diff --git a/Sources/Entities/CredentialIssuer/CredentialIssuerMetadata.swift b/Sources/Entities/CredentialIssuer/CredentialIssuerMetadata.swift
index d8bd604..e22238c 100644
--- a/Sources/Entities/CredentialIssuer/CredentialIssuerMetadata.swift
+++ b/Sources/Entities/CredentialIssuer/CredentialIssuerMetadata.swift
@@ -19,7 +19,7 @@ import JOSESwift
 
 public struct CredentialIssuerMetadata: Decodable, Equatable {
   public let credentialIssuerIdentifier: CredentialIssuerId
-  public let authorizationServers: [URL]
+  public let authorizationServers: [URL]?
   public let credentialEndpoint: CredentialIssuerEndpoint
   public let batchCredentialEndpoint: CredentialIssuerEndpoint?
   public let deferredCredentialEndpoint: CredentialIssuerEndpoint?
diff --git a/Sources/Issuers/Issuer.swift b/Sources/Issuers/Issuer.swift
index 45ea59f..2da9860 100644
--- a/Sources/Issuers/Issuer.swift
+++ b/Sources/Issuers/Issuer.swift
@@ -145,9 +145,13 @@ public actor Issuer: IssuerType {
     let authorizationServerSupportsPar = credentialOffer.authorizationServerMetadata.authorizationServerSupportsPar
 
     let state = StateValue().value
-    
+
     if authorizationServerSupportsPar {
       do {
+        let resource: String? = issuerMetadata.authorizationServers.map { _ in
+          credentialOffer.credentialIssuerIdentifier.url.absoluteString
+        }
+
         let result: (
           verifier: PKCEVerifier,
           code: GetAuthorizationCodeURL
@@ -155,7 +159,8 @@ public actor Issuer: IssuerType {
           scopes: scopes,
           credentialConfigurationIdentifiers: credentialConfogurationIdentifiers,
           state: state,
-          issuerState: issuerState
+          issuerState: issuerState,
+          resource: resource
         ).get()
         
         return .success(
diff --git a/Sources/Main/Authorisers/AuthorizationServerClient.swift b/Sources/Main/Authorisers/AuthorizationServerClient.swift
index 4cac653..66a1ec7 100644
--- a/Sources/Main/Authorisers/AuthorizationServerClient.swift
+++ b/Sources/Main/Authorisers/AuthorizationServerClient.swift
@@ -31,7 +31,8 @@ public protocol AuthorizationServerClientType {
     scopes: [Scope],
     credentialConfigurationIdentifiers: [CredentialConfigurationIdentifier],
     state: String,
-    issuerState: String?
+    issuerState: String?,
+    resource: String?
   ) async throws -> Result<(PKCEVerifier, GetAuthorizationCodeURL), Error>
   
   func requestAccessTokenAuthFlow(
@@ -181,7 +182,8 @@ public actor AuthorizationServerClient: AuthorizationServerClientType {
     scopes: [Scope],
     credentialConfigurationIdentifiers: [CredentialConfigurationIdentifier],
     state: String,
-    issuerState: String?
+    issuerState: String?,
+    resource: String? = nil
   ) async throws -> Result<(PKCEVerifier, GetAuthorizationCodeURL), Error> {
     guard !scopes.isEmpty else {
       throw ValidationError.error(reason: "No scopes provided. Cannot submit par with no scopes.")
@@ -197,6 +199,7 @@ public actor AuthorizationServerClient: AuthorizationServerClientType {
       state: state,
       codeChallenge: PKCEGenerator.generateCodeChallenge(codeVerifier: codeVerifier),
       codeChallengeMethod: CodeChallenge.sha256.rawValue,
+      resource: resource,
       issuerState: issuerState
     )
     
diff --git a/Sources/Main/Resolvers/CredentialOffer/CredentialOfferRequestResolver.swift b/Sources/Main/Resolvers/CredentialOffer/CredentialOfferRequestResolver.swift
index afd57d2..7730610 100644
--- a/Sources/Main/Resolvers/CredentialOffer/CredentialOfferRequestResolver.swift
+++ b/Sources/Main/Resolvers/CredentialOffer/CredentialOfferRequestResolver.swift
@@ -86,7 +86,7 @@ public actor CredentialOfferRequestResolver {
           return .failure(ValidationError.error(reason: "Invalid credential metadata"))
         }
         
-        guard let authorizationServer = credentialIssuerMetadata.authorizationServers.first,
+        guard let authorizationServer = credentialIssuerMetadata.authorizationServers?.first,
               let authorizationServerMetadata = try? await authorizationServerMetadataResolver.resolve(url: authorizationServer).get() else {
           return .failure(ValidationError.error(reason: "Invalid authorization metadata"))
         }
@@ -107,7 +107,7 @@ public actor CredentialOfferRequestResolver {
             return .failure(ValidationError.error(reason: "Invalid credential metadata"))
           }
           
-          guard let authorizationServer = credentialIssuerMetadata.authorizationServers.first,
+          guard let authorizationServer = credentialIssuerMetadata.authorizationServers?.first,
                   let authorizationServerMetadata = try? await authorizationServerMetadataResolver.resolve(url: authorizationServer).get() else {
             return .failure(ValidationError.error(reason: "Invalid authorization metadata"))
           }
diff --git a/Tests/Helpers/Wallet.swift b/Tests/Helpers/Wallet.swift
index af4d16b..34ebef9 100644
--- a/Tests/Helpers/Wallet.swift
+++ b/Tests/Helpers/Wallet.swift
@@ -66,7 +66,7 @@ extension Wallet {
     
     switch issuerMetadata {
     case .success(let metaData):
-      if let authorizationServer = metaData?.authorizationServers.first,
+      if let authorizationServer = metaData?.authorizationServers?.first,
          let metaData {
           let resolver = AuthorizationServerMetadataResolver(
             oidcFetcher: Fetcher(session: self.session),