public static void Encode(DEREncodingASN1Type type, byte[] value, Stream s)
{
s.WriteByte((byte)type);
int valueLength = value.Length;
if (valueLength < 128)
{
s.WriteByte((byte)valueLength);
}
else
{
byte[] bytesValueLength = BitConverter.GetBytes(valueLength);
Array.Reverse(bytesValueLength);
for (int i = 0; i < bytesValueLength.Length; i++)
{
if (bytesValueLength[i] != 0)
{
s.WriteByte((byte)(0x80 | (bytesValueLength.Length - i)));
s.Write(bytesValueLength, i, bytesValueLength.Length - i);
break;
}
}
}
s.Write(value, 0, valueLength);
}
public static DEREncoding Decode(Stream s)
{
DEREncodingASN1Type type = (DEREncodingASN1Type)s.ReadByte();
int valueLength;
int length1 = s.ReadByte();
if (length1 > 127)
{
int numberLenBytes = length1 & 0x7F;
byte[] valueBytes = new byte[4];
s.Read(valueBytes, 0, numberLenBytes);
switch (numberLenBytes)
{
case 1:
valueLength = valueBytes[0];
break;
case 2:
Array.Reverse(valueBytes, 0, 2);
valueLength = BitConverter.ToInt16(valueBytes, 0);
break;
case 3:
Array.Reverse(valueBytes, 0, 3);
valueLength = BitConverter.ToInt32(valueBytes, 0);
break;
case 4:
Array.Reverse(valueBytes, 0, 4);
valueLength = BitConverter.ToInt32(valueBytes, 0);
break;
default:
throw new IOException("DER encoding length not supported.");
}
}
else
{
valueLength = length1;
}
byte[] value = new byte[valueLength];
s.Read(value, 0, valueLength);
return(new DEREncoding(type, value));
}
private DEREncoding(DEREncodingASN1Type type, byte[] value)
{
_type = type;
_value = value;
}