couldn't compile OpenSSL example: EVP Symmetric Encryption and Decryption - c++

Question

I'm building an encryption/decryption example from OpenSSL docs on CentOS7:
// g++ -Wall -std=c++11 evp-encrypt.cxx -o evp-encrypt.exe -lcrypto
#include <iostream>
#include <string>
#include <memory>
#include <limits>
#include <stdexcept>
#include <openssl/evp.h>
#include <openssl/rand.h>
static const unsigned int KEY_SIZE = 32;
static const unsigned int BLOCK_SIZE = 16;
template <typename T>
struct zallocator
{
public:
typedef T value_type;
typedef value_type* pointer;
typedef const value_type* const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
pointer address (reference v) const {return &v;}
const_pointer address (const_reference v) const {return &v;}
pointer allocate (size_type n, const void* hint = 0) {
if (n > std::numeric_limits<size_type>::max() / sizeof(T))
throw std::bad_alloc();
return static_cast<pointer> (::operator new (n * sizeof (value_type)));
}
void deallocate(pointer p, size_type n) {
OPENSSL_cleanse(p, n*sizeof(T));
::operator delete(p);
}
size_type max_size() const {
return std::numeric_limits<size_type>::max() / sizeof (T);
}
template<typename U>
struct rebind
{
typedef zallocator<U> other;
};
void construct (pointer ptr, const T& val) {
new (static_cast<T*>(ptr) ) T (val);
}
void destroy(pointer ptr) {
static_cast<T*>(ptr)->~T();
}
#if __cpluplus >= 201103L
template<typename U, typename... Args>
void construct (U* ptr, Args&& ... args) {
::new (static_cast<void*> (ptr) ) U (std::forward<Args> (args)...);
}
template<typename U>
void destroy(U* ptr) {
ptr->~U();
}
#endif
};
typedef unsigned char byte;
typedef std::basic_string<char, std::char_traits<char>, zallocator<char> > secure_string;
using EVP_CIPHER_CTX_free_ptr = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>;
void gen_params(byte key[KEY_SIZE], byte iv[BLOCK_SIZE]);
void aes_encrypt(const byte key[KEY_SIZE], const byte iv[BLOCK_SIZE], const secure_string& ptext, secure_string& ctext);
void aes_decrypt(const byte key[KEY_SIZE], const byte iv[BLOCK_SIZE], const secure_string& ctext, secure_string& rtext);
// g++ -Wall -std=c++11 evp-encrypt.cxx -o evp-encrypt.exe -lcrypto
int main(int argc, char* argv[])
{
// Load the necessary cipher
EVP_add_cipher(EVP_aes_256_cbc());
// plaintext, ciphertext, recovered text
secure_string ptext = "Now is the time for all good men to come to the aide of their country";
secure_string ctext, rtext;
byte key[KEY_SIZE], iv[BLOCK_SIZE];
gen_params(key, iv);
aes_encrypt(key, iv, ptext, ctext);
aes_decrypt(key, iv, ctext, rtext);
OPENSSL_cleanse(key, KEY_SIZE);
OPENSSL_cleanse(iv, BLOCK_SIZE);
std::cout << "Original message:\n" << ptext << std::endl;
std::cout << "Recovered message:\n" << rtext << std::endl;
return 0;
}
void gen_params(byte key[KEY_SIZE], byte iv[BLOCK_SIZE])
{
int rc = RAND_bytes(key, KEY_SIZE);
if (rc != 1)
throw std::runtime_error("RAND_bytes key failed");
rc = RAND_bytes(iv, BLOCK_SIZE);
if (rc != 1)
throw std::runtime_error("RAND_bytes for iv failed");
}
void aes_encrypt(const byte key[KEY_SIZE], const byte iv[BLOCK_SIZE], const secure_string& ptext, secure_string& ctext)
{
EVP_CIPHER_CTX_free_ptr ctx(EVP_CIPHER_CTX_new(), ::EVP_CIPHER_CTX_free);
int rc = EVP_EncryptInit_ex(ctx.get(), EVP_aes_256_cbc(), NULL, key, iv);
if (rc != 1)
throw std::runtime_error("EVP_EncryptInit_ex failed");
// Recovered text expands upto BLOCK_SIZE
ctext.resize(ptext.size()+BLOCK_SIZE);
int out_len1 = (int)ctext.size();
rc = EVP_EncryptUpdate(ctx.get(), (byte*)&ctext[0], &out_len1, (const byte*)&ptext[0], (int)ptext.size());
if (rc != 1)
throw std::runtime_error("EVP_EncryptUpdate failed");
int out_len2 = (int)ctext.size() - out_len1;
rc = EVP_EncryptFinal_ex(ctx.get(), (byte*)&ctext[0]+out_len1, &out_len2);
if (rc != 1)
throw std::runtime_error("EVP_EncryptFinal_ex failed");
// Set cipher text size now that we know it
