Refactor parseDateYYMMDD to handle future dates correctly & Fix sm tests

lib/src/extension/string_apis.dart

@@ -15,27 +15,34 @@ extension StringDecodeApis on String {
 }
 
 extension StringYYMMDDateApi on String {
-  DateTime parseDateYYMMDD() {
+  DateTime parseDateYYMMDD({bool futureDate = false}) {
     if (length < 6) {
-      throw FormatException("invalid length of compact date string");
+      throw FormatException("Invalid length of compact date string");
     }
 
     int y = int.parse(substring(0, 2)) + 2000;
     int m = int.parse(substring(2, 4));
     int d = int.parse(substring(4, 6));
 
-    // Sub 100 years from parsed year if greater than 10 years and 5 months from now.
     final now = DateTime.now();
-    final tenYearsFromNow = now.year + 10;
-    if (y > tenYearsFromNow || (y == tenYearsFromNow && now.month + 5 < m)) {
+    int maxYear  = now.year;
+    int maxMonth = now.month;
+    if (futureDate) {
+      maxYear  += 20; // cut off year 20 years from now
+      maxMonth += 5;
+    }
+
+    // If parsed year is greater than max wind back for 100 years
+    if (y > maxYear || ( y == maxYear && maxMonth < m)) {
       y -= 100;
     }
+
     return DateTime(y, m, d);
   }
 
-  DateTime parseDate() {
+  DateTime parseDate({bool futureDate = false}) {
     if (length == 6) {
-      return this.parseDateYYMMDD();
+      return this.parseDateYYMMDD(futureDate: futureDate);
     } else {
       return DateTime.parse(this);
     }

lib/src/lds/df1/efdg12.dart

@@ -41,7 +41,7 @@ class EfDG12 extends DataGroup {
 
   DateTime? get dateOfIssue => _dateOfIssue;
   String? get issuingAuthority => _issuingAuthority;
-  
+
 
   EfDG12.fromBytes(Uint8List data) : super.fromBytes(data);
 

lib/src/lds/mrz.dart

@@ -112,13 +112,13 @@ class MRZ {
     _docNum = _read(istream, 9);
     final cdDocNum = _readWithPad(istream, 1);
     _optData = _read(istream, 15);
-    dateOfBirth = _readDate(istream);
+    dateOfBirth = _readDate(istream, futureDate: false);
 
     _assertCheckDigit(dateOfBirth.formatYYMMDD(), _readCD(istream),
         "Data of Birth check digit mismatch");
 
     gender = _read(istream, 1);
-    dateOfExpiry = _readDate(istream);
+    dateOfExpiry = _readDate(istream, futureDate: true);
 
     _assertCheckDigit(dateOfExpiry.formatYYMMDD(), _readCD(istream),
         "Data of Expiry check digit mismatch");
@@ -151,12 +151,12 @@ class MRZ {
     final cdDocNum = _readWithPad(istream, 1);
 
     nationality = _read(istream, 3);
-    dateOfBirth = _readDate(istream);
+    dateOfBirth = _readDate(istream, futureDate: false);
     _assertCheckDigit(dateOfBirth.formatYYMMDD(), _readCD(istream),
         "Data of Birth check digit mismatch");
 
     gender = _read(istream, 1);
-    dateOfExpiry = _readDate(istream);
+    dateOfExpiry = _readDate(istream, futureDate: true);
     _assertCheckDigit(dateOfExpiry.formatYYMMDD(), _readCD(istream),
         "Data of Expiry check digit mismatch");
 
@@ -185,12 +185,12 @@ class MRZ {
         _docNum, _readCD(istream), "Document Number check digit mismatch");
 
     nationality = _read(istream, 3);
-    dateOfBirth = _readDate(istream);
+    dateOfBirth = _readDate(istream, futureDate: false);
     _assertCheckDigit(dateOfBirth.formatYYMMDD(), _readCD(istream),
         "Data of Birth check digit mismatch");
 
     gender = _read(istream, 1);
-    dateOfExpiry = _readDate(istream);
+    dateOfExpiry = _readDate(istream, futureDate: true);
     _assertCheckDigit(dateOfExpiry.formatYYMMDD(), _readCD(istream),
         "Data of Expiry check digit mismatch");
 
