Secure SD card- 2 -SD card copier
Next logical sequel in our secure crypto-device series, necessary to securely copy and manage sensitive files, before and after encryption/decryption.
So, Alice has just prepared a few gigabytes of good random number OTP sequences using our RNG:
https://www.elektormagazine.com/labs/random-number-generator-150116
They are now stored on the SD. She can give a copy to Bob hand-to-hand, or she can also use the tamper-evident paper-mail box to send it to Bob using any snail-mail service:
https://www.elektormagazine.com/labs/tamper-evident-paper-mail-box-for-secure-distribution-of-one-time-pads
But wait, how is she actually going to make that copy? Using a PC or any general-purpose computer for copying SD cards with security-crytical info is a "crypto-suicide" by itself. So, this copier device comes in to fill in this security gap! Besides for copying one-time pads, this device will be a complete secure FAT32 file-handling system with the following features:
1.) Direct secure copying from SD1 to SD2. Reaches a speed up to 20Mbit/sec, tested at 32MHz DMA transfer. Entire SD card cloning is also possible.
2.) Comparison and verification of the copied data.
3.) A simple text editor, to securely type simple text messages and store them to SD card before offline encryption with our OTP crypto device:
https://www.elektormagazine.com/labs/one-time-pad-otp-crypto-system
4.) Other basic FAT32 file functions, like delete, rename, format etc.
This can also be used as a secure link between one "dirty" and one "clean" SD card - will copy only the selected data, sector-wise, and keep any infections out of the "clean" part of the system, so a "dirty" card, with encrypted data only copied, can then be securely put to a "dirty" PC or smartphone to e-mail the encrypted files.
Hardware is tested in "spaghetti-breadboard" version, software needs to be completed.
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