Jericho Comms

You need truly random data for information-theoretically secure communications using one-time pads. This program provides a True Random Number Generator (TRNG).

Entropy is extracted from two images that you provide. For best results, use photographs from a standalone digital camera or digital SLR that have been captured in your camera's RAW image format. This best preserves the original data when the shot was taken. You should then transfer them directly to your computer by USB cable or SD memory card. Then convert them as-is (without post processing) to a lossless image format e.g. PNG or BMP. Avoid JPEG and other lossy compression formats where possible as they may affect the output in predictable ways. Avoid using your mobile phone as they generally have poor security and the contents can be secretly collected from them at any time due to the closed baseband processor.

Take photos of something that is generally random in nature. Photos taken in macro mode of sand at a beach, grass and gravel work best. Trees, bushes, rocks and ocean waves also work well. Avoid studio photography with plain backgrounds. The photos should be clear and in focus as much as possible.

The program will run randomness tests on the data after it has been run through the randomness extractor. Check that all of the tests pass otherwise you may need to try different photos. Be sure to permanently delete the original photos from the camera and your computer after the one-time pads have been created from them. To be absolutely safe, run this program from a non-networked (air gapped) computer. On export, the one-time pads will be encrypted for transport and use.

This process should be run from a desktop or laptop PC as it is resource intensive and the page is not mobile optimised. The website has details about how the algorithm processes and extracts the random data from the photo.



Alternatively you can import your own truly random data which will be split it into separate one-time pads for use with the program. This is at your own risk. Do not use data generated from a PRNG or even a CSPRNG as it will not be strong enough for one-time pads and will reduce the security to that of a stream cipher.

Other tools

This tool is useful if you do not have a standalone digital camera capable of RAW mode and wish to capture photographs using your webcam. After you have saved two photographs you can process them in the TRNG. If the webcam photograph capture does not provide enough random data you can always export and combine the extracted random data together from multiple sets of images into a larger file, then load the file as custom random data and create the one-time pads from it.



This tool is useful if you have processed multiple sets of images with the TRNG and you want to concatenate all the files of random data together and convert it into a single binary file for testing in an external tool. In the TRNG you should have exported the random data as text files containing only ASCII hexadecimal symbols. Then use this tool to combine the data from all the files and output a single binary file. This has been tested to only work in Firefox at the moment.



This tool is useful if you have processed multiple sets of images with the TRNG and you want to XOR all the files of random data together and convert it into a single binary file for testing in an external tool. In the TRNG you should have exported the random data as text files containing only ASCII hexadecimal symbols. Then use this tool to combine the data from all the files and output a single binary file.