private bool VerifyCounterSignature (PKCS7.SignerInfo cs, byte[] signature)
{
// SEQUENCE {
// INTEGER 1
if (cs.Version != 1)
return false;
// SEQUENCE {
// SEQUENCE {
string contentType = null;
ASN1 messageDigest = null;
for (int i=0; i < cs.AuthenticatedAttributes.Count; i++)
{
// SEQUENCE {
// OBJECT IDENTIFIER
ASN1 attr = (ASN1) cs.AuthenticatedAttributes [i];
string oid = ASN1Convert.ToOid (attr[0]);
switch (oid)
{
case "1.2.840.113549.1.9.3":
// contentType
contentType = ASN1Convert.ToOid (attr[1][0]);
break;
case "1.2.840.113549.1.9.4":
// messageDigest
messageDigest = attr[1][0];
break;
case "1.2.840.113549.1.9.5":
// SEQUENCE {
// OBJECT IDENTIFIER
// signingTime (1 2 840 113549 1 9 5)
// SET {
// UTCTime '030124013651Z'
// }
// }
timestamp = ASN1Convert.ToDateTime (attr[1][0]);
break;
default:
break;
}
}
if (contentType != PKCS7.Oid.data)
return false;
// verify message digest
if (messageDigest == null)
return false;
// TODO: must be read from the ASN.1 structure
string hashName = null;
switch (messageDigest.Length)
{
case 16:
hashName = "MD5";
break;
case 20:
hashName = "SHA1";
break;
}
HashAlgorithm ha = HashAlgorithm.Create (hashName);
if (!messageDigest.CompareValue (ha.ComputeHash (signature)))
return false;
// verify signature
byte[] counterSignature = cs.Signature;
// change to SET OF (not [0]) as per PKCS #7 1.5
ASN1 aa = new ASN1 (0x31);
foreach (ASN1 a in cs.AuthenticatedAttributes)
aa.Add (a);
byte[] p7hash = ha.ComputeHash (aa.GetBytes ());
// we need to try all certificates
string issuer = cs.IssuerName;
byte[] serial = cs.SerialNumber;
foreach (X509Certificate x509 in coll)
{
if (CompareIssuerSerial (issuer, serial, x509))
{
if (x509.PublicKey.Length > counterSignature.Length)
{
RSACryptoServiceProvider rsa = (RSACryptoServiceProvider) x509.RSA;
// we need to HACK around bad (PKCS#1 1.5) signatures made by Verisign Timestamp Service
// and this means copying stuff into our own RSAManaged to get the required flexibility
RSAManaged rsam = new RSAManaged ();
rsam.ImportParameters (rsa.ExportParameters (false));
if (PKCS1.Verify_v15 (rsam, ha, p7hash, counterSignature, true))
{
timestampChain.LoadCertificates (coll);
return (timestampChain.Build (x509));
}
}
}
}
// no certificate can verify this signature!
return false;
}
//private bool VerifySignature (ASN1 cs, byte[] calculatedMessageDigest, string hashName)
private bool VerifySignature (PKCS7.SignedData sd, byte[] calculatedMessageDigest, HashAlgorithm ha)
{
string contentType = null;
ASN1 messageDigest = null;
// string spcStatementType = null;
// string spcSpOpusInfo = null;
for (int i=0; i < sd.SignerInfo.AuthenticatedAttributes.Count; i++)
{
ASN1 attr = (ASN1) sd.SignerInfo.AuthenticatedAttributes [i];
string oid = ASN1Convert.ToOid (attr[0]);
switch (oid)
{
case "1.2.840.113549.1.9.3":
// contentType
contentType = ASN1Convert.ToOid (attr[1][0]);
break;
case "1.2.840.113549.1.9.4":
// messageDigest
messageDigest = attr[1][0];
break;
case "1.3.6.1.4.1.311.2.1.11":
// spcStatementType (Microsoft code signing)
// possible values
// - individualCodeSigning (1 3 6 1 4 1 311 2 1 21)
// - commercialCodeSigning (1 3 6 1 4 1 311 2 1 22)
// spcStatementType = ASN1Convert.ToOid (attr[1][0][0]);
break;
case "1.3.6.1.4.1.311.2.1.12":
// spcSpOpusInfo (Microsoft code signing)
/* try {
spcSpOpusInfo = System.Text.Encoding.UTF8.GetString (attr[1][0][0][0].Value);
}
catch (NullReferenceException) {
spcSpOpusInfo = null;
}*/
break;
default:
break;
}
}
if (contentType != spcIndirectDataContext)
return false;
// verify message digest
if (messageDigest == null)
return false;
if (!messageDigest.CompareValue (calculatedMessageDigest))
return false;
// verify signature
