public void VerifyLongDerStringRoundTrip()
{
string TestString = new string('A', 64000);
Assert.AreEqual(TestString, DerUtils.DecodeString(DerUtils.EncodePrintableString(TestString)), "PrintableString should make encoding round trip unchanged");
Assert.AreEqual(TestString, DerUtils.DecodeString(DerUtils.EncodeBMPString(TestString)), "BMPString should make encoding round trip unchanged");
}
public void VerifyDerSequenceOfRoundTrip()
{
var testCases = new[] {
new { entryData = new List <string>()
{
"data1"
}, description = "single entry" },
new { entryData = new List <string>()
{
"data1", "data2", "data3"
}, description = "multiple entries" },
new { entryData = new List <string>()
{
}, description = "no entries" },
};
foreach (var testCase in testCases)
{
// convert the input data from strings to der encoding, since that's the expected input format
List <byte[]> derEntries = new List <byte[]>();
foreach (string entry in testCase.entryData)
{
derEntries.Add(DerUtils.EncodePrintableString(entry));
}
List <byte[]> outputEntries = DerUtils.DecodeSequenceOf(DerUtils.EncodeSequenceOf(derEntries));
// verify the output matches the input
Assert.AreEqual(testCase.entryData.Count, outputEntries.Count, "number of output entries should match the number of input entries for test case: " + testCase.description);
for (int i = 0; i < outputEntries.Count; i++)
{
Assert.AreEqual(testCase.entryData[i], DerUtils.DecodeString(outputEntries[i]), "Output data should match input data for test case: " + testCase.description);
}
}
}
public void VerifyDecodeDerStringInvalid()
{
string SomeShortText = "short text";
string SomeLongText = new string('A', 2000); // text more than 127 bytes long is encoded using DER long form length encoding
byte[] DerLongFormLength2000 = new byte[] { 2 | 0x80, 7, 208 }; // long form DER length encoding for length=2000
byte[] IncorrectDerLongFormLength2000 = new byte[] { 3 | 0x80, 7, 208 }; // incorrect long form (claims 3 bytes are used for length but only 2 are actually provided). Used to test the case when the length of length here would extend past array bounds.
var errorCases = new[] {
new { test = (byte[])null, description = "null bytes" },
new { test = new byte[] { }, description = "empty bytes" },
new { test = new byte[] { DerUtils.TagIA5String }, description = "only tag" },
new { test = (new byte[] { 0xE, (byte)(SomeShortText.Length) }).Concat(Encoding.ASCII.GetBytes(SomeShortText)).ToArray(), description = "string encoding type not yet implemented" }, // technically tag 0xE is reserved so should never be implemented, meaning this test will be valid long-term even if other encodings are added
new { test = (new byte[] { DerUtils.TagIA5String, (byte)(SomeShortText.Length + 1) }).Concat(Encoding.ASCII.GetBytes(SomeShortText)).ToArray(), description = "incorrect short form length (+1)" },
new { test = (new byte[] { DerUtils.TagIA5String, (byte)(SomeShortText.Length - 1) }).Concat(Encoding.ASCII.GetBytes(SomeShortText)).ToArray(), description = "incorrect short form length (-1)" },
new { test = (new byte[] { DerUtils.TagIA5String }).Concat(DerLongFormLength2000).Concat(Encoding.ASCII.GetBytes("Shorter text than header claims")).ToArray(), description = "incorrect long form length (actual data too short)" },
new { test = (new byte[] { DerUtils.TagIA5String }).Concat(DerLongFormLength2000).Concat(Encoding.ASCII.GetBytes(SomeLongText + "longer text than header claims")).ToArray(), description = "incorrect long form length (actual data too long)" },
new { test = (new byte[] { DerUtils.TagIA5String }).Concat(IncorrectDerLongFormLength2000).ToArray(), description = "long form length of length extends beyond array bounds" },
};
foreach (var errorCase in errorCases)
{
bool caughtError = false;
try
{
DerUtils.DecodeString(errorCase.test);
}
catch (Exception)
{
caughtError = true;
}
Assert.IsTrue(caughtError, "DecodeDerString did not throw exception on test case: " + errorCase.description);
}
}
public void VerifyDecodeDerStringValid()
{
string SomeShortText = "short text";
string SomeLongText = new string('A', 2000); // text more than 127 bytes long is encoded using DER long form length encoding
byte[] DerLongFormLength2000 = new byte[] { 2 | 0x80, 0x7, 0xD0 }; // long form DER length encoding for length=2000
byte[] DerLongFormLength4000 = new byte[] { 2 | 0x80, 0xF, 0xA0 }; // long form DER length encoding for length=4000 (used for multibyte Unicode test cases)
var testCases = new[] {
new { test = new byte[] { DerUtils.TagIA5String, 0 }, expected = string.Empty, description = "IA5String empty string" },
new { test = new byte[] { DerUtils.TagPrintableString, 0 }, expected = string.Empty, description = "PrintableString empty string" },
new { test = new byte[] { DerUtils.TagBMPString, 0 }, expected = string.Empty, description = "BMPString empty string" },
new { test = (new byte[] { DerUtils.TagIA5String, (byte)(SomeShortText.Length) }).Concat(Encoding.ASCII.GetBytes(SomeShortText)).ToArray(), expected = SomeShortText, description = "IA5String that falls into short form length encoding" },
new { test = (new byte[] { DerUtils.TagIA5String }).Concat(DerLongFormLength2000).Concat(Encoding.ASCII.GetBytes(SomeLongText)).ToArray(), expected = SomeLongText, description = "IA5String that falls into long form length encoding" },
new { test = (new byte[] { DerUtils.TagPrintableString, (byte)(SomeShortText.Length) }).Concat(Encoding.ASCII.GetBytes(SomeShortText)).ToArray(), expected = SomeShortText, description = "PrintableString that falls into short form length encoding" },
new { test = (new byte[] { DerUtils.TagPrintableString }).Concat(DerLongFormLength2000).Concat(Encoding.ASCII.GetBytes(SomeLongText)).ToArray(), expected = SomeLongText, description = "PrintableString that falls into long form length encoding" },
new { test = (new byte[] { DerUtils.TagBMPString, (byte)(Encoding.BigEndianUnicode.GetBytes(SomeShortText).Length) }).Concat(Encoding.BigEndianUnicode.GetBytes(SomeShortText)).ToArray(), expected = SomeShortText, description = "BMPString that falls into short form length encoding" },
new { test = (new byte[] { DerUtils.TagBMPString }).Concat(DerLongFormLength4000).Concat(Encoding.BigEndianUnicode.GetBytes(SomeLongText)).ToArray(), expected = SomeLongText, description = "BMPString that falls into long form length encoding" },
};
foreach (var testCase in testCases)
{
string output = null;
try
{
output = DerUtils.DecodeString(testCase.test);
}
catch (Exception ex)
{
throw new AggregateException("Error on test case: " + testCase.description, ex);
}
Assert.AreEqual(testCase.expected, output, testCase.description);
}
}
