Javascript encryption using RSA compatible with .NET using bouncy castle library

// Generate public key using RSA encryption
protected void Session_Start(object sender, EventArgs e)
        {
            if (System.Runtime.Caching.MemoryCache.Default.Get("privateKey") == null)
            {
                RsaKeyPairGenerator rsaKeyPairGnr = new RsaKeyPairGenerator();
                rsaKeyPairGnr.Init(new Org.BouncyCastle.Crypto.KeyGenerationParameters(new SecureRandom(), 1024));
                Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair keyPair = rsaKeyPairGnr.GenerateKeyPair();

                SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public);

                var pubKeyPEM = FormatPem(publicKeyInfo.GetEncoded().ToBase64(), "PUBLIC KEY");
                RsaKeyParameters publicKey = (RsaKeyParameters)keyPair.Public;
                RsaKeyParameters privateKey = (RsaKeyParameters)keyPair.Private;

                System.Runtime.Caching.MemoryCache.Default.Add("publicKey", pubKeyPEM, DateTimeOffset.MaxValue);
                System.Runtime.Caching.MemoryCache.Default.Add("publicKeyX", publicKey, DateTimeOffset.MaxValue);
                System.Runtime.Caching.MemoryCache.Default.Add("privateKey", privateKey, DateTimeOffset.MaxValue);
            }
        }
		
// Convert SubjectPublicKeyInfo object to PEM format
private static string FormatPem(string pem, string keyType)
        {
            var sb = new StringBuilder();
            sb.AppendFormat("-----BEGIN {0}-----\n", keyType);

            int line = 1, width = 64;

            while ((line - 1) * width < pem.Length)
            {
                int startIndex = (line - 1) * width;
                int len = line * width > pem.Length
                              ? pem.Length - startIndex
                              : width;
                sb.AppendFormat("{0}\n", pem.Substring(startIndex, len));
                line++;
            }

            sb.AppendFormat("-----END {0}-----\n", keyType);
            return sb.ToString();
        }

//Login aspx : javascript code for the login button get public key and password and encrypt using JSEncrypt library
<asp:Button ID="LoginButton" runat="server" OnClientClick="onLoginButtonClicked()" CommandName="Login" Text="Log In" ValidationGroup="Login1" />

    function onLoginButtonClicked() {
			var key = $("#&lt;%= hdnkey.ClientID%>").val();
            var password = $("#Login1_Password").val();
            var encrypt = new JSEncrypt();
            encrypt.setPublicKey(key);
            var encrypted = encrypt.encrypt(password);
            $("#&lt;%= hdnEncryptedPass.ClientID%>").val(encrypted);
        }


//Login aspx.cs
 protected void Page_Load(object sender, EventArgs e)
        {
            if (IsPostBack) return;
            if (System.Runtime.Caching.MemoryCache.Default.Get("publicKey") != null)
            {
                var publicKey = System.Runtime.Caching.MemoryCache.Default.Get("publicKey");
                this.hdnkey.Value = publicKey.ToString();
            }
		}
		
// servre side code that decrypt the encrypted password using the private key
// it gives error while decrypt in the follwoing line
// byte[] deciphered = cipher.ProcessBlock(ciphered, 0, ciphered.Length);
//the error message is: input too large for RSA cipher.
protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
        {
            try
            {
                RsaKeyParameters privateKey = (RsaKeyParameters)System.Runtime.Caching.MemoryCache.Default.Get("privateKey");
                
                string encrypted = this.hdnEncryptedPass.Value;

                SHA512Managed hash = new SHA512Managed();
                SecureRandom randomNumber = new SecureRandom();
                byte[] encodingParam = hash.ComputeHash(Encoding.UTF8.GetBytes(randomNumber.ToString()));

                IAsymmetricBlockCipher cipher = new RsaEngine();
                UTF8Encoding utf8enc = new UTF8Encoding();
                
                cipher.Init(false, privateKey);
                byte[] ciphered = Encoding.UTF8.GetBytes(encrypted);
                byte[] deciphered = cipher.ProcessBlock(ciphered, 0, ciphered.Length);
                var pass = utf8enc.GetString(deciphered);
            }
            catch (Exception ee)
            {

                throw;
            }

            e.Authenticated = Membership.ValidateUser(Login1.UserName, Login1.Password);
        }