public SignerInfo Generate(DerObjectIdentifier contentType, AlgorithmIdentifier digestAlgorithm,
byte[] calculatedDigest)
{
try
{
string digestName = Helper.GetDigestAlgName(_digestOID);
string signatureName = digestName + "with" + _encName;
// AlgorithmIdentifier digAlgId = DigestAlgorithmID;
//
// byte[] hash = (byte[])outer._messageHashes[Helper.GetDigestAlgName(this._digestOID)];
// outer._digests[_digestOID] = hash.Clone();
byte[] bytesToSign = calculatedDigest;
/* RFC 3852 5.4
* The result of the message digest calculation process depends on
* whether the signedAttrs field is present. When the field is absent,
* the result is just the message digest of the content as described
*
* above. When the field is present, however, the result is the message
* digest of the complete DER encoding of the SignedAttrs value
* contained in the signedAttrs field.
*/
Asn1Set signedAttr = null;
if (_sAttr != null)
{
IDictionary parameters = outer.GetBaseParameters(
contentType, digestAlgorithm, calculatedDigest);
// Asn1.Cms.AttributeTable signed = _sAttr.GetAttributes(Collections.unmodifiableMap(parameters));
Asn1.Cms.AttributeTable signed = _sAttr.GetAttributes(parameters);
// TODO Handle countersignatures (see CMSSignedDataGenerator)
signedAttr = outer.GetAttributeSet(signed);
// sig must be composed from the DER encoding.
bytesToSign = signedAttr.GetEncoded(Asn1Encodable.Der);
}
else
{
// Note: Need to use raw signatures here since we have already calculated the digest
if (_encName.Equals("RSA"))
{
DigestInfo dInfo = new DigestInfo(digestAlgorithm, calculatedDigest);
bytesToSign = dInfo.GetEncoded(Asn1Encodable.Der);
}
}
_sig.BlockUpdate(bytesToSign, 0, bytesToSign.Length);
byte[] sigBytes = _sig.GenerateSignature();
Asn1Set unsignedAttr = null;
if (_unsAttr != null)
{
IDictionary parameters = outer.GetBaseParameters(
contentType, digestAlgorithm, calculatedDigest);
parameters[CmsAttributeTableParameter.Signature] = sigBytes.Clone();
// Asn1.Cms.AttributeTable unsigned = _unsAttr.getAttributes(Collections.unmodifiableMap(parameters));
Asn1.Cms.AttributeTable unsigned = _unsAttr.GetAttributes(parameters);
unsignedAttr = outer.GetAttributeSet(unsigned);
}
// TODO[RSAPSS] Need the ability to specify non-default parameters
Asn1Encodable sigX509Parameters = SignerUtilities.GetDefaultX509Parameters(signatureName);
AlgorithmIdentifier digestEncryptionAlgorithm = CmsSignedGenerator.GetEncAlgorithmIdentifier(
new DerObjectIdentifier(_encOID), sigX509Parameters);
return new SignerInfo(_signerIdentifier, digestAlgorithm,
signedAttr, digestEncryptionAlgorithm, new DerOctetString(sigBytes), unsignedAttr);
}
catch (IOException e)
{
throw new CmsStreamException("encoding error.", e);
}
catch (SignatureException e)
{
throw new CmsStreamException("error creating signature.", e);
}
}
private byte[] derEncode(DerObjectIdentifier oid, byte[] hash)
{
AlgorithmIdentifier algId = new AlgorithmIdentifier(oid, DerNull.Instance);
DigestInfo dInfo = new DigestInfo(algId, hash);
return dInfo.GetEncoded(Asn1Encodable.Der);
}