@@ -240,8 +240,8 @@ class MRZ {
     return _readWithPad(istream, maxLength).replaceAll(RegExp(r'<+$'), '');
   }
 
-  static DateTime _readDate(InputStream istream) {
-    return _read(istream, 6).parseDateYYMMDD();
+  static DateTime _readDate(InputStream istream, {bool futureDate = false}) {
+    return _read(istream, 6).parseDateYYMMDD(futureDate: futureDate);
   }
 
   static int _readCD(InputStream istream) {

lib/src/proto/dba_key.dart

@@ -99,10 +99,10 @@ class DBAKey extends AccessKey {
   String get mrtdNumber => _mrtdNum;
 
   /// Returns passport owner's date of birth used for calculating key seed.
-  DateTime get dateOfBirth => _dob.parseDateYYMMDD();
+  DateTime get dateOfBirth => _dob.parseDateYYMMDD(futureDate: false);
 
   /// Returns passport date of expiry used for calculating key seed.
-  DateTime get dateOfExpiry => _doe.parseDateYYMMDD();
+  DateTime get dateOfExpiry => _doe.parseDateYYMMDD(futureDate: true);
 
   /// Very sensitive data. Do not use in production!
   @override

lib/src/proto/mrtd_sm.dart

@@ -74,7 +74,7 @@ class MrtdSM extends SecureMessaging {
       return rapdu;
     }
 
-    //increment SSC should be made before decrypting data
+    // Increment SSC should be made before decrypting data
     _ssc.increment();
 
     _log.debug("Unprotecting RAPDU: $rapdu");

test/extensions_test.dart

@@ -80,19 +80,43 @@ void main() {
       expect( '121212'.parseDateYYMMDD() , DateTime(2012, 12, 12) );
       expect( '201212'.parseDateYYMMDD() , DateTime(2020, 12, 12) );
 
+      expect( '891109'.parseDateYYMMDD(futureDate: false) , DateTime(1989, 11, 9)  );
+      expect( '760501'.parseDateYYMMDD(futureDate: false) , DateTime(1976, 05, 01) );
+      expect( '000215'.parseDateYYMMDD(futureDate: false) , DateTime(2000, 02, 15) );
+      expect( '111111'.parseDateYYMMDD(futureDate: false) , DateTime(2011, 11, 11) );
+      expect( '121212'.parseDateYYMMDD(futureDate: false) , DateTime(2012, 12, 12) );
+      expect( '201212'.parseDateYYMMDD(futureDate: false) , DateTime(2020, 12, 12) );
+
+      expect( '891109'.parseDateYYMMDD(futureDate: true) , DateTime(1989, 11, 9)  );
+      expect( '760501'.parseDateYYMMDD(futureDate: true) , DateTime(1976, 05, 01) );
+      expect( '000215'.parseDateYYMMDD(futureDate: true) , DateTime(2000, 02, 15) );
+      expect( '111111'.parseDateYYMMDD(futureDate: true) , DateTime(2011, 11, 11) );
+      expect( '121212'.parseDateYYMMDD(futureDate: true) , DateTime(2012, 12, 12) );
+      expect( '201212'.parseDateYYMMDD(futureDate: true) , DateTime(2020, 12, 12) );
+
       final now = DateTime(DateTime.now().year, DateTime.now().month, DateTime.now().day);
-      expect( now.formatYYMMDD().parseDateYYMMDD() , now );
+      expect( now.formatYYMMDD().parseDateYYMMDD(), now );
+      expect( now.formatYYMMDD().parseDateYYMMDD(futureDate: false), now );
+      expect( now.formatYYMMDD().parseDateYYMMDD(futureDate: true) , now );
 
