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using System;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Math.EC;
namespace Org.BouncyCastle.Bcpg
{
/// <remarks>Base class for an ECDH Public Key.</remarks>
public class ECDHPublicBcpgKey
: ECPublicBcpgKey
{
private byte reserved;
private HashAlgorithmTag hashFunctionId;
private SymmetricKeyAlgorithmTag symAlgorithmId;
/// <param name="bcpgIn">The stream to read the packet from.</param>
public ECDHPublicBcpgKey(BcpgInputStream bcpgIn)
: base(bcpgIn)
{
int length = bcpgIn.ReadByte();
if (length != 3)
throw new InvalidOperationException("KDF parameters size of 3 expected.");
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
Span<byte> kdfParameters = stackalloc byte[3];
#else
byte[] kdfParameters = new byte[3];
#endif
bcpgIn.ReadFully(kdfParameters);
reserved = kdfParameters[0];
hashFunctionId = (HashAlgorithmTag)kdfParameters[1];
symAlgorithmId = (SymmetricKeyAlgorithmTag)kdfParameters[2];
VerifyHashAlgorithm();
VerifySymmetricKeyAlgorithm();
}
public ECDHPublicBcpgKey(
DerObjectIdentifier oid,
ECPoint point,
HashAlgorithmTag hashAlgorithm,
SymmetricKeyAlgorithmTag symmetricKeyAlgorithm)
: base(oid, point)
{
reserved = 1;
hashFunctionId = hashAlgorithm;
symAlgorithmId = symmetricKeyAlgorithm;
VerifyHashAlgorithm();
VerifySymmetricKeyAlgorithm();
}
public virtual byte Reserved
{
get { return reserved; }
}
public virtual HashAlgorithmTag HashAlgorithm
{
get { return hashFunctionId; }
}
public virtual SymmetricKeyAlgorithmTag SymmetricKeyAlgorithm
{
get { return symAlgorithmId; }
}
public override void Encode(
BcpgOutputStream bcpgOut)
{
base.Encode(bcpgOut);
bcpgOut.WriteByte(0x3);
bcpgOut.WriteByte(reserved);
bcpgOut.WriteByte((byte)hashFunctionId);
bcpgOut.WriteByte((byte)symAlgorithmId);
}
private void VerifyHashAlgorithm()
{
switch (hashFunctionId)
{
case HashAlgorithmTag.Sha256:
case HashAlgorithmTag.Sha384:
case HashAlgorithmTag.Sha512:
break;
default:
throw new InvalidOperationException("Hash algorithm must be SHA-256 or stronger.");
}
}
private void VerifySymmetricKeyAlgorithm()
{
switch (symAlgorithmId)
{
case SymmetricKeyAlgorithmTag.Aes128:
case SymmetricKeyAlgorithmTag.Aes192:
case SymmetricKeyAlgorithmTag.Aes256:
break;
default:
throw new InvalidOperationException("Symmetric key algorithm must be AES-128 or stronger.");
}
}
}
}
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