Base64URL Use Cases

This sections cover some typical use cases related to Base64URL decoding and encoding, for a description of the all functionality refer to the API section.

Note that for simplicity, there is no error handling in the examples shown.

#1: Decoding with a large preallocated buffer

#include "bde/bde.h"

// Prepare data to decode.
const bde_enc_t * enc = "SGVsbG8gV29ybGQh";
const size_t enc_len = 16U;

// Prepare preallocated large buffer for the decoded data.
bde_dec_t dec_buf[48U];
size_t dec_buf_len = sizeof(dec_buf) / sizeof(*dec_buf);

// Perform decoding.
size_t dec_len = 0U;
bde_base64url_decode(enc, enc_len, dec_buf_len, dec_buf, &dec_len);

#2: Decoding using Variable Length Arrays

#include "bde/bde.h"

// Prepare data to decode.
const bde_enc_t * enc = "SGVsbG8gV29ybGQh";
const size_t enc_len = 16U;

// Calculate size of the decoded data prior to decoding, and allocate VLA of that size.
size_t dec_buf_len = 0U;
bde_base64url_decode_length(enc_len, &dec_buf_len);
bde_dec_t dec_buf[dec_buf_len];

// Perform decoding.
size_t dec_len = 0U;
bde_base64url_decode(enc, enc_len, dec_buf_len, dec_buf, &dec_len);

#3: Decoding using dynamic memory allocation

#include <stdlib.h>
#include "bde/bde.h"

// Prepare data to decode.
const bde_enc_t * enc = "SGVsbG8gV29ybGQh";
const size_t enc_len = 16U;

// Calculate size of the decoded data prior to decoding, and allocate VLA of that size.
size_t dec_buf_len = 0U;
bde_base64url_decode_length(enc_len, &dec_buf_len);
bde_dec_t * const dec_buf = malloc(dec_buf_len * sizeof(bde_dec_t));

// Perform decoding.
size_t dec_len = 0U;
bde_base64url_decode(enc, enc_len, dec_buf_len, dec_buf, &dec_len);

#4: Decoding in-place

#include "bde/bde.h"

// Prepare inplace buffer with the encoded data and large enough for the decoded data.
bde_dec_t inp_buf[48U] = "SGVsbG8gV29ybGQh";
const size_t inp_buf_len = sizeof(inp_buf) / sizeof(*inp_buf);
const size_t enc_len = 16U;

// Perform decoding.
size_t dec_len = 0U;
bde_base64url_decode((const bde_enc_t *)inp_buf,
                     enc_len, inp_buf_len, inp_buf, &dec_len);

#5: Encoding with a large preallocated buffer

#include "bde/bde.h"

// Prepare data to encode.
const bde_dec_t dec[] = {'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!'};
const size_t dec_len = sizeof(dec) / sizeof(*dec);

// Prepare preallocated large buffer for the encoded data.
bde_enc_t enc_buf[48U];
size_t enc_buf_len = sizeof(enc_buf) / sizeof(*enc_buf);

// Perform encoding.
size_t enc_str_len = 0U;
bde_base64url_encode(dec, dec_len, enc_buf_len, enc_buf, &enc_str_len);

#6: Encoding using Variable Length Arrays

#include "bde/bde.h"

// Prepare data to encode.
const bde_dec_t dec[] = {'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!'};
const size_t dec_len = sizeof(dec) / sizeof(*dec);

// Calculate size of the encoded data prior to decoding, and allocate VLA of that size.
size_t enc_buf_len = 0U;
bde_base64url_encode_length(dec_len, &enc_buf_len);
enc_buf_len += 1U; // Increment to have space for the NULL terminator.
bde_enc_t enc_buf[enc_buf_len];

// Perform encoding.
size_t enc_str_len = 0U;
bde_base64url_encode(dec, dec_len, enc_buf_len, enc_buf, &enc_str_len);

#7: Encoding using dynamic memory allocation

#include <stdlib.h>
#include "bde/bde.h"

// Prepare data to encode.
const bde_dec_t dec[] = {'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!'};
const size_t dec_len = sizeof(dec) / sizeof(*dec);

// Calculate size of the encoded data prior to decoding, and allocate buffer of that size.
size_t enc_buf_len = 0U;
bde_base64url_encode_length(dec_len, &enc_buf_len);
enc_buf_len += 1U; // Increment to have space for the NULL terminator.
bde_enc_t * const enc_buf = malloc(enc_buf_len * sizeof(bde_enc_t));

// Perform encoding.
size_t enc_str_len = 0U;
bde_base64url_encode(dec, dec_len, enc_buf_len, enc_buf, &enc_str_len);

#8: Encoding in-place

#include "bde/bde.h"

// Prepare inplace buffer with the decoded data and large enough for the encoded data.
bde_enc_t inp_buf[48U] = {'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!'};
const size_t inp_buf_len = sizeof(inp_buf) / sizeof(*inp_buf);
const size_t dec_len = 12U;

// Perform encoding.
size_t enc_str_len = 0U;
bde_base64url_encode((const bde_dec_t *)inp_buf,
                     dec_len, inp_buf_len, inp_buf, &enc_str_len);