ctext.resize(out_len1 + out_len2);
}
void aes_decrypt(const byte key[KEY_SIZE], const byte iv[BLOCK_SIZE], const secure_string& ctext, secure_string& rtext)
{
EVP_CIPHER_CTX_free_ptr ctx(EVP_CIPHER_CTX_new(), ::EVP_CIPHER_CTX_free);
int rc = EVP_DecryptInit_ex(ctx.get(), EVP_aes_256_cbc(), NULL, key, iv);
if (rc != 1)
throw std::runtime_error("EVP_DecryptInit_ex failed");
// Recovered text contracts upto BLOCK_SIZE
rtext.resize(ctext.size());
int out_len1 = (int)rtext.size();
rc = EVP_DecryptUpdate(ctx.get(), (byte*)&rtext[0], &out_len1, (const byte*)&ctext[0], (int)ctext.size());
if (rc != 1)
throw std::runtime_error("EVP_DecryptUpdate failed");
int out_len2 = (int)rtext.size() - out_len1;
rc = EVP_DecryptFinal_ex(ctx.get(), (byte*)&rtext[0]+out_len1, &out_len2);
if (rc != 1)
throw std::runtime_error("EVP_DecryptFinal_ex failed");
// Set recovered text size now that we know it
rtext.resize(out_len1 + out_len2);
}
When compiling it with g++ -Wall -std=c++11 evp-encrypt.cxx -o evp-encrypt.exe -lcrypto, g++ reports:
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/basic_string.tcc:568:28: error: no match for 'operator==' (operand types are 'const zallocator<char>' and 'zallocator<char>')
if (__beg == __end && __a == _Alloc())
~~~~^~~~~~~~~~~
more error info:
In file included from /opt/rh/devtoolset-7/root/usr/include/c++/7/string:53:0,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/bits/locale_classes.h:40,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/bits/ios_base.h:41,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/ios:42,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/ostream:38,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/iostream:39,
from evp-encrypt.cpp:1:
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/basic_string.tcc: In instantiation of 'static _CharT* std::basic_string<_CharT, _Traits, _Alloc>::_S_construct(_InIterator, _InIterator, const _Alloc&, std::forward_iterator_tag) [with _FwdIterator = const char*; _CharT = char; _Traits = std::char_traits<char>; _Alloc = zallocator<char>]':
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/basic_string.h:5033:30: required from 'static _CharT* std::basic_string<_CharT, _Traits, _Alloc>::_S_construct_aux(_InIterator, _InIterator, const _Alloc&, std::__false_type) [with _InIterator = const char*; _CharT = char; _Traits = std::char_traits<char>; _Alloc = zallocator<char>]'
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/basic_string.h:5054:27: required from 'static _CharT* std::basic_string<_CharT, _Traits, _Alloc>::_S_construct(_InIterator, _InIterator, const _Alloc&) [with _InIterator = const char*; _CharT = char; _Traits = std::char_traits<char>; _Alloc = zallocator<char>]'
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/basic_string.tcc:664:31: required from 'std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = zallocator<char>]'
evp-encrypt.cpp:85:27: required from here
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/basic_string.tcc:568:28: error: no match for 'operator==' (operand types are 'const zallocator<char>' and 'zallocator<char>')
if (__beg == __end && __a == _Alloc())
~~~~^~~~~~~~~~~
In file included from /opt/rh/devtoolset-7/root/usr/include/c++/7/iosfwd:40:0,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/ios:38,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/ostream:38,
from /opt/rh/devtoolset-7/root/usr/include/c++/7/iostream:39,
from evp-encrypt.cpp:1:
/opt/rh/devtoolset-7/root/usr/include/c++/7/bits/postypes.h:216:5: note: candidate: template<class _StateT> bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
^~~~~~~~
How do I fix it to get it working?
environment:
g++ (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
OpenSSL version: 1.1.1-pre5-dev

Answer 1

Here the error: https://godbolt.org/z/7fGh3qGeM
Compiled with GCC 5.1 https://godbolt.org/z/EbsKzGb34
You need to update your GCC.