Develop Reference

Can you check python code in csharp before pythonNet execution?

i have recently started using pythonNet for executing scripts from Csharp, on an algorithm i was doing in csharp up until now, it works pretty well:
using (Py.GIL())
{
PythonEngine.Initialize();
using (var scope = Py.CreateScope())
{
string code = File.ReadAllText(fileName);
var scriptCompiled = PythonEngine.Compile(code, "Analyze.py");
scope.Execute(scriptCompiled);
dynamic func = scope.Get("predictFromData");
PyList Pydata = new PyList(data.ToPython());
PyTuple rettp = new PyTuple(func(Pydata));
PyList pyIndexList = new PyList(rettp[0]);
foreach (PyObject intobj in pyIndexList)
{
indexList.Add(intobj.As<int>());
}
}
}
But i'd like to know if there is a way to check if the code can be executed before actually running it, since it works with compiled code, and since PythonNet does require an external python installation to see if every modules are here ect... And then switch back to my previous csharp algorithm if it is not possible in python.
For now i'm thinking about simply executing a python unit test importing modules and testing functions with dummy values and returning exceptions and units tests values to csharp code, but i'd prefer a cleaner way if anyone has an idea.
Cheers.

There are few things you can check here:
first is to see if Python code has correct syntax, it can be done with the code like this:
public static IReadOnlyList<ScriptCompilationDiagnostic> CheckErrors(ScriptEngine engine, string script, string fileName, RunFlagType mode)
{
try
{
PythonEngine.Compile(script, fileName, mode);
}
catch (PythonException e)
{
dynamic error = e.Value;
return new[]
{
new ScriptCompilationDiagnostic
{
Kind = ScriptCompilationDiagnosticKind.Error,
Line = error.lineno - 1,
Column = error.offset - 1,
Message = error.msg,
Code = error.text,
FileName = error.filename,
},
};
}
return new ScriptCompilationDiagnostic[0];
}
second is that you can check if Python is installed on a target machine, with the code like this:
var pythonHome = TryGetFullPathFromPathEnvironmentVariable("python.exe");
private static string? TryGetFullPathFromPathEnvironmentVariable(string fileName)
{
if (fileName.Length >= MAXPATH)
throw new ArgumentException($"The executable name '{fileName}' must have less than {MAXPATH} characters.", nameof(fileName));
var sb = new StringBuilder(fileName, MAXPATH);
return PathFindOnPath(sb, null) ? sb.ToString() : null;
}
[DllImport("shlwapi.dll", CharSet = CharSet.Unicode, SetLastError = false)]
private static extern bool PathFindOnPath([In, Out] StringBuilder pszFile, [In] string[]? ppszOtherDirs);
If your script is using third-party modules, you may check that they're installed as well:
public bool IsModuleInstalled(string module)
{
string moduleDir = Path.Combine(PythonHome, "Lib", "site-packages", module);
return Directory.Exists(moduleDir) && File.Exists(Path.Combine(moduleDir, "__init__.py"));
}
Please note that Python.NET does not officially support the latest Python version 3.9, so alternatively you can distribute and install embedded python with your application from here:
https://www.python.org/ftp/python/3.7.3/
alongside with all required third-party modules as wheels.
We use this approach in our AlterNET Studio product to check if Python is installed for our Python debugger based on Debug Adapter Protocol, and install embedded Python with wheels for our Python.NET based scripter/debugger.

Convert from console to string for return [duplicate]

What I really want to do is this
static string Main(string[] args)
but that doesn't work, your only options are void and int. So, What are some different ways to return the string that I need to return to the calling application?
Background
I need to write a console app that is specifically designed to be called from another application
Process.Start("MyCode.exe -Option 12aaa1234");
How can this calling program receive a string returned from that executable?
Research
From what I can tell, at this point in time my only option is to have the calling application attach a listening stream to the Standard Output stream of the process before starting it, and send the "return" using Console.Out.Write from inside my executable. Is this in fact the ONLY way to do this, or is there something different/better I can use?

