choice, he requests the shop to provide a credential issued by the chamber of commerce, that contains proof of legitimacy. After having verified that the shop is legit, he can purchase his gift.

3.3 Finance

The Finance domain includes banking, brokerage, insurance, and other industries where there is a high value placed on knowing exactly with whom you are dealing.

F.1 Reuse know your customer

Jane is opening an account at MidBank in Finland. As part of that process, the bank asks her to provide two from a variety of possible sources to confirm her identity — a so-called "Know Your Customer" check. She selects government-supplied verifiable credentials that confirm she receives postal mail at a certain address and that she has a national ID card. Confirming these allows the bank to open her account and be confident in her identity when she conducts transactions.

Now that the account is open, Jane is issued a digitally-signed credential for her checking account at MidBank. This credential verifies that Jane has an account at MidBank and has access to her associated checking account. Since MidBank (and all banks in Finland) are required to perform "Know Your Customer" checks on accounts, this credential can also be used as sufficient verification by other financial institutions. This can help Jane assure destination banks that she is verified, thereby allaying concerns about misdirected transactions and money laundering.

F.2 Money transfer

Susan wants to send funds to her family in another country via a popular money transfer service. She has verifiable credentials in her credential repository that can be used to share her identity profile. She has also been sent a credential from her family verifying their banking information. By sharing these with the money transfer service, they can automatically verify the source and destination of funds, thus being confident in the delivery of those funds and satisfying various regulations regarding prevention of money laundering.

F.3 Closing account

John opens a checking account at Big Bank Co and is issued a verifiable credential indicating that the account exists, that the bank verified John's identity, and that John has access to the account. Some time later, John is moving to a new city and decides to close that account. Big Bank Co needs to revoke that claim as part of their normal account closing process.

F.4 Trying out a new service

Nikita has several accounts with BigBank, as well as a brokerage account with WallStreetCo. She had placed all of her claims in a credential repository at BigBank that came free when she opened her accounts. WallStreetCo is now offering a new repository that has an interface she thinks she will prefer. Nikita copies her claims from BigBank into the repository at WallStreetCo to experiment with their service, but continues to use the service from BigBank while she is testing.

F.5 New bank account from home

Alice wants to open a new bank account. BigOnlineBank offers the ability to do this from home if she can provide electronic credentials. She offers government-issued certificates that verify her identity (address, national identity number, etc.), and opens her new account from her couch.

3.4 Healthcare

Privacy is critically important in the healthcare industry. This domain looks at everything from physical interaction to connecting patients and providers with service organizations.

H.1 Prescribing

Barney is a physician, and has recently become board certified in his state. The state's board issues Barney a digital certificate confirming that he is certified to practice medicine in that state. Barney can now use this certificate when writing prescriptions and referrals, thereby improving accountability and verifiability.

H.2 Online pharmacy

iPharmacy receives a prescription for Bob electronically from a local clinic. It includes a certificate about the physician that issued the prescription as well as one about Bob. iPharmacy's system automatically verifies the ability of the physician to write prescriptions, as well as Bob's insurance coverage. When Bob arrives to pick up his medication, iPharmacy further correlates his identity with the certificate, thereby improving the end-to-end accountability of their system.

H.3 Insurance claim

Tracy has a sore throat soon after moving to a new town. She finds a physician through her health care network and goes in for treatment. She is a new patient, so the clinic needs to know who she is and how she will be paying. When checking in, she presents her verifiable credential that demonstrates her identity and her proof of insurance. When the clinic submits this to the insurance company, they can automatically ascertain that she submitted her proof of identity and insurance to the provider and granted the physician the ability to submit the claim for payment.

H.4 Traveling illness

John is on the vacation of a lifetime, travelling the world. Falling ill, he visits a health clinic in a country in which he does not live. At the clinic, he is asked for proof of identity. He provides a credential that verifies his name and address, but elects not to disclose his marital status nor his social security number, as those are neither requested nor required at this clinic. He further marks the disclosure as expiring in 30 days—he does not want his information verifiable after that time.

