Header GenerateArcMessageSignature(FormatOptions options, MimeMessage message, int instance, TimeSpan t, IList <string> headers)
{
if (message.MimeVersion == null && message.Body != null && message.Body.Headers.Count > 0)
{
message.MimeVersion = new Version(1, 0);
}
var value = CreateArcHeaderBuilder(instance);
byte[] signature, hash;
Header ams;
value.AppendFormat("; d={0}; s={1}", Domain, Selector);
value.AppendFormat("; c={0}/{1}",
HeaderCanonicalizationAlgorithm.ToString().ToLowerInvariant(),
BodyCanonicalizationAlgorithm.ToString().ToLowerInvariant());
value.AppendFormat("; t={0}", (long)t.TotalSeconds);
using (var stream = new DkimSignatureStream(CreateSigningContext())) {
using (var filtered = new FilteredStream(stream)) {
filtered.Add(options.CreateNewLineFilter());
// write the specified message headers
DkimVerifierBase.WriteHeaders(options, message, headers, HeaderCanonicalizationAlgorithm, filtered);
value.AppendFormat("; h={0}", string.Join(":", headers.ToArray()));
hash = message.HashBody(options, SignatureAlgorithm, BodyCanonicalizationAlgorithm, -1);
value.AppendFormat("; bh={0}", Convert.ToBase64String(hash));
value.Append("; b=");
ams = new Header(HeaderId.ArcMessageSignature, value.ToString());
switch (HeaderCanonicalizationAlgorithm)
{
case DkimCanonicalizationAlgorithm.Relaxed:
DkimVerifierBase.WriteHeaderRelaxed(options, filtered, ams, true);
break;
default:
DkimVerifierBase.WriteHeaderSimple(options, filtered, ams, true);
break;
}
filtered.Flush();
}
signature = stream.GenerateSignature();
ams.Value += Convert.ToBase64String(signature);
return(ams);
}
}
void DkimSign(FormatOptions options, MimeMessage message, IList <string> headers)
{
var value = new StringBuilder("v=1");
var t = GetTimestamp();
byte[] signature, hash;
Header dkim;
options = options.Clone();
options.NewLineFormat = NewLineFormat.Dos;
options.EnsureNewLine = true;
switch (SignatureAlgorithm)
{
case DkimSignatureAlgorithm.Ed25519Sha256:
value.Append("; a=ed25519-sha256");
break;
case DkimSignatureAlgorithm.RsaSha256:
value.Append("; a=rsa-sha256");
break;
default:
value.Append("; a=rsa-sha1");
break;
}
value.AppendFormat("; d={0}; s={1}", Domain, Selector);
value.AppendFormat("; c={0}/{1}",
HeaderCanonicalizationAlgorithm.ToString().ToLowerInvariant(),
BodyCanonicalizationAlgorithm.ToString().ToLowerInvariant());
if (!string.IsNullOrEmpty(QueryMethod))
{
value.AppendFormat("; q={0}", QueryMethod);
}
if (!string.IsNullOrEmpty(AgentOrUserIdentifier))
{
value.AppendFormat("; i={0}", AgentOrUserIdentifier);
}
value.AppendFormat("; t={0}", t);
using (var stream = new DkimSignatureStream(CreateSigningContext())) {
using (var filtered = new FilteredStream(stream)) {
filtered.Add(options.CreateNewLineFilter());
// write the specified message headers
DkimVerifierBase.WriteHeaders(options, message, headers, HeaderCanonicalizationAlgorithm, filtered);
value.AppendFormat("; h={0}", string.Join(":", headers.ToArray()));
hash = message.HashBody(options, SignatureAlgorithm, BodyCanonicalizationAlgorithm, -1);
value.AppendFormat("; bh={0}", Convert.ToBase64String(hash));
value.Append("; b=");
dkim = new Header(HeaderId.DkimSignature, value.ToString());
message.Headers.Insert(0, dkim);
switch (HeaderCanonicalizationAlgorithm)
{
case DkimCanonicalizationAlgorithm.Relaxed:
DkimVerifierBase.WriteHeaderRelaxed(options, filtered, dkim, true);
break;
default:
DkimVerifierBase.WriteHeaderSimple(options, filtered, dkim, true);
break;
}
filtered.Flush();
}
signature = stream.GenerateSignature();
dkim.Value += Convert.ToBase64String(signature);
}
}