string hashOID = CryptoConfig.MapNameToOID (ha.ToString ());
// change to SET OF (not [0]) as per PKCS #7 1.5
ASN1 aa = new ASN1 (0x31);
foreach (ASN1 a in sd.SignerInfo.AuthenticatedAttributes)
aa.Add (a);
ha.Initialize ();
byte[] p7hash = ha.ComputeHash (aa.GetBytes ());
byte[] signature = sd.SignerInfo.Signature;
// we need to find the specified certificate
string issuer = sd.SignerInfo.IssuerName;
byte[] serial = sd.SignerInfo.SerialNumber;
foreach (X509Certificate x509 in coll)
{
if (CompareIssuerSerial (issuer, serial, x509))
{
// don't verify is key size don't match
if (x509.PublicKey.Length > (signature.Length >> 3))
{
// return the signing certificate even if the signature isn't correct
// (required behaviour for 2.0 support)
signingCertificate = x509;
RSACryptoServiceProvider rsa = (RSACryptoServiceProvider) x509.RSA;
if (rsa.VerifyHash (p7hash, hashOID, signature))
{
signerChain.LoadCertificates (coll);
trustedRoot = signerChain.Build (x509);
break;
}
}
}
}
// timestamp signature is optional
if (sd.SignerInfo.UnauthenticatedAttributes.Count == 0)
{
trustedTimestampRoot = true;
}
else
{
for (int i = 0; i < sd.SignerInfo.UnauthenticatedAttributes.Count; i++)
{
ASN1 attr = (ASN1) sd.SignerInfo.UnauthenticatedAttributes[i];
string oid = ASN1Convert.ToOid (attr[0]);
switch (oid)
{
case PKCS7.Oid.countersignature:
// SEQUENCE {
// OBJECT IDENTIFIER
// countersignature (1 2 840 113549 1 9 6)
// SET {
PKCS7.SignerInfo cs = new PKCS7.SignerInfo (attr[1]);
trustedTimestampRoot = VerifyCounterSignature (cs, signature);
break;
default:
// we don't support other unauthenticated attributes
break;
}
}
}
return (trustedRoot && trustedTimestampRoot);
}
private bool VerifySignature(PKCS7.SignedData sd, byte[] calculatedMessageDigest, HashAlgorithm ha)
{
string a = null;
ASN1 aSN = null;
for (int i = 0; i < sd.SignerInfo.AuthenticatedAttributes.Count; i++)
{
ASN1 aSN2 = (ASN1)sd.SignerInfo.AuthenticatedAttributes[i];
switch (ASN1Convert.ToOid(aSN2[0]))
{
case "1.2.840.113549.1.9.3":
a = ASN1Convert.ToOid(aSN2[1][0]);
break;
case "1.2.840.113549.1.9.4":
aSN = aSN2[1][0];
break;
}
}
if (a != "1.3.6.1.4.1.311.2.1.4")
{
return(false);
}
if (aSN == null)
{
return(false);
}
if (!aSN.CompareValue(calculatedMessageDigest))
{
return(false);
}
string str = CryptoConfig.MapNameToOID(ha.ToString());
ASN1 aSN3 = new ASN1(49);
foreach (ASN1 authenticatedAttribute in sd.SignerInfo.AuthenticatedAttributes)
{
aSN3.Add(authenticatedAttribute);
}
ha.Initialize();
byte[] rgbHash = ha.ComputeHash(aSN3.GetBytes());
byte[] signature = sd.SignerInfo.Signature;
string issuerName = sd.SignerInfo.IssuerName;
byte[] serialNumber = sd.SignerInfo.SerialNumber;
foreach (X509Certificate item in coll)
{
if (CompareIssuerSerial(issuerName, serialNumber, item) && item.PublicKey.Length > signature.Length >> 3)
{
signingCertificate = item;
RSACryptoServiceProvider rSACryptoServiceProvider = (RSACryptoServiceProvider)item.RSA;
if (rSACryptoServiceProvider.VerifyHash(rgbHash, str, signature))
{
signerChain.LoadCertificates(coll);
trustedRoot = signerChain.Build(item);
break;
}
}
}
if (sd.SignerInfo.UnauthenticatedAttributes.Count == 0)
{
trustedTimestampRoot = true;
}
else
{
for (int j = 0; j < sd.SignerInfo.UnauthenticatedAttributes.Count; j++)
{
ASN1 aSN4 = (ASN1)sd.SignerInfo.UnauthenticatedAttributes[j];
switch (ASN1Convert.ToOid(aSN4[0]))
{
case "1.2.840.113549.1.9.6":
{
PKCS7.SignerInfo cs = new PKCS7.SignerInfo(aSN4[1]);
trustedTimestampRoot = VerifyCounterSignature(cs, signature);
break;
}
}
}
}
return(trustedRoot && trustedTimestampRoot);
}
private bool VerifyCounterSignature(PKCS7.SignerInfo cs, byte[] signature)
{
if (cs.Version != 1)
{
return(false);
}
string a = null;
ASN1 aSN = null;
