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Merge pull request #55 from SnaffCon/l0sscrimes
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Oh So Many Things
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@l0ss
l0ss authored Aug 18, 2021
2 parents 5d36184 + 4bc512b commit 15409e4
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355 changes: 355 additions & 0 deletions SnaffCore/Classifiers/Certificate.cs
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace SnaffCore.Classifiers
{

// c/o Mario Majčica @ https://www.codeproject.com/Articles/162194/Certificates-to-DB-and-Back

public class Certificate
{
public Certificate() { }

public Certificate(string cert, string key, string password)
{
this.PublicCertificate = cert;
this.PrivateKey = key;
this.Password = password;
}

#region Fields
private string _publicCertificate;
private string _privateKey;
private string _password;
#endregion

#region Properties
public string PublicCertificate
{
get { return _publicCertificate; }
set { _publicCertificate = value; }
}

public string PrivateKey
{
get { return _privateKey; }
set { _privateKey = value; }
}

public string Password
{
get { return _password; }
set { _password = value; }
}
#endregion

public X509Certificate2 GetCertificateFromPEMstring(bool certOnly)
{
if (certOnly)
return GetCertificateFromPEMstring(this.PublicCertificate);
else
return GetCertificateFromPEMstring(this.PublicCertificate, this.PrivateKey, this.Password);
}

public static X509Certificate2 GetCertificateFromPEMstring(string publicCert)
{
return new X509Certificate2(Encoding.UTF8.GetBytes(publicCert));
}

public static X509Certificate2 GetCertificateFromPEMstring(string publicCert, string privateKey, string password)
{
byte[] certBuffer = Helpers.GetBytesFromPEM(publicCert, PemStringType.Certificate);
byte[] keyBuffer = Helpers.GetBytesFromPEM(privateKey, PemStringType.RsaPrivateKey);

X509Certificate2 certificate = new X509Certificate2(certBuffer, password);

RSACryptoServiceProvider prov = Crypto.DecodeRsaPrivateKey(keyBuffer);
certificate.PrivateKey = prov;

return certificate;
}

}
public class Helpers
{
/// <summary>
/// This helper function parses an integer size from the reader using the ASN.1 format
/// </summary>
/// <param name="rd"></param>
/// <returns></returns>
public static int DecodeIntegerSize(System.IO.BinaryReader rd)
{
byte byteValue;
int count;

byteValue = rd.ReadByte();
if (byteValue != 0x02) // indicates an ASN.1 integer value follows
return 0;

byteValue = rd.ReadByte();
if (byteValue == 0x81)
{
count = rd.ReadByte(); // data size is the following byte
}
else if (byteValue == 0x82)
{
byte hi = rd.ReadByte(); // data size in next 2 bytes
byte lo = rd.ReadByte();
count = BitConverter.ToUInt16(new[] { lo, hi }, 0);
}
else
{
count = byteValue; // we already have the data size
}

//remove high order zeros in data
while (rd.ReadByte() == 0x00)
{
count -= 1;
}
rd.BaseStream.Seek(-1, System.IO.SeekOrigin.Current);

return count;
}

/// <summary>
///
/// </summary>
/// <param name="pemString"></param>
/// <param name="type"></param>
/// <returns></returns>
public static byte[] GetBytesFromPEM(string pemString, PemStringType type)
{
try
{
string header; string footer;

switch (type)
{
case PemStringType.Certificate:
header = "-----BEGIN CERTIFICATE-----";
footer = "-----END CERTIFICATE-----";
break;
case PemStringType.RsaPrivateKey:
header = "-----BEGIN RSA PRIVATE KEY-----";
footer = "-----END RSA PRIVATE KEY-----";
break;
default:
return null;
}

int start = pemString.IndexOf(header) + header.Length;
int end = pemString.IndexOf(footer, start) - start;
return Convert.FromBase64String(pemString.Substring(start, end));
}
catch (Exception e)
{

}
return null;
}

/// <summary>
///
/// </summary>
/// <param name="inputBytes"></param>
/// <param name="alignSize"></param>
/// <returns></returns>
public static byte[] AlignBytes(byte[] inputBytes, int alignSize)
{
int inputBytesSize = inputBytes.Length;

if ((alignSize != -1) && (inputBytesSize < alignSize))
{
byte[] buf = new byte[alignSize];
for (int i = 0; i < inputBytesSize; ++i)
{
buf[i + (alignSize - inputBytesSize)] = inputBytes[i];
}
return buf;
}
else
{
return inputBytes; // Already aligned, or doesn't need alignment
}
}
}

public class Crypto
{
/// <summary>
/// This helper function parses an RSA private key using the ASN.1 format
/// </summary>
/// <param name="privateKeyBytes">Byte array containing PEM string of private key.</param>
/// <returns>An instance of <see cref="RSACryptoServiceProvider"/> rapresenting the requested private key.
/// Null if method fails on retriving the key.</returns>
public static RSACryptoServiceProvider DecodeRsaPrivateKey(byte[] privateKeyBytes)
{
MemoryStream ms = new MemoryStream(privateKeyBytes);
BinaryReader rd = new BinaryReader(ms);

