using System;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.X509;

public class SubjectKeyIdentifier : Asn1Encodable
{
	private readonly byte[] keyIdentifier;

	public static SubjectKeyIdentifier GetInstance(Asn1TaggedObject obj, bool explicitly)
	{
		return GetInstance(Asn1OctetString.GetInstance(obj, explicitly));
	}

	public static SubjectKeyIdentifier GetInstance(object obj)
	{
		if (obj is SubjectKeyIdentifier)
		{
			return (SubjectKeyIdentifier)obj;
		}
		if (obj is SubjectPublicKeyInfo)
		{
			return new SubjectKeyIdentifier((SubjectPublicKeyInfo)obj);
		}
		if (obj is Asn1OctetString)
		{
			return new SubjectKeyIdentifier((Asn1OctetString)obj);
		}
		if (obj is X509Extension)
		{
			return GetInstance(X509Extension.ConvertValueToObject((X509Extension)obj));
		}
		throw new ArgumentException("Invalid SubjectKeyIdentifier: " + Platform.GetTypeName(obj));
	}

	public SubjectKeyIdentifier(byte[] keyID)
	{
		if (keyID == null)
		{
			throw new ArgumentNullException("keyID");
		}
		keyIdentifier = keyID;
	}

	public SubjectKeyIdentifier(Asn1OctetString keyID)
	{
		keyIdentifier = keyID.GetOctets();
	}

	public SubjectKeyIdentifier(SubjectPublicKeyInfo spki)
	{
		keyIdentifier = GetDigest(spki);
	}

	public byte[] GetKeyIdentifier()
	{
		return keyIdentifier;
	}

	public override Asn1Object ToAsn1Object()
	{
		return new DerOctetString(keyIdentifier);
	}

	public static SubjectKeyIdentifier CreateSha1KeyIdentifier(SubjectPublicKeyInfo keyInfo)
	{
		return new SubjectKeyIdentifier(keyInfo);
	}

	public static SubjectKeyIdentifier CreateTruncatedSha1KeyIdentifier(SubjectPublicKeyInfo keyInfo)
	{
		byte[] digest = GetDigest(keyInfo);
		byte[] array = new byte[8];
		Array.Copy(digest, digest.Length - 8, array, 0, array.Length);
		byte[] array2;
		(array2 = array)[0] = (byte)(array2[0] & 0xF);
		(array2 = array)[0] = (byte)(array2[0] | 0x40);
		return new SubjectKeyIdentifier(array);
	}

	private static byte[] GetDigest(SubjectPublicKeyInfo spki)
	{
		IDigest digest = new Sha1Digest();
		byte[] array = new byte[digest.GetDigestSize()];
		byte[] bytes = spki.PublicKeyData.GetBytes();
		digest.BlockUpdate(bytes, 0, bytes.Length);
		digest.DoFinal(array, 0);
		return array;
	}
}