Adam H Secure Communication (AHSC)

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Adam H Secure Communication (AHSC)
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Frequencies 350 Hz,700 Hz
Frequency Range 350 Hz - 700 Hz
Mode USB
Modulation Unknown
ACF None
Bandwidth 440 Hz,700 Hz
Location United Kingdom
Short Description AHSC uses a randomly generated One-Time-Pad to secure communications between transmitter and receiver. Used for unscheduled transferring of data due to the architecture of the protocol / mode which makes decoding the message impossible if the transmission was not listened to from the beginning.
I/Q Raw Recording
Audio Sample

AHSC works by encrypting the real data with a One-Time-Pad. This, theoretically, means that the data cannot be decoded if the message is not listened to in its entirety. (https://en.wikipedia.org/wiki/One-time_pad)

The transmission is split into two parts,

1. The data of the key
2. The data encrypted with the key

This means that if the receiver cannot receive the key or is late in recording / decoding the transmission, then the message cannot be decrypted and read.

Problems arise with this mode, however, since,

A. The real receiver must know the exact time in which the transmission will occur
B. If the imposter receiver also knows the exact time, the security of the communication can, if the right software is used, be cracked


AHSC structure for transmission:[edit]

Period Purpose Correlation
800MS Sync / Start 400Hz
200-300MS Bit 0 [OTP] 400Hz
400-500MS Bit 1 [OTP] 400Hz
700MS End of OTP / Start of encrypted data 400Hz
200-300MS Bit 0 [REAL DATA] 400Hz
400-500MS Bit 1 [REAL DATA] 400Hz
800MS Sync / End 400Hz


Large waterfall showing the entire transmission:[edit]

(Take note of the periodic space around the centre of the transmission that indicates the end of the OTP data and the start of the real, encrypted data)


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