private static string SecureInput(Dictionary <string, object> header, Dictionary <string, object> payload)
{
var encodeHeader = UrlBase64.Encode(Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(header)));
var encodePayload = UrlBase64.Encode(Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(payload)));
return(string.Format("{0}.{1}", encodeHeader, encodePayload));
}
/// <summary>
/// Generates a Jws Signature.
/// </summary>
/// <param name="header"></param>
/// <param name="payload"></param>
/// <returns></returns>
public string GenerateSignature(Dictionary <string, object> header, Dictionary <string, object> payload)
{
var securedInput = SecureInput(header, payload);
var message = Encoding.UTF8.GetBytes(securedInput);
byte[] hashedMessage;
using (var sha256Hasher = SHA256.Create())
{
hashedMessage = sha256Hasher.ComputeHash(message);
}
var signer = new ECDsaSigner();
signer.Init(true, _privateKey);
var results = signer.GenerateSignature(hashedMessage);
// Concated to create signature
var a = results[0].ToByteArrayUnsigned();
var b = results[1].ToByteArrayUnsigned();
// a,b are required to be exactly the same length of bytes
if (a.Length != b.Length)
{
var largestLength = Math.Max(a.Length, b.Length);
a = ByteArrayPadLeft(a, largestLength);
b = ByteArrayPadLeft(b, largestLength);
}
var signature = UrlBase64.Encode(a.Concat(b).ToArray());
return(string.Format("{0}.{1}", securedInput, signature));
}
public static EncryptionResult Encrypt(string userKey, string userSecret, string payload)
{
var userKeyBytes = UrlBase64.Decode(userKey);
var userSecretBytes = UrlBase64.Decode(userSecret);
var payloadBytes = Encoding.UTF8.GetBytes(payload);
return(Encrypt(userKeyBytes, userSecretBytes, payloadBytes));
}
/// <summary>
/// Generate vapid keys
/// </summary>
public static VapidDetails GenerateVapidKeys()
{
var results = new VapidDetails();
var keys = ECKeyHelper.GenerateKeys();
var publicKey = ((ECPublicKeyParameters)keys.Public).Q.GetEncoded(false);
var privateKey = ((ECPrivateKeyParameters)keys.Private).D.ToByteArrayUnsigned();
results.PublicKey = UrlBase64.Encode(publicKey);
results.PrivateKey = UrlBase64.Encode(ByteArrayPadLeft(privateKey, 32));
return(results);
}
public static void ValidatePrivateKey(string privateKey)
{
if (string.IsNullOrEmpty(privateKey))
{
throw new ArgumentException(@"Valid private key not set");
}
var decodedPrivateKey = UrlBase64.Decode(privateKey);
if (decodedPrivateKey.Length != 32)
{
throw new ArgumentException(@"Vapid private key should be 32 bytes long when decoded.");
}
}
public static void ValidatePublicKey(string publicKey)
{
if (string.IsNullOrEmpty(publicKey))
{
throw new ArgumentException(@"Valid public key not set");
}
var decodedPublicKey = UrlBase64.Decode(publicKey);
if (decodedPublicKey.Length != 65)
{
throw new ArgumentException(@"Vapid public key must be 65 characters long when decoded");
}
}
/// <summary>
/// This method takes the required VAPID parameters and returns the required
/// header to be added to a Web Push Protocol Request.
/// </summary>
/// <param name="audience">This must be the origin of the push service.</param>
/// <param name="subject">This should be a URL or a 'mailto:' email address</param>
/// <param name="publicKey">The VAPID public key as a base64 encoded string</param>
/// <param name="privateKey">The VAPID private key as a base64 encoded string</param>
/// <param name="expiration">The expiration of the VAPID JWT.</param>
/// <returns>A dictionary of header key/value pairs.</returns>
public static Dictionary <string, string> GetVapidHeaders(string audience, string subject, string publicKey,
string privateKey, long expiration = -1)
{
ValidateAudience(audience);
ValidateSubject(subject);
ValidatePublicKey(publicKey);
ValidatePrivateKey(privateKey);
var decodedPrivateKey = UrlBase64.Decode(privateKey);
if (expiration == -1)
{
expiration = UnixTimeNow() + 43200;
}
var header = new Dictionary <string, object>();
header.Add("typ", "JWT");
header.Add("alg", "ES256");
var jwtPayload = new Dictionary <string, object>();
jwtPayload.Add("aud", audience);
jwtPayload.Add("exp", expiration);
jwtPayload.Add("sub", subject);
var signingKey = ECKeyHelper.GetPrivateKey(decodedPrivateKey);
var signer = new JWSSigner(signingKey);
var token = signer.GenerateSignature(header, jwtPayload);
var results = new Dictionary <string, string>();
results.Add("Authorization", "WebPush " + token);
results.Add("Crypto-Key", "p256ecdsa=" + publicKey);
return(results);
}