H.5 Proving Legal Disability Status

Trina, who is legally blind, is currently unemployed, and needs to use the local free disability ride service to get to the employment office. To use this service, she is required to verify that she maintains legal disability status. Trina provides her government-issued disability credential to sign up for the ride service, and is not required to disclose her specific disability to the ride service, as this could put her at personal risk.

3.5 Professional Credentials

In many aspects of life it is important to know that entities are who they say they are, and that they can do what they say. Professional accreditation is one way of learning about the abilities of an entity. Being able to verify these credentials is essential to their value.

C.1 Find a doctor

Jason is looking for a new primary care physician. His health provider includes information on their web site about the physicians they have on staff, including verifiable credentials about their education, board certification, and continuing education. Jason can verify these credentials and be confident that his new physician satisfies his requirements.

C.2 Busy doctor

Barney was a board-certified physician, but he ran out of time to complete his continuing education requirements and his certification lapsed. Since the board can revoke his certification, credential verifiers will automatically be aware that he can no longer issue prescriptions or perform medical procedures.

C.3 Bad university

Jane was issued a certificate by BigTraining Co., indicating that she was a trained Project Manager. It was later discovered that BigTraining Co. was not actually training anyone, and their organization's certificate was revoked via the US Department of Education's Accreditation Database. Jane's credential is therefore invalid, and prospective employers will be aware of this when they check her certifications.

C.4 New employer

Jessica is a medical doctor practicing in the United States. She has a variety of digital claims that explain her qualifications, schooling, continuing education achievements, and board certifications. These are all stored in the credential repository provided by her employer. When she is offered a position with another health provider network, she can automatically transfer all of these claims to her new employer.

C.5 Social authority

Josie is a healthcare worker that has created a profile on a professional social network to make herself readily available for new opportunities in the workforce. She lists her employment history and credentials including degrees, certificates, and digital badges. The website requests verification of her credential claims in order for her credentials to be visible when she posts messages. Josie authorizes the sharing of the relevant claims with the website, and the site verifies them before allowing Josie to expose them.

"Freedom?" is an online forum that encourages free discussion about issues controversial in Freedonia. The forum allows users to register anonymous accounts, but it also allows users to obtain badges based upon real-world certifications. Paula has been certified as an aid worker, and wishes that information to be marked on her posts. She shares her certificate with the forum, but limits it to only verifying that she is the holder of the certificate, that she is the subject of it, and that she is an aid worker. In this way she maintains her anonymity in this controversial forum while still being able to assist her fellow countrymen.

C.6 Job applicant

Software Co. has posted an open position online and they are receiving thousands of applications. Cindy has applied for the job. Unlike many applicants, she has attached her education credentials—college degree, additional specific software training, etc. Software Co. evaluates these credentials automatically as they receive her application. Because her materials are verifiable and verified, her application is immediately forwarded as a viable candidate.

3.6 Legal Identity

For many transactions, an entity must be able to prove some aspect of their identity in a way that can be quickly verified. Governments and other widely recognized entities are well positioned to provide such identification in a verifiable digital form.

L.1 Digital driving license

Asako just passed the final test to receive a drivers license. As she is still a new driver, and may be pulled over for a traffic violation, she would like to receive a credential that asserts a claim that she has right to drive a car. She requests a credential from the certifying authority (issuer) that she can use to prove to the officer (credential verifier) that her claim is valid.

L.2 Seamless immigration

Tom is a frequent international traveler. In order to speed processing through immigration check points, he applies for a digital passport from his governmental authority. After satisfying background check requirements, the authority issues Tom an electronic version of his passport. This version is verifiable and retains a history of all the places he visits so that immigration officials can quickly and easily evaluate his suitability as a visitor to their country. Once they are satisfied, they will automatically add the details of this new visit to Tom's passport.

L.3 Speedy air travel

Security for air travel is more and more rigorous, requiring more and more time to validate each passenger. Ivan has a collection of verifiable credentials that are assembled into his air travel Identity Profile. When Ivan needs to pass through a security checkpoint at his airport, he presents this profile before entering the line. Because his identification can be immediately and automatically verified, he is permitted to skip the long line and go straight to the metal detector.

