Linux can use the file command.
It's been possible since NT 4.0 to enable running Linux commands on Windows, though the things to enable it change.
This lists info on all files ending in .azw3
Code:
someone@shoebox-7050:~/some_files/eBooks_bought$ file *.azw3
A Baffling Murder at the Midsummer Ball (A Dizzy Heights Mystery).azw3: Mobipocket E-book "A Baffling Murder at the Midsummer Ball", 685533 bytes uncompressed, version 8, codepage 65001, encrypted (type 2)
A BODY ON THE BEACH.azw3: Mobipocket E-book "A BODY ON THE BEACH a gripping Welsh crime mystery full of twists", 1246140 bytes uncompressed, version 8, codepage 65001
Above the Bay of Angels.azw3: Mobipocket E-book "Above the Bay of Angels", 700687 bytes uncompressed, version 8, codepage 65001, encrypted (type 2)
A Cat's Guide to Bonding with Dragons.azw3: Mobipocket E-book "A Cat\342\200\231s Guide to Bonding with Dragons 6x9: Dragoncat Book 1", 554195 bytes uncompressed, version 8, codepage 65001, encrypted (type 2)
Can be redirected via filter for "encrypted" to a text file.
Some mobi ones. Only one is encrypted.
Code:
*.azw
Christmas Classics Cookbook.azw: Mobipocket E-book "Gooseberry Patch Christmas Classics", 55920 bytes uncompressed, version 6, codepage 65001
Dreamwalker (The Red Dragon Academy Book 1).azw: Mobipocket E-book "Dreamwalker (The Red Dragon Academy) (Volume 1)", 580741 bytes uncompressed, version 6, codepage 65001
The Funeral Photographer-1.azw: Mobipocket E-book "Number One: The Funeral Photographer", 49448 bytes uncompressed, version 6, codepage 65001, encrypted (type 2)