private unsafe static CMSG_SIGNER_ENCODE_INFO CreateSignerInfo(
CmsSigner cmsSigner,
CngKey privateKey,
HeapBlockRetainer hb)
{
var signerInfo = new CMSG_SIGNER_ENCODE_INFO();
signerInfo.cbSize = (uint)Marshal.SizeOf(signerInfo);
signerInfo.pCertInfo = Marshal.PtrToStructure <CERT_CONTEXT>(cmsSigner.Certificate.Handle).pCertInfo;
signerInfo.hCryptProvOrhNCryptKey = privateKey.Handle.DangerousGetHandle();
signerInfo.HashAlgorithm.pszObjId = cmsSigner.DigestAlgorithm.Value;
if (cmsSigner.SignerIdentifierType == SubjectIdentifierType.SubjectKeyIdentifier)
{
var certContextHandle = IntPtr.Zero;
try
{
certContextHandle = NativeMethods.CertDuplicateCertificateContext(cmsSigner.Certificate.Handle);
uint cbData = 0;
var pbData = IntPtr.Zero;
ThrowIfFailed(NativeMethods.CertGetCertificateContextProperty(
certContextHandle,
NativeMethods.CERT_KEY_IDENTIFIER_PROP_ID,
pbData,
ref cbData));
if (cbData > 0)
{
pbData = hb.Alloc((int)cbData);
ThrowIfFailed(NativeMethods.CertGetCertificateContextProperty(
certContextHandle,
NativeMethods.CERT_KEY_IDENTIFIER_PROP_ID,
pbData,
ref cbData));
signerInfo.SignerId.dwIdChoice = NativeMethods.CERT_ID_KEY_IDENTIFIER;
signerInfo.SignerId.KeyId.cbData = cbData;
signerInfo.SignerId.KeyId.pbData = pbData;
}
}
finally
{
if (certContextHandle != IntPtr.Zero)
{
NativeMethods.CertFreeCertificateContext(certContextHandle);
}
}
}
if (cmsSigner.SignedAttributes.Count != 0)
{
signerInfo.cAuthAttr = cmsSigner.SignedAttributes.Count;
checked
{
var attributeSize = Marshal.SizeOf <CRYPT_ATTRIBUTE>();
var blobSize = Marshal.SizeOf <CRYPT_INTEGER_BLOB>();
var attributesArray = (CRYPT_ATTRIBUTE *)hb.Alloc(attributeSize * cmsSigner.SignedAttributes.Count);
var currentAttribute = attributesArray;
foreach (var attribute in cmsSigner.SignedAttributes)
{
currentAttribute->pszObjId = hb.AllocAsciiString(attribute.Oid.Value);
currentAttribute->cValue = (uint)attribute.Values.Count;
currentAttribute->rgValue = hb.Alloc(blobSize);
foreach (var value in attribute.Values)
{
var attrData = value.RawData;
if (attrData.Length > 0)
{
var blob = (CRYPT_INTEGER_BLOB *)currentAttribute->rgValue;
blob->cbData = (uint)attrData.Length;
blob->pbData = hb.Alloc(value.RawData.Length);
Marshal.Copy(attrData, 0, blob->pbData, attrData.Length);
}
}
currentAttribute++;
}
signerInfo.rgAuthAttr = new IntPtr(attributesArray);
}
}
return(signerInfo);
}
public static extern bool CryptMsgCountersign(
SafeCryptMsgHandle hCryptMsg,
uint dwIndex,
int cCountersigners,
CMSG_SIGNER_ENCODE_INFO rgCountersigners);