Extract RSA Parameters(Modulus and Exponent) from encoded String (RSA Public key)
<p>I am trying to upgrade my RSA key pair size from 1024 to 2048. I am going to give the sample code here.</p>

<p><strong>For 1024:</strong>
The first step in my code is to build a signature using Java code</p>

<pre><code>   try {
        // Generate Public &amp; Private Keys
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
        kpg.initialize(1024);
        KeyPair keyPair = kpg.genKeyPair();

        RSAPublicKey key = (RSAPublicKey) keyPair.getPublic();
        System.out.println("Modulus");
        System.out.println(key.getModulus());


        String publicKey = encode(key.getModulus().toByteArray()) + encode(key.getPublicExponent().toByteArray());


        // Build the Signature
        Signature sig = Signature.getInstance("SHA256withRSA");
        sig.initSign(keyPair.getPrivate());
        seedData = seedData + "ABC";

        sig.update(seedData.getBytes("UTF-8"));
        String signature = encode(sig.sign());

        signatureString.append(signature);
        // Embed the public key in the signature
        int publicKeyLocation = signatureString.charAt(signatureString.length() - 2) % 40;
        // Add some random bytes at the end
        int randomBytesToAdd = signatureString.charAt(signatureString.length() - 10) % 9;
        System.out.println("Random bytes to add");
        System.out.println(randomBytesToAdd);
        System.out.println("Adding Random bytes that are:");
        String s = randomString(randomBytesToAdd);
        signatureString.insert(publicKeyLocation, s);
    } catch (Exception e) {

    }

    return signatureString.toString();
}
</code></pre>

<p><strong>Now this encoded string in passed to .NET application</strong>
Where in the .NET application i used to get public key and signature</p>

<pre><code> protected RSAParameters GetPublicKey(string encodedString)
    {
        int bytesToSkip = encodedString.Substring((encodedString.Length - 10), 1).ToCharArray()[0] % 9;
        int publicKeyStarts = bytesToSkip + encodedString.Substring((encodedString.Length - 2), 1).ToCharArray()[0] % 40;
        string keyString = encodedString.Substring(publicKeyStarts, 176);
        string modulusString = keyString.Substring(0, 172);
        string exponentString = keyString.Substring(172);
        RSAParameters publicKey = new RSAParameters();
        publicKey.Modulus = new byte[128];
        Array.Copy(System.Convert.FromBase64String(modulusString), 1, publicKey.Modulus, 0, 128);
        publicKey.Exponent = System.Convert.FromBase64String(exponentString);
        return publicKey;
    }

    protected byte[] GetSignature(string encodedString)
    {
        int bytesToSkip = encodedString.Substring((encodedString.Length - 10), 1).ToCharArray()[0] % 9;
        int publicKeyStarts = bytesToSkip + encodedString.Substring((encodedString.Length - 2), 1).ToCharArray()[0] % 40;
        String digSig = encodedString.Substring(0, publicKeyStarts - bytesToSkip) + encodedString.Substring(publicKeyStarts + 176);
        return System.Convert.FromBase64String(digSig);
    }
</code></pre>

<p><strong>If I change the key pair size from 1024 to 2048 what are the changes i need to make in my .NET code</strong></p>

<p><strong>The answer I am looking for is: from the generated RSA public key how can I get length of Modulus and Exponent</strong> </p>