• Fix 4 CRITICAL security vulnerabilities in RSA key generation and temp file handling
• Fix 2 CRITICAL bugs in ToolTipControl property accessors
• Improve CI/CD workflow security by applying least-privilege principle

Add explicit RSA key size specification

• Specify 2048-bit key size for RSACryptoServiceProvider constructor (S4426)
• Ensures minimum secure RSA key length instead of using default

ExternalConnectors/CPS/PasswordstateInterface.cs

Add explicit RSA key size specification

• Specify 2048-bit key size for RSACryptoServiceProvider constructor (S4426)
• Ensures minimum secure RSA key length instead of using default

ExternalConnectors/DSS/SecretServerInterface.cs

Fix property accessor backing field assignments

• Fix HasBorder setter to assign hasBorder backing field after updating window style (S4275)
• Fix Font getter to return cached backing field instead of re-reading from native handle (S4275)
• Ensures property consistency and prevents redundant native calls

ObjectListView/SubControls/ToolTipControl.cs

Description

PuttyBase.Connect() now generates a temp private-key path via GetRandomFileName() and then writes it
with File.WriteAllText(), which is non-atomic and can overwrite/delete an existing file if the name
already exists or is pre-created. This can clobber unrelated files and weakens the safety of
handling sensitive private-key material.

Code

mRemoteNG/Connection/Protocol/PuttyBase.cs[R124-126]

+                                    optionalTemporaryPrivateKeyPath = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
                                    File.WriteAllText(optionalTemporaryPrivateKeyPath, privatekey);
                                    FileInfo fileInfo = new(optionalTemporaryPrivateKeyPath)

Evidence

The temp key file path is generated without creating the file atomically, then written via
File.WriteAllText() (two occurrences). In the finally block, the code unconditionally deletes the
same path—so if an existing file was overwritten or the path was pre-created, the cleanup can delete
the wrong file.

mRemoteNG/Connection/Protocol/PuttyBase.cs[116-151]
mRemoteNG/Connection/Protocol/PuttyBase.cs[399-407]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

### Issue description
`PuttyBase.Connect()` creates a temporary private-key file by generating a random name (`Path.GetRandomFileName()`) and then writing with `File.WriteAllText()`. This is not an exclusive/atomic create and can overwrite an existing file (collision or pre-creation), and the `finally` block then deletes whatever exists at that path.

### Issue Context
This temp file contains SSH private key material and is passed to PuTTY via `-i`, so we still need a real filesystem path. The key requirement is to create the file *atomically* (no overwrite) and only delete the file that we created.

### Fix Focus Areas
- mRemoteNG/Connection/Protocol/PuttyBase.cs[116-151]
- mRemoteNG/Connection/Protocol/PuttyBase.cs[399-407]

### Suggested fix approach
- Replace `Path.Combine(Path.GetTempPath(), Path.GetRandomFileName())` + `File.WriteAllText(...)` with an atomic create:
 - Generate a candidate path (optionally add `.ppk` extension for clarity).
 - Open with `new FileStream(path, FileMode.CreateNew, FileAccess.Write, FileShare.None)` and write the content via `StreamWriter`.
 - Retry on `IOException` for name collisions.
- Track a boolean like `tempKeyFileCreated` and only delete the file in `finally` if creation succeeded.
- (Optional hardening) Apply restrictive ACLs on Windows so only the current user can read the temp key file.

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