Is this in fact the ONLY way to do this, or is there something different/better I can use?
This isn't the only way to do this, but it is the most common.
The other options would involve some form of interprocess communication, which is likely going to be significantly more development effort for a single string.
Note that, if the calling application is a .NET application, and you have control over both applications, it might make more sense to just write a class library instead of a console application. This would allow you to keep the code completely separate, but have the executable "call into" your library to get the string data.

Idea 1:
Using MyCode.exe, create an encrypted text file, which is saved in a specified path, which can then be decrypted in the current app and read.
In the app: "MyCode.exe", add this code:
public void ReturnToOther()
{
string ToReturn = "MyString";
System.IO.File.WriteAllText("Path", Encrypt(ToReturn));
}
public String Encrypt(string ToEncrypt)
{
string Encrypted = null
char[] Array = ToEncrypt.ToCharArray();
for (int i = 0; i < Array.Length; i++)
{
Encrypted += Convert.ToString(Convert.ToChar(Convert.ToInt32(Array[i]) + 15));
}
return Encrypted;
}
In the app you are making now:
public void GetString()
{
string STR = Decrypt(System.IO.File.ReadAllText("Path"));
Console.WriteLine("The string is: {0}", STR);
}
// If you want to keep this running before the file exists, use this:
/*
public void GetString()
{
for(int i = 0; i > -1; ++i)
{
if(System.IO.File.Exists("Path"))
{
string STR = Decrypt(System.IO.File.ReadAllText("Path"));
Console.WriteLine("The string is: {0}", STR);
break;
}
else
{
//Do something if you want
}
}
} */
public String Decrypt(string ToDecrypt)
{
string Decrypted = null
char[] Array = ToDecrypt.ToCharArray();
for (int i = 0; i < Array.Length; i++)
{
Decrypted += Convert.ToString(Convert.ToChar(Convert.ToInt32(Array[i]) - 15));
}
return Decrypted;
}
Idea 2:
Use TCP to upload the string to a port, e.g. LocalHost (127.0.0.1), and then receive the string on the app you are developing, using a TCP Listener
An article on TCP - http://msdn.microsoft.com/en-us/library/system.net.sockets.tcpclient.aspx
Hope this helps :)
EDIT:
Have a look at Sockets too: http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx

Why is SecureString decryption giving different results between executables?

In proxy.exe I am creating a secure string the following way:
public SecureString GetSecureEncryptionKey()
{
string strPassword = "8charPwd";
SecureString secureStr = new SecureString();
if (strPassword.Length > 0)
{
foreach (var c in strPassword.ToCharArray()) secureStr.AppendChar(c);
}
return secureStr;
}
Then in main.exe I am decrypting it using this function:
public string convertToUNSecureString(SecureString secstrPassword)
{
IntPtr unmanagedString = IntPtr.Zero;
try
{
unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(secstrPassword);
return Marshal.PtrToStringUni(unmanagedString);
}
finally
{
Marshal.ZeroFreeGlobalAllocUnicode(unmanagedString);
}
}
The issue is that the returned string is empty, unless I encrypt the initial string within main.exe, then the returned decrypted string is indeed "8charPwd". Why is this happening? Is SecureString encryption bound to the executable?

The purpose of SecureString is to keep strings safety inside your application memory(keep the string secure in RAM)
SecureString object is not a serialize-able.
You cannot transfer an instance between applications.
SecureString encrypt the string by using RtlEncryptMemory (WINAPI) with the flag:"0" (only the same process can decrypt the content). RtlEncryptMemory API
if you don't want to expose the password(at any time) in the RAM, you can create a simple obfuscation(or encryption) logic, and then transfer the content.
Edit:
I found 2 old questions that might be helpful for you:
When would I need a SecureString in .NET?
Wcf-Authentication and Logging

