private bool CheckForVersion3(
Asn1Set signerInfs)
{
foreach (object obj in signerInfs)
{
SignerInfo s = SignerInfo.GetInstance(obj);
if (s.Version.Value.IntValue == 3)
{
return(true);
}
}
return(false);
}
/**
* Return a SignerInformationStore containing the counter signatures attached to this
* signer. If no counter signatures are present an empty store is returned.
*/
public SignerInformationStore GetCounterSignatures()
{
// TODO There are several checks implied by the RFC3852 comments that are missing
/*
* The countersignature attribute MUST be an unsigned attribute; it MUST
* NOT be a signed attribute, an authenticated attribute, an
* unauthenticated attribute, or an unprotected attribute.
*/
AttributeTable unsignedAttributeTable = UnsignedAttributes;
if (unsignedAttributeTable == null)
{
return(new SignerInformationStore(Platform.CreateArrayList(0)));
}
IList counterSignatures = Platform.CreateArrayList();
/*
* The UnsignedAttributes syntax is defined as a SET OF Attributes. The
* UnsignedAttributes in a signerInfo may include multiple instances of
* the countersignature attribute.
*/
Asn1EncodableVector allCSAttrs = unsignedAttributeTable.GetAll(CmsAttributes.CounterSignature);
foreach (Attribute counterSignatureAttribute in allCSAttrs)
{
/*
* A countersignature attribute can have multiple attribute values. The
* syntax is defined as a SET OF AttributeValue, and there MUST be one
* or more instances of AttributeValue present.
*/
Asn1Set values = counterSignatureAttribute.AttrValues;
if (values.Count < 1)
{
// TODO Throw an appropriate exception?
}
foreach (Asn1Encodable asn1Obj in values)
{
/*
* Countersignature values have the same meaning as SignerInfo values
* for ordinary signatures, except that:
*
* 1. The signedAttributes field MUST NOT contain a content-type
* attribute; there is no content type for countersignatures.
*
* 2. The signedAttributes field MUST contain a message-digest
* attribute if it contains any other attributes.
*
* 3. The input to the message-digesting process is the contents
* octets of the DER encoding of the signatureValue field of the
* SignerInfo value with which the attribute is associated.
*/
SignerInfo si = SignerInfo.GetInstance(asn1Obj.ToAsn1Object());
string digestName = CmsSignedHelper.Instance.GetDigestAlgName(si.DigestAlgorithm.Algorithm.Id);
counterSignatures.Add(new SignerInformation(si, null, null, new CounterSignatureDigestCalculator(digestName, GetSignature())));
}
}
return(new SignerInformationStore(counterSignatures));
}