public FullEmailSigner(
[NotNull] IPrivateKeySigner privateKey,
[NotNull] Encoding encoding,
[NotNull] string domain,
[NotNull] string dkimSelector,
[NotNull] string domainKeySelector,
[NotNull] string[] headers)
{
if (privateKey == null) throw new ArgumentNullException("privateKey");
if (encoding == null) throw new ArgumentNullException("encoding");
if (domain == null) throw new ArgumentNullException("domain");
if (dkimSelector == null) throw new ArgumentNullException("dkimSelector");
if (domainKeySelector == null) throw new ArgumentNullException("domainKeySelector");
if (headers == null) throw new ArgumentNullException("headers");
var dkim = new DkimSigner(
privateKey,
domain,
dkimSelector,
headers
);
//var debugger = new ConsoleDebug();
//dkim.Debug = debugger;
dkim.Encoding = encoding;
dkim.BodyCanonicalization = DkimCanonicalizationAlgorithm.Simple;
_dkimSigner = dkim;
var domainKeySigner = new DomainKeySigner(
privateKey,
domain,
domainKeySelector,
headers
);
domainKeySigner.Encoding = encoding;
domainKeySigner.Canonicalization = DomainKeyCanonicalizationAlgorithm.Nofws;
_domainKeySigner = domainKeySigner;
}
public static MailMessage DkimSign([NotNull]this MailMessage message, DkimSigner signer)
{
if (message == null)
{
throw new ArgumentNullException("message");
}
if (signer == null)
{
throw new ArgumentNullException("signer");
}
message.BodyEncoding = signer.Encoding;
message.SubjectEncoding = signer.Encoding;
message.HeadersEncoding = signer.Encoding;
// get email content and generate initial signature
var email = Email.Parse(message.GetText());
if (!CanSign(email))
{
throw new InvalidOperationException("Unable to Domain Key sign the message");
}
var value = signer.GenerateDkimHeaderValue(email);
// signature value get formatted so add dummy signature value then remove it
message.Headers.Prepend(DkimSigner.SignatureKey, value + new string('0', 70));
email = message.Parse();
var formattedSig = email.Headers[DkimSigner.SignatureKey].Value;
email.Headers[DkimSigner.SignatureKey].Value = formattedSig.Substring(0, formattedSig.Length - 70);
// sign email
value += signer.GenerateSignature(email);
message.Headers.Set(DkimSigner.SignatureKey, value);
return message;
}
private static void GetDkimSigners()
{
try
{
var files = new DirectoryInfo(Config.PrivateKeyFolder).GetFiles("*.pem");
if (files.Length == 0)
throw new Exception("No private key files (*.pem) found");
foreach (var file in files)
{
var key = file.Name.Replace(".pem", "");
var selector = key.Split('@')[0];
var domain = key.Split('@')[1];
var pKeySig = PrivateKeySigner.LoadFromFile(file.FullName);
var dkimSig = new DkimSigner(pKeySig, domain, selector, new[] { "From", "To", "Subject" });
var domainKeySig = new DomainKeySigner(pKeySig, domain, selector, new[] { "From", "To", "Subject" });
dkimSig.HeaderCanonicalization = DkimCanonicalizationAlgorithm.RELAXED;
dkimSig.BodyCanonicalization = DkimCanonicalizationAlgorithm.RELAXED;
_dkimSignerCache.TryAdd(key, dkimSig);
_domailKeySignerCache.TryAdd(key, domainKeySig);
}
}
catch (Exception ex)
{
Logger.Log.Warn("Unable to turn on DKIM: {0}", ex.Message);
}
}