CredUIPromptForCredentials from .NET with SecureString

I'd like to show the standard system dialog to ask the user for an account username and password to use this information to start a process with these credentials.
I've been pointed to the CredUIPromptForCredentials function that shows that dialog. It returns username and password as string. But the ProcessStartInfo structure expects a password as SecureString.
I understand that I could now use the password as string and convert it to a SecureString character by character (there's no single function for that) - but it would defeat the idea behind the SecureString entirely.
So I guess there must be some way to directly accept the password from the unmanaged call to CredUIPromptForCredentials as SecureString in .NET. After all, I really don't need to access the password in my application in any way. It's just supposed to be used to start another process and can then be forgotten as soon as possible.
So how would my P/Invoke declaration for CredUIPromptForCredentials look like with a SecureString? (I've started with the one from pinvoke.net for C#.)
Update: Oh, and if somebody has an example for the new function CredUIPromptForWindowsCredentials in Windows Vista/7, that would be cool as well, because I can't even figure out how to use that at the moment.

You can cast the IntPtr of an unmanaged string buffer to char* and use the SecureString(char*, int) constructor.
// somehow, we come into posession of an IntPtr to a string
// obviously, this would be a foolish way to come into it in
// production, since stringOriginalContents is already in managed
// code, and the lifetime can therefore not be guaranteed...
var stringOriginalContents = "foobar";
IntPtr strPtr = Marshal.StringToHGlobalUni(stringOriginalContents);
int strLen = stringOriginalContents.Length;
int maxLen = 100;
// we copy the IntPtr to a SecureString, and zero out the old location
SecureString ssNew;
unsafe
{
char* strUPtr = (char*)strPtr;
// if we don't know the length, calculate
//for (strLen = 0; *(strUPtr + strLen) != '\0'
// // stop if the string is invalid
// && strLen < maxLen; strLen++)
// ;
ssNew = new SecureString((char*)strPtr, strLen);
// zero out the old memory and release, or use a Zero Free method
//for (int i = 0; i < strLen; i++)
// *(strUPtr + i) = '\0';
//Marshal.FreeHGlobal(strPtr);
// (only do one of these)
Marshal.ZeroFreeGlobalAllocUnicode(strPtr);
}
// now the securestring has the protected data, and the old memory has been
// zeroed, we can check that the securestring is correct. This, also should
// not be in production code.
string strInSecureString =
Marshal.PtrToStringUni(
Marshal.SecureStringToGlobalAllocUnicode(ssNew));
Assert.AreEqual(strInSecureString, stringOriginalContents);

Modify Emdeded String in C# compiled exe

I have an issue where I need to be able to have a compiled exe ( .net 3.5 c# ) that I will make copies of to distribute that will need to change a key for example before the exe is sent out.
I cannot compile each time a new exe is needed. This is a thin client that will be used as part of a registration process.
Is it possible to add a entry to a resource file with a blank value then when a request comes in have another application grab the blank default thin client, copy it, populate the blank value with the data needed.
If yes how? If no do you have any ideas? I have been scratching my head for a few days now and the limitation as due to the boundaries I am required to work in.
The other idea I has was to inject the value into a method, which I have no idea how I would even attempt that.
Thanks.

Convert the assembly to IL, do a textual search and replace, recompile the IL to an assembly again. Use the standard tools from the .NET SDK.

