#! /usr/bin/env python
# -*- coding: utf-8 -*-
import sys
#rsa
from rsa import PublicKey, common, transform, core
def f(cipher, PUBLIC_KEY):
 public_key = PublicKey.load_pkcs1(PUBLIC_KEY)
 encrypted = transform.bytes2int(cipher)
 decrypted = core.decrypt_int(encrypted, public_key.e, public_key.n)
 text = transform.int2bytes(decrypted) 
 if len(text) > 0 and text[0] == '\x01':
  pos = text.find('\x00')
  if pos > 0:
  return text[pos+1:]
  else:
  return None 
fn = sys.stdin.readline()[:-1]
public_key = sys.stdin.readline()[:-1]
x = f(open(fn).read(), open(public_key).read())
print x

$ openssl genrsa -out pri2048.pem 2048
Generating RSA private key, 2048 bit long modulus
..+++
..............................................+++
e is 65537 (0x10001)
 $ openssl rsa -in pri2048.pem -out pub2048.pem -RSAPublicKey_out
writing RSA key
 $ echo -n 'Just a test' >1.txt
 $ openssl rsautl -sign -in 1.txt -inkey pri2048.pem -out 1.bin
 $ { echo 1.bin; echo pub2048.pem; } | ./test_rsa.py
Just a test