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using System;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.Kisa;
using Org.BouncyCastle.Asn1.Nist;
using Org.BouncyCastle.Asn1.Ntt;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Cms
{
internal class KekRecipientInfoGenerator : RecipientInfoGenerator
{
private static readonly CmsEnvelopedHelper Helper = CmsEnvelopedHelper.Instance;
private KeyParameter keyEncryptionKey;
// TODO Can get this from keyEncryptionKey?
private string keyEncryptionKeyOID;
private KekIdentifier kekIdentifier;
// Derived
private AlgorithmIdentifier keyEncryptionAlgorithm;
internal KekRecipientInfoGenerator()
{
}
internal KekIdentifier KekIdentifier
{
set { this.kekIdentifier = value; }
}
internal KeyParameter KeyEncryptionKey
{
set
{
this.keyEncryptionKey = value;
this.keyEncryptionAlgorithm = DetermineKeyEncAlg(keyEncryptionKeyOID, keyEncryptionKey);
}
}
internal string KeyEncryptionKeyOID
{
set { this.keyEncryptionKeyOID = value; }
}
public RecipientInfo Generate(KeyParameter contentEncryptionKey, SecureRandom random)
{
byte[] keyBytes = contentEncryptionKey.GetKey();
IWrapper keyWrapper = WrapperUtilities.GetWrapper(keyEncryptionAlgorithm.Algorithm.Id);
keyWrapper.Init(true, new ParametersWithRandom(keyEncryptionKey, random));
Asn1OctetString encryptedKey = new DerOctetString(
keyWrapper.Wrap(keyBytes, 0, keyBytes.Length));
return new RecipientInfo(new KekRecipientInfo(kekIdentifier, keyEncryptionAlgorithm, encryptedKey));
}
private static AlgorithmIdentifier DetermineKeyEncAlg(
string algorithm, KeyParameter key)
{
if (Platform.StartsWith(algorithm, "DES"))
{
return new AlgorithmIdentifier(
PkcsObjectIdentifiers.IdAlgCms3DesWrap,
DerNull.Instance);
}
else if (Platform.StartsWith(algorithm, "RC2"))
{
return new AlgorithmIdentifier(
PkcsObjectIdentifiers.IdAlgCmsRC2Wrap,
new DerInteger(58));
}
else if (Platform.StartsWith(algorithm, "AES"))
{
int length = key.KeyLength * 8;
DerObjectIdentifier wrapOid;
if (length == 128)
{
wrapOid = NistObjectIdentifiers.IdAes128Wrap;
}
else if (length == 192)
{
wrapOid = NistObjectIdentifiers.IdAes192Wrap;
}
else if (length == 256)
{
wrapOid = NistObjectIdentifiers.IdAes256Wrap;
}
else
{
throw new ArgumentException("illegal keysize in AES");
}
return new AlgorithmIdentifier(wrapOid); // parameters absent
}
else if (Platform.StartsWith(algorithm, "SEED"))
{
// parameters absent
return new AlgorithmIdentifier(KisaObjectIdentifiers.IdNpkiAppCmsSeedWrap);
}
else if (Platform.StartsWith(algorithm, "CAMELLIA"))
{
int length = key.KeyLength * 8;
DerObjectIdentifier wrapOid;
if (length == 128)
{
wrapOid = NttObjectIdentifiers.IdCamellia128Wrap;
}
else if (length == 192)
{
wrapOid = NttObjectIdentifiers.IdCamellia192Wrap;
}
else if (length == 256)
{
wrapOid = NttObjectIdentifiers.IdCamellia256Wrap;
}
else
{
throw new ArgumentException("illegal keysize in Camellia");
}
return new AlgorithmIdentifier(wrapOid); // parameters must be absent
}
else
{
throw new ArgumentException("unknown algorithm");
}
}
}
}
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