private byte[] GetContentHash(ExcelVbaProject proj)
{
//MS-OVBA 2.4.2
var enc = System.Text.Encoding.GetEncoding(proj.CodePage);
BinaryWriter bw = new BinaryWriter(new MemoryStream());
bw.Write(enc.GetBytes(proj.Name));
bw.Write(enc.GetBytes(proj.Constants));
foreach (var reference in proj.References)
{
if (reference.ReferenceRecordID == 0x0D)
{
bw.Write((byte)0x7B);
}
if (reference.ReferenceRecordID == 0x0E)
{
//var r = (ExcelVbaReferenceProject)reference;
//BinaryWriter bwTemp = new BinaryWriter(new MemoryStream());
//bwTemp.Write((uint)r.Libid.Length);
//bwTemp.Write(enc.GetBytes(r.Libid));
//bwTemp.Write((uint)r.LibIdRelative.Length);
//bwTemp.Write(enc.GetBytes(r.LibIdRelative));
//bwTemp.Write(r.MajorVersion);
//bwTemp.Write(r.MinorVersion);
foreach (byte b in BitConverter.GetBytes((uint)reference.Libid.Length)) //Length will never be an UInt with 4 bytes that aren't 0 (> 0x00FFFFFF), so no need for the rest of the properties.
{
if (b != 0)
{
bw.Write(b);
}
else
{
break;
}
}
}
}
foreach (var module in proj.Modules)
{
var lines = module.Code.Split(new char[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
foreach (var line in lines)
{
if (!line.StartsWith("attribute", true, null))
{
bw.Write(enc.GetBytes(line));
}
}
}
var buffer = (bw.BaseStream as MemoryStream).ToArray();
var hp = System.Security.Cryptography.MD5CryptoServiceProvider.Create();
return(hp.ComputeHash(buffer));
}
internal byte[] SignProject(ExcelVbaProject proj)
{
if (!Certificate.HasPrivateKey)
{
//throw (new InvalidOperationException("The certificate doesn't have a private key"));
Certificate = null;
return(null);
}
var hash = GetContentHash(proj);
BinaryWriter bw = new BinaryWriter(new MemoryStream());
bw.Write((byte)0x30); //Constructed Type
bw.Write((byte)0x32); //Total length
bw.Write((byte)0x30); //Constructed Type
bw.Write((byte)0x0E); //Length SpcIndirectDataContent
bw.Write((byte)0x06); //Oid Tag Indentifier
bw.Write((byte)0x0A); //Lenght OId
bw.Write(new byte[] { 0x2B, 0x06, 0x01, 0x04, 0x01, 0x82, 0x37, 0x02, 0x01, 0x1D }); //Encoded Oid 1.3.6.1.4.1.311.2.1.29
bw.Write((byte)0x04); //Octet String Tag Identifier
bw.Write((byte)0x00); //Zero length
bw.Write((byte)0x30); //Constructed Type (DigestInfo)
bw.Write((byte)0x20); //Length DigestInfo
bw.Write((byte)0x30); //Constructed Type (Algorithm)
bw.Write((byte)0x0C); //length AlgorithmIdentifier
bw.Write((byte)0x06); //Oid Tag Indentifier
bw.Write((byte)0x08); //Lenght OId
bw.Write(new byte[] { 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05 }); //Encoded Oid for 1.2.840.113549.2.5 (AlgorithmIdentifier MD5)
bw.Write((byte)0x05); //Null type identifier
bw.Write((byte)0x00); //Null length
bw.Write((byte)0x04); //Octet String Identifier
bw.Write((byte)hash.Length); //Hash length
bw.Write(hash); //Content hash
ContentInfo contentInfo = new ContentInfo(((MemoryStream)bw.BaseStream).ToArray());
contentInfo.ContentType.Value = "1.3.6.1.4.1.311.2.1.4";
Verifier = new SignedCms(contentInfo);
var signer = new CmsSigner(Certificate);
Verifier.ComputeSignature(signer, false);
return(Verifier.Encode());
}
internal ExcelVbaModuleCollection(ExcelVbaProject project)
{
_project = project;
}
internal ExcelVbaProtection(ExcelVbaProject project)
{
_project = project;
VisibilityState = true;
}