Разные результаты base64

Всех приветствую. Пытаюсь на python расшифровать сообщения C++'a.

Но я столкнулся с такой проблемой:

Одну и ту же строку C++ и python шифруют по-разному

К примеру:

# Python
import  base64
encoded = base64.b64encode(b'hello')
print(encoded)

b'aGVsbG8='

Но C++ уже выводит такое:

aGVsbG8A

Как с этим быть?

// C++:
// Main: 
#include "base64.h"
int main()
{
    const unsigned char f[6] = "hello";
    string encoded = base64_encode(f, sizeof(f));
    cout << encoded << endl;
    return 0;
}

// base64.h:
#ifndef BASE64_H_C0CE2A47_D10E_42C9_A27C_C883944E704A
#define BASE64_H_C0CE2A47_D10E_42C9_A27C_C883944E704A
#include <string>
std::string base64_encode(unsigned char const*, unsigned int len);
std::string base64_decode(std::string const& s);
#endif
// base 64.cpp:

#include "base64.h"
#include <iostream>
static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";

static inline bool is_base64(unsigned char c) {
    return (isalnum(c) || (c == '+') || (c == '/'));
}
std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
    std::string ret;
    int i = 0;
    int j = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];
    while (in_len--) {
        char_array_3[i++] = *(bytes_to_encode++);
        if (i == 3) {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;
            for (i = 0; (i < 4); i++)
                ret += base64_chars[char_array_4[i]];
            i = 0;
        }
    }
    if (i)
    {
        for (j = i; j < 3; j++)
            char_array_3[j] = '\0';
        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
        for (j = 0; (j < i + 1); j++)
            ret += base64_chars[char_array_4[j]];
        while ((i++ < 3))
            ret += '=';
    }
    return ret;
}
std::string base64_decode(std::string const& encoded_string) {
    int in_len = encoded_string.size();
    int i = 0;
    int j = 0;
    int in_ = 0;
    unsigned char char_array_4[4], char_array_3[3];
    std::string ret;
    while (in_len-- && (encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
        char_array_4[i++] = encoded_string[in_]; in_++;
        if (i == 4) {
            for (i = 0; i < 4; i++)
                char_array_4[i] = base64_chars.find(char_array_4[i]);
            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
            for (i = 0; (i < 3); i++)
                ret += char_array_3[i];
            i = 0;
        }
    }
if (i) {
    for (j = 0; j < i; j++)
        char_array_4[j] = base64_chars.find(char_array_4[j]);
    char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
    char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
    for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
}
return ret;

}