function str2ab(str) {
    const buf = new ArrayBuffer(str.length);
    const bufView = new Uint8Array(buf);
    for (let i = 0, strLen = str.length; i < strLen; i ++) {
        bufView[i] = str.charCodeAt(i);
    }
    return buf;
}

function importRsaKey(pem) {
    // fetch the part of the PEM string between header and footer
    const pemHeader = "---
--BEGIN PUBLIC KEY---
--";
    const pemFooter = "---
--END PUBLIC KEY---
--";
    const pemContents = pem.substring(pemHeader.length, pem.length - pemFooter.length);
    // base64 decode the string to get the binary data
    const binaryDerString = window.atob(pemContents);
    // convert from a binary string to an ArrayBuffer
    const binaryDer = str2ab(binaryDerString);

    return window.crypto.subtle.importKey(
        'spki',
        binaryDer,
        {
            name: 'RSA-OAEP',
            hash: 'SHA-256'
        },
        true,
        ['encrypt']
    )
}

async function encryptMessage(value) {
    let encoder = new TextEncoder();
    const data = encoder.encode(value);
    const key = await importRsaKey(pem_text);
    return window.crypto.subtle.encrypt({
        name: 'RSA-OAEP',
        hash: 'SHA-256'
    }, key, data)
}