test_decr.c

#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/rsa.h>
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int padding = RSA_PKCS1_PADDING;
 
RSA * createRSA(unsigned char * key, int public)
{
  RSA *rsa= NULL;
  BIO *keybio ;
  keybio = BIO_new_mem_buf(key, -1);
  if (keybio==NULL)
    {
      printf( "Failed to create key BIO");
      return 0;
    }
  if(public)
    {
      rsa = PEM_read_bio_RSA_PUBKEY(keybio, &rsa,NULL, NULL);
    }
  else
    {
      rsa = PEM_read_bio_RSAPrivateKey(keybio, &rsa,NULL, NULL);
    }
  if(rsa == NULL)
    {
      printf( "Failed to create RSA");
    }
 
  return rsa;
}
 
int public_encrypt(unsigned char * data,int data_len, unsigned char * key, unsigned char *encrypted)
{
  RSA * rsa = createRSA(key,1);
  int result = RSA_public_encrypt(data_len,data,encrypted,rsa,padding);
  return result;
}
int private_decrypt(unsigned char * enc_data, int data_len, unsigned char * key, unsigned char *decrypted)
{
  RSA * rsa = createRSA(key,0);
  int  result = RSA_private_decrypt(data_len, enc_data, decrypted, rsa, padding);
  return result;
}
 
void printLastError(char *msg)
{
  char * err = malloc(130);;
  ERR_load_crypto_strings();
  ERR_error_string(ERR_get_error(), err);
  printf("%s ERROR: %s\n",msg, err);
  free(err);
}
 
int main(){

  //key length : 2048
  const char plainText[2048/8] = "Hello I'm Michele";
 
  unsigned char publicKey[]="-----BEGIN PUBLIC KEY-----\n"\
    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAy8Dbv8prpJ/0kKhlGeJY\n"\
    "ozo2t60EG8L0561g13R29LvMR5hyvGZlGJpmn65+A4xHXInJYiPuKzrKUnApeLZ+\n"\
    "vw1HocOAZtWK0z3r26uA8kQYOKX9Qt/DbCdvsF9wF8gRK0ptx9M6R13NvBxvVQAp\n"\
    "fc9jB9nTzphOgM4JiEYvlV8FLhg9yZovMYd6Wwf3aoXK891VQxTr/kQYoq1Yp+68\n"\
    "i6T4nNq7NWC+UNVjQHxNQMQMzU6lWCX8zyg3yH88OAQkUXIXKfQ+NkvYQ1cxaMoV\n"\
    "PpY72+eVthKzpMeyHkBn7ciumk5qgLTEJAfWZpe4f4eFZj/Rc8Y8Jj2IS5kVPjUy\n"\
    "wQIDAQAB\n"\
    "-----END PUBLIC KEY-----\n";
  
