Skip to content

Instantly share code, notes, and snippets.

@cjavad

cjavad/base64.cpp

Created February 20, 2020 08:41
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save cjavad/2cda436e5f1d77fa358fa0109350116a to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save cjavad/2cda436e5f1d77fa358fa0109350116a to your computer and use it in GitHub Desktop.
Download ZIP
[base64 command line tool - detects base64 w/ regex]
Raw
base64.cpp
#include "base64.hpp"
#include <regex>
/*
ENCODE/DECODE Functions
*/
std::string b64_encode(const std::string &input, bool strip_padding = false) {
static std::string encoded; // define output string
// resize string for space for the base64 string
encoded.resize(Base64::EncodedLength(input));
// try to decode string
if (!Base64::Encode(input.c_str(), input.size(), &encoded[0], encoded.size())) {
std::cout << "Failed to encode input string" << std::endl;
return "";
}
//strip it if needed
if (strip_padding) Base64::StripPadding(&encoded);
// and return string
return encoded;
}
std::string b64_decode(const std::string &input, bool strip_padding = false) {
// convert input
static std::string encoded = input.c_str();
// define out string
static std::string decoded;
// check if it needs to be stripped
if (strip_padding) Base64::StripPadding(&encoded);
// resize out string
decoded.resize(Base64::DecodedLength(encoded));
// try to decode
if (!Base64::Decode(encoded.c_str(), encoded.size(), &decoded[0], decoded.size())) {
std::cout << "Failed to decode encoded string" << std::endl;
return "";
}
// and return decoded
return decoded;
}
int main(int argc, char * argv[]) {
std::string input;
// Check the number of parameters
if (argc < 2) {
std::cin >> input;
} else {
input = argv[1];
}
if (std::regex_match(input.c_str(), std::regex("^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)?$"))) {
std::cout << b64_decode(input) << "\n";
} else {
std::cout << b64_encode(input) << "\n";
}
}
Raw
base64.hpp
/*
Copyright (C) 2020 Javad Shafique (small changes and integrations with clib)
Copyright (C) 2013 Tomas Kislan (compatibility with c++ std::strings)
Copyright (C) 2013 Adam Rudd (algortihm originally for use with arduino)
MIT LICENSE
*/
#ifndef BASE64_H
#define BASE64_H
#include <iostream>
#include <string>
const char kBase64Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
class Base64 {
public:
static bool Encode(const std::string &in, std::string *out) {
int i = 0, j = 0;
size_t enc_len = 0;
unsigned char a3[3];
unsigned char a4[4];
out->resize(EncodedLength(in));
int input_len = in.size();
std::string::const_iterator input = in.begin();
while (input_len--) {
a3[i++] = *(input++);
if (i == 3) {
a3_to_a4(a4, a3);
for (i = 0; i < 4; i++) {
(*out)[enc_len++] = kBase64Alphabet[a4[i]];
}
i = 0;
}
}
if (i) {
for (j = i; j < 3; j++) {
a3[j] = '\0';
}
a3_to_a4(a4, a3);
for (j = 0; j < i + 1; j++) {
(*out)[enc_len++] = kBase64Alphabet[a4[j]];
}
while ((i++ < 3)) {
(*out)[enc_len++] = '=';
}
}
return (enc_len == out->size());
}
static bool Encode(const char *input, size_t input_length, char *out, size_t out_length) {
int i = 0, j = 0;
char *out_begin = out;
unsigned char a3[3];
unsigned char a4[4];
size_t encoded_length = EncodedLength(input_length);
if (out_length < encoded_length) return false;
