Verify and Use JWT

Upon receiving the JWT, the verifier needs to validate it. The JWT can be verified in the following two ways.

• Validate whether the JWT is a valid token of a valid DID signature (generic validation)

• Validate whether the JWT is a valid token of a specified DID signature (specified validation)

Generic Validation

let token: String = ... // the JWT token from 3rd party
// Create a JWT parser
let parser = try JwtParserBuilder().build()
// Parse and verify the token
do {
	  let jwt = try parser.parseClaimsJwt(token)
} catch {
    // Handle the parse and verify errors
}

Under such circumstances, the JWT parser will resolve the signer in the JWT and try verifying the JWT based on the signer’s DID after resolving its DID.

Specified Validation

let token: DIDStore = ...  // the JWT token from 3rd party
let did = try DID("did:elastos:igyq8SV5RT33HVqgCTCGU48u2pfnyH4XMn") // expected signer
// resolve signer's DIDDocument
let signer = try did.resolve()
if try !signer.isValid() {
    // should report errorss  
// Create a JWT parser with signer
let parser = signer.jwtParserBuilder().build()
// Parse and verify the token
do {
	  let jwt = try parser.parseClaimsJwt(token)
} catch {
    // Handle the parse and verify errors

In this case, this token is assumed to have a specified DID signature. If the signed DID of JWT is inconsistent with the signer’s DID, the verification will fail.

Read JWT Information

After resolving and validating the token, Swift SDK will return a JWT object through the interface of which the attributes and data encapsulated in the JWT can be accessed. For example:

let jwt = parser.parseClaimsJwt(token)
// Read the JWT header
let header = jwt.header
let contentType = header.getContentType()
let version = header.get("version")
// ...
// Read the claims
let claims = jwt.claims
let subject = claims.getSubject()
let audience = claims.getAudience()
// ...