2023-06-06 19:49:44 +02:00
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---
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title: OTP Controller
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description:
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published: 1
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date: 2023-06-06T17:49:41.428Z
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tags:
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editor: markdown
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dateCreated: 2023-06-05T20:29:50.762Z
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---
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2023-06-05 22:23:49 +02:00
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Common crypto software runs on systems with an OS. Our approach is to
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reduce the attack surface of an operating system with its user programs
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by delegating the crypto part to a system as simple as possible.
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## System scetch:
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<!-- {{attachment:sketch.gif|system setup|width="500"}} -->
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An AVR controller with keyboard and display is used to gather the plain
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text which is held only in the controllers RAM. An One Time Pad
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encryption is performed using a large keyfile stored on the SDCARD
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attached to the AVR.
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The AVR communicates using an ES8266 module.
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The encrypted text is sent to an central server. That could be done via
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SMTP or an simple HTTP request.
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The encrypted answer is downloaded and decrypted in the AVR. the plain
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text is shown on the display attached to the AVR.
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