The PROPID_M_PROV_NAME_LEN property identifies the length of the name of the cryptographic provider used for validating the message signature.
When a message is sent, PROPID_M_PROV_NAME_LEN is set by MSMQ when PROPID_M_PROV_NAME is passed to MQSendMessage.
The PROPID_M_PROV_NAME_LEN property is only used by the receiving application when calling MQReceiveMessage. It is required whenever PROPID_M_PROV_NAME is passed to MQReceiveMessage.
On input, PROPID_M_PROV_NAME_LEN specifies the size (in Unicode characters) of the buffer allocated by the receiving application. The buffer should be large enough to hold the complete provider name string including the end-of-string character.
On return, this property holds the length (in Unicode characters) of the provider name string plus the end-of-string character.
MQReceiveMessage succeeds if the buffer is large enough to hold the provider name. If the buffer is too small, MQReceiveMessage fails and PROPID_M_PROV_NAME_LEN can be used to obtain the required buffer length of the provider name string.
When passing PROPID_M_PROV_NAME_LEN to MQReceiveMessage, the corresponding VT field in the aPropVar array can be set to VT_NULL.
PROPID_M_PROV_NAME is typically used when working with foreign queues. For information on sending authenticated messages to a foreign queue, see MSMQ Connector Server.
MQSendMessage, PROPID_M_PROV_NAME