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CrowdHailer/sign.js

Last active May 29, 2023 06:19
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Revisions

  1. CrowdHailer revised this gist Mar 8, 2019. 1 changed file with 1 addition and 0 deletions.
    1 change: 1 addition & 0 deletions sign.js
    View file
    Original file line number Diff line number Diff line change
    @@ -1,3 +1,4 @@
    // NEEDS TO RUN IN SECURE (HTTPS) CONTEXT.
    async function run() {
    // New key pair
    var keyPair = await window.crypto.subtle.generateKey(
  2. CrowdHailer created this gist Mar 8, 2019.
    70 changes: 70 additions & 0 deletions sign.js
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,70 @@
    async function run() {
    // New key pair
    var keyPair = await window.crypto.subtle.generateKey(
    {
    name: "ECDSA",
    namedCurve: "P-521"
    },
    true,
    ["sign", "verify"]
    );

    // Format public key

    var publicPEM = spkiToPEM(await window.crypto.subtle.exportKey(
    "spki",
    keyPair.publicKey
    ));
    console.log(publicPEM)

    // Encode message
    var message = "abc";
    var encoder = new TextEncoder();
    var bytes = (encoder).encode(message);

    var signature = await window.crypto.subtle.sign(
    {
    name: "ECDSA",
    hash: {name: "SHA-256"},
    },
    keyPair.privateKey,
    bytes
    );

    var encodedSignature = window.btoa(arrayBufferToString(signature));
    console.log(encodedSignature);
    }

    // https://stackoverflow.com/questions/40314257/export-webcrypto-key-to-pem-format
    function spkiToPEM(keydata){
    var keydataS = arrayBufferToString(keydata);
    var keydataB64 = window.btoa(keydataS);
    var keydataB64Pem = formatAsPem(keydataB64);
    return keydataB64Pem;
    }

    function arrayBufferToString( buffer ) {
    var binary = '';
    var bytes = new Uint8Array( buffer );
    var len = bytes.byteLength;
    for (var i = 0; i < len; i++) {
    binary += String.fromCharCode( bytes[ i ] );
    }
    return binary;
    }

    function formatAsPem(str) {
    var finalString = '-----BEGIN PUBLIC KEY-----\n';

    while(str.length > 0) {
    finalString += str.substring(0, 64) + '\n';
    str = str.substring(64);
    }

    finalString = finalString + "-----END PUBLIC KEY-----";

    return finalString;
    }

    run();
    // Example out put for encodedSignature and publicPEM included below
    23 changes: 23 additions & 0 deletions verify.ex
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,23 @@
    message = "abc"

    encoded_signature = "AOqjfvb1P0fYdbnq+f3XsbOR/Lylq4csC5e1Ks4cKRTcWKQyH4CVr/XRHCmZDEWOpaA8gwuM3Z3qD21vMaixySUPASTDnd1J8shNx51MCbONIReTNuH53kzxykLpf0riSyMbEBQtie4/pxlrolUOsDja2f/ikgM/lGXtCTXz2faV4m2Y"

    public_PEM = "-----BEGIN PUBLIC KEY-----
    MIGbMBAGByqGSM49AgEGBSuBBAAjA4GGAAQB7PNQVbADLNyobtijE5NVZUvHs74h
    iMntCbp0C8pdU1IQRWlAfDeEs/iuxA32VARw9Q5/0mim8Si8JcpCJnhS0u8AESMf
    Ux3WqzHhB33t4q3iPsJbM7zmN91QNnbYErrGqEDCmSruPpKw1iK5dJ3/xQZbkpmR
    ztoVwrZoCoGUu+WTqEI=
    -----END PUBLIC KEY-----"

    signature = Base.decode64(encoded_signature)

    [key_entry] = :public_key.pem_decode(public_PEM)
    public_key = :public_key.pem_entry_decode(key_entry)

    :public_key.verify(
    message,
    :sha256,
    signature,
    public_key
    )
    # returns false