//
// AuthenticodeFormatter.cs: Authenticode signature generator
//
// Author:
//	Sebastien Pouliot <sebastien@ximian.com>
//
// (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004, 2006-2007 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Collections;
using System.Globalization;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Net;

using Mono.Security;
using Mono.Security.X509;

namespace Mono.Security.Authenticode {

	public class AuthenticodeFormatter : AuthenticodeBase {

		private Authority authority;
		private X509CertificateCollection certs;
		private ArrayList crls;
		private string hash;
		private RSA rsa;
		private Uri timestamp;
		private ASN1 authenticode;
		private PKCS7.SignedData pkcs7;
		private string description;
		private Uri url;

		public AuthenticodeFormatter () : base () 
		{
			certs = new X509CertificateCollection ();
			crls = new ArrayList ();
			authority = Authority.Maximum;
			pkcs7 = new PKCS7.SignedData ();
		}

		public Authority Authority {
			get { return authority; }
			set { authority = value; }
		}

		public X509CertificateCollection Certificates {
			get { return certs; }
		}

		public ArrayList Crl {
			get { return crls; }
		}

		public string Hash {
			get { 
				if (hash == null)
					hash = "SHA1";
				return hash; 
			}
			set {
				if (value == null)
					throw new ArgumentNullException ("Hash");

				string h = value.ToUpper (CultureInfo.InvariantCulture);
				switch (h) {
					case "MD5":
					case "SHA1":
					case "SHA256":
					case "SHA384":
					case "SHA512":
						hash = h;
						break;
					case "SHA2":
						hash = "SHA256";
						break;
					default:
						throw new ArgumentException ("Invalid Authenticode hash algorithm");
				}
			}
		}

		public RSA RSA {
			get { return rsa; }
			set { rsa = value; }
		}

		public Uri TimestampUrl {
			get { return timestamp; }
			set { timestamp = value; }
		}

		public string Description {
			get { return description; }
			set { description = value; }
		}

		public Uri Url {
			get { return url; }
			set { url = value; }
		}

		private ASN1 AlgorithmIdentifier (string oid) 
		{
			ASN1 ai = new ASN1 (0x30);
			ai.Add (ASN1Convert.FromOid (oid));
			ai.Add (new ASN1 (0x05));	// NULL
			return ai;
		}

		private ASN1 Attribute (string oid, ASN1 value)
		{
			ASN1 attr = new ASN1 (0x30);
			attr.Add (ASN1Convert.FromOid (oid));
			ASN1 aset = attr.Add (new ASN1 (0x31));
			aset.Add (value);
			return attr;
		}

		private ASN1 Opus (string description, string url) 
		{
			ASN1 opus = new ASN1 (0x30);
			if (description != null) {
				ASN1 part1 = opus.Add (new ASN1 (0xA0));
				part1.Add (new ASN1 (0x80, Encoding.BigEndianUnicode.GetBytes (description)));
			}
			if (url != null) {
				ASN1 part2 = opus.Add (new ASN1 (0xA1));
				part2.Add (new ASN1 (0x80, Encoding.ASCII.GetBytes (url)));
			}
			return opus;
		}

		// pkcs 1
		// private const string rsaEncryption = "1.2.840.113549.1.1.1";
		// pkcs 7
		// private const string data = "1.2.840.113549.1.7.1";
		private const string signedData = "1.2.840.113549.1.7.2";
		// pkcs 9
		// private const string contentType = "1.2.840.113549.1.9.3";
		// private const string messageDigest  = "1.2.840.113549.1.9.4";
		private const string countersignature = "1.2.840.113549.1.9.6";
		// microsoft spc (software publisher certificate)
		private const string spcStatementType = "1.3.6.1.4.1.311.2.1.11";
		private const string spcSpOpusInfo = "1.3.6.1.4.1.311.2.1.12";
		private const string spcPelmageData = "1.3.6.1.4.1.311.2.1.15";
		// private const string individualCodeSigning = "1.3.6.1.4.1.311.2.1.21";
		private const string commercialCodeSigning = "1.3.6.1.4.1.311.2.1.22";
		private const string timestampCountersignature = "1.3.6.1.4.1.311.3.2.1";

