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using System;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Asn1
{
public class DerInteger
: Asn1Object
{
public const string AllowUnsafeProperty = "Org.BouncyCastle.Asn1.AllowUnsafeInteger";
internal static bool AllowUnsafe()
{
string allowUnsafeValue = Platform.GetEnvironmentVariable(AllowUnsafeProperty);
return allowUnsafeValue != null && Platform.EqualsIgnoreCase("true", allowUnsafeValue);
}
internal const int SignExtSigned = -1;
internal const int SignExtUnsigned = 0xFF;
private readonly byte[] bytes;
private readonly int start;
/**
* return an integer from the passed in object
*
* @exception ArgumentException if the object cannot be converted.
*/
public static DerInteger GetInstance(
object obj)
{
if (obj == null || obj is DerInteger)
{
return (DerInteger)obj;
}
throw new ArgumentException("illegal object in GetInstance: " + Platform.GetTypeName(obj));
}
/**
* return an Integer from a tagged object.
*
* @param obj the tagged object holding the object we want
* @param isExplicit true if the object is meant to be explicitly
* tagged false otherwise.
* @exception ArgumentException if the tagged object cannot
* be converted.
*/
public static DerInteger GetInstance(
Asn1TaggedObject obj,
bool isExplicit)
{
if (obj == null)
throw new ArgumentNullException("obj");
Asn1Object o = obj.GetObject();
if (isExplicit || o is DerInteger)
{
return GetInstance(o);
}
return new DerInteger(Asn1OctetString.GetInstance(o).GetOctets());
}
public DerInteger(int value)
{
this.bytes = BigInteger.ValueOf(value).ToByteArray();
this.start = 0;
}
public DerInteger(long value)
{
this.bytes = BigInteger.ValueOf(value).ToByteArray();
this.start = 0;
}
public DerInteger(BigInteger value)
{
if (value == null)
throw new ArgumentNullException("value");
this.bytes = value.ToByteArray();
this.start = 0;
}
public DerInteger(byte[] bytes)
: this(bytes, true)
{
}
internal DerInteger(byte[] bytes, bool clone)
{
if (IsMalformed(bytes))
throw new ArgumentException("malformed integer", "bytes");
this.bytes = clone ? Arrays.Clone(bytes) : bytes;
this.start = SignBytesToSkip(bytes);
}
/**
* in some cases positive values Get crammed into a space,
* that's not quite big enough...
*/
public BigInteger PositiveValue
{
get { return new BigInteger(1, bytes); }
}
public BigInteger Value
{
get { return new BigInteger(bytes); }
}
public bool HasValue(int x)
{
return (bytes.Length - start) <= 4
&& IntValue(bytes, start, SignExtSigned) == x;
}
public bool HasValue(long x)
{
return (bytes.Length - start) <= 8
&& LongValue(bytes, start, SignExtSigned) == x;
}
public bool HasValue(BigInteger x)
{
return null != x
// Fast check to avoid allocation
&& IntValue(bytes, start, SignExtSigned) == x.IntValue
&& Value.Equals(x);
}
public int IntPositiveValueExact
{
get
{
int count = bytes.Length - start;
if (count > 4 || (count == 4 && 0 != (bytes[start] & 0x80)))
throw new ArithmeticException("ASN.1 Integer out of positive int range");
return IntValue(bytes, start, SignExtUnsigned);
}
}
public int IntValueExact
{
get
{
int count = bytes.Length - start;
if (count > 4)
throw new ArithmeticException("ASN.1 Integer out of int range");
return IntValue(bytes, start, SignExtSigned);
}
}
public long LongValueExact
{
get
{
int count = bytes.Length - start;
if (count > 8)
throw new ArithmeticException("ASN.1 Integer out of long range");
return LongValue(bytes, start, SignExtSigned);
}
}
internal override void Encode(DerOutputStream derOut)
{
derOut.WriteEncoded(Asn1Tags.Integer, bytes);
}
protected override int Asn1GetHashCode()
{
return Arrays.GetHashCode(bytes);
}
protected override bool Asn1Equals(Asn1Object asn1Object)
{
DerInteger other = asn1Object as DerInteger;
if (other == null)
return false;
return Arrays.AreEqual(this.bytes, other.bytes);
}
public override string ToString()
{
return Value.ToString();
}
internal static int IntValue(byte[] bytes, int start, int signExt)
{
int length = bytes.Length;
int pos = System.Math.Max(start, length - 4);
int val = (sbyte)bytes[pos] & signExt;
while (++pos < length)
{
val = (val << 8) | bytes[pos];
}
return val;
}
internal static long LongValue(byte[] bytes, int start, int signExt)
{
int length = bytes.Length;
int pos = System.Math.Max(start, length - 8);
long val = (sbyte)bytes[pos] & signExt;
while (++pos < length)
{
val = (val << 8) | bytes[pos];
}
return val;
}
/**
* Apply the correct validation for an INTEGER primitive following the BER rules.
*
* @param bytes The raw encoding of the integer.
* @return true if the (in)put fails this validation.
*/
internal static bool IsMalformed(byte[] bytes)
{
switch (bytes.Length)
{
case 0:
return true;
case 1:
return false;
default:
return (sbyte)bytes[0] == ((sbyte)bytes[1] >> 7) && !AllowUnsafe();
}
}
internal static int SignBytesToSkip(byte[] bytes)
{
int pos = 0, last = bytes.Length - 1;
while (pos < last
&& (sbyte)bytes[pos] == ((sbyte)bytes[pos + 1] >> 7))
{
++pos;
}
return pos;
}
}
}
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