/**
* Fetches the signature time-stamp attributes from a SignerInformation object.
* Checks that the MessageImprint for each time-stamp matches the signature field.
* (see RFC 3161 Appendix A).
*
* @param signerInfo a SignerInformation to search for time-stamps
* @return a collection of TimeStampToken objects
* @throws TSPValidationException
*/
public static ICollection GetSignatureTimestamps(
SignerInformation signerInfo)
{
IList timestamps = Platform.CreateArrayList();
AttributeTable unsignedAttrs = signerInfo.UnsignedAttributes;
if (unsignedAttrs != null)
{
foreach (Attribute tsAttr in unsignedAttrs.GetAll(
PkcsObjectIdentifiers.IdAASignatureTimeStampToken))
{
foreach (Asn1Encodable asn1 in tsAttr.AttrValues)
{
try
{
ContentInfo contentInfo = ContentInfo.GetInstance(
asn1.ToAsn1Object());
TimeStampToken timeStampToken = new TimeStampToken(contentInfo);
TimeStampTokenInfo tstInfo = timeStampToken.TimeStampInfo;
byte[] expectedDigest = DigestUtilities.CalculateDigest(
GetDigestAlgName(tstInfo.MessageImprintAlgOid),
signerInfo.GetSignature());
if (!Arrays.ConstantTimeAreEqual(expectedDigest, tstInfo.GetMessageImprintDigest()))
{
throw new TspValidationException("Incorrect digest in message imprint");
}
timestamps.Add(timeStampToken);
}
catch (SecurityUtilityException)
{
throw new TspValidationException("Unknown hash algorithm specified in timestamp");
}
catch (Exception)
{
throw new TspValidationException("Timestamp could not be parsed");
}
}
}
}
return(timestamps);
}
public TimeStampToken(
CmsSignedData signedData)
{
this.tsToken = signedData;
if (!this.tsToken.SignedContentType.Equals(PkcsObjectIdentifiers.IdCTTstInfo))
{
throw new TspValidationException("ContentInfo object not for a time stamp.");
}
ICollection signers = tsToken.GetSignerInfos().GetSigners();
if (signers.Count != 1)
{
throw new ArgumentException("Time-stamp token signed by "
+ signers.Count
+ " signers, but it must contain just the TSA signature.");
}
IEnumerator signerEnum = signers.GetEnumerator();
signerEnum.MoveNext();
tsaSignerInfo = (SignerInformation)signerEnum.Current;
try
{
CmsProcessable content = tsToken.SignedContent;
MemoryStream bOut = new MemoryStream();
content.Write(bOut);
this.tstInfo = new TimeStampTokenInfo(
TstInfo.GetInstance(
Asn1Object.FromByteArray(bOut.ToArray())));
Attribute attr = tsaSignerInfo.SignedAttributes[
PkcsObjectIdentifiers.IdAASigningCertificate];
// if (attr == null)
// {
// throw new TspValidationException(
// "no signing certificate attribute found, time stamp invalid.");
// }
//
// SigningCertificate signCert = SigningCertificate.GetInstance(
// attr.AttrValues[0]);
//
// this.certID = EssCertID.GetInstance(signCert.GetCerts()[0]);
if (attr != null)
{
SigningCertificate signCert = SigningCertificate.GetInstance(attr.AttrValues[0]);
this.certID = new CertID(EssCertID.GetInstance(signCert.GetCerts()[0]));
}
else
{
attr = tsaSignerInfo.SignedAttributes[PkcsObjectIdentifiers.IdAASigningCertificateV2];
if (attr == null)
{
throw new TspValidationException("no signing certificate attribute found, time stamp invalid.");
}
SigningCertificateV2 signCertV2 = SigningCertificateV2.GetInstance(attr.AttrValues[0]);
this.certID = new CertID(EssCertIDv2.GetInstance(signCertV2.GetCerts()[0]));
}
}
catch (CmsException e)
{
throw new TspException(e.Message, e.InnerException);
}
}