Instead of embedding the key in the assembly, put it in the app.config file (or another file delivered with the application) and prevent your application from running if the key is not present and valid. To protect it against modification by users, also add an RSA signature the config file.
This code could be used to generate XML containing your key.
public static void Main()
{
Console.WriteLine(GenerateKey());
}
public static Byte[] Transform(Byte[] bytes, ICryptoTransform xform)
{
using (System.IO.MemoryStream stream = new System.IO.MemoryStream())
{
using (CryptoStream cstream = new CryptoStream(stream, xform, CryptoStreamMode.Write))
{
cstream.Write(bytes, 0, bytes.Length);
cstream.Close();
stream.Close();
return stream.ToArray();
}
}
}
public static string GenerateKey()
{
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
// This is the private key and should never be shared.
// Generate your own with RSA.Create().ToXmlString(true).
String rsaPrivateKey = "<RSAKeyValue><Modulus>uPCow37yEzlKQXgbqO9E3enSOXY1MCQB4TMbOZyk9eXmc7kuiCMhJRbrwild0LGO8KE3zci9ETBWVVSJEqUqwtZyfUjvWOLHrf5EmzribtSU2e2hlsNoB2Mu11M0SaGd3qZfYcs2gnEnljfvkDAbCyJhUlxmHeI+35w/nqSCjCk=</Modulus><Exponent>AQAB</Exponent><P>4SMSdNcOP0qAIoT2qzODgyl5yu9RubpIU3sSqky+85ZqJHXLUDjlgqAZvT71ROexJ4tMfMOgSWezHQwKWpz3sw==</P><Q>0krr7cmorhWgwCDG8jmzLMo2jafAy6tQout+1hU0bBKAQaPTGGogPB3hTnFIr84kHcRalCksI6jk4Xx/hiw+sw==</Q><DP>DtR9mb60zIx+xkdV7E8XYaNwx2JeUsqniwA3aYpmpasJ0N8FhoJI9ALRzzp/c4uDiuRNJIbKXyt6i/ZIFFH0qw==</DP><DQ>mGCxlBwLnhkN4ind/qbQriPYY8yqZuo8A9Ggln/G/IhrZyTOUWKU+Pqtx6lOghVdFjSxbapn0W8QalNMFGz7AQ==</DQ><InverseQ>WDYfqefukDvMhPHqS8EBFJFpls/pB1gKsEmTwbJu9fBxN4fZfUFPuTnCIJsrEsnyRfeNTAUFYl3hhlRYZo5GiQ==</InverseQ><D>qB8WvAmWFMW67EM8mdlReI7L7jK4bVf+YXOtJzVwfJ2PXtoUI+wTgH0Su0IRp9sR/0v/x9HZlluj0BR2O33snQCxYI8LIo5NoWhfhkVSv0QFQiDcG5Wnbizz7w2U6pcxEC2xfcoKG4yxFkAmHCIkgs/B9T86PUPSW4ZTXcwDmqU=</D></RSAKeyValue>";
rsa.FromXmlString(rsaPrivateKey);
String signedData = "<SignedData><Key>Insert your key here</Key></SignedData>";
Byte[] licenseData = System.Text.Encoding.UTF8.GetBytes(signedData);
Byte[] sigBytes = rsa.SignData(licenseData, new SHA1CryptoServiceProvider());
String sigText = System.Text.Encoding.UTF8.GetString(Transform(sigBytes, new ToBase64Transform()));
System.Text.StringBuilder sb = new StringBuilder();
using (System.Xml.XmlWriter xw = System.Xml.XmlTextWriter.Create(sb))
{
xw.WriteStartElement("License");
xw.WriteRaw(signedData);
xw.WriteElementString("Signature", sigText);
xw.WriteEndElement();
}
return sb.ToString();
}
Example output from this code:
<?xml version="1.0" encoding="utf-16"?>
<License>
<SignedData>
<Key>Insert your key here</Key>
</SignedData>
<Signature>cgpmyqaDlHFetCZbm/zo14NEcBFZWaQpyHXViuDa3d99AQ5Dw5Ya8C9WCHbTiGfRvaP4nVGyI+ezAAKj287dhHi7l5fQAggUmh9xTfDZ0slRtvYD/wISCcHfYkEhofXUFQKFNItkM9PnOTExZvo75pYPORkvKBF2UpOIIFvEIU=</Signature>
</License>
Then you can use code like this to verify it. You never have to distribute the private key:
public static Boolean CheckLicenseSignature(String licXml)
{
try
{
System.Xml.XmlDocument xd = new System.Xml.XmlDocument();
xd.LoadXml(licXml);
String licSig = xd.SelectSingleNode("/License/Signature").InnerText;
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
String rsaPublicKey = "<RSAKeyValue><Modulus>uPCow37yEzlKQXgbqO9E3enSOXY1MCQB4TMbOZyk9eXmc7kuiCMhJRbrwild0LGO8KE3zci9ETBWVVSJEqUqwtZyfUjvWOLHrf5EmzribtSU2e2hlsNoB2Mu11M0SaGd3qZfYcs2gnEnljfvkDAbCyJhUlxmHeI+35w/nqSCjCk=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
rsa.FromXmlString(rsaPublicKey);
Byte[] licenseData = System.Text.Encoding.UTF8.GetBytes(xd.SelectSingleNode("/License/SignedData").OuterXml);
return rsa.VerifyData(licenseData, new SHA1CryptoServiceProvider(), Transform(System.Text.Encoding.UTF8.GetBytes(licSig), new FromBase64Transform()));
}
catch (System.Xml.XmlException ex)
{
return false;
}
catch (InvalidOperationException ex)
{
return false;
}
}

