X509Certificate2 オブジェクトからサブジェクト代替名を取得する簡単な方法はありますか?
foreach (X509Extension ext in certificate.Extensions)
{
if (ext.Oid.Value.Equals(/* SAN OID */"2.5.29.17"))
{
byte[] raw = ext.RawData;
// ?????? parse to get type and name ????????
}
}
印刷可能なバージョンの拡張機能のFormat メソッドを使用します。
X509Certificate2 cert = /* your code here */;
foreach (X509Extension extension in cert.Extensions)
{
// Create an AsnEncodedData object using the extensions information.
AsnEncodedData asndata = new AsnEncodedData(extension.Oid, extension.RawData);
Console.WriteLine("Extension type: {0}", extension.Oid.FriendlyName);
Console.WriteLine("Oid value: {0}",asndata.Oid.Value);
Console.WriteLine("Raw data length: {0} {1}", asndata.RawData.Length, Environment.NewLine);
Console.WriteLine(asndata.Format(true));
}
証明書から「サブジェクトの別名」を取得するには:
X509Certificate2 cert = /* your code here */;
Console.WriteLine("UpnName : {0}{1}", cert.GetNameInfo(X509NameType.UpnName, false), Environment.NewLine);
.net コアを使用すると、これを行うにはクロスプラットフォームの方法が必要になります。@Jason Shuler ソリューションは Windows のみですが、追加の作業を行うことで、プラットフォームに依存しないようにすることができます。次のスニペットでこれを行うために WCF が使用するコードを適応させました (MIT ライセンス)。
// Adapted from https://github.com/dotnet/wcf/blob/a9984490334fdc7d7382cae3c7bc0c8783eacd16/src/System.Private.ServiceModel/src/System/IdentityModel/Claims/X509CertificateClaimSet.cs
// We don't have a strongly typed extension to parse Subject Alt Names, so we have to do a workaround
// to figure out what the identifier, delimiter, and separator is by using a well-known extension
// If https://github.com/dotnet/corefx/issues/22068 ever goes anywhere, we can remove this
private static class X509SubjectAlternativeNameParser
{
private const string SAN_OID = "2.5.29.17";
private static readonly string platform_identifier;
private static readonly char platform_delimiter;
private static readonly string platform_seperator;
static X509SubjectAlternativeNameParser()
{
// Extracted a well-known X509Extension
byte[] x509ExtensionBytes = new byte[] {
48, 36, 130, 21, 110, 111, 116, 45, 114, 101, 97, 108, 45, 115, 117, 98, 106, 101, 99,
116, 45, 110, 97, 109, 101, 130, 11, 101, 120, 97, 109, 112, 108, 101, 46, 99, 111, 109
};
const string subjectName1 = "not-real-subject-name";
X509Extension x509Extension = new X509Extension(SAN_OID, x509ExtensionBytes, true);
string x509ExtensionFormattedString = x509Extension.Format(false);
// Each OS has a different dNSName identifier and delimiter
// On Windows, dNSName == "DNS Name" (localizable), on Linux, dNSName == "DNS"
// e.g.,
// Windows: x509ExtensionFormattedString is: "DNS Name=not-real-subject-name, DNS Name=example.com"
// Linux: x509ExtensionFormattedString is: "DNS:not-real-subject-name, DNS:example.com"
// Parse: <identifier><delimter><value><separator(s)>
int delimiterIndex = x509ExtensionFormattedString.IndexOf(subjectName1) - 1;
platform_delimiter = x509ExtensionFormattedString[delimiterIndex];
// Make an assumption that all characters from the the start of string to the delimiter
// are part of the identifier
platform_identifier = x509ExtensionFormattedString.Substring(0, delimiterIndex);
int separatorFirstChar = delimiterIndex + subjectName1.Length + 1;
int separatorLength = 1;
for (int i = separatorFirstChar + 1; i < x509ExtensionFormattedString.Length; i++)
{
// We advance until the first character of the identifier to determine what the
// separator is. This assumes that the identifier assumption above is correct
if (x509ExtensionFormattedString[i] == platform_identifier[0])
{
break;
}
separatorLength++;
}
platform_seperator = x509ExtensionFormattedString.Substring(separatorFirstChar, separatorLength);
}
public static IEnumerable<string> ParseSubjectAlternativeNames(X509Certificate2 cert)
{
return cert.Extensions
.Cast<X509Extension>()
.Where(ext => ext.Oid.Value.Equals(SAN_OID)) // Only use SAN extensions
.Select(ext => new AsnEncodedData(ext.Oid, ext.RawData).Format(false)) // Decode from ASN
// This is dumb but AsnEncodedData.Format changes based on the platform, so our static initialization code handles making sure we parse it correctly
.SelectMany(text => text.Split(platform_seperator, StringSplitOptions.RemoveEmptyEntries))
.Select(text => text.Split(platform_delimiter))
.Where(x => x[0] == platform_identifier)
.Select(x => x[1]);
}
}
これを行う関数を作成しました：
private static List<string> ParseSujectAlternativeName(X509Certificate2 cert)
{
var result = new List<string>();
var subjectAlternativeName = cert.Extensions.Cast<X509Extension>()
.Where(n => n.Oid.FriendlyName.EqualsCase(SubjectAlternativeName))
.Select(n => new AsnEncodedData(n.Oid, n.RawData))
.Select(n => n.Format(true))
.FirstOrDefault();
if (subjectAlternativeName != null)
{
var alternativeNames = subjectAlternativeName.Split(new[] { "\r\n", "\r", "\n" }, StringSplitOptions.None);
foreach (var alternativeName in alternativeNames)
{
var groups = Regex.Match(alternativeName, @"^DNS Name=(.*)").Groups;
if (groups.Count > 0 && !String.IsNullOrEmpty(groups[1].Value))
{
result.Add(groups[1].Value);
}
}
}
return result;
}