L.4 Refugee crisis

Thousands of people each year are displaced because of man-made and natural disasters. Anoushka is one such, having been forced to flee her village along with her mother and younger brother. They reach an IFRC center just across the border in a relatively safe area, but with no documentation. Since the government of her homeland is in turmoil, there is no way for the IFRC staff to easily establish their identities. Fortunately, Anoushka had been issued a self-sovereign proof of birth, attached to which is the proof of birth and marriage for her parents. She is able to retrieve this because it is available from many places often the Internet. Since it is verifiable, the IFRC is comfortable vouching for them and resettling them in a safer area for the duration of the conflict.

3.7 Devices

Intelligence devices are created and deployed so that they can interact with other entities (people, organizations, devices). Establishing trust and maintaining secure relationships with these devices is especially critical.

D.1 Devices during manufacturing

Bob, the director of production at HVAC Manufacturing, issues a device-identifying verifiable credential (e.g. IDevID, IAK) at the factory for an energy-saving fan controller IoT device.

Carol, senior quality engineer at Certifications Testing Lab, issues a certification of specification-compliance verifiable credential to the fan-controller device at the certification lab during the manufacturing process.

When the fan controller is installed at the customer's office at Modern Office Spaces, the controller's identifying credential can be verified by Sam, IT technician, to establish the identity of the controller as part of the on-boarding of the new controller. The controller's specification-compliance credential is verified to demonstrate the controller's Energy-Star compliance.

D.2 Devices during delivery

As the fan controller leaves the factory, additional verifiable credentials are issued by Vince, a systems engineer at VAR Resellers, as he verifies the manufacturer's configuration matches the verifiable credentials accompanying the device. He then installs a software package specific to Modern Office Spaces needs and issues verifiable credentials that establish evidence of possession by VAR Resellers and the software additions Vince made to the device.

Finally, upon delivery to Sam, the end customer, the verifiable credentials show that the fan controller has been securely handled and contains the correct features and certifications.

D.3 Devices setup for operating autonomously

Sam, the new device owner, needs to trust the device originated from HVAC Manufacturing and was handled correctly at Certifications Testing Lab and installed with the correct software package at VAR Resellers. After Sam verifies each of the verifiable credentials, he issues another verifiable credential for fan controller #37 which includes assertions relating to trust: device manufacturer model/version, software manufacturer model/version, security versions of components TCB, and associated devices the fan controller is authorized to interact with including thermostat-board-room.

The thermostat-board-room monitors room temperature. When the temperature is too hot it switches the fan controller #37 on and later when the temperature reaches a comfortable level, off. The device makes sure the control signals from thermostat-board-room are authorized (namely, that Sam intended for thermostat-board-room to control the fan controller).

Sam is concerned about the security of the smart board room. He configures the autonomously interacting devices to re-verify device trustworthiness attributes periodically by re-checking that the device originated from HVAC Manufacturing and was handled correctly by Certifications Testing Lab and installed with the correct software package by VAR Resellers.

Sam may update the device’s software occasionally during its lifetime. Even though Sam is applying the update, VAR Resellers supplies the correct update. The device ensures that only VAR Resellers is able to supply the updated software image and that only Sam is able to apply the update.

4.1 Issue Claim

Requirement

It MUST be possible for any entity to issue a verifiable credential.

Motivation

Individuals and organizations need a way to issue claims about themselves or others that can be verified and trusted.

Needs

F.1 Reuse know your customer, E.1 Digital transcript, L.1 Digital driving license, H.1 Prescribing

4.2 Assert Claim

Requirement

It MUST be possible for the holder of a verifiable credential to restrict the amount of information exposed in a credential they choose to share. It also MUST be possible for the holder to limit the duration for which that information is shared.

Motivations

Credentials may be issued about a subject that include multiple attributes, only some of which are required when verifying a specific criteria is satisfied. The holder should have the ability to satisfy the criteria without revealing additional attributes that are not required.

Needs

R.2 Adult beverages, H.4 Traveling illness

4.3 Verify Claim

Requirement

It MUST be possible for a verifier to verify that the credential is an authentic statement of an issuer's claims about the subject. The verifying entity must have the capability to connect the issuer’s identity to its credential identifier and the subject's identity to their identifier as indicated in the credential. The issuer’s verification information, such as its public key, must be discoverable from the credential record and verifiably linked to the issuer. It MUST be possible to do this in an automated fashion.

