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Fixed OID encoder and decoder #9

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Merged
Crypt32 merged 2 commits into from
Aug 1, 2024
Merged

Fixed OID encoder and decoder #9

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f99d0f0
Addressed OID encoding part of bug #6. Decoder fix is pending.
Crypt32 Aug 1, 2024
bf66406
fixed OID decoder #6 and updated related unit tests
Crypt32 Aug 1, 2024
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69 changes: 48 additions & 21 deletions Asn1Parser/Universal/Asn1ObjectIdentifier.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@ namespace SysadminsLV.Asn1Parser.Universal;
/// </summary>
public sealed class Asn1ObjectIdentifier : Asn1Universal {
const Asn1Type TYPE = Asn1Type.OBJECT_IDENTIFIER;
const Byte ITU_T_ROOT = 0;
const Byte ISO_ROOT = 1;

/// <summary>
/// Initializes a new instance of the <strong>Asn1ObjectIdentifier</strong> class from an existing
Expand All @@ -21,7 +23,6 @@ public sealed class Asn1ObjectIdentifier : Asn1Universal {
/// <exception cref="Asn1InvalidTagException">
/// The current state of <strong>ASN1</strong> object is not object identifier.
/// </exception>
///
public Asn1ObjectIdentifier(Asn1Reader asn) : base(asn, TYPE) {
Value = new Oid(decode(asn));
}
Expand Down Expand Up @@ -61,7 +62,7 @@ public Asn1ObjectIdentifier(Oid oid) : base(TYPE) {

void m_encode(Oid oid) {
if (String.IsNullOrWhiteSpace(oid.Value)) {
Initialize(new Asn1Reader(new Byte[] { Tag, 0 }));
Initialize(new Asn1Reader([Tag, 0]));
Value = new Oid();
return;
}
Expand All @@ -77,17 +78,29 @@ void m_encode(Oid oid) {

static Byte[] encode(IList<BigInteger> tokens) {
var rawOid = new List<Byte>();
for (Int32 token = 0; token < tokens.Count; token++) {
// first two arcs are encoded in a single byte
switch (token) {
for (Int32 tokenIndex = 0; tokenIndex < tokens.Count; tokenIndex++) {
BigInteger token = tokens[tokenIndex];
BigInteger temp = token;
// first two arcs are encoded as a single arc
switch (tokenIndex) {
case 0:
rawOid.Add((Byte)(40 * tokens[token] + tokens[token + 1]));
continue;
//
token = 40 * token + tokens[tokenIndex + 1];
// if first two arcs can be encoded using 7 bits (single byte where most significant bit is 0),
// then nothing fancy, simply add it as single byte.
if (token < 0x80) {
rawOid.Add((Byte)token);
continue;
}
// otherwise first two arcs are encoded using multiple bytes, and we have to go through
// standard OID arc encoding routine.
temp = token;
break;
// we already handled 2nd arc, so skip its processing.
case 1:
continue;
}
Int16 bitLength = 0;
BigInteger temp = tokens[token];
// calculate how many bits are occupied by the current integer value
do {
temp = (BigInteger)Math.Floor((Double)temp / 2);
Expand All @@ -99,37 +112,43 @@ static Byte[] encode(IList<BigInteger> tokens) {
// http://msdn.microsoft.com/en-us/library/bb540809(v=vs.85).aspx
// loop may not execute if arc value is less than 128.
for (Int32 index = (bitLength - 1) / 7; index > 0; index--) {
rawOid.Add((Byte)(0x80 | ((tokens[token] >> (index * 7)) & 0x7f)));
rawOid.Add((Byte)(0x80 | ((token >> (index * 7)) & 0x7f)));
}
rawOid.Add((Byte)(tokens[token] & 0x7f));
rawOid.Add((Byte)(token & 0x7f));
}
return rawOid.ToArray();
}
static String decode(Asn1Reader asn) {
var SB = new StringBuilder();
Int32 token = 0;
Boolean topArcsProcessed = false;
for (Int32 i = 0; i < asn.PayloadLength; i++) {
Int32 pi = asn.PayloadStartOffset + i;
if (token == 0) {
SB.Append(asn[pi] / 40);
SB.Append("." + asn[pi] % 40);
token++;
continue;
}

BigInteger value = 0;
Boolean proceed;
do {
value <<= 7;
value += asn[pi] & 0x7f;
proceed = (asn[pi] & 0x80) > 0;
if (proceed) {
token++;
i++;
pi++;
}
} while (proceed);
if (!topArcsProcessed) {
topArcsProcessed = true;
// max value for first two arcs in ITU-T and ISO is 79 (OID=1.39). If this value is larger, then
// it belongs to 'joint-iso-itu-t' (OID=2.x)
if (value >= 80) {
SB.Append("2.").Append(value - 80);
} else {
SB.Append(value / 40);
SB.Append("." + value % 40);
}
continue;
}

