/// <summary>
/// 对邮件内容进行签名，如果出错将返回错误
/// </summary>
public Result <string> Sign(EMail_DKIM_RAW_EML eml)
{
var rtv = new Result <string>();
rtv.Value = "";
var body = eml.GetSignBody(true);
var signHeadNames = eml.SelectSignHeaderNames(SignHeaderNames);
var param = new List <string>();
param.Add("v=1");
param.Add("a=rsa-sha256");
param.Add("c=relaxed/relaxed");
param.Add("d=" + _EmailDomain);
param.Add("s=" + _EmailSelector);
param.Add("q=dns/txt");
param.Add("t=" + EMail_Unit.GetMS() / 1000);
param.Add("h=" + signHeadNames.join(":"));
param.Add("bh=" + Hash.SHA256.Base64(body));
param.Add("b=");
var paramStr = param.join("; ");
var signParams = eml.GetSignHeader(true, paramStr, null, signHeadNames);
if (signParams.IsError)
{
signParams.errorTo(rtv);
return(rtv);
}
rtv.Value = paramStr + _RSA.Sign("SHA256", signParams.Value);
return(rtv);
}
/// <summary>
/// 验证邮件eml文件内容DKIM签名是否正确，没有签名或签名错误返回false
/// </summary>
public bool Verify(EMail_DKIM_RAW_EML eml)
{
if (eml == null)
{
return(false);
}
var sign = eml.GetHeader(DKIMKey);
if (sign == null)
{
return(false);
}
var kvs = sign.split(";");
var kvDic = new Dictionary <string, string>();
var exp = new Regex(@"\s");
foreach (var kv in kvs)
{
var val = kv.splitTow("=");
if (val[0] != "")
{
kvDic[exp.Replace(val[0], "")] = exp.Replace(val[1], "");
}
}
var hash256 = kvDic.getString("a") == "rsa-sha256";
Hash hash = hash256 ? Hash.SHA256 : Hash.SHA1;
var cv = kvDic.getString("c").splitTow("/");
bool headRelaxed = true;
bool bodyRelaxed = true;
if (cv[1] == "")
{
headRelaxed = cv[0] == "relaxed";
bodyRelaxed = false;
}
else
{
headRelaxed = cv[0] == "relaxed";
bodyRelaxed = cv[1] == "relaxed";
}
//验证body
var body = eml.GetSignBody(bodyRelaxed);
if (kvDic.getString("bh") != hash.Base64(body))
{
return(false);
}
//验证head
var heads = kvDic.getString("h").split(":");
var exp2 = new Regex(@"^([\S\s]+;\s+b=)([\S\s]+)$");
var m = exp2.Match(sign);
if (!m.Success)
{
return(false);
}
var paramStr = m.Groups[1].Value;
var signCode = exp.Replace(m.Groups[2].Value, "");
var signParams = eml.GetSignHeader(headRelaxed, paramStr, eml.GetHeaderMPKey(DKIMKey), heads);
if (signParams.IsError)
{
return(false);
}
if (!_RSA.Verify(hash256 ? "SHA256" : "SHA1", signCode, signParams.Value))
{
return(false);
}
return(true);
}
