I have a minifilter which protect special files by adding a header and encrypt data of file.
Now, It’s successful for docx, pptx, xlsx. These file types save correct and open without any problem.
If I save my file as ppt file, it saved without visible error. file will encrypt(header is added and data is encrypted). But I open my file and get “PowerPoint found a problem with content”. There is similar problem in doc files.
I compare procmon and filespy logs. there isn’t great difference between correct and problem scenarios. size of files is ok. writefile and readfile IRP is ok. There are both cached and Non-cached write and read.
Are you handling the directory query as well for these files? Office
tools have a way of querying the file size in different ways and
comparing them to ensure the file saved correctly.
Pete
–
Kernel Drivers
Windows File System and Device Driver Consulting www.KernelDrivers.com
866.263.9295
------ Original Message ------
From: “xxxxx@gmail.com” To: “Windows File Systems Devs Interest List” Sent: 9/20/2017 5:14:04 AM Subject: [ntfsd] minifilter failed to read encrypted ppt file
>Hi, > >I have a minifilter which protect special files by adding a header and >encrypt data of file. >Now, It’s successful for docx, pptx, xlsx. These file types save >correct and open without any problem. >If I save my file as ppt file, it saved without visible error. file >will encrypt(header is added and data is encrypted). But I open my file >and get “PowerPoint found a problem with content”. There is similar >problem in doc files. >I compare procmon and filespy logs. there isn’t great difference >between correct and problem scenarios. size of files is ok. writefile >and readfile IRP is ok. There are both cached and Non-cached write and >read. > >Can you help me to find solution. > >— >NTFSD is sponsored by OSR > > >MONTHLY seminars on crash dump analysis, WDF, Windows internals and >software drivers! >Details at http: > >To unsubscribe, visit the List Server section of OSR Online at >http:</http:></http:>