chore: add challenge to presentation

docs/getting-started.md

@@ -518,15 +518,18 @@ A verifier usually requires a claimer to fulfil some requirements before providi
 The verifier needs to initiate the verification process by requesting a presentation for a specific CType.
 In this case, the verifier wants to verify the name of the claimer.
 To do so, it will send a request for credential message to the claimer.
+The request for credential can optionally contain a challenge that will be used by the verifier to ensure that the claimer owns the identity specified in the provided credentials at the time the presentation is generated.
 
 ```typescript
+const challenge = Kilt.Utils.UUID.generate()
 const requestForCredentialMessage = new Kilt.Message(
   {
     type: Kilt.Message.BodyType.REQUEST_CREDENTIAL,
     content: {
       cTypes: [
         { cTypeHash: ctype.hash, trustedAttesters: [attesterFullDid.did] },
       ],
+      challenge,
     },
   },
   verifierLightDid.did,
@@ -548,6 +551,7 @@ const selectedCredential = await credential.createPresentation({
   selectedAttributes: ['name'],
   signer: keystore,
   claimerDid: claimerLightDid,
+  challenge,
 })
 console.log('Presentation:')
 console.log(JSON.stringify(selectedCredential))

docs/getting-started.ts

@@ -281,13 +281,15 @@ async function main(): Promise<void> {
   console.log(`Verifier DID: ${verifierLightDid.did}`)
 
   /* 5.2 Ask for credentials */
+  const challenge = Kilt.Utils.UUID.generate()
   const requestForCredentialMessage = new Kilt.Message(
     {
       type: Kilt.Message.BodyType.REQUEST_CREDENTIAL,
       content: {
         cTypes: [
           { cTypeHash: ctype.hash, trustedAttesters: [attesterFullDid.did] },
         ],
+        challenge,
       },
     },
     verifierLightDid.did,
@@ -301,6 +303,7 @@ async function main(): Promise<void> {
     selectedAttributes: ['name'],
     signer: keystore,
     claimerDid: claimerLightDid,
+    challenge,
   })
   console.log('Presentation:')
   console.log(JSON.stringify(selectedCredential))