Motivations

In many environments (such as order processing) information such as a payer's address, citizenship, or age need to be automatically verified in order to complete the transaction.

Needs

F.2 Money transfer, C.1 Find a doctor, E.2 Taking a test, R.1 Address verification, F.5 New bank account from home, H.2 Online pharmacy, C.6 Job applicant

4.4 Store / Move Claim

Requirement

It MUST be possible for the holder of a claim to store that claim in one or more credential repositories. It MUST also be possible for the holder to move a claim among credential repositories, and to do so without requesting a new claim from the claim issuer.

Motivation

A claim is under the control of its holder. That holder will choose where their claims are stored based upon a variety of factors (e.g., employer requirements, convenience, service levels, provider cost, business intelligence). The holder needs to be able to easily choose among various credential repositories, and also to be able to migrate their claims to another without requesting new claims from the claim issuer.

Needs

F.4 Trying out a new service, E.3 Transferring schools, C.4 New employer

4.5 Retrieve Claim

Requirement

It MUST be possible for a holder to select if and which appropriate credential should be sent to a verifier.

Motivations

A verifier may require that a holder verify aspects of their suitability for a transaction. In this case, the holder must be able to select which, if any, verifiable credential stored with their credential repository is used to satisfy the verifier.

Needs

C.5 Social authority, E.4 Online classes

4.6 Revoke Claim

Requirement

It MUST be possible for the issuer of a claim to revoke it, after which it will no longer satisfy verification procedures.

Motivation

An entity (issuer) discovers that a claim they have issued and are endorsing for an end user (subject), is no longer valid and wishes to revoke the issued claim.

Needs

F.3 Closing account, C.2 Busy doctor, C.3 Bad university

5.1 Citizenship by Parentage

Background

Sam wants to claim US citizenship because his mother is American. Sam has a digital birth certificate from Kenya, where he was born while his Mother was in the Peace corps. He also has a digital version of his mother's US passport. Because his mother’s name changed between his birth and the issuance of the passport, Sam also has a marriage license with her maiden and married names. Sam is applying for a new passport from the US Secretary of State.

Distinction

This use case is challenging because the mother’s name changed, by marriage, between the issuance of the birth certificate and passport.

Scenario

Sam’s mother emailed him the certificate, license, and passport as independent Verifiable Credentials. He then creates a verifiable presentation which includes those credentials, a statement of their relationship to each other and his relationship to his mother. He then visits the US Secretary of State website, creates an account, starts the application for a passport, and uploads his new verifiable presentation as supporting evidence. After processing the application, Sam is issued both a traditional passport and a new digital passport.

Verifiable Credentials

Birth Certificate

Establishes relationship to mother with maiden name

Marriage License

Establishes mother's name change

Mother’s Passport

Establishes mother's US citizenship

Sam’s Passport

Establishes Sam is the child in the birth certificate

Verifiable Presentation

A verifiable presentation which includes those three credentials, adds his name, photo, and demographic data along with the assertions that —

• He is the child in the birth certificate.
• The mother in the birth certificate, the person in the passport, the spouse in the marriage license are all the same person.

Trust Hierarchy

Sam is legally liable for his claim to the rights of citizenship. The state department is on the hook for verifying the underlying credentials and Sam’s claims, including correlating against any additional data they might already have.

Threat model

• Threat: Terrorist / Identity fraud. A bad actor could be impersonating Sam to attain a passport. Of course, if a bad actor were to be able to collect the required verifiable credentials—mother’s passport, birth certificate, and marriage license, that actor has already significantly compromised the system.
  • Response: Identity assurance based on the presentation and other data, above and beyond what is in the presentation and the claims.
  • Response: Identity assurance based on the contents of the claims, potentially with enhanced data embedded in the claims, i.e., data not currently in passports, birth certificates, or marriage license. For example, a biometric template could be embedded in the birth certificate claim and that template could be used for interactive identity assurance at the time of submitting the presentation.
• Threat: Exposure of private information. By storing potentially compromising information in credentials and sending them over the network, we are increasing the attack surface for the subjects of those credentials.
  • Response: Encrypt the claims (once by issuer, every verifier gets the same encrypted blob)
  • Response: Encrypt the claims uniquely for each verifier. This may leak usage data to the issuer, assuming the holder must ask for a new, encrypted credential for each verifier.
  • Response: Blind the claims uniquely for each verifier.
  • Response: Encrypt the presentation uniquely for each verifier. No issuer involved.

