309 lines
7.8 KiB
C#
309 lines
7.8 KiB
C#
using System;
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using System.Diagnostics;
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using System.IO;
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using Org.BouncyCastle.Asn1.Utilities;
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using Org.BouncyCastle.Utilities.IO;
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namespace Org.BouncyCastle.Asn1
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{
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/**
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* a general purpose ASN.1 decoder - note: this class differs from the
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* others in that it returns null after it has read the last object in
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* the stream. If an ASN.1 Null is encountered a Der/BER Null object is
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* returned.
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*/
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public class Asn1InputStream
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: FilterStream
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{
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private readonly int limit;
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public Asn1InputStream(
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Stream inputStream)
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: this(inputStream, int.MaxValue)
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{
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}
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/**
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* Create an ASN1InputStream where no DER object will be longer than limit.
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*
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* @param input stream containing ASN.1 encoded data.
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* @param limit maximum size of a DER encoded object.
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*/
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public Asn1InputStream(
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Stream inputStream,
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int limit)
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: base(inputStream)
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{
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this.limit = limit;
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}
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/**
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* Create an ASN1InputStream based on the input byte array. The length of DER objects in
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* the stream is automatically limited to the length of the input array.
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*
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* @param input array containing ASN.1 encoded data.
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*/
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public Asn1InputStream(
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byte[] input)
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: this(new MemoryStream(input, false), input.Length)
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{
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}
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internal Asn1EncodableVector BuildEncodableVector()
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{
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Asn1EncodableVector v = new Asn1EncodableVector();
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Asn1Object o;
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while ((o = ReadObject()) != null)
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{
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v.Add(o);
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}
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return v;
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}
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internal virtual Asn1EncodableVector BuildDerEncodableVector(
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DefiniteLengthInputStream dIn)
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{
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return new Asn1InputStream(dIn).BuildEncodableVector();
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}
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internal virtual DerSequence CreateDerSequence(
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DefiniteLengthInputStream dIn)
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{
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return DerSequence.FromVector(BuildDerEncodableVector(dIn));
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}
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internal virtual DerSet CreateDerSet(
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DefiniteLengthInputStream dIn)
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{
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return DerSet.FromVector(BuildDerEncodableVector(dIn), false);
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}
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public Asn1Object ReadObject()
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{
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int tag = ReadByte();
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if (tag <= 0)
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{
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if (tag == 0)
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throw new IOException("unexpected end-of-contents marker");
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return null;
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}
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//
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// calculate tag number
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//
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int tagNo = ReadTagNumber(this, tag);
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bool isConstructed = (tag & Asn1Tags.Constructed) != 0;
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//
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// calculate length
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//
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int length = ReadLength(this, limit);
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if (length < 0) // indefinite length method
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{
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if (!isConstructed)
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throw new IOException("indefinite length primitive encoding encountered");
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IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(this);
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if ((tag & Asn1Tags.Application) != 0)
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{
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Asn1StreamParser sp2 = new Asn1StreamParser(indIn);
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return new BerApplicationSpecificParser(tagNo, sp2).ToAsn1Object();
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}
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if ((tag & Asn1Tags.Tagged) != 0)
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{
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// TODO Investigate passing an Asn1StreamParser into this constructor
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return new BerTaggedObjectParser(tag, tagNo, indIn).ToAsn1Object();
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}
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Asn1StreamParser sp = new Asn1StreamParser(indIn);
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// TODO There are other tags that may be constructed (e.g. BitString)
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switch (tagNo)
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{
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case Asn1Tags.OctetString:
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return new BerOctetStringParser(sp).ToAsn1Object();
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case Asn1Tags.Sequence:
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return new BerSequenceParser(sp).ToAsn1Object();
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case Asn1Tags.Set:
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return new BerSetParser(sp).ToAsn1Object();
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default:
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throw new IOException("unknown BER object encountered");
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}
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}
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else
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{
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DefiniteLengthInputStream defIn = new DefiniteLengthInputStream(this, length);
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if ((tag & Asn1Tags.Application) != 0)
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{
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return new DerApplicationSpecific(isConstructed, tagNo, defIn.ToArray());
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}
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if ((tag & Asn1Tags.Tagged) != 0)
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{
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return new BerTaggedObjectParser(tag, tagNo, defIn).ToAsn1Object();
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}
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if (isConstructed)
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{
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// TODO There are other tags that may be constructed (e.g. BitString)
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switch (tagNo)
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{
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case Asn1Tags.OctetString:
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//
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// yes, people actually do this...