  unsigned char privateKey[]="-----BEGIN RSA PRIVATE KEY-----\n"\
    "MIIEowIBAAKCAQEAy8Dbv8prpJ/0kKhlGeJYozo2t60EG8L0561g13R29LvMR5hy\n"\
    "vGZlGJpmn65+A4xHXInJYiPuKzrKUnApeLZ+vw1HocOAZtWK0z3r26uA8kQYOKX9\n"\
    "Qt/DbCdvsF9wF8gRK0ptx9M6R13NvBxvVQApfc9jB9nTzphOgM4JiEYvlV8FLhg9\n"\
    "yZovMYd6Wwf3aoXK891VQxTr/kQYoq1Yp+68i6T4nNq7NWC+UNVjQHxNQMQMzU6l\n"\
    "WCX8zyg3yH88OAQkUXIXKfQ+NkvYQ1cxaMoVPpY72+eVthKzpMeyHkBn7ciumk5q\n"\
    "gLTEJAfWZpe4f4eFZj/Rc8Y8Jj2IS5kVPjUywQIDAQABAoIBADhg1u1Mv1hAAlX8\n"\
    "omz1Gn2f4AAW2aos2cM5UDCNw1SYmj+9SRIkaxjRsE/C4o9sw1oxrg1/z6kajV0e\n"\
    "N/t008FdlVKHXAIYWF93JMoVvIpMmT8jft6AN/y3NMpivgt2inmmEJZYNioFJKZG\n"\
    "X+/vKYvsVISZm2fw8NfnKvAQK55yu+GRWBZGOeS9K+LbYvOwcrjKhHz66m4bedKd\n"\
    "gVAix6NE5iwmjNXktSQlJMCjbtdNXg/xo1/G4kG2p/MO1HLcKfe1N5FgBiXj3Qjl\n"\
    "vgvjJZkh1as2KTgaPOBqZaP03738VnYg23ISyvfT/teArVGtxrmFP7939EvJFKpF\n"\
    "1wTxuDkCgYEA7t0DR37zt+dEJy+5vm7zSmN97VenwQJFWMiulkHGa0yU3lLasxxu\n"\
    "m0oUtndIjenIvSx6t3Y+agK2F3EPbb0AZ5wZ1p1IXs4vktgeQwSSBdqcM8LZFDvZ\n"\
    "uPboQnJoRdIkd62XnP5ekIEIBAfOp8v2wFpSfE7nNH2u4CpAXNSF9HsCgYEA2l8D\n"\
    "JrDE5m9Kkn+J4l+AdGfeBL1igPF3DnuPoV67BpgiaAgI4h25UJzXiDKKoa706S0D\n"\
    "4XB74zOLX11MaGPMIdhlG+SgeQfNoC5lE4ZWXNyESJH1SVgRGT9nBC2vtL6bxCVV\n"\
    "WBkTeC5D6c/QXcai6yw6OYyNNdp0uznKURe1xvMCgYBVYYcEjWqMuAvyferFGV+5\n"\
    "nWqr5gM+yJMFM2bEqupD/HHSLoeiMm2O8KIKvwSeRYzNohKTdZ7FwgZYxr8fGMoG\n"\
    "PxQ1VK9DxCvZL4tRpVaU5Rmknud9hg9DQG6xIbgIDR+f79sb8QjYWmcFGc1SyWOA\n"\
    "SkjlykZ2yt4xnqi3BfiD9QKBgGqLgRYXmXp1QoVIBRaWUi55nzHg1XbkWZqPXvz1\n"\
    "I3uMLv1jLjJlHk3euKqTPmC05HoApKwSHeA0/gOBmg404xyAYJTDcCidTg6hlF96\n"\
    "ZBja3xApZuxqM62F6dV4FQqzFX0WWhWp5n301N33r0qR6FumMKJzmVJ1TA8tmzEF\n"\
    "yINRAoGBAJqioYs8rK6eXzA8ywYLjqTLu/yQSLBn/4ta36K8DyCoLNlNxSuox+A5\n"\
    "w6z2vEfRVQDq4Hm4vBzjdi3QfYLNkTiTqLcvgWZ+eX44ogXtdTDO7c+GeMKWz4XX\n"\
    "uJSUVL5+CVjKLjZEJ6Qc2WZLl94xSwL71E41H4YciVnSCQxVc4Jw\n"\
    "-----END RSA PRIVATE KEY-----\n";
     
  unsigned char encrypted[4098]={};
  unsigned char decrypted[4098]={};
 
  int encrypted_length= public_encrypt((unsigned char *) plainText, strlen(plainText), publicKey, encrypted);
  if(encrypted_length == -1)
    {
      printLastError("Public Encrypt failed ");
      exit(0);
    }
  printf("Encrypted length =%d\n",encrypted_length);
 
  int decrypted_length = private_decrypt(encrypted, encrypted_length, privateKey, decrypted);
  if(decrypted_length == -1)
    {
      printLastError("Private Decrypt failed ");
      exit(0);
    }
  printf("Decrypted Text =%s\n",decrypted);
  printf("Decrypted Length =%d\n",decrypted_length);

}