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using System;
using System.Diagnostics;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Asn1
{
public class BerBitString
: DerBitString
{
private const int DefaultSegmentLimit = 1000;
internal static byte[] FlattenBitStrings(DerBitString[] bitStrings)
{
int count = bitStrings.Length;
switch (count)
{
case 0:
// No bits
return new byte[]{ 0 };
case 1:
return bitStrings[0].contents;
default:
{
int last = count - 1, totalLength = 0;
for (int i = 0; i < last; ++i)
{
byte[] elementContents = bitStrings[i].contents;
if (elementContents[0] != 0)
throw new ArgumentException("only the last nested bitstring can have padding", "bitStrings");
totalLength += elementContents.Length - 1;
}
// Last one can have padding
byte[] lastElementContents = bitStrings[last].contents;
byte padBits = lastElementContents[0];
totalLength += lastElementContents.Length;
byte[] contents = new byte[totalLength];
contents[0] = padBits;
int pos = 1;
for (int i = 0; i < count; ++i)
{
byte[] elementContents = bitStrings[i].contents;
int length = elementContents.Length - 1;
Array.Copy(elementContents, 1, contents, pos, length);
pos += length;
}
Debug.Assert(pos == totalLength);
return contents;
}
}
}
private readonly int segmentLimit;
private readonly DerBitString[] elements;
public BerBitString(byte data, int padBits)
: base(data, padBits)
{
this.elements = null;
this.segmentLimit = DefaultSegmentLimit;
}
public BerBitString(byte[] data)
: this(data, 0)
{
}
public BerBitString(byte[] data, int padBits)
: this(data, padBits, DefaultSegmentLimit)
{
}
public BerBitString(byte[] data, int padBits, int segmentLimit)
: base(data, padBits)
{
this.elements = null;
this.segmentLimit = segmentLimit;
}
public BerBitString(int namedBits)
: base(namedBits)
{
this.elements = null;
this.segmentLimit = DefaultSegmentLimit;
}
public BerBitString(Asn1Encodable obj)
: this(obj.GetDerEncoded(), 0)
{
}
public BerBitString(DerBitString[] elements)
: this(elements, DefaultSegmentLimit)
{
}
public BerBitString(DerBitString[] elements, int segmentLimit)
: base(FlattenBitStrings(elements), false)
{
this.elements = elements;
this.segmentLimit = segmentLimit;
}
internal BerBitString(byte[] contents, bool check)
: base(contents, check)
{
this.elements = null;
this.segmentLimit = DefaultSegmentLimit;
}
internal override bool EncodeConstructed()
{
// NOTE: Assumes BER encoding
return null != elements || contents.Length > segmentLimit;
}
internal override int EncodedLength(bool withID)
{
throw Platform.CreateNotImplementedException("BerBitString.EncodedLength");
// TODO This depends on knowing it's not DER
//if (!EncodeConstructed())
// return EncodedLength(withID, contents.Length);
//int totalLength = withID ? 4 : 3;
//if (null != elements)
//{
// for (int i = 0; i < elements.Length; ++i)
// {
// totalLength += elements[i].EncodedLength(true);
// }
//}
//else if (contents.Length < 2)
//{
// // No bits
//}
//else
//{
// int extraSegments = (contents.Length - 2) / (segmentLimit - 1);
// totalLength += extraSegments * EncodedLength(true, segmentLimit);
// int lastSegmentLength = contents.Length - (extraSegments * (segmentLimit - 1));
// totalLength += EncodedLength(true, lastSegmentLength);
//}
//return totalLength;
}
internal override void Encode(Asn1OutputStream asn1Out, bool withID)
{
if (!asn1Out.IsBer)
{
base.Encode(asn1Out, withID);
return;
}
if (!EncodeConstructed())
{
Encode(asn1Out, withID, contents, 0, contents.Length);
return;
}
asn1Out.WriteIdentifier(withID, Asn1Tags.Constructed | Asn1Tags.BitString);
asn1Out.WriteByte(0x80);
if (null != elements)
{
asn1Out.WritePrimitives(elements);
}
else if (contents.Length < 2)
{
// No bits
}
else
{
byte pad = contents[0];
int length = contents.Length;
int remaining = length - 1;
int segmentLength = segmentLimit - 1;
while (remaining > segmentLength)
{
Encode(asn1Out, true, (byte)0, contents, length - remaining, segmentLength);
remaining -= segmentLength;
}
Encode(asn1Out, true, pad, contents, length - remaining, remaining);
}
asn1Out.WriteByte(0x00);
asn1Out.WriteByte(0x00);
}
}
}
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