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arash khajooei
arash khajooei vor 2 Stunden
hi  i used your PCB to make a power meter and used a blue light LCD 1602 but the characters show in black not white in LCD screen ! what should I do? I know that in your layout your are not connected vss to gnd ! do you think there is a problem with my power supply?
RF Power Meter with 1MHz-10GHz bandwidth and 55dB dynamic range
HaSch vor 3 Stunden
I calibrated the sketch with the LDR I use bit the display doesn't dim. I checked the values in serial console and they should be right (going from 255 to 1). Any hints where to search the error?
3 displays alarm-clock with TFT screen, developped with Arduino [170112]
lux36 vor 18 Stunden
Answers to oetelaarNG: 1.) Yes, this is the OTP random number sequence generated with the TRNG, to be used for OTP encryption. 2.) This random data is a random meaningless sequence that is to be used for encryption of sensitive data if the box gets delivered to the recepient without tampering along the way.  This data is not an encrypted message - anyone can open the box along the way and read it and eventually decrypt it, so we don't risk that. 3.) The answer is  at 1.) 4.) -You don't actually destroy the data on the SD because zeroising the data in SD card is very slow and difficult. You simply declare it invalid and insecure   by zeroising the the challenge and response in MCU SRAM which is much easier. -If the box has been tampered with, the recepient can use his RNG to generate a new sequence on a new SD card and send it to the original sender. Maybe it won't be tampered with this time... No special secure vault is needed, every pair of peers can generate the random numbers from their RNGs. -Check my answer to Poul Borg Petersen about the challenge-response procedure to check for possible tampering during the transport. As you can see, intercepting it is actually no big deal if the secure key (random seauence) on the SD hasn't been read. The only problem is if somebody manages to actually alter the challenge or response, but this is much harder to do. -Someone else getting the data is not a problem because this is a meningless random sequence. It is enough to simply warn the recepinet about it. -I read "Secrets and lies" from Bruce Schneier and also "Applied Cryptography" from the same author. Basically I like Bruce as an expert, although I don't share his harsh legalistic attitudes - like calling Kevin Mitnick "a convicted criminal hacker". -A good RNG and a good crypto device solve the problem of virtually unbreakable OTP encryption. Tamper-evident box solves a problem of secure distribution of OTP keys. I am not a very good mathematician, so I trust OTP method because its mathematical background is very simple. That's why I chose the OTP.  
Tamper-evident paper-mail box for secure distribution of one-time pads
Axiris vor 19 Stunden
We looked into the issue and it is indeed caused by a firmware bug. We will correct this in the next software release. Thanks for letting me know, Ilse
6-digit VFD Clock with ESP32
lux36 vor 19 Stunden
Answer to Poul Borg Petersen : After a reception of the packet, the recepient does the following: 1.) He simply calls the sender (or sends him an e-mail), and informs him about the reception . Both sides can now use any unsecure communication channel.  2.) Sender now gives him both challenge and response codes. Please note that now it is completely irrelevant if this communication is intercepted (unsecure channel is used), when the box is in secure place (recepinet's hands).  A potential eavesdropper would need to have the codes before, so he could open the box (now the SRAM will zeroise), take the SD card, read the data from the SD, put the card back, close the box, and re-enter both codes to SRAM to cover up everything. 3.) Recepient communicates with the box through the IRDA. Enters the challenge and checks the response.  4.) If the response is correct, it means that there was no tampering during the transport. 5.) The recepient now opens the box and takes the SD card. Secure communication through OTP crypto system is now clear to start.    
Tamper-evident paper-mail box for secure distribution of one-time pads