Make GeneralizedTime correctly read down to the tick

TimeSpan.From* rounds to the millisecond, but the writer is 10000x as precise,
so make the reader be as precise as the writer.

For future work around cryptographic timestamps the microseconds and
hundred-nanoseconds might be relevant.

2 files changed, 25 insertions, 3 deletions

diff --git a/src/System.Security.Cryptography.Encoding/tests/Asn1/Reader/ReadGeneralizedTime.cs b/src/System.Security.Cryptography.Encoding/tests/Asn1/Reader/ReadGeneralizedTime.cs
index 02dfa3810d..6798b068a4 100644
--- a/src/System.Security.Cryptography.Encoding/tests/Asn1/Reader/ReadGeneralizedTime.cs
+++ b/src/System.Security.Cryptography.Encoding/tests/Asn1/Reader/ReadGeneralizedTime.cs
@@ -53,13 +53,13 @@ namespace System.Security.Cryptography.Tests.Asn1
         // yyyyMMddHHmmss+HHmm (20161106012345+0118)
         [InlineData(PublicEncodingRules.BER, "181332303136313130363031323334352B30313138", 2016, 11, 6, 1, 23, 45, 0, 1, 18)]
         // yyyyMMddHHmmss.secondFrac (20161106012345.6789) - Ambiguous time due to DST "fall back" in US & Canada
-        [InlineData(PublicEncodingRules.BER, "181332303136313130363031323334352E36373839", 2016, 11, 6, 1, 23, 45, 679, null, 0)]
+        [InlineData(PublicEncodingRules.BER, "181332303136313130363031323334352E36373839", 2016, 11, 6, 1, 23, 45, 678, null, 0)]
         // yyyyMMddHHmmss,secondFracZ (20161106012345,7654Z)
         [InlineData(PublicEncodingRules.BER, "181432303136313130363031323334352C373635345A", 2016, 11, 6, 1, 23, 45, 765, 0, 0)]
         // yyyyMMddHHmmss.secondFrac-HH (20161106012345.001-01)
         [InlineData(PublicEncodingRules.BER, "181532303136313130363031323334352E3030312D3031", 2016, 11, 6, 1, 23, 45, 1, -1, 0)]
         // yyyyMMddHHmmss,secondFrac+HHmm (20161106012345,0009+0118)
-        [InlineData(PublicEncodingRules.BER, "181832303136313130363031323334352C303030392B30313138", 2016, 11, 6, 1, 23, 45, 1, 1, 18)]
+        [InlineData(PublicEncodingRules.BER, "181832303136313130363031323334352C303030392B30313138", 2016, 11, 6, 1, 23, 45, 0, 1, 18)]
 
         // yyyyMMddHHmmssZ (20161106012345Z)
         [InlineData(PublicEncodingRules.CER, "180F32303136313130363031323334355A", 2016, 11, 6, 1, 23, 45, 0, 0, 0)]
@@ -208,6 +208,27 @@ namespace System.Security.Cryptography.Tests.Asn1
             Assert.True(derReader.HasData, "derReader.HasData");
         }
 
+        [Theory]
+        [InlineData(PublicEncodingRules.BER, "2017121900.06861111087Z")]
+        [InlineData(PublicEncodingRules.BER, "201712190004.11666665167Z")]
+        [InlineData(PublicEncodingRules.BER, "201712190004.11666665167Z")]
+        [InlineData(PublicEncodingRules.BER, "20171219000406.9999991Z")]
+        [InlineData(PublicEncodingRules.CER, "20171219000406.9999991Z")]
+        [InlineData(PublicEncodingRules.DER, "20171219000406.9999991Z")]
+        public static void MaximumEffectivePrecision(PublicEncodingRules ruleSet, string dateAscii)
+        {
+            DateTimeOffset expectedTime = new DateTimeOffset(2017, 12, 19, 0, 4, 6, TimeSpan.Zero);
+            expectedTime += new TimeSpan(TimeSpan.TicksPerSecond - 9);
+
+            byte[] inputData = new byte[dateAscii.Length + 2];
+            inputData[0] = 0x18;
+            inputData[1] = (byte)dateAscii.Length;
+            Text.Encoding.ASCII.GetBytes(dateAscii, 0, dateAscii.Length, inputData, 2);
+
+            AsnReader reader = new AsnReader(inputData, (AsnEncodingRules)ruleSet);
+            Assert.Equal(expectedTime, reader.GetGeneralizedTime());
+        }
+
         [Fact]
         public static void ExcessivelyPreciseFraction()
         {
@@ -218,6 +239,7 @@ namespace System.Security.Cryptography.Tests.Asn1
             Assert.False(berReader.HasData, "berReader.HasData");
 
             DateTimeOffset expected = new DateTimeOffset(2017, 9, 21, 18, 0, 44, 444, TimeSpan.Zero);
+            expected += new TimeSpan(4440);
 
             Assert.Equal(expected, value);
         }
diff --git a/src/System.Security.Cryptography.Encoding/tests/Asn1/Serializer/SimpleDeserialize.cs b/src/System.Security.Cryptography.Encoding/tests/Asn1/Serializer/SimpleDeserialize.cs
index 2fe1e1acb4..a99e323abc 100644
--- a/src/System.Security.Cryptography.Encoding/tests/Asn1/Serializer/SimpleDeserialize.cs
+++ b/src/System.Security.Cryptography.Encoding/tests/Asn1/Serializer/SimpleDeserialize.cs
@@ -133,7 +133,7 @@ namespace System.Security.Cryptography.Tests.Asn1
             Assert.Equal(new byte[] { 0, 1, 254, 127, 255 }, atst.LittleUInts);
             Assert.Equal(new DateTimeOffset(1950, 1, 2, 12, 34, 56, TimeSpan.Zero), atst.UtcTime2049);
             Assert.Equal(new DateTimeOffset(2050, 1, 2, 12, 34, 56, TimeSpan.Zero), atst.UtcTime2099);
-            Assert.Equal(new DateTimeOffset(2016, 11, 6, 1, 23, 45, 765, TimeSpan.Zero), atst.GeneralizedTimeWithFractions);
+            Assert.Equal(new DateTimeOffset(2016, 11, 6, 1, 23, 45, TimeSpan.Zero) + new TimeSpan(7654000), atst.GeneralizedTimeWithFractions);
             Assert.Equal(new DateTimeOffset(2016, 11, 6, 1, 23, 45, TimeSpan.Zero), atst.GeneralizedTimeNoFractions);
             Assert.Equal(BigInteger.Parse("0102030405060708090A0B0C0D0E0F", NumberStyles.HexNumber), atst.BigInteger);
         }