using System;
using System.Collections;
using System.IO;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.CryptoPro;
using Org.BouncyCastle.Asn1.Nist;
using Org.BouncyCastle.Asn1.Oiw;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.TeleTrust;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Cms;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.X509;
namespace Org.BouncyCastle.Tsp{
public class TspUtil
{
private static readonly IDictionary digestLengths = new Hashtable();
private static readonly IDictionary digestNames = new Hashtable();
static TspUtil()
{
digestLengths.Add(PkcsObjectIdentifiers.MD5.Id, 16);
digestLengths.Add(OiwObjectIdentifiers.IdSha1.Id, 20);
digestLengths.Add(NistObjectIdentifiers.IdSha224.Id, 28);
digestLengths.Add(NistObjectIdentifiers.IdSha256.Id, 32);
digestLengths.Add(NistObjectIdentifiers.IdSha384.Id, 48);
digestLengths.Add(NistObjectIdentifiers.IdSha512.Id, 64);
digestNames.Add(PkcsObjectIdentifiers.MD5.Id, "MD5");
digestNames.Add(OiwObjectIdentifiers.IdSha1.Id, "SHA1");
digestNames.Add(NistObjectIdentifiers.IdSha224.Id, "SHA224");
digestNames.Add(NistObjectIdentifiers.IdSha256.Id, "SHA256");
digestNames.Add(NistObjectIdentifiers.IdSha384.Id, "SHA384");
digestNames.Add(NistObjectIdentifiers.IdSha512.Id, "SHA512");
digestNames.Add(PkcsObjectIdentifiers.Sha1WithRsaEncryption.Id, "SHA1");
digestNames.Add(PkcsObjectIdentifiers.Sha224WithRsaEncryption.Id, "SHA224");
digestNames.Add(PkcsObjectIdentifiers.Sha256WithRsaEncryption.Id, "SHA256");
digestNames.Add(PkcsObjectIdentifiers.Sha384WithRsaEncryption.Id, "SHA384");
digestNames.Add(PkcsObjectIdentifiers.Sha512WithRsaEncryption.Id, "SHA512");
digestNames.Add(TeleTrusTObjectIdentifiers.RipeMD128.Id, "RIPEMD128");
digestNames.Add(TeleTrusTObjectIdentifiers.RipeMD160.Id, "RIPEMD160");
digestNames.Add(TeleTrusTObjectIdentifiers.RipeMD256.Id, "RIPEMD256");
digestNames.Add(CryptoProObjectIdentifiers.GostR3411.Id, "GOST3411");
}
/**
* 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 = new ArrayList();
Asn1.Cms.AttributeTable unsignedAttrs = signerInfo.UnsignedAttributes;
if (unsignedAttrs != null)
{
foreach (Asn1.Cms.Attribute tsAttr in unsignedAttrs.GetAll(
PkcsObjectIdentifiers.IdAASignatureTimeStampToken))
{
foreach (Asn1Encodable asn1 in tsAttr.AttrValues)
{
try
{
Asn1.Cms.ContentInfo contentInfo = Asn1.Cms.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;
}
/**
* Validate the passed in certificate as being of the correct type to be used
* for time stamping. To be valid it must have an ExtendedKeyUsage extension
* which has a key purpose identifier of id-kp-timeStamping.
*
* @param cert the certificate of interest.
* @throws TspValidationException if the certicate fails on one of the check points.
*/
public static void ValidateCertificate(
X509Certificate cert)
{
if (cert.Version != 3)
throw new ArgumentException("Certificate must have an ExtendedKeyUsage extension.");
Asn1OctetString ext = cert.GetExtensionValue(X509Extensions.ExtendedKeyUsage);
if (ext == null)
throw new TspValidationException("Certificate must have an ExtendedKeyUsage extension.");
if (!cert.GetCriticalExtensionOids().Contains(X509Extensions.ExtendedKeyUsage.Id))
throw new TspValidationException("Certificate must have an ExtendedKeyUsage extension marked as critical.");
try
{
ExtendedKeyUsage extKey = ExtendedKeyUsage.GetInstance(
Asn1Object.FromByteArray(ext.GetOctets()));
if (!extKey.HasKeyPurposeId(KeyPurposeID.IdKPTimeStamping) || extKey.Count != 1)
throw new TspValidationException("ExtendedKeyUsage not solely time stamping.");
}
catch (IOException)
{
throw new TspValidationException("cannot process ExtendedKeyUsage extension");
}
}
/// <summary>
/// Return the digest algorithm using one of the standard JCA string
/// representations rather than the algorithm identifier (if possible).
/// </summary>
internal static string GetDigestAlgName(
string digestAlgOID)
{
string digestName = (string) digestNames[digestAlgOID];
return digestName != null ? digestName : digestAlgOID;
}
internal static int GetDigestLength(
string digestAlgOID)
{
try
{
if (digestLengths.Contains(digestAlgOID))
{
return (int) digestLengths[digestAlgOID];
}
return CreateDigestInstance(digestAlgOID).GetDigestSize();
}
catch (SecurityUtilityException e)
{
throw new TspException("digest algorithm cannot be found.", e);
}
}
internal static IDigest CreateDigestInstance(
String digestAlgOID)
{
string digestName = GetDigestAlgName(digestAlgOID);
return DigestUtilities.GetDigest(digestName);
}
}
}
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