如何在 TimeStampToken (Bouncy Castle) 中获取签名

Question

根据 RFC 3852（和 RFC 3161），我了解到签名值存储为 TimestampToken（这是一种签名数据内容类型）的 SignerInfo 类型的属性。

如何从 Bouncy Castle 的 TimeStampToken 实例（在 C# 中）获取签名值？

Answer 1

您可以将 class 与辅助方法一起使用：

public static class TimeStampTokenHelper
{
    public static IEnumerable<SignedData> GetTimeStampTokensAsSignedData(byte[] input)
    {
        var cmsInputStream = new Asn1InputStream(input);
        var asn1Object = cmsInputStream.ReadObject();
        Assert.IsNotNull(asn1Object);

        var rootSequence = Asn1Sequence.GetInstance(asn1Object);
        var signedData = GetSignedData(rootSequence);
        return GetTimeStampTokensFromSignedData(signedData);
    }

    private static SignedData GetSignedData(Asn1Sequence sequence)
    {
        var rootContent = ContentInfo.GetInstance(sequence);
        Assert.That(rootContent.ContentType.Id, Is.EqualTo("1.2.840.113549.1.7.2")); // signedData
        var signedData = SignedData.GetInstance(rootContent.Content);
        return signedData;
    }

    private static IEnumerable<SignedData> GetTimeStampTokensFromSignedData(SignedData signedData)
    {
        return GetTimeStampTokensFromSignerInfos(signedData.SignerInfos);
    }

    private static IEnumerable<SignedData> GetTimeStampTokensFromSignerInfos(Asn1Set signerInfos)
    {
        var timestampTokens = signerInfos
            .OfType<Asn1Sequence>()
            .SelectMany(GetTimeStampTokensFromSignerInfo);
        return timestampTokens;
    }

    private static IEnumerable<SignedData> GetTimeStampTokensFromSignerInfo(Asn1Sequence signerInfoSequence)
    {
        var signerInfo = SignerInfo.GetInstance(signerInfoSequence);
        var result = signerInfo.UnauthenticatedAttributes.ToArray()
            .Select(Asn1Sequence.GetInstance)
            .Where(x => ((DerObjectIdentifier)x.GetObjectAt(0)).Id == "1.2.840.113549.1.9.16.2.14")
            .Select(x => GetSignedData(Asn1Sequence.GetInstance(Asn1Set.GetInstance(x.GetObjectAt(1)).GetObjectAt(0))));
        return result;
    }

TimeStampTokenHelper.GetTimeStampTokensAsSignedData 辅助方法将提取时间戳标记作为 SignedData 结构。您可以使用返回的 SignedData 数据做任何您想做的事情。

以下是如何从 SignerInfo 中提取签名的示例：

var signatures = TimeStampTokenHelper.GetTimeStampTokensAsSignedData(cadesTBytes)
    .SelectMany(token => token.SignerInfos.ToArray().Select(SignerInfo.GetInstance))
    .Select(signerInfo => signerInfo.EncryptedDigest);

最后提示：

您可以使用 free online ASN.1 viewer 深入了解 Cades T 签名的结构
您可以使用 Org.BouncyCastle.Asn1.Utilities.Asn1Dump.DumpAsString 方法转储 Bouncycastle 的 ASN.1 对象的字符串表示形式

希望对您有所帮助。

Answer 2

我能够使用这个获得签名：

CmsSignedData tsTokenCms = timestampToken.ToCmsSignedData();
SignerInformationStore signerInfoStore = tsTokenCms.GetSignerInfos();
SignerInformation signerInfo = signerInfoStore.GetFirstSigner(timestampToken.SignerID);
byte[] signatureBytes = signerInfo.GetSignature();
string signatureString = BitConverter.ToString(signatureBytes);
Console.WriteLine("Signature is: " + signatureString);

如何在 TimeStampToken (Bouncy Castle) 中获取签名

How do I get the signature in a TimeStampToken (Bouncy Castle)

c#

bouncycastle