function encodeRSAPrivateKeyToPem(privateKey) {
    return forge.pki.privateKeyToPem(privateKey);
}

function encodeRSAPublicKeyToPem(publicKey) {
    return forge.pki.publicKeyToPem(publicKey);
}

function rsaPrivateKeyFromPem(pem) {
    return forge.pki.privateKeyFromPem(pem);
}

function generateToken(time, userId, deviceToken, privateKeyPem) {
    const privateKey = forge.pki.privateKeyFromPem(privateKeyPem);
    const data = `${userId}-${deviceToken}-${time}`;
    const md = forge.md.sha256.create();
    md.update(data, 'utf8');
    const signature = privateKey.sign(md);
    return forge.util.encode64(signature);
}