How do I base64 encode (decode) in C?

Question

I have binary data in an unsigned char variable. I need to convert them to PEM base64 in c. I looked in openssl library but i could not find any function. Does any body have

Answer 1

The EVP_EncodeBlock and EVP_DecodeBlock functions make it very easy:

#include 
#include 
#include 

char *base64(const unsigned char *input, int length) {
  const int pl = 4*((length+2)/3);
  char *output = calloc(pl+1, 1); //+1 for the terminating null that EVP_EncodeBlock adds on
  const int ol = EVP_EncodeBlock(output, input, length);
  if (ol != pl) { fprintf(stderr, "Whoops, encode predicted %d but we got %d\n", pl, ol); }
  return output;
}

unsigned char *decode64(const char *input, int length) {
  const int pl = 3*length/4;
  unsigned char *output = calloc(pl+1, 1);
  const int ol = EVP_DecodeBlock(output, input, length);
  if (pl != ol) { fprintf(stderr, "Whoops, decode predicted %d but we got %d\n", pl, ol); }
  return output;
}