/// <summary>
/// Generate an enveloped object that contains a CMS Enveloped Data
/// object using the passed in key generator.
/// </summary>
private CmsEnvelopedData Generate(
CmsProcessable content,
string encryptionOid,
CipherKeyGenerator keyGen)
{
AlgorithmIdentifier encAlgId = null;
KeyParameter encKey;
Asn1OctetString encContent;
try
{
IBufferedCipher cipher = CipherUtilities.GetCipher(encryptionOid);
byte[] encKeyBytes = keyGen.GenerateKey();
encKey = ParameterUtilities.CreateKeyParameter(encryptionOid, encKeyBytes);
Asn1Encodable asn1Params = null;
try
{
if (encryptionOid.Equals(RC2Cbc))
{
// mix in a bit extra...
rand.SetSeed(DateTime.Now.Ticks);
byte[] iv = rand.GenerateSeed(8);
// TODO Is this detailed repeat of Java version really necessary?
int effKeyBits = encKeyBytes.Length * 8;
int parameterVersion;
if (effKeyBits < 256)
{
parameterVersion = rc2Table[effKeyBits];
}
else
{
parameterVersion = effKeyBits;
}
asn1Params = new RC2CbcParameter(parameterVersion, iv);
}
else
{
asn1Params = ParameterUtilities.GenerateParameters(encryptionOid, rand);
}
}
catch (SecurityUtilityException)
{
// No problem... no parameters generated
}
Asn1Object asn1Object;
ICipherParameters cipherParameters;
if (asn1Params != null)
{
asn1Object = asn1Params.ToAsn1Object();
cipherParameters = ParameterUtilities.GetCipherParameters(
encryptionOid, encKey, asn1Object);
}
else
{
asn1Object = DerNull.Instance;
cipherParameters = encKey;
}
encAlgId = new AlgorithmIdentifier(
new DerObjectIdentifier(encryptionOid),
asn1Object);
cipher.Init(true, cipherParameters);
MemoryStream bOut = new MemoryStream();
CipherStream cOut = new CipherStream(bOut, null, cipher);
content.Write(cOut);
cOut.Close();
encContent = new BerOctetString(bOut.ToArray());
}
catch (SecurityUtilityException e)
{
throw new CmsException("couldn't create cipher.", e);
}
catch (InvalidKeyException e)
{
throw new CmsException("key invalid in message.", e);
}
catch (IOException e)
{
throw new CmsException("exception decoding algorithm parameters.", e);
}
Asn1EncodableVector recipientInfos = new Asn1EncodableVector();
foreach (RecipientInf recipient in recipientInfs)
{
try
{
recipientInfos.Add(recipient.ToRecipientInfo(encKey));
}
catch (IOException e)
{
throw new CmsException("encoding error.", e);
}
catch (InvalidKeyException e)
{
throw new CmsException("key inappropriate for algorithm.", e);
}
catch (GeneralSecurityException e)
{
throw new CmsException("error making encrypted content.", e);
}
}
EncryptedContentInfo eci = new EncryptedContentInfo(
PkcsObjectIdentifiers.Data,
encAlgId,
encContent);
Asn1.Cms.ContentInfo contentInfo = new Asn1.Cms.ContentInfo(
PkcsObjectIdentifiers.EnvelopedData,
new EnvelopedData(null, new DerSet(recipientInfos), eci, null));
return new CmsEnvelopedData(contentInfo);
}
protected internal virtual Asn1Encodable GenerateAsn1Parameters(
string encryptionOid,
byte[] encKeyBytes)
{
Asn1Encodable asn1Params = null;
try
{
if (encryptionOid.Equals(RC2Cbc))
{
byte[] iv = new byte[8];
rand.NextBytes(iv);
// TODO Is this detailed repeat of Java version really necessary?
int effKeyBits = encKeyBytes.Length * 8;
int parameterVersion;
if (effKeyBits < 256)
{
parameterVersion = rc2Table[effKeyBits];
}
else
{
parameterVersion = effKeyBits;
}
asn1Params = new RC2CbcParameter(parameterVersion, iv);
}
else
{
asn1Params = ParameterUtilities.GenerateParameters(encryptionOid, rand);
}
}
catch (SecurityUtilityException)
{
// No problem... no parameters generated
}
return asn1Params;
}
/// <summary>
/// Generate an enveloped object that contains an CMS Enveloped Data
/// object using the passed in key generator.
/// </summary>
private Stream Open(
Stream outStream,
string encryptionOid,
CipherKeyGenerator keyGen)
{
Asn1Encodable asn1Params = null;
byte[] encKeyBytes = keyGen.GenerateKey();
KeyParameter encKey = ParameterUtilities.CreateKeyParameter(encryptionOid, encKeyBytes);
try
{
if (encryptionOid.Equals(RC2Cbc))
{
// mix in a bit extra...
rand.SetSeed(DateTime.Now.Ticks);
byte[] iv = rand.GenerateSeed(8);
// TODO Is this detailed repeat of Java version really necessary?
int effKeyBits = encKeyBytes.Length * 8;
int parameterVersion;
if (effKeyBits < 256)
{
parameterVersion = rc2Table[effKeyBits];
}
else
{
parameterVersion = effKeyBits;
}
asn1Params = new RC2CbcParameter(parameterVersion, iv);
}
else
{
asn1Params = ParameterUtilities.GenerateParameters(encryptionOid, rand);
}
}
catch (SecurityUtilityException)
{
// No problem... no parameters generated
}
Asn1EncodableVector recipientInfos = new Asn1EncodableVector();
foreach (RecipientInf recipient in recipientInfs)
{
try
{
recipientInfos.Add(recipient.ToRecipientInfo(encKey));
}
catch (IOException e)
{
throw new CmsException("encoding error.", e);
}
catch (InvalidKeyException e)
{
throw new CmsException("key inappropriate for algorithm.", e);
}
catch (GeneralSecurityException e)
{
throw new CmsException("error making encrypted content.", e);
}
}
return Open(outStream, encryptionOid, encKey, asn1Params, recipientInfos);
}