5.2 Expert Dive Instructor

Background

Pat earned multiple diving credentials while living and working in Fiji and Australia. Later, Pat is hired by NOAA as a Dive Instructor, which requires that they maintain certification as an instructor with additional specialist diver certifications in dry suit, night diving, and search and recovery. The dive instructor certification is public record, but the additional specialist certifications are private because they are for personal diving, not acting as an instructor.

Part of Pat's job is logging the certifications of fellow divers during NOAA sanctioned dives.

Distinction

This use case is difficult because:

• Certification in Fiji and Australia. NOAA relies on an international certification agency, PADI, with relevance in multiple jurisdictions.
• Each of these credentials is issued by different schools in the name of PADI.
• Each credential has an independent expiration cycle.
• Pat grants NOAA permission (the capability) to validate future credential status changes.
• On each trip, Pat creates a certified log of all divers, effectively issuing a verified credential about other credentials.

Scenario

When Pat applied for his job at NOAA, he provided verifiable credentials issued by different dive schools licensed by PADI to do so. NOAA verifies cryptographically that the certifications were issued by PADI-approved dive schools and that the credentials were still in good standing by checking both the certifications' *and* the dive schools' revocation services.

Upon accepting the job, Pat issues NOAA a revocable token that allows NOAA to check the current status of all of his certifications — not just the status of a single verifiable credential. After any specific certification expires — and Pat renews it — NOAA's next check of Pat's certifications returns the status of the renewed certification, not just the status of the (now expired) verifiable credential.

When Pat takes a group of divers on NOAA sanctioned dives, he records the verifiable credentials for each diver (which demonstrate their diving certifications), creates a verifiable credential including those credentials; he signs and archives it on his laptop.

When Pat retires from NOAA, he revokes that token and NOAA staff is no longer able to monitor his non-public certification status.

Verifiable Credentials

• Advanced Open Water Instructor
• Drysuit Dive Certification
• Night Diving Certification
• Search & Recovery Dive Certification
• Fiji PADI School Affiliation Certification
• Australia PADI School Affiliation Certification
• Signed log entry of dive event

Verifiable Presentation

• Verifiable credentials submitted with job application

Trust Hierarchy

• PADI is liable for correctly certifying dive schools.
• Dive schools are liable for correctly certifying Pat's knowledge and skills.
• Pat is liable for representing the facts in their application and maintaining the revocable capability.
• NOAA is liable for verifying the credentials and Pat's assertions claiming them, and for assuring Pat's continued good standing for the required credentials.
• Pat is liable for making sure all divers, on each trip, have valid credentials and are properly logged.
• Diver's are liable for presenting valid credentials, specifically credentials for which they are the subject, including any formal identity credentials, e.g., passport or driver's license.