		//private static byte[] version = { 0x01 };
		private static byte[] obsolete = { 0x03, 0x01, 0x00, 0xA0, 0x20, 0xA2, 0x1E, 0x80, 0x1C, 0x00, 0x3C, 0x00, 0x3C, 0x00, 0x3C, 0x00, 0x4F, 0x00, 0x62, 0x00, 0x73, 0x00, 0x6F, 0x00, 0x6C, 0x00, 0x65, 0x00, 0x74, 0x00, 0x65, 0x00, 0x3E, 0x00, 0x3E, 0x00, 0x3E };

		private byte[] Header (byte[] fileHash, string hashAlgorithm) 
		{
			string hashOid = CryptoConfig.MapNameToOID (hashAlgorithm);
			ASN1 content = new ASN1 (0x30);
			ASN1 c1 = content.Add (new ASN1 (0x30));
			c1.Add (ASN1Convert.FromOid (spcPelmageData));
			c1.Add (new ASN1 (0x30, obsolete));
			ASN1 c2 = content.Add (new ASN1 (0x30));
			c2.Add (AlgorithmIdentifier (hashOid));
			c2.Add (new ASN1 (0x04, fileHash));

			pkcs7.HashName = hashAlgorithm;
			pkcs7.Certificates.AddRange (certs);
			pkcs7.ContentInfo.ContentType = spcIndirectDataContext;
			pkcs7.ContentInfo.Content.Add (content);

			pkcs7.SignerInfo.Certificate = certs [0];
			pkcs7.SignerInfo.Key = rsa;

			ASN1 opus = null;
			if (url == null)
				opus = Attribute (spcSpOpusInfo, Opus (description, null));
			else
				opus = Attribute (spcSpOpusInfo, Opus (description, url.ToString ()));
			pkcs7.SignerInfo.AuthenticatedAttributes.Add (opus);
			// When using the MS Root Agency (test) we can't include this attribute in the signature or it won't validate!
			// pkcs7.SignerInfo.AuthenticatedAttributes.Add (Attribute (spcStatementType, new ASN1 (0x30, ASN1Convert.FromOid (commercialCodeSigning).GetBytes ())));
			pkcs7.GetASN1 (); // sign
			return pkcs7.SignerInfo.Signature;
		}

		public ASN1 TimestampRequest (byte[] signature) 
		{
			PKCS7.ContentInfo ci = new PKCS7.ContentInfo (PKCS7.Oid.data);
			ci.Content.Add (new ASN1 (0x04, signature));
			return PKCS7.AlgorithmIdentifier (timestampCountersignature, ci.ASN1);
		}

		public void ProcessTimestamp (byte[] response)
		{
			ASN1 ts = new ASN1 (Convert.FromBase64String (Encoding.ASCII.GetString (response)));
			// first validate the received message
			// TODO

			// add the supplied certificates inside our signature
			for (int i=0; i < ts[1][0][3].Count; i++)
				pkcs7.Certificates.Add (new X509Certificate (ts[1][0][3][i].GetBytes ()));

			// add an unauthentified attribute to our signature
			pkcs7.SignerInfo.UnauthenticatedAttributes.Add (Attribute (countersignature, ts[1][0][4][0]));
		}

		private byte[] Timestamp (byte[] signature)
		{
			ASN1 tsreq = TimestampRequest (signature);
			WebClient wc = new WebClient ();
			wc.Headers.Add ("Content-Type", "application/octet-stream");
			wc.Headers.Add ("Accept", "application/octet-stream");
			byte[] tsdata = Encoding.ASCII.GetBytes (Convert.ToBase64String (tsreq.GetBytes ()));
			return wc.UploadData (timestamp.ToString (), tsdata);
		}

