WebCrypto GOST: Generation key tools

This is a live on-line tool. All buttons execute appropriate javascript algorithms with values from the page. The tool is intended for experimentation with data processing. Feel free to make changes in the javascript algorithms, their settings..

Generate private and calculate public keys

For elliptic curves algorithms used in GOST 34.10-2012 it's possible to split generation key procedure on two stages. In the first step we obtain the private key using the random number generator or by manual entry. In the second step procedure calculates an open key for the selected private key.

In different sources we can find different hex view of keys - in Big-endian or in Little-endial. It's a common error for first stages of study. Feel free to use swap procedure

Private key. Note: private key should be less then parameter q - order of cyclic group
Public key
Generate random key procedure 
// Generate random
var random = new Uint8Array(namedCurve.value.indexOf('512') >=0 ? 64 : 32); 
gostCrypto.getRandomValues(random);
privateKey.textContent = gostCoding.Hex.encode(random);
Calculate keys procedure 
// Generate public key
var algorithm = {name: 'GOST R 34.10'};
if (namedCurve.value.indexOf('512') >= 0) 
    algorithm.name = algorithm.name + '-512';

// Preset if private key already defined
if (privateKey.textContent)
    algorithm.ukm = gostCoding.Hex.decode(privateKey.textContent);

// Set curve parameters
if (namedCurve.value === 'Other') {
    algorithm.a = gostCoding.Hex.decode(paramA.value, 'BigEndian');
    algorithm.b = gostCoding.Hex.decode(paramB.value, 'BigEndian');
    algorithm.p = gostCoding.Hex.decode(paramP.value, 'BigEndian');
    algorithm.q = gostCoding.Hex.decode(paramQ.value, 'BigEndian');
    algorithm.x = gostCoding.Hex.decode(paramX.value, 'BigEndian');
    algorithm.y = gostCoding.Hex.decode(paramY.value, 'BigEndian');
} else
    algorithm.namedCurve = namedCurve.value;

// Generate keys
gostCrypto.subtle.generateKey(algorithm, true, ['sign', 'verify']).then(function(keyPair) {

    // Store key in secluded place
    return gostCrypto.subtle.exportKey('raw', keyPair.privateKey).then(function(result) {
        privateKey.textContent = gostCoding.Hex.encode(result);

        // Provide the public key to recepient
        return gostCrypto.subtle.exportKey('raw', keyPair.publicKey).then(function(result) {
            publicKey.textContent = gostCoding.Hex.encode(result);
        });
    });
});
Swap bytes procedure 
// Swap bytes in keys
if (privateKey.textContent)
    privateKey.textContent = gostCoding.Hex.encode(gostCoding.Hex.decode(privateKey.textContent, true));
if (publicKey.textContent)
    publicKey.textContent = gostCoding.Hex.encode(gostCoding.Hex.decode(publicKey.textContent, true));