FileUpload.. Change file name on display?

I have some unique, encrypted signed urls for uploaded files. But in the file upload field I want them to render the original name. How can we achieve it?

example:

/lt/sdhoudyahasjd3o2423..fdfs[ds

is the signed url

decrypted is

/lt/myfile.jpg

I'd like to show file.jpg as the file name in the file upload field, at the moment it shows:

sdhoudyahasjd3o2423..fdfs[ds