From within the capability of the .NET code itself, I'm not sure if this is doable. But it is possible to dynamically generate a .NET DLL which contains some key that can be referred from the main application. That is, if you wouldn't mind a second file in the distribution.
Or if you don't mind to use Ildasm to disassemble the .exe, change the key, then use Ilasm to reassemble, then you can do something to automate that.

The accepted answer is GARBAGE!
I HAVE DONE THIS SUCCESSFULLY. MUCH EASIER
Just put your base application (.net) that needs the key somewhere with a string resource FILLED WITH "XXXXXXXXXXXXXXX" (more than you'll need)
.Net resources are usually kept at the top of the code so you will find them fast skipping the first 100,000 bytes in my case.
Then you just read it in and look for those XXXXXX's. When you find them you replace them with the real API key and replace the rest of the X's with spaces you just trim off in code. This is the answer. It works and it works well.
ApiToken at = new ApiToken(UserId, SelectedCID);
at.MakeToken();
byte[] app = System.IO.File.ReadAllBytes(Path.Combine(AppDomain.CurrentDomain.GetData("DataDirectory").ToString(), "notkeyedapp.exe"));
for (int i = 100000; i < app.Length; i++)
{
if (app[i] == 0x58 && app[i + 1] == 0x58 && app[i + 2] == 0x58)
{
for (int j = 0; j < 128; j++)
{
if (at.Token.Length >= j + 1)
app[i + j] = System.Text.Encoding.ASCII.GetBytes(at.Token[j].ToString())[0];
else
app[i + j] = 0x20;
}
break;
}
}
string filename = "SoftwareProduct for - " + BaseModel.CompanyName.Replace(".", "") + ".exe";
return File(app, System.Net.Mime.MediaTypeNames.Application.Octet, filename);

I don't think You can get away without recompiling Your .exe and having key embedded into said .exe. The compilation process can be automated though via use of ildasm.exe and ilasm.exe as Daniel Earwicker suggested in his response https://stackoverflow.com/a/2742902/2358659
I'd like to expand on that if anyone else stumbles across this topic in the future.
I recently was facing similar problem due to my poor source code version control habits. In a nutshell I had an executable that was supposed to write some data to a Google Spreadsheet by referencing it's ID. Long after executable was released came another request from a different team to use the tool, but it had to write same information into a different spreadsheet in order to keep data separate for two teams. At the time I did not have the original source code, hence I was not able to change the static variable holding the original spreadsheet ID. What I did was as follows:
Using CMD.exe → call "C:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools\ildasm.exe" "myApplication.exe" /out="myApplication.il"
Using Notepad++ → Find and replace original ID to new ID inside myApplication.il file. This action can also be automated by writing own C# application to do this, or using PowerShell, or using vb/j-script or using some other find and replace tool available off-the-shelf, like FART (using CMD.exe → call fart.exe myApplication.il "OldKey" "NewKey")
Using CMD.exe → call "C:\Windows\Microsoft.NET\Framework\v4.0.30319\ilasm.exe" "myApplication.il" /res="myApplication.res" /key="myApplicationKeyFile.snk"
As You see, all of these steps can be put into one .bat file that takes "NewKey" as an input and produces new .exe with NewKey embedded.
I hope that helps.

What comes to my mind, but not tried yet: Create a default String in your program, for example as
static public string regGuid = "yourguidhere";
Then, search the compiled EXE with any decent hex editor. If you find the string, replace it with another test. If you still can execute the program, you could try to automate this process and voila! Here you are.