Decrypt pdf file with public key on iOS

[bechirghodbane]

Hello,
I want to encrypt a pdf file with public key before sending it to the server where i can decrypt it with a private key.
Before that, I was using the demo application on ios and I was trying to read pdf file as NSData then generate the encrytion and decryption result in order to validate the output of the hole process , in other words , I wanted to check if the output file after the encrytion and decryption is still a valid pdf file like the original one.
Unfortenetly , it seems that the output file is corrupted since I get this error when I tried to show the final pdf file on a webview .

failed to find `endstream' marker; trying to recover.
FlateDecode: decoding error: invalid bit length repeat.