SB.Append("." + value);
token++;
}
return SB.ToString();
}
Expand All @@ -143,8 +162,16 @@ static Boolean validateOidString(String oid, out List<BigInteger> tokens) {
for (Int32 index = 0; index < strTokens.Length; index++) {
try {
var value = BigInteger.Parse(strTokens[index]);
if (index == 0 && value > 2 || index == 1 && value > 39) {
return false;
if (index == 0) {
// check if root arc is 0, 1, or 2
if (value > 2) {
return false;
}
var secondArc = BigInteger.Parse(strTokens[1]);
// check if 2nd arc under ITU-T and ISO is <=39
if ((Byte)value is ITU_T_ROOT or ISO_ROOT && secondArc > 39) {
return false;
}
}
tokens.Add(value);
} catch {
Expand Down
70 changes: 54 additions & 16 deletions tests/Asn1Parser.Tests/Asn1OidTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,33 +7,71 @@ namespace Asn1Parser.Tests;

[TestClass]
public class Asn1OidTests {
[TestMethod, Description("Test if at least two arcs are encoded.")]
public void TestMinStringLengthEncode() {
var oid = new Asn1ObjectIdentifier("0.0");
Assert.AreEqual("0.0", oid.Value.Value);
String encodedB64 = Convert.ToBase64String(oid.GetRawData());
Assert.AreEqual("BgEA", encodedB64);
}
[TestMethod, Description("Test if at least two arcs are required.")]
public void TestMinStringLengthDecode() {
Byte[] rawData = Convert.FromBase64String("BgEA");
var oid = new Asn1ObjectIdentifier(rawData);
Assert.AreEqual("0.0", oid.Value.Value);
String encodedB64 = Convert.ToBase64String(oid.GetRawData());
Assert.AreEqual("BgEA", encodedB64);
public void TestMinStringLength() {
// must be 06 01 00
testOidBiDirectional("0.0", "BgEA");
}
[TestMethod, Description("Test if single arc encoding fails.")]
[ExpectedException(typeof(InvalidDataException))]
public void TestSingleArcEncodeFail() {
new Asn1ObjectIdentifier("0");
}
[TestMethod, Description("Test if 2nd arc under 'ITU' root node encoded up to 39.")]
[TestMethod, Description("Test if 2nd arc under 'itu-t' root node encoded up to 39.")]
public void TestItuRootArcConstraintsPass() {
new Asn1ObjectIdentifier("1.39");
// must be 06 01 27
testOidBiDirectional("0.39", "BgEn");
}
[TestMethod, Description("Test if 2nd arc under 'ITU' root node >39 fails.")]
[TestMethod, Description("Test if 2nd arc under 'itu-t' root node >39 fails.")]
[ExpectedException(typeof(InvalidDataException))]
public void TestItuRootArcConstraintsFail() {
new Asn1ObjectIdentifier("0.40");
}
[TestMethod, Description("Test if 2nd arc under 'iso' root node encoded up to 39.")]
public void TestIsoRootArcConstraintsPass() {
// must be 06 01 4f
testOidBiDirectional("1.39", "BgFP");
}
[TestMethod, Description("Test if 2nd arc under 'iso' root node >39 fails.")]
[ExpectedException(typeof(InvalidDataException))]
public void TestIsoRootArcConstraintsFail() {
new Asn1ObjectIdentifier("1.40");
}
[TestMethod, Description("Test if 2nd arc under 'joint-iso-itu-t' root do not impose 2nd arc limits.")]
public void TestJointIsoItuRootArcPass() {
// must be 06 01 78
testOidBiDirectional("2.40", "BgF4");
}
[TestMethod, Description("Test random cert template OID, which includes short and long arcs")]
public void TestCertTemplateOid() {
testOidBiDirectional("1.3.6.1.4.1.311.21.8.149510.7314491.15746959.9320746.3700693.37.1.25", "Bh8rBgEEAYI3FQiJkAaDvrg7h8GPD4S48iqB4e9VJQEZ");
}
[TestMethod, Description("Test if first first two arcs can span multiple bytes if first byte >= 128")]
public void TestLargeTopArcs() {
// must be 06 01 50
// OID 2.0 is identical to invalid 1.40, which is prohibited
testOidBiDirectional("2.0", "BgFQ");
// must be 06 02 88 37
testOidBiDirectional("2.999", "BgKINw==");
// must be 06 03 88 37 03
testOidBiDirectional("2.999.3", "BgOINwM=");
// must be 06 04 82 4B 09 79
testOidBiDirectional("2.251.9.121", "BgSCSwl5");
// must be 06 04 88 37 89 52
testOidBiDirectional("2.999.1234", "BgSIN4lS");
// must be 06 04 82 00 09 79
testOidBiDirectional("2.176.9.121", "BgSCAAl5");
// must be 06 04 79 00 09 79
testOidBiDirectional("2.81.0.9.121", "BgWBIQAJeQ==");
}

static void testOidBiDirectional(String oidString, String expectedB64) {
// test OID string -> binary encoding process
var oid = new Asn1ObjectIdentifier(oidString);
String encodedB64 = Convert.ToBase64String(oid.GetRawData());
Assert.AreEqual(expectedB64, encodedB64);
// test binary -> OID string decoding process
oid = new Asn1ObjectIdentifier(Convert.FromBase64String(expectedB64));
Assert.AreEqual(oidString, oid.Value.Value);
}
}