		private bool Save (string fileName, byte[] asn)
		{
#if DEBUG
			using (FileStream fs = File.Open (fileName + ".sig", FileMode.Create, FileAccess.Write)) {
				fs.Write (asn, 0, asn.Length);
				fs.Close ();
			}
#endif
			// someday I may be sure enough to move this into DEBUG ;-)
			File.Copy (fileName, fileName + ".bak", true);

			using (FileStream fs = File.Open (fileName, FileMode.Open, FileAccess.ReadWrite)) {
				int filesize;
				if (SecurityOffset > 0) {
					// FIXME Does it fit? Is it always the same size?
					// file was already signed, we'll reuse the position for the updated signature
					filesize = SecurityOffset;
				} else if (CoffSymbolTableOffset > 0) {
					// FIXME This is not documented as something to remove.
					// However some documentation says to remove after the last
					// section, and some does not, and this might be there,
					// or it might not.
					// strip (deprecated) COFF symbol table
					fs.Seek (PEOffset + 12, SeekOrigin.Begin);
					for (int i = 0; i < 8; i++)
						fs.WriteByte (0);
					// we'll put the Authenticode signature at this same place (just after the last section)
					filesize = CoffSymbolTableOffset;
				} else {
					// file was never signed, nor does it contains (deprecated) COFF symbols
					filesize = (int)fs.Length;
				}
				// must be a multiple of 8 bytes
				int addsize = (filesize & 7);
				if (addsize > 0)
					addsize = 8 - addsize;

				// IMAGE_DIRECTORY_ENTRY_SECURITY (offset, size)
				byte[] data = BitConverterLE.GetBytes (filesize + addsize);
				if (PE64)
					fs.Seek (PEOffset + 168, SeekOrigin.Begin);
				else
					fs.Seek (PEOffset + 152, SeekOrigin.Begin);

				fs.Write (data, 0, 4);
				int size = asn.Length + 8;
				int addsize_signature = (size & 7);
				if (addsize_signature > 0)
					addsize_signature = 8 - addsize_signature;
				data = BitConverterLE.GetBytes (size + addsize_signature);
				if (PE64)
					fs.Seek (PEOffset + 168 + 4, SeekOrigin.Begin);
				else
					fs.Seek (PEOffset + 156, SeekOrigin.Begin);

				fs.Write (data, 0, 4);
				fs.Seek (filesize, SeekOrigin.Begin);
				// align certificate entry to a multiple of 8 bytes
				if (addsize > 0) {
					byte[] fillup = new byte[addsize];
					fs.Write (fillup, 0, fillup.Length);
				}

				/*
				https://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/Authenticode_PE.docx
				The Authenticode signature is in a WIN_CERTIFICATE structure, which is declared in Wintrust.h as follows:
				typedef struct _WIN_CERTIFICATE
				{
				    DWORD       dwLength;
				    WORD        wRevision;
				    WORD        wCertificateType;
				    BYTE        bCertificate[ANYSIZE_ARRAY];
				} WIN_CERTIFICATE, *LPWIN_CERTIFICATE;
				
				The fields in WIN_CERTIFICATE are set to the following values:
				dwLength is set to the length of bCertificate.
				wRevision is set to the WIN_CERTIFICATE version number.