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//
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return new BerOctetString(BuildDerEncodableVector(defIn));
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case Asn1Tags.Sequence:
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return CreateDerSequence(defIn);
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case Asn1Tags.Set:
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return CreateDerSet(defIn);
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default:
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return new DerUnknownTag(true, tagNo, defIn.ToArray());
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}
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}
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return CreatePrimitiveDerObject(tagNo, defIn.ToArray());
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}
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}
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internal static int ReadTagNumber(
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Stream s,
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int tag)
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{
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int tagNo = tag & 0x1f;
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//
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// with tagged object tag number is bottom 5 bits, or stored at the start of the content
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//
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if (tagNo == 0x1f)
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{
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tagNo = 0;
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int b = s.ReadByte();
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// X.690-0207 8.1.2.4.2
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// "c) bits 7 to 1 of the first subsequent octet shall not all be zero."
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if ((b & 0x7f) == 0) // Note: -1 will pass
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{
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throw new IOException("corrupted stream - invalid high tag number found");
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}
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while ((b >= 0) && ((b & 0x80) != 0))
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{
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tagNo |= (b & 0x7f);
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tagNo <<= 7;
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b = s.ReadByte();
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}
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if (b < 0)
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throw new EndOfStreamException("EOF found inside tag value.");
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tagNo |= (b & 0x7f);
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}
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return tagNo;
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}
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internal static int ReadLength(
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Stream s,
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int limit)
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{
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int length = s.ReadByte();
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if (length < 0)
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throw new EndOfStreamException("EOF found when length expected");
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if (length == 0x80)
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return -1; // indefinite-length encoding
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if (length > 127)
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{
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int size = length & 0x7f;
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if (size > 4)
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throw new IOException("DER length more than 4 bytes");
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length = 0;
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for (int i = 0; i < size; i++)
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{
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int next = s.ReadByte();
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if (next < 0)
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throw new EndOfStreamException("EOF found reading length");
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length = (length << 8) + next;
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}
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if (length < 0)
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throw new IOException("Corrupted stream - negative length found");
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if (length >= limit) // after all we must have read at least 1 byte
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throw new IOException("Corrupted stream - out of bounds length found");
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}
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return length;
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}
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internal static Asn1Object CreatePrimitiveDerObject(
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int tagNo,
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byte[] bytes)
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{
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switch (tagNo)
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{
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case Asn1Tags.BitString:
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{
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int padBits = bytes[0];
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byte[] data = new byte[bytes.Length - 1];
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Array.Copy(bytes, 1, data, 0, bytes.Length - 1);
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return new DerBitString(data, padBits);
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}
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case Asn1Tags.BmpString:
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return new DerBmpString(bytes);
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case Asn1Tags.Boolean:
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return new DerBoolean(bytes);
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case Asn1Tags.Enumerated:
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return new DerEnumerated(bytes);
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case Asn1Tags.GeneralizedTime:
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return new DerGeneralizedTime(bytes);
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case Asn1Tags.GeneralString:
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return new DerGeneralString(bytes);
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case Asn1Tags.IA5String:
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return new DerIA5String(bytes);
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case Asn1Tags.Integer:
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return new DerInteger(bytes);
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case Asn1Tags.Null:
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return DerNull.Instance; // actual content is ignored (enforce 0 length?)
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case Asn1Tags.NumericString:
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return new DerNumericString(bytes);
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case Asn1Tags.ObjectIdentifier:
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return new DerObjectIdentifier(bytes);
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case Asn1Tags.OctetString:
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return new DerOctetString(bytes);
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case Asn1Tags.PrintableString:
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return new DerPrintableString(bytes);
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case Asn1Tags.T61String:
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return new DerT61String(bytes);
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case Asn1Tags.UniversalString:
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return new DerUniversalString(bytes);
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case Asn1Tags.UtcTime:
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return new DerUtcTime(bytes);
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case Asn1Tags.Utf8String:
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return new DerUtf8String(bytes);
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case Asn1Tags.VisibleString:
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return new DerVisibleString(bytes);
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default:
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return new DerUnknownTag(false, tagNo, bytes);
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}
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}
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}
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}
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