while (input_length--) {
a3[i++] = *input++;
if (i == 3) {
a3_to_a4(a4, a3);
for (i = 0; i < 4; i++) {
*out++ = kBase64Alphabet[a4[i]];
}
i = 0;
}
}
if (i) {
for (j = i; j < 3; j++) {
a3[j] = '\0';
}
a3_to_a4(a4, a3);
for (j = 0; j < i + 1; j++) {
*out++ = kBase64Alphabet[a4[j]];
}
while ((i++ < 3)) {
*out++ = '=';
}
}
return (out == (out_begin + encoded_length));
}
static bool Decode(const std::string &in, std::string *out) {
int i = 0, j = 0;
size_t dec_len = 0;
unsigned char a3[3];
unsigned char a4[4];
int input_len = in.size();
std::string::const_iterator input = in.begin();
out->resize(DecodedLength(in));
while (input_len--) {
if (*input == '=') {
break;
}
a4[i++] = *(input++);
if (i == 4) {
for (i = 0; i <4; i++) {
a4[i] = b64_lookup(a4[i]);
}
a4_to_a3(a3,a4);
for (i = 0; i < 3; i++) {
(*out)[dec_len++] = a3[i];
}
i = 0;
}
}
if (i) {
for (j = i; j < 4; j++) {
a4[j] = '\0';
}
for (j = 0; j < 4; j++) {
a4[j] = b64_lookup(a4[j]);
}
a4_to_a3(a3,a4);
for (j = 0; j < i - 1; j++) {
(*out)[dec_len++] = a3[j];
}
}
return (dec_len == out->size());
}
static bool Decode(const char *input, size_t input_length, char *out, size_t out_length) {
int i = 0, j = 0;
char *out_begin = out;
unsigned char a3[3];
unsigned char a4[4];
size_t decoded_length = DecodedLength(input, input_length);
if (out_length < decoded_length) return false;
while (input_length--) {
if (*input == '=') {
break;
}
a4[i++] = *(input++);
if (i == 4) {
for (i = 0; i <4; i++) {
a4[i] = b64_lookup(a4[i]);
}
a4_to_a3(a3,a4);
for (i = 0; i < 3; i++) {
*out++ = a3[i];
}
i = 0;
}
}
if (i) {
for (j = i; j < 4; j++) {
a4[j] = '\0';
}
for (j = 0; j < 4; j++) {
a4[j] = b64_lookup(a4[j]);
}
a4_to_a3(a3,a4);
for (j = 0; j < i - 1; j++) {
*out++ = a3[j];
}
}
return (out == (out_begin + decoded_length));
}
static int DecodedLength(const char *in, size_t in_length) {
int numEq = 0;
const char *in_end = in + in_length;
while (*--in_end == '=') ++numEq;
return ((6 * in_length) / 8) - numEq;
}
static int DecodedLength(const std::string &in) {
int numEq = 0;
int n = in.size();
for (std::string::const_reverse_iterator it = in.rbegin(); *it == '='; ++it) {
++numEq;
}
return ((6 * n) / 8) - numEq;
}
inline static int EncodedLength(size_t length) {
return (length + 2 - ((length + 2) % 3)) / 3 * 4;
}
inline static int EncodedLength(const std::string &in) {
return EncodedLength(in.length());
}
inline static void StripPadding(std::string *in) {
while (!in->empty() && *(in->rbegin()) == '=') in->resize(in->size() - 1);
}
private:
static inline void a3_to_a4(unsigned char * a4, unsigned char * a3) {
a4[0] = (a3[0] & 0xfc) >> 2;
a4[1] = ((a3[0] & 0x03) << 4) + ((a3[1] & 0xf0) >> 4);
a4[2] = ((a3[1] & 0x0f) << 2) + ((a3[2] & 0xc0) >> 6);
a4[3] = (a3[2] & 0x3f);
}
static inline void a4_to_a3(unsigned char * a3, unsigned char * a4) {
a3[0] = (a4[0] << 2) + ((a4[1] & 0x30) >> 4);
a3[1] = ((a4[1] & 0xf) << 4) + ((a4[2] & 0x3c) >> 2);
a3[2] = ((a4[2] & 0x3) << 6) + a4[3];
}
static inline unsigned char b64_lookup(unsigned char c) {
if(c >='A' && c <='Z') return c - 'A';
if(c >='a' && c <='z') return c - 71;
if(c >='0' && c <='9') return c + 4;
if(c == '+') return 62;
if(c == '/') return 63;
return 255;
}
}; //Base64 class
#endif // BASE64_H
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment