CDView encrypted image
CDView encrypted image refers to an encrypted image file format that was used on some adult-content French-language CDROMs and DVDs.
It is apparently associated with CDView, a specialized viewer for 32-bit Windows, credited to "E.S.I.". The known version of CDView is named "CDView 2001", though it sometimes accidentally(?) calls itself "CDView 98".
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Format details
An encrypted file decrypts to a standard JPEG, or rarely GIF, file. Other formats might also be supported, but have not been observed. Even GIF files use extension .jpg.
Essentially, to decrypt or encrypt a file, xor every byte with 0xa5. But there is an apparent bug where the last byte of the file doesn't always get encrypted, particularly if the file size equals 3 (mod 4).
Identification
Encrypted JPEG files start with bytes 5a 7d 5a. It's possible to be more precise, but the JPEG files used for this are fairly diverse, so it would take some effort.
Encrypted GIF files start with bytes e2 ec e3 9d 92 c4 (=GIF87a) or e2 ec e3 9d 9c c4 (=GIF89a).
Software
CDView might require some sort of passcode to make it work.
- CDView 2001: The files in this directory (excluding subdirectories)
Sample files
All images should be assumed to be NSFW.
- dexvert samples — image/cdViewEncryptedJPG
- [1] - Some JPEG, some GIF