Threat model

• Threat: Issuer is compromised. One of the dive schools had their private keys stolen, but the school itself only ever issues valid certificates.
  • Response: Use multi-sig to prevent theft of a single key from relevance
  • Response: Hardware wallet to minimize threat of network-based attack
  • Response: Biometrically locked hardware wallet
  • Response: Frequent rotation to minimize exposure from stolen keys
  • Response: Enhanced background checks for all individuals with access to keys
  • Response: Instead of institutional keys, sign certificates with individuals' keys plus credential from the school.
• Threat: A dive school could issue unearned certificates.
  • Response: Audit certificate issuance. Record all issuance, systemically spot check for validity.
  • Response: Background checks on schools prior to authorization
  • Response: Limit the number of certificates that can be issued to limit impact of violation
  • Response: Limit time horizon that the school may issue on behalf of PADI to require re-validation of qualifications
  • Response: Use revocation mechanisms for school's authorization credentials
• Threat: Dive school could issue certificates with a revoked authorization.
  • Response: Holders should verify the authorization, before they buy the course
  • Response: Holders should verify the authorization at the point of receiving the credential
  • Response: Verifiers should also verify the authorization of the issuer
• Threat: Pat could send a proxy to earn their certificate.
  • Response: School should use multi-factor identity assurance during registration and onsite when testing.
  • Response: Dive school retains video surveillance of event for future audits
  • Response: Dive boat or test center takes photos of participants and logs them for later audit
• Threat: Pat or another dive master could lie about a diver being on the boat.
  • Response: NOAA requires divers listed to submit endorsement that they were there (they endorse the dive log); divers mutually sign each other's log entries
  • Response: Boat owner signs dive log
  • Response: Pre-register excursion and expected diver list
  • Response: Ongoing signed provenance data about Pat's job assignments (location, dates, correspondence, etc) by/with NOAA Manifest "souls on board" before/after including crew
  • Response: Independent ID proofing of offline credentials (signed picture and/or photo ID)
• Threat: Malware could take control of issuer or verifier agent.
  • Response: Run virus and malware scans regularly
  • Response: Isolate issuer agent system to an air-gapped environment
• Threat: Pat is phished, and Pat gives capability to the wrong person/entity.
  • Response: Use better identity assurance for the verifier, i.e., don't give capability to strangers.
  • Response: Use Object Capabilities based on strong authentication and well-known public keys.
• Threat: Issuer spoofs Pat, and Pat receives VC from non-PADI-certified instructor.
  • Response: Pat runs PADI's wallet software to make sure any certificates they receive are authentic.
  • Response: Pat checks the VC with a PADI-provided tool before accepting it
  • Response: Pat checks the VC with a standard tool, to see that (1) There really is a PADI authentication and (2) PADI authentication is actually from PADI
• Threat: Pat presents a fake credential as a PADI certification.
  • Response: NOAA verifies the signature on the certification credential AND on the PADI authentication credential.
• Threat: Pat's laptop on the boat could be compromised.
  • Response: Use air-gapping techniques, such as QR codes, to limit impact of compromise

5.3 International Travel with Minor and Upgrade

Background

Malathi is traveling internationally with her 8-month-old son, Anand. His father, Rajesh, is staying home. Malathi has enough frequent flyer miles to upgrade the ticket to first class.

Distinction

This use case is difficult because:

• Current US passports do not establish explicit relationship between parent and child.
• When one parent travels with a minor, the other parent is required to grant permission for the trip, thus implying guardianship or responsibility.
• The DID or other Digital Identity system replaces the role of the notary in the paper/physical world
• Credentials must be coordinated between two verifiers (agent and airline) for two individuals, and a digital coupon is used.
• The relationship of the minor to the non-traveling parent must be established, in order for the permission to be considered.
• In the minor's passport case, the subject is not the holder of the verifiable credential. The holder of the passport is a parent, not the minor.

Scenario

Malathi obtains permission from Rajesh stating she is allowed to take the baby out of the country.

Prior to booking the trips, Malathi visits HappyAir.com to request an upgrade to first class. HappyAir issues a verifiable credential redeemable for a first class upgrade on an international flight.

She books the plane tickets through her travel agent who adds the lap child to the ticket.

HappyAir verifies that Malathi has a signed statement from Anand’s other parent stating that she may exit the country with him.

Verifiable Credentials

Malathi's passport

Establishes identity of the traveling parent

Anand's passport

Establishes identity of the minor

Anand's Birth Certificate

Establishes relationship to parents and provides link from Rajesh to Anand that qualifies the permission to travel

Permission to travel from Rajesh

• Grants permission from non-traveling parent for minor to travel.
• Identity matches identity of the parent in the birth certificate, establishing relevance.

Upgrade coupon for first class ticket

Introduces commercial value in a verifiable credential

For details, refer to Example Verifiable Credentials in Appendix

Verifiable Presentation

Submitted to HappyAir, includes Malathi and Anand's passport, assertion of permission, birth certificate and Frequent Flyer coupon.