try
{
byte byteValue;
ushort shortValue;

shortValue = rd.ReadUInt16();

switch (shortValue)
{
case 0x8130:
// If true, data is little endian since the proper logical seq is 0x30 0x81
rd.ReadByte(); //advance 1 byte
break;
case 0x8230:
rd.ReadInt16(); //advance 2 bytes
break;
default:
Debug.Assert(false); // Improper ASN.1 format
return null;
}

shortValue = rd.ReadUInt16();
if (shortValue != 0x0102) // (version number)
{
Debug.Assert(false); // Improper ASN.1 format, unexpected version number
return null;
}

byteValue = rd.ReadByte();
if (byteValue != 0x00)
{
Debug.Assert(false); // Improper ASN.1 format
return null;
}

// The data following the version will be the ASN.1 data itself, which in our case
// are a sequence of integers.

// In order to solve a problem with instancing RSACryptoServiceProvider
// via default constructor on .net 4.0 this is a hack
CspParameters parms = new CspParameters();
parms.Flags = CspProviderFlags.NoFlags;
parms.KeyContainerName = Guid.NewGuid().ToString().ToUpperInvariant();
parms.ProviderType = ((Environment.OSVersion.Version.Major > 5) || ((Environment.OSVersion.Version.Major == 5) && (Environment.OSVersion.Version.Minor >= 1))) ? 0x18 : 1;

RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(parms);
RSAParameters rsAparams = new RSAParameters();

rsAparams.Modulus = rd.ReadBytes(Helpers.DecodeIntegerSize(rd));

// Argh, this is a pain. From emperical testing it appears to be that RSAParameters doesn't like byte buffers that
// have their leading zeros removed. The RFC doesn't address this area that I can see, so it's hard to say that this
// is a bug, but it sure would be helpful if it allowed that. So, there's some extra code here that knows what the
// sizes of the various components are supposed to be. Using these sizes we can ensure the buffer sizes are exactly
// what the RSAParameters expect. Thanks, Microsoft.
RSAParameterTraits traits = new RSAParameterTraits(rsAparams.Modulus.Length * 8);

rsAparams.Modulus = Helpers.AlignBytes(rsAparams.Modulus, traits.size_Mod);
rsAparams.Exponent = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_Exp);
rsAparams.D = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_D);
rsAparams.P = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_P);
rsAparams.Q = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_Q);
rsAparams.DP = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_DP);
rsAparams.DQ = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_DQ);
rsAparams.InverseQ = Helpers.AlignBytes(rd.ReadBytes(Helpers.DecodeIntegerSize(rd)), traits.size_InvQ);

rsa.ImportParameters(rsAparams);
return rsa;
}
catch (Exception)
{
Debug.Assert(false);
return null;
}
finally
{
rd.Close();
}
}
}

public enum PemStringType
{
Certificate,
RsaPrivateKey
}


internal class RSAParameterTraits
{
public RSAParameterTraits(int modulusLengthInBits)
{
// The modulus length is supposed to be one of the common lengths, which is the commonly referred to strength of the key,
// like 1024 bit, 2048 bit, etc. It might be a few bits off though, since if the modulus has leading zeros it could show
// up as 1016 bits or something like that.
int assumedLength = -1;
double logbase = Math.Log(modulusLengthInBits, 2);
if (logbase == (int)logbase)
{
// It's already an even power of 2
assumedLength = modulusLengthInBits;
}
else
{
// It's not an even power of 2, so round it up to the nearest power of 2.
assumedLength = (int)(logbase + 1.0);
assumedLength = (int)(Math.Pow(2, assumedLength));
System.Diagnostics.Debug.Assert(false); // Can this really happen in the field? I've never seen it, so if it happens
// you should verify that this really does the 'right' thing!
}

switch (assumedLength)
{
case 1024:
this.size_Mod = 0x80;
this.size_Exp = -1;
this.size_D = 0x80;
this.size_P = 0x40;
this.size_Q = 0x40;
this.size_DP = 0x40;
this.size_DQ = 0x40;
this.size_InvQ = 0x40;
break;
case 2048:
this.size_Mod = 0x100;
this.size_Exp = -1;
this.size_D = 0x100;
this.size_P = 0x80;
this.size_Q = 0x80;
this.size_DP = 0x80;
this.size_DQ = 0x80;
this.size_InvQ = 0x80;
break;
case 4096:
this.size_Mod = 0x200;
this.size_Exp = -1;
this.size_D = 0x200;
this.size_P = 0x100;
this.size_Q = 0x100;
this.size_DP = 0x100;
this.size_DQ = 0x100;
this.size_InvQ = 0x100;
break;
default:
System.Diagnostics.Debug.Assert(false); // Unknown key size?
break;
}
}

public int size_Mod = -1;
public int size_Exp = -1;
public int size_D = -1;
public int size_P = -1;
public int size_Q = -1;
public int size_DP = -1;
public int size_DQ = -1;
public int size_InvQ = -1;
}
}
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