OpenSSL RSA Encryption / Decryption C++ Wrapper

rsa.hpp

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>

#define CRYPTO_RSA_KEY_LEN_4096 4096
#define CRYPTO_RSA_KEY_LEN_2048 2048
#define CRYPTO_RSA_KEY_LEN_1024 1024
#define CRYPTO_RSA_KEY_EXP      65535

#define CRYPTO_PRINT_ERROR fprintf(stderr, "[x] %s\n", strerror(errno))

using namespace std;

class CryptoRSA{
public:
  bool GenerateKeys(int key_length){
    SetKeyLength(key_length);
    pRSA = RSA_generate_key(GetKeyLength(), CRYPTO_RSA_KEY_EXP, NULL, NULL);
    if (RSA_check_key(pRSA) != 1){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    return true;
  }
  void SetKeyLength(int key_length){
    keylen = key_length;
  }
  int GetKeyLength(){
    return keylen;
  }
  bool WritePublicKeyFile(char * key_public){
    FILE *fp = fopen(key_public, "w");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (PEM_write_RSAPublicKey(fp, pRSA) == 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp);
    return true;
  }
  bool WritePrivateKeyFile(char *key_private){
    FILE *fp = fopen(key_private, "w");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (PEM_write_RSAPrivateKey(fp, pRSA, NULL, NULL, 0, NULL, NULL) == 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    return true;
  }
  bool ReadPublicKeyBuffer(void *src, size_t src_size){
    FILE *fp = fmemopen(src, src_size, "rb");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (PEM_read_RSAPublicKey(fp, &pRSA, NULL, NULL) == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp);
    return true;
  }
  bool ReadPublicKeyFile(char *key_public){
    FILE *fp = fopen(key_public, "rb");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (PEM_read_RSAPublicKey(fp, &pRSA, NULL, NULL) == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp);
    return true;
  }
  bool ReadPrivateKeyBuffer(void *src, size_t src_size){
    FILE *fp = fmemopen(src, src_size, "rb");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (PEM_read_RSAPrivateKey(fp, &pRSA, NULL, NULL) == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp);
    return true;
  }
  bool ReadPrivateKeyFile(char *key_private){
    FILE *fp = fopen(key_private, "rb");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (PEM_read_RSAPrivateKey(fp, &pRSA, NULL, NULL) == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp);
    return true;
  }
  void InitKeyPair(){
    pRSA = RSA_new();
  }
  bool InitPlainText(){
    plaintext = malloc(GetCipherTextSize());
    if (plaintext == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    memset(plaintext, 0, GetCipherTextSize());
    return true;
  }
  bool InitCipherText(){
    ciphertext = malloc(GetCipherTextSize());
    if (ciphertext == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    memset(ciphertext, 0, GetCipherTextSize());
    return true;
  }
  void CleanupCipherText(){
    free(ciphertext);
  }
  void CleanupPlainText(){
    free(plaintext);
  }
  void CleanupKeyPair(){
    RSA_free(pRSA);
  }
  void Initialize(){
    InitKeyPair();
    InitPlainText();
    InitCipherText();
  }
  void InitBuffers(){
    InitPlainText();
    InitCipherText();
  }
  void Cleanup(){
    CleanupKeyPair();
    CleanupPlainText();
    CleanupCipherText();
  }
  void CleanupBuffers(){
    CleanupPlainText();
    CleanupCipherText();
  }
  bool SetPlainText(void *src, size_t src_size){
    if (src_size > (size_t)GetCipherTextSize()){
      fprintf(stderr,
              "[x] the data size of %d bytes exceeds the limit of %d bytes\n",
              (int)src_size,
              (int)GetCipherTextSize());
      return false;
    }
    plaintext_size = src_size;
    memcpy(plaintext, src, plaintext_size);
    return true;
  }
  bool SetCipherText(void *src, size_t src_size){
    if (src_size > (size_t)GetCipherTextSize()){
      fprintf(stderr,
              "[x] the data size of %d bytes exceeds the limit of %d bytes\n",
              (int)src_size,
              (int)GetCipherTextSize());
      return false;
    }
    memcpy(ciphertext, src, src_size);
    return true;
  }
  void *GetPlainText(){
    return plaintext;
  }
  int GetPlainTextSize(){
    return plaintext_size;
  }
  void *GetCipherText(){
    return ciphertext;
  }
  RSA *GetRSABlob(){
    return pRSA;
  }
  int GetCipherTextSize(){
    return RSA_size(pRSA);
  }
  void DebugCipherText(){
    hex_dump((char *)"ciphertext", ciphertext, GetCipherTextSize());
  }
  void DebugPlainText(){
    hex_dump((char *)"plaintext", plaintext, plaintext_size);
  }
  bool WriteCipherTextFile(char *ciphertext_file){
    FILE *fp = fopen(ciphertext_file, "wb");
    if (fp == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (fwrite(ciphertext, GetCipherTextSize(), 1, fp) <= 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp);
    return true;
  }
  bool WritePlainTextFile(char *plaintext_file){
    FILE *fp_decrypted = fopen(plaintext_file, "wb");
    if (fp_decrypted == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (fwrite(plaintext, GetPlainTextSize(), 1, fp_decrypted) <= 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp_decrypted);