Trust Hierarchy

• Malathi is liable for her claim of parentage as well as securing right to admission for herself and her son at their destination (visa may be required).
• Malathi and Rajesh are both liable for attestation of permission to fly with Anand without the other parent.
• Malathi is liable for the cost of her ticket and her son’s ticket.
• The agency is liable for issuing valid tickets and for verifying the credentials provided by the travelers.
• The airline is liable for issuing tickets and, ultimately, fulfilling the terms of travel
• The airline is liable for accepting the upgrade coupons at ticketing.
• The airline is liable for verifying the credentials in the birth certificate match the credentials in the permission letter.
• The check-in agent, TSA agent, and passport control at the destination are liable for identity assurance at various points of travel, using information contained in the verifiable credentials.

Threat model

• Threat: Stolen Key. Malathi steals Rajesh’s key in order to fake travel permission. (Kidnapping her own kids and fleeing Rajesh.)
  • Response: Rajesh could store his key with a trusted third party, such as an attorney.
  • Response: Rajesh could use a hardware wallet with pin or biometric.
  • Response: Rajesh could use a passphrase on his key
• Threat: Stolen Key 2 Ticket purchaser has Malathi’s credentials, impersonating her to purchase a ticket. This could enable a third-party kidnapping.
  • Response: Travel permission can be restricted to specific date and or trip minimizing abuse potential.
  • Response: Embed identifying characteristics or biometric into the credentials so that verifiers can independently verify the subject in front of them is the subject in the credential.
  • Response: Malathi could use a hardware wallet with pin or biometric.
  • Response: Malathi could use a passphrase on her key
• Threat: Exposure of private information. By storing potentially compromising information in credentials and sending them over the network, we are increasing the attack surface for the subjects of those credentials.
  • Response: Encrypt the claims (once by issuer; every verifier gets the same encrypted blob)
  • Response: Encrypt the claims uniquely for each verifier. This may leak usage data to the issuer, assuming the holder must ask for a new, encrypted credential for each verifier.
  • Response: Blind the claims uniquely for each verifier.
  • Response: Encrypt the presentation uniquely for each verifier. No issuer involved
• Threat: Stolen coupon Rajesh falsifies the upgrade coupon.
  • Response: HappyAir signs the coupon with secure credentials.
  • Response: Travel agent verifies the coupon through a distributed status registry, verifying it is still valid

6.1 How a Verifiable Credential Might Be Created

In this first example, a user will request a verifiable credential—a confirmation of their identity. Consider this illustration:

Expanding on these steps:

1. Jane asks her User Agent to help her get a verifiable credential about her identity.
2. Her user agent connects her to a credential issuer that is able to verify her identity.
3. The issuer examines her documentation.
4. They are satisfied, so the issuer generates a verifiable credential for Jane that includes information about her identity linked to their own trusted credential.
5. The issuer delivers the verifiable credential back to Jane's User Agent.
6. Jane views the verifiable credential to ensure it reflects her requirements.
7. When she is satisfied, she instructs her User Agent to save the verifiable credential so she can use it in the future.
8. The UA communicates with her credential repository, instructing it to store the new verifiable credential.
9. The credential repository returns a list of the verifiable credentials it is holding for Jane to the UA.
10. The UA shows Jane her verifiable credential collection — confirming everything she has available.

6.2 How a Verifiable Credential Might Be Used

In this example, a holder of a claim needs to use that claim in a typical commerce situation:

1. Jane decides to shop on the website WinesOfTheWorld.example.com (merchant).
2. The merchant's site requires Jane be 21 years of age and requests (via a user agent-supported API call) that Jane prove this.
3. Jane's user agent asks her credential repository for the proof.
4. The credential repository shows Jane some verifiable credentials it holds that can support her age claim (e.g., her passport, driving license, and birth certificate).
5. Jane selects one of these, and authorizes that it be shared with the merchant.
6. The credential repository returns the selected credential as a response to the user agent-supported API call, which in turn delivers it to the merchant.
7. The merchant's server verifies that the claim is valid and satisfies the requirement.
8. The merchant redirects the user agent to the web site with appropriate authorization.