diff --git a/Sources/NFCPassportReader/PassportReader.swift b/Sources/NFCPassportReader/PassportReader.swift
index 773f469..0335c18 100644
--- a/Sources/NFCPassportReader/PassportReader.swift
+++ b/Sources/NFCPassportReader/PassportReader.swift
@@ -34,6 +34,7 @@ public class PassportReader : NSObject {
     private var caHandler : ChipAuthenticationHandler?
     private var paceHandler : PACEHandler?
     private var mrzKey : String = ""
+    private var aaChallenge: [UInt8]?
     private var dataAmountToReadOverride : Int? = nil
     
     private var scanCompletedHandler: ((NFCPassportModel?, NFCPassportReaderError?)->())!
@@ -63,10 +64,11 @@ public class PassportReader : NSObject {
         dataAmountToReadOverride = amount
     }
     
-    public func readPassport( mrzKey : String, tags : [DataGroupId] = [], skipSecureElements : Bool = true, skipCA : Bool = false, skipPACE : Bool = false, useExtendedMode : Bool = false, customDisplayMessage : ((NFCViewDisplayMessage) -> String?)? = nil) async throws -> NFCPassportModel {
+    public func readPassport( mrzKey : String, tags : [DataGroupId] = [], aaChallenge: [UInt8]? = nil, skipSecureElements : Bool = true, skipCA : Bool = false, skipPACE : Bool = false, useExtendedMode : Bool = false, customDisplayMessage : ((NFCViewDisplayMessage) -> String?)? = nil) async throws -> NFCPassportModel {
         
         self.passport = NFCPassportModel()
         self.mrzKey = mrzKey
+        self.aaChallenge = aaChallenge
         self.skipCA = skipCA
         self.skipPACE = skipPACE
         self.useExtendedMode = useExtendedMode
@@ -267,7 +269,7 @@ extension PassportReader {
 
         Logger.passportReader.info( "Performing Active Authentication" )
 
-        let challenge = generateRandomUInt8Array(8)
+        let challenge = aaChallenge ?? generateRandomUInt8Array(8)
         Logger.passportReader.debug( "Generated Active Authentication challange - \(binToHexRep(challenge))")
         let response = try await tagReader.doInternalAuthentication(challenge: challenge, useExtendedMode: useExtendedMode)
         self.passport.verifyActiveAuthentication( challenge:challenge, signature:response.data )