public static CryptographicAttributeObjectCollection GetUnprotectedAttributes(this SafeCryptMsgHandle hCryptMsg)
{
// For some reason, you can't ask how many attributes there are - you have to ask for the attributes and
// get a CRYPT_E_ATTRIBUTES_MISSING failure if the count is 0.
int cbUnprotectedAttr = 0;
if (!Interop.Crypt32.CryptMsgGetParam(hCryptMsg, CryptMsgParamType.CMSG_UNPROTECTED_ATTR_PARAM, 0, null, ref cbUnprotectedAttr))
{
int lastError = Interop.CPError.GetLastWin32Error();
if (lastError == (int)ErrorCode.CRYPT_E_ATTRIBUTES_MISSING)
{
return(new CryptographicAttributeObjectCollection());
}
throw lastError.ToCryptographicException();
}
using (SafeHandle sh = hCryptMsg.GetMsgParamAsMemory(CryptMsgParamType.CMSG_UNPROTECTED_ATTR_PARAM))
{
unsafe
{
CRYPT_ATTRIBUTES *pCryptAttributes = (CRYPT_ATTRIBUTES *)(sh.DangerousGetHandle());
return(ToCryptographicAttributeObjectCollection(pCryptAttributes));
}
}
}
internal static DecryptorPalWindows Decode(
ReadOnlySpan <byte> encodedMessage,
out int version,
out ContentInfo contentInfo,
out AlgorithmIdentifier contentEncryptionAlgorithm,
out X509Certificate2Collection originatorCerts,
out CryptographicAttributeObjectCollection unprotectedAttributes
)
{
SafeCryptMsgHandle hCryptMsg = Interop.Crypt32.CryptMsgOpenToDecode(MsgEncodingType.All, 0, 0, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
if (hCryptMsg == null || hCryptMsg.IsInvalid)
{
throw Marshal.GetLastWin32Error().ToCryptographicException();
}
if (!Interop.Crypt32.CryptMsgUpdate(
hCryptMsg,
ref MemoryMarshal.GetReference(encodedMessage),
encodedMessage.Length,
fFinal: true))
{
throw Marshal.GetLastWin32Error().ToCryptographicException();
}
CryptMsgType cryptMsgType = hCryptMsg.GetMessageType();
if (cryptMsgType != CryptMsgType.CMSG_ENVELOPED)
{
throw ErrorCode.CRYPT_E_INVALID_MSG_TYPE.ToCryptographicException();
}
version = hCryptMsg.GetVersion();
contentInfo = hCryptMsg.GetContentInfo();
AlgorithmIdentifierAsn contentEncryptionAlgorithmAsn;
using (SafeHandle sh = hCryptMsg.GetMsgParamAsMemory(CryptMsgParamType.CMSG_ENVELOPE_ALGORITHM_PARAM))
{
unsafe
{
CRYPT_ALGORITHM_IDENTIFIER *pCryptAlgorithmIdentifier = (CRYPT_ALGORITHM_IDENTIFIER *)(sh.DangerousGetHandle());
contentEncryptionAlgorithm = (*pCryptAlgorithmIdentifier).ToAlgorithmIdentifier();
contentEncryptionAlgorithmAsn.Algorithm = contentEncryptionAlgorithm.Oid.Value !;
contentEncryptionAlgorithmAsn.Parameters = (*pCryptAlgorithmIdentifier).Parameters.ToByteArray();
}
}
originatorCerts = hCryptMsg.GetOriginatorCerts();
unprotectedAttributes = hCryptMsg.GetUnprotectedAttributes();
RecipientInfoCollection recipientInfos = CreateRecipientInfos(hCryptMsg);
return(new DecryptorPalWindows(hCryptMsg, recipientInfos, contentEncryptionAlgorithmAsn));
}
private static RecipientInfoCollection CreateRecipientInfos(SafeCryptMsgHandle hCryptMsg)
{
int numRecipients;
int cbRecipientsCount = sizeof(int);
if (!Interop.Crypt32.CryptMsgGetParam(hCryptMsg, CryptMsgParamType.CMSG_CMS_RECIPIENT_COUNT_PARAM, 0, out numRecipients, ref cbRecipientsCount))
{
throw Marshal.GetLastPInvokeError().ToCryptographicException();
}
List <RecipientInfo> recipientInfos = new List <RecipientInfo>(numRecipients);
for (int index = 0; index < numRecipients; index++)
{
// Do not dispose this safehandle. The RecipientInfoPal objects we create hold on to these and they get freed through garbage collection.
SafeHandle pCmsgCmsRecipientInfoMemory = hCryptMsg.GetMsgParamAsMemory(CryptMsgParamType.CMSG_CMS_RECIPIENT_INFO_PARAM, index);
IEnumerable <RecipientInfo> recipientInfosForThisIndex = ToRecipientInfosForThisIndex(pCmsgCmsRecipientInfoMemory, index);
recipientInfos.AddRange(recipientInfosForThisIndex);
}
return(new RecipientInfoCollection(recipientInfos));
}