				wCertificateType is set to 0x0002 for Authenticode signatures.
				This value is defined in Wintrust.h as WIN_CERT_TYPE_PKCS_SIGNED_DATA.
				bCertificate is set to a variable-length binary array that contains the Authenticode PKCS #7 signedData.
				The PKCS #7 integrity is verified as described in ”PKCS #7: Cryptographic Message Syntax Standard.”
				*/
				// write WIN_CERTIFICATE.dwLength
				fs.Write (data, 0, data.Length);		// length (again)
				// write WIN_CERTIFICATE.wRevision = 0x0200 and wCertificateType = 2.
				// /usr/local/Cellar/mingw-w64/5.0.3/toolchain-x86_64/x86_64-w64-mingw32/include/wintrust.h
				// const short WIN_CERT_REVISION_1_0 = 0x0100;
				const short WIN_CERT_REVISION_2_0 = 0x0200;
				// const short WIN_CERT_TYPE_X509 = 0x0001;
				const short WIN_CERT_TYPE_PKCS_SIGNED_DATA = 0x0002;
				// const short WIN_CERT_TYPE_RESERVED_1 = 0x0003;
				// const short WIN_CERT_TYPE_TS_STACK_SIGNED = 0x0004;
				data = BitConverterLE.GetBytes (WIN_CERT_REVISION_2_0);
				fs.Write (data, 0, data.Length);
				data = BitConverterLE.GetBytes (WIN_CERT_TYPE_PKCS_SIGNED_DATA);
				fs.Write (data, 0, data.Length);
				fs.Write (asn, 0, asn.Length);
				if (addsize_signature > 0) {
					byte[] fillup = new byte[addsize_signature];
					fs.Write (fillup, 0, fillup.Length);
				}
				fs.Close ();
			}
			return true;
		}

		public bool Sign (string fileName) 
		{
			try {
				Open (fileName);

				HashAlgorithm hash = HashAlgorithm.Create (Hash);
				// 0 to 215 (216) then skip 4 (checksum)

				byte[] digest = GetHash (hash);
				byte[] signature = Header (digest, Hash);
				if (timestamp != null) {
					byte[] ts = Timestamp (signature);
					// add timestamp information inside the current pkcs7 SignedData instance
					// (this is possible because the data isn't yet signed)
					ProcessTimestamp (ts);
				}

				PKCS7.ContentInfo sign = new PKCS7.ContentInfo (signedData);
				sign.Content.Add (pkcs7.ASN1);
				authenticode = sign.ASN1;
				Close ();

				return Save (fileName, authenticode.GetBytes ());
			}
			catch (Exception e) {
				Console.WriteLine (e);
			}
			return false;
		}

		// in case we just want to timestamp the file
		public bool Timestamp (string fileName) 
		{
			try {
				AuthenticodeDeformatter def = new AuthenticodeDeformatter (fileName);
				byte[] signature = def.Signature;
				if (signature != null) {
					Open (fileName);
					PKCS7.ContentInfo ci = new PKCS7.ContentInfo (signature);
					pkcs7 = new PKCS7.SignedData (ci.Content);

					byte[] response = Timestamp (pkcs7.SignerInfo.Signature);
					ASN1 ts = new ASN1 (Convert.FromBase64String (Encoding.ASCII.GetString (response)));
					// insert new certificates and countersignature into the original signature
					ASN1 asn = new ASN1 (signature);
					ASN1 content = asn.Element (1, 0xA0);
					if (content == null)
						return false;

					ASN1 signedData = content.Element (0, 0x30);
					if (signedData == null)
						return false;

					// add the supplied certificates inside our signature
					ASN1 certificates = signedData.Element (3, 0xA0);
					if (certificates == null) {
						certificates = new ASN1 (0xA0);
						signedData.Add (certificates);
					}
					for (int i = 0; i < ts[1][0][3].Count; i++) {
						certificates.Add (ts[1][0][3][i]);
					}

					// add an unauthentified attribute to our signature
					ASN1 signerInfoSet = signedData[signedData.Count - 1];
					ASN1 signerInfo = signerInfoSet[0];
					ASN1 unauthenticated = signerInfo[signerInfo.Count - 1];
					if (unauthenticated.Tag != 0xA1) {
						unauthenticated = new ASN1 (0xA1);
						signerInfo.Add (unauthenticated);
					}
					unauthenticated.Add (Attribute (countersignature, ts[1][0][4][0]));

					return Save (fileName, asn.GetBytes ());
				}
			}
			catch (Exception e) {
				Console.WriteLine (e);
			}
			return false;
		}
	}
}