+      // 1 month future date
       final nextMonth = DateTime(now.year, now.month + 1, now.day);
-      expect( nextMonth.formatYYMMDD().parseDateYYMMDD(), nextMonth );
+      expect( nextMonth.formatYYMMDD().parseDateYYMMDD()                  != nextMonth, true ); // by default future date is not expected
+      expect( nextMonth.formatYYMMDD().parseDateYYMMDD(futureDate: false) != nextMonth, true );
+      expect( nextMonth.formatYYMMDD().parseDateYYMMDD(futureDate: true)  == nextMonth, true );
 
+      // 10 years future date
       final tenFromNow  = DateTime(now.year + 10, now.month, now.day);
-      expect( tenFromNow.formatYYMMDD().parseDateYYMMDD(), tenFromNow );
+      expect( tenFromNow.formatYYMMDD().parseDateYYMMDD()                  != tenFromNow, true ); // by default future date is not expected
+      expect( tenFromNow.formatYYMMDD().parseDateYYMMDD(futureDate: false) != tenFromNow, true );
+      expect( tenFromNow.formatYYMMDD().parseDateYYMMDD(futureDate: true)  == tenFromNow, true );
 
-      // 10 years and 6 months from now should wind date back for a century.
+      // 10 years and 6 months future date
       final tenAnd6MonthsFromNow = DateTime(now.year + 10, now.month + 6, now.day);
       final ninetyYearsAgo       = DateTime(now.year - 90, now.month + 6, now.day);
-      expect( tenAnd6MonthsFromNow.formatYYMMDD().parseDateYYMMDD(), ninetyYearsAgo );
+      expect( tenAnd6MonthsFromNow.formatYYMMDD().parseDateYYMMDD()                 , ninetyYearsAgo );
+      expect( tenAnd6MonthsFromNow.formatYYMMDD().parseDateYYMMDD(futureDate: false), ninetyYearsAgo );
+      expect( tenAnd6MonthsFromNow.formatYYMMDD().parseDateYYMMDD(futureDate: true) , tenAnd6MonthsFromNow );
     });
   });
 
@@ -152,7 +176,7 @@ void main() {
       Logger.root.level = Level.FINEST;
       Logger.root.trace(traceMsg);
       expect( logMsg, traceMsg     );
-      expect( level , Level.FINEST );     
+      expect( level , Level.FINEST );
     });
 
     test('Sensitive data log test', () {
@@ -404,7 +428,7 @@ void main() {
       dlog.sdDebug(debugMsg);
       expect( dlogMsg, debugMsg   );
       expect( dlevel , Level.FINE );
-      
+
       // Verbose test
       Logger.root.logSensitiveData = false;
       dlog.logSensitiveData = false;

test/sm_test.dart

@@ -31,6 +31,7 @@ void testProtecting(final CommandAPDU cmd, final SMCipher cipher, final SSC ssc,
   final M = sm.generateM(cmd: pcmd, dataDO: dataDO, do97: do97);
   expect( M, tvM );
 
+  ssc.increment(); // ssc has to be incremented prior to generating N
   final N = sm.generateN(M: M);
   expect( N, tvN );
 
@@ -64,6 +65,7 @@ void testUprotecting(final ResponseAPDU rapdu, final SMCipher cipher, final SSC
   final do8E      = sm.parseDO8EFromRAPDU(rapdu, do8EStart);
   expect( TLV.encode(do8E.tag.value, do8E.value) , tvDO8E );
 
+  ssc.increment(); // ssc has to be incremented prior to generating K
   final K = sm.generateK(data: rapdu.data!.sublist(0, do8EStart));
   expect( K , tvK );
 
@@ -81,7 +83,7 @@ void testUprotecting(final ResponseAPDU rapdu, final SMCipher cipher, final SSC
 void main() {
   test('Testing MRTD Secure Messaging', () {
 
-    // Test vectors taken from Appendix D.4 to the Part 11 of ICAO 7816 p11 doc
+    // Test vectors taken from Appendix D.4 to the Part 11 of ICAO 9303 p11 doc
     final tvKSEnc  = "979EC13B1CBFE9DCD01AB0FED307EAE5".parseHex();
     final tvKSMAC  = "F1CB1F1FB5ADF208806B89DC579DC1F8".parseHex();
     final smCipher = DES_SMCipher(tvKSEnc, tvKSMAC);