Blind protocol and mnemonic seeds

In a previous post, we illustrated our Blind Protocol, which allows two operators to create a paper wallet splitting the private key so that nobody has access to it and it is not shown before the need to spend the funds. 

In some cases, it is definitely more useful to have the private key stored in the form of a BIP39 mnemonic seed, since it can be used easily with most of the nowadays clients. So we developed BlindMnemonic, a new tool with the same approach, which generates two parts of a mnemonic seed and provides some deposit addresses, so that it is possible to receive funds with no one having access to the whole mneminic seed.

How to use the tool

Also this tool requires two different operators, each one obtaining a part of the mnemonic seed.

In real case scenarios, don't forget to use the "Offline" button on the desktop to disable all the network interfaces and prevent any data leakage.

When starting the tool, it is possible to specify if we prefer a 12 or 24 words mnemonic seed phrase. We knoe It is also possible to have valid mnemonic phrases with other lenghts, but 12 and 24 are the most used out there.

Once we have choses the lenght of our mnemonic seed, the two operators have to type some random words in the proper text box.

It is important to know that this step is totally not deterministic and the provided words are only part of the entropy used during the seed generation process so, even providing the same words, it is not possible to obtain the same mnemonic seed phrase.

When clicking on the "Generat first words" button, the tool automatically generates a pdf file containing the first part of the mnemonic seed phrase.

By clicking on the other button, the pdf file will be irremediably deleted so it is important to save it in this stage of the process. Then the second operator is supposed to do the same, inserting other random words and obtaining another pdf file containing the remaining part of the mnemonic seed phrase.

In the last step the tool allows to choose among several types of public address to receive the transfers. This capability is helpful to avoid to put the mnemonic seed phrase into some kind of client to obtain the related public addresses.

In our example we are choosing to obtain Bitcoin public addresses and the tool is automatically providing a .pdf file with the public address and the corresponding QR code.

Verifying the tool

To confirm that the mnemonic seed phrase we obtained running the tool is working properly we can check it using Ian Coleman's BIP39 tool.

This is supposed to be done only while testing the tool, since the tool was designed to never put together the two parts of the mnemonic seed phrase.