What is the MENC file format?
A .menc file is an AES-encrypted wrapper created by the built-in Storage Card Encryption feature of Windows Mobile 6.x, introduced with Windows Mobile 6.0 in 2007. When a device is configured to encrypt its removable storage, every file written to the memory card is automatically encrypted and renamed to FILENAME.GUID.menc, where the GUID is a key identifier unique to that device.
On the originating device the encryption filter runs transparently - the .menc extension is hidden and files appear under their original names in the file browser. The encryption uses AES with a key derived from the device's hardware GUID, making each file device-locked: it can only be decrypted by the same physical device (or one provisioned with an identical key).
Transferring a .menc file to a PC via ActiveSync or Windows Mobile Device Center (WMDC) copies the encrypted blob unchanged. No PC-side decryption utility exists; recovery without the originating device is generally not possible.
Windows Mobile reached end of life in 2010, replaced by Windows Phone 7, which uses BitLocker-based device encryption and produces no .menc files. Neither ActiveSync nor WMDC is officially supported on Windows 10 or Windows 11 without compatibility workarounds, making access to legacy .menc files increasingly difficult.
Security & safety
RISK: LOWMENC files are encrypted data containers - content is inaccessible without the originating device. No known malware specifically targets .menc. The format is from an EOL platform (Windows Mobile) with negligible attack surface today.
Format details
in a nutshellPrograms that open MENC files
Windows2 apps
Windows Mobile Device Center (WMDC)
Free Connect the originating Windows Mobile device; sync files - WMDC decrypts during transfer via the device.
ActiveSync 4.5
Free Windows XP only: connect originating device; sync to PC. ActiveSync manages decryption via the device. Technical details
deep spec| Encryption algorithm | AES - device-specific key derived from the hardware GUID of the originating Windows Mobile device |
| Key binding | Device-locked - only the originating device (or one provisioned with an identical key) can decrypt the file |
| File naming on device | Original file renamed to FILENAME.GUID.menc on the storage card; GUID portion identifies the encryption key |
| Transparency on device | Encryption filter hides the .menc extension on-device; file appears under its original name to the user |
| File header content | Original filename + GUID key identifier + AES-encrypted payload of the source file |
| Byte order | Little-endian |
| Compression | None - source file content is AES-encrypted directly without pre-compression |
| Typical file size | Approximately equal to the source file; header adds only minimal overhead |
| Platform (device) | Windows Mobile 6.0, 6.1, and 6.5 |
| Platform (PC access) | Windows XP - 7 via ActiveSync 4.5 or Windows Mobile Device Center (WMDC); not supported on Windows 10 or 11 |
| PC decryption | No PC-side decryption tool exists; ActiveSync and WMDC transfer the encrypted blob unchanged |
| Platform EOL | Windows Mobile discontinued 2010; replaced by Windows Phone 7/8 with BitLocker-based encryption - no .menc equivalent |
| Released | 2007 (Windows Mobile 6.0) |
| Latest version | Windows Mobile 6.5 (2009; platform EOL) |
| Specification | learn.microsoft.com |
MENC conversions
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