Saurik aka Jay Freeman (founder of Cydia) has just released an add-on tool to the updated version of Cydia Impactor called 'Cydia Extender', which enables installing and re-signing of .ipa files locally on iOS devices, without a computer. However, the tool is not yet capable of handling the 7-day signing limitation on iOS jailbroken devices.
Folks at iDownloadBlog have confirmed that the latest build 0.9.39 of Cydia Impactor brings fix for the SSL certificate verification error while trying to sign .ipa files in Windows, Linux and macOS.
It must be noted that the Cydia Extender works on iOS devices with access to a paid developer account, wherein the user can simply sign the Yalu app for a year using the Impactor. Consequently, the Extender add-on for Cydia Impactor has no effect on the current 7-day signing limitation for the public release of Yalu jailbreak.
Despite its obvious limitations, the Cydia Extender app enables all those users with paid developer accounts to browse, install and re-sign apps indefinitely, without a computer.
Here is what Saurik had to say regarding the purpose of Cydia Extender and its use in signing Yalu jailbreak:
"It (apparently) requires a developer account to install, due to the crazy indirect technique it uses for the install process (a loopback VPN network extension). This limitation seriously was not noticed by me until a user reported it as an issue a few minutes after I had already released it. This makes this new application only valuable to developers."
According to Saurik's own statement (above), it is clear that he was unaware of the tool's limitation and its inability to resolve 7-day signing issues with Yalu jailbreak, until the time of its release when a user reported the shortcoming to him.
Saurik has cleared the confusion stating that he really did not intend to create a permanent solution for the 7-day signing problem with iOS jailbreaks. However, he is still working on an appropriate solution with another developer to address this issue.