Secrets In Case Of Death

It's a morbid reality that one day you will die. When that happens, how do those you leave behind take care of your personal details: websites, accounts, passwords, etc? Using this tool you can securely spread your secrets to a wide number of people, none of whom will individually posses your secrets, yet, by combining their shares together can recover your secrets in case of death.

The algorithm Shamir's Secret Sharing allows for this: take a piece of data, split it into N shares, but only require Y (where Y<=N and Y>1) shares to recover the original.

Important Security Information: All data manipulation is done on your machine, never transmitted elsewhere. In fact, it's highly reccommended that you use this tool offline. You can save this webpage and load it from your local machine.

Practical example: Add your passwords and personal information to the text field below, click "Make Shares". Click the 3 generated links to download 3 HTML files. Send one of these files to 3 people you trust (through email is fine, in fact). Now, if something happens to you, any two of those people can combine their shares in order to unlock your information. However, any single person could not -- this is why the email is secure.

You can make more shares and split them up in novel ways to give certain people more "weight". Perhaps you generate 5 shares and require 3 to recover. Now, instead of a single share per person, give your partner 2 shares and send the remaining out individually. This way, your partner needs only one other person to recover the data, but any other person would need 2 additional individuals to collaborate.

Generate Secrets

Select the number of shares, shares required to decrypt, and enter your secret data. After submitting the form, all keys and resulting documents will be generated below. You can save these documents and email them to your trusted parties.

Number of shares to generate:

Number of shares required to decrypt:

Note: "Shares to decrypt" must be less than or equal to total shares

Data to encrypt:

Generated Documents

<title>Recover Secrets</title>

<script type="text/javascript">
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    </script>

var shareCount = {sharecount};

document.addEventListener("DOMContentLoaded", function() {

var form = document.getElementById('theform');

form.innerHTML += '<p><label>Share 1: <input type="text" id="share1" value="{givenShare}" /></label></p>';
        for (var i = 2; i <= shareCount; i++) {
            form.innerHTML += '<p><label>Share '+i+': <input type="text" id="share'+i+'" value="" /></label></p>';
        }
        form.innerHTML += '<p><input type="submit" value="Recover Secrets"></p>';

form.addEventListener("submit", function(evt){
            evt.preventDefault();

var shares = [];
            for (var i = 1; i <= shareCount; i++) {
                shares[i-1] = document.getElementById('share' + i).value;
                if (shares[i-1].length == 0) { alert("You must provide enough shares; Share "+ i +" is empty"); }
            }

var combined = secrets.combine(shares);
            var recovered = secrets.hex2str(combined);

document.getElementById('recovered').value = recovered;

alert("The secrets have been recovered and are now on page");

return false;
        });

});
    </script>

</head>
    <body>
    <p>This secret requires {sharecount} shares to recover. Collect enough shares, enter them all below, and submit. No data leaves your browser.</p>
    <form id="theform"></form>
    <textarea id="recovered" style="width: 100%;height: 600px">

Javascript implementation of Shamir's Secret Sharing care of Alexander Stetsyuk