I could not downgrade my iOS 12.3.1

[elrodrix]

Hey guys!
 
I was wondering if I can downgrade my iphone 7 GSM (ios 12.3.1) to 12.1.2, and then install a jailbreak.
 
The problem is that I can not find a signed IPSW for version 12.1.2.
 
Is this possible?.

I mean, I understand that I can not install ipsw through iTunes if it is not signed, so, Can I install ipsw (not signed) using another tool?
 
Thank in advance.

[Comet]

Hey guys!
 
I was wondering if I can downgrade my iphone 7 GSM (ios 12.3.1) to 12.1.2, and then install a jailbreak.
 
The problem is that I can not find a signed IPSW for version 12.1.2.
 
Is this possible?.

I mean, I understand that I can not install ipsw through iTunes if it is not signed, so, Can I install ipsw (not signed) using another tool?
 
Thank in advance.

No. There're no currently signed version of iOS 12.1.2 on any device. If you had blobs, you could downgrade when a nonce setter is released for 12.3.1 (not going to be soon).