    return true;
  }
  bool PublicEncrypt(void *src, size_t src_size){
    if (SetPlainText(src, src_size) == false){
      return false;
    }
    int result = RSA_public_encrypt(plaintext_size,
                                    (unsigned char *)plaintext,
                                    (unsigned char *)ciphertext,
                                    pRSA,
                                    RSA_PKCS1_PADDING);
    if (result < 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    return true;
  }
  bool PublicDecrypt(void *src, size_t src_size){
    if (SetCipherText(src, src_size) == false){
      return false;
    }
    int result = RSA_public_decrypt(GetCipherTextSize(),
                                    (unsigned char *)ciphertext,
                                    (unsigned char *)plaintext,
                                    pRSA,
                                    RSA_PKCS1_PADDING);
    if (result < 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    plaintext_size = result;
    return true;
  }
  bool PrivateEncrypt(void *src, size_t src_size){
    if (SetPlainText(src, src_size) == false){
      return false;
    }
    int result = RSA_private_encrypt(plaintext_size,
                                     (unsigned char *)plaintext,
                                     (unsigned char *)ciphertext,
                                     pRSA,
                                     RSA_PKCS1_PADDING);
    if (result < 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    return true;
  }
  bool PrivateDecrypt(void *src, size_t src_size){
    if (SetCipherText(src, src_size) == false){
      return false;
    }
    int result = RSA_private_decrypt(GetCipherTextSize(),
                                     (unsigned char *)ciphertext,
                                     (unsigned char *)plaintext,
                                     pRSA,
                                     RSA_PKCS1_PADDING);
    if (result < 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    plaintext_size = result;
    return true;
  }
  bool ReadPlainTextFile(char *plaintext_file){
    FILE *fp_plaintext = fopen(plaintext_file, "rb");
    if (fp_plaintext == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (file_size(fp_plaintext) > GetCipherTextSize()){
      fprintf(stderr,
              "[x] the data size of %d bytes exceeds the limit of %d bytes\n",
              file_size(fp_plaintext),
              GetCipherTextSize());
      return false;
    }
    if (fread(plaintext, file_size(fp_plaintext), 1, fp_plaintext) <= 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    plaintext_size = file_size(fp_plaintext);
    fclose(fp_plaintext);
    return true;
  }
  bool ReadCipherTextFile(char *ciphertext_file){
    FILE *fp_encrypted = fopen(ciphertext_file, "rb");
    if (fp_encrypted == NULL){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    if (fread(ciphertext, GetCipherTextSize(), 1, fp_encrypted) <= 0){
      CRYPTO_PRINT_ERROR;
      return false;
    }
    fclose(fp_encrypted);
    return true;
  }
  bool PrivateDecryptFile(char *encrypted_file, char *decrypted_file){
    if (ReadCipherTextFile(encrypted_file) == false){
      return false;
    }
    if (PrivateDecrypt(ciphertext, GetCipherTextSize()) == false){
      return false;
    }
    if (WritePlainTextFile(decrypted_file) == false){
      return false;
    }
    return true;
  }
  bool PublicDecryptFile(char *encrypted_file, char *decrypted_file){
    if (ReadCipherTextFile(encrypted_file) == false){
      return false;
    }
    if (PublicDecrypt(ciphertext, GetCipherTextSize()) == false){
      return false;
    }
    if (WritePlainTextFile(decrypted_file) == false){
      return false;
    }
    return true;
  }
private:
  void hex_dump(char *desc, void *addr, size_t len){
    int i;
    unsigned char buff[17];
    const unsigned char *pc = (const unsigned char*)addr;
    if (desc != NULL){
      printf ("%s:\n", desc);
    }
    for (i = 0; i < (int)len; i++) {
      if ((i % 16) == 0) {
        if (i != 0){
          printf ("  %s\n", buff);
        }
        printf ("  %04x ", i);
      }
      printf (" %02x", pc[i]);
      if ((pc[i] < 0x20) || (pc[i] > 0x7e)){
        buff[i % 16] = '.';
      } else{
        buff[i % 16] = pc[i];
      }
      buff[(i % 16) + 1] = '\0';
    }
    while ((i % 16) != 0){
      printf ("   ");
      i++;
    }
    printf ("  %s\n", buff);
  }
  int file_size(FILE *fp){
    int prev=ftell(fp);
    fseek(fp, 0L, SEEK_END);
    int sz=ftell(fp);
    fseek(fp,prev,SEEK_SET);
    return sz;
  }
  void *plaintext;
  void *ciphertext;
  int keylen;
  size_t plaintext_size;
  RSA *pRSA;
};

Thank you for sharing this code, thanks to this I managed to make a password database encoder/decoder for my json server using pub & priv keys. Regards

Can someone briefly explain how to use this class? I would really like to use this implementation in my project but I need a short explanation on how to use it. I'm sorry for such a trivial question, but I'm just starting.