Howto base64 encode and decode with C and OpenSSL

The first here is how to base64 encode a chunk of memory using OpenSSL.

#include <string.h>#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/buffer.h>char *base64(const unsigned char *input, int length);

int main(int argc, char **argv)
{
char *output = base64(“YOYO!”, sizeof(“YOYO!”));
printf(“Base64: *%s*\n“, output);
free(output);
}

char *base64(const unsigned char *input, int length)
{
BIO *bmem, *b64;
BUF_MEM *bptr;

b64 = BIO_new(BIO_f_base64());
bmem = BIO_new(BIO_s_mem());
b64 = BIO_push(b64, bmem);
BIO_write(b64, input, length);
BIO_flush(b64);
BIO_get_mem_ptr(b64, &bptr);

char *buff = (char *)malloc(bptr->length);
memcpy(buff, bptr->data, bptr->length-1);
buff[bptr->length-1] = 0;

BIO_free_all(b64);

return buff;
}

base64 decode goes here:

#include <string.h>

#include <openssl/sha.h>

#include <openssl/hmac.h>

#include <openssl/evp.h>

#include <openssl/bio.h>

#include <openssl/buffer.h>

char *unbase64(unsigned char *input, int length);int main(int argc, char **argv)
{
char *output = unbase64(“WU9ZTyEA\n“, strlen(“WU9ZTyEA\n“));
printf(“Unbase64: *%s*\n“, output);
free(output);
}

char *unbase64(unsigned char *input, int length)
{
BIO *b64, *bmem;

char *buffer = (char *)malloc(length);
memset(buffer, 0, length);

b64 = BIO_new(BIO_f_base64());
bmem = BIO_new_mem_buf(input, length);
bmem = BIO_push(b64, bmem);

BIO_read(bmem, buffer, length);

BIO_free_all(bmem);

return buffer;
}

words of Swami Vivekananda

Be a hero. Always say, “I have no fear.” Tell this to everyone — “Have no fear.”. Fear is death, fear is sin, fear is hell, fear is unrighteousness, fear is wrong life. All the negative thoughts and ideas that are in the world have proceeded from this evil spirit of fear.

These words can help you in realizing your potential.

Bye