for (int i = 0; i < cs.AuthenticatedAttributes.Count; i++)
{
ASN1 aSN2 = (ASN1)cs.AuthenticatedAttributes[i];
switch (ASN1Convert.ToOid(aSN2[0]))
{
case "1.2.840.113549.1.9.3":
a = ASN1Convert.ToOid(aSN2[1][0]);
break;
case "1.2.840.113549.1.9.4":
aSN = aSN2[1][0];
break;
case "1.2.840.113549.1.9.5":
timestamp = ASN1Convert.ToDateTime(aSN2[1][0]);
break;
}
}
if (a != "1.2.840.113549.1.7.1")
{
return(false);
}
if (aSN == null)
{
return(false);
}
string hashName = null;
switch (aSN.Length)
{
case 16:
hashName = "MD5";
break;
case 20:
hashName = "SHA1";
break;
}
HashAlgorithm hashAlgorithm = HashAlgorithm.Create(hashName);
if (!aSN.CompareValue(hashAlgorithm.ComputeHash(signature)))
{
return(false);
}
byte[] signature2 = cs.Signature;
ASN1 aSN3 = new ASN1(49);
foreach (ASN1 authenticatedAttribute in cs.AuthenticatedAttributes)
{
aSN3.Add(authenticatedAttribute);
}
byte[] hashValue = hashAlgorithm.ComputeHash(aSN3.GetBytes());
string issuerName = cs.IssuerName;
byte[] serialNumber = cs.SerialNumber;
foreach (X509Certificate item in coll)
{
if (CompareIssuerSerial(issuerName, serialNumber, item) && item.PublicKey.Length > signature2.Length)
{
RSACryptoServiceProvider rSACryptoServiceProvider = (RSACryptoServiceProvider)item.RSA;
RSAManaged rSAManaged = new RSAManaged();
rSAManaged.ImportParameters(rSACryptoServiceProvider.ExportParameters(includePrivateParameters: false));
if (PKCS1.Verify_v15(rSAManaged, hashAlgorithm, hashValue, signature2, tryNonStandardEncoding: true))
{
timestampChain.LoadCertificates(coll);
return(timestampChain.Build(item));
}
}
}
return(false);
}
private bool VerifyCounterSignature(PKCS7.SignerInfo cs, byte[] signature)
{
// SEQUENCE {
// INTEGER 1
if (cs.Version != 1)
{
return(false);
}
// SEQUENCE {
// SEQUENCE {
string contentType = null;
ASN1 messageDigest = null;
for (int i = 0; i < cs.AuthenticatedAttributes.Count; i++)
{
// SEQUENCE {
// OBJECT IDENTIFIER
ASN1 attr = (ASN1)cs.AuthenticatedAttributes [i];
string oid = ASN1Convert.ToOid(attr[0]);
switch (oid)
{
case "1.2.840.113549.1.9.3":
// contentType
contentType = ASN1Convert.ToOid(attr[1][0]);
break;
case "1.2.840.113549.1.9.4":
// messageDigest
messageDigest = attr[1][0];
break;
case "1.2.840.113549.1.9.5":
// SEQUENCE {
// OBJECT IDENTIFIER
// signingTime (1 2 840 113549 1 9 5)
// SET {
// UTCTime '030124013651Z'
// }
// }
timestamp = ASN1Convert.ToDateTime(attr[1][0]);
break;
default:
break;
}
}
if (contentType != PKCS7.Oid.data)
{
return(false);
}
// verify message digest
if (messageDigest == null)
{
return(false);
}
// TODO: must be read from the ASN.1 structure
string hashName = null;
switch (messageDigest.Length)
{
case 16:
hashName = "MD5";
break;
case 20:
hashName = "SHA1";
break;
}
HashAlgorithm ha = HashAlgorithm.Create(hashName);
if (!messageDigest.CompareValue(ha.ComputeHash(signature)))
{
return(false);
}
// verify signature
byte[] counterSignature = cs.Signature;
string hashOID = CryptoConfig.MapNameToOID(hashName);
// change to SET OF (not [0]) as per PKCS #7 1.5
ASN1 aa = new ASN1(0x31);
foreach (ASN1 a in cs.AuthenticatedAttributes)
{
aa.Add(a);
}
byte[] p7hash = ha.ComputeHash(aa.GetBytes());
// we need to try all certificates
string issuer = cs.IssuerName;
byte[] serial = cs.SerialNumber;
foreach (X509Certificate x509 in coll)
{
if (CompareIssuerSerial(issuer, serial, x509))
{
// don't verify if key size don't match
if (x509.PublicKey.Length > (counterSignature.Length >> 3))
{
RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)x509.RSA;
if (rsa.VerifyHash(p7hash, hashOID, counterSignature))
{
timestampChain.LoadCertificates(coll);
return(timestampChain.Build(x509));
}
}
}
}
// no certificate can verify this signature!
return(false);
}