public class SecurityModel
{
    public string Token { get; set; }
    public string PublicKey { get; set; }
}

public class EncryptedModel
{
    public string Token { get; set; }
    public string Encrypted { get; set; }
}

[HttpGet]
public async Task<SecurityModel> GeneratePublicKey()
{
    var model = new SecurityModel();
    using (var generator = new RSACryptoServiceProvider(1024))
    {
        try
        {
            var token = Convert.ToBase64String(Guid.NewGuid().ToByteArray());
            var keys = generator.ExportParameters(true);
            var pemString = generator.GetPublicKeyAsPemString();

            MemoryCache.Default.Add(token, keys, new CacheItemPolicy
            {
                AbsoluteExpiration = ObjectCache.InfiniteAbsoluteExpiration,
                SlidingExpiration = TimeSpan.FromMinutes(30),
                Priority = CacheItemPriority.NotRemovable
            });

            model.Token = token;
            model.PublicKey = pemString;
        }
        finally
        {
            generator.PersistKeyInCsp = false;
        }
    }
    return model;
}

[HttpPost]
public async Task<bool> ReadSensitiveData(EncryptedModel model)
{
    using (var generator = new RSACryptoServiceProvider(1024))
    {
        try
        {
            var keys = (RSAParameters)MemoryCache.Default.Get(model.Token);
            generator.ImportParameters(keys);

            var binary = Convert.FromBase64String(model.Encrypted);
            var decrypted = generator.Decrypt(binary, false);
            var sensitive = Encoding.UTF8.GetString(decrypted);

            return sensitive == "Sensitive Data";
        }
        finally
        {
            generator.PersistKeyInCsp = false;
        }
    }
    return false;
}

-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDlOJu6TyygqxfWT7eLtGDwajtN
FOb9I5XRb6khyfD1Yt3YiCgQWMNW649887VGJiGr/L5i2osbl8C9+WJTeucF+S76
xFxdU6jE0NQ+Z+zEdhUTooNRaY5nZiu5PgDB0ED/ZKBUSLKL7eibMxZtMlUDHjm4
gwQco1KRMDSmXSMkDwIDAQAB
-----END PUBLIC KEY-----

var encrypt = new JSEncrypt();
var token = "";
var generatePublicKey = function () {
    var httpRequest = new XMLHttpRequest();
    httpRequest.open('GET', '/api/Security/', true);
    httpRequest.responseType = "json";
    httpRequest.addEventListener("readystatechange", function (event) {
        if (httpRequest.readyState == 4) {
            token = httpRequest.response.Token;
            encrypt.setPublicKey(httpRequest.response.PublicKey);
            sendSensitiveData();
        }
    });
    httpRequest.send();
}

var sendSensitiveData = function () {
    var sensitive = "Sensitive Data";
    var encrypted = encrypt.encrypt(sensitive);

    var httpRequest = new XMLHttpRequest();
    httpRequest.open('POST', '/api/Security/', true);
    httpRequest.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
    httpRequest.addEventListener("readystatechange", function (event) {
        if (httpRequest.readyState == 4) {
            console.log(httpRequest);
        }
    });
    httpRequest.send(JSON.stringify({ Token: token, Encrypted: encrypted }));
}

generatePublicKey();