File syn_base64.h¶

FileList > src > syntropic > util > syn_base64.h

RFC 4648 Base64 and Base64URL encoding and decoding. More...

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

Public Functions¶

Type	Name
bool	syn_base64_decode (const char * src, size_t src_len, uint8_t * dst, size_t dst_size, size_t * out_len) Decode an RFC 4648 standard Base64 string into binary data.
bool	syn_base64_encode (const uint8_t * src, size_t src_len, char * dst, size_t dst_size, size_t * out_len) Encode binary data to standard RFC 4648 Base64 string.
bool	syn_base64url_decode (const char * src, size_t src_len, uint8_t * dst, size_t dst_size, size_t * out_len) Decode an RFC 4648 Base64URL string into binary data.
bool	syn_base64url_encode (const uint8_t * src, size_t src_len, char * dst, size_t dst_size, bool with_padding, size_t * out_len) Encode binary data to RFC 4648 Base64URL string.

Public Static Functions¶

Type	Name
size_t	syn_base64_calc_encoded_size (size_t raw_len) Calculate the buffer size needed for standard Base64 encoding.
size_t	syn_base64_calc_max_decoded_size (size_t b64_len) Calculate the maximum binary buffer size needed to decode a Base64 string.

Detailed Description¶

Implements pure C99 zero-allocation streaming Base64 (standard and URL-safe). Supports both padded and unpadded Base64URL formats, whitespace-tolerant decoding, and precise buffer length calculation.

** **

const uint8_t data[] = "Hello World";
char b64[32];
size_t out_len = 0;
syn_base64_encode(data, sizeof(data) - 1, b64, sizeof(b64), &out_len);
// b64 is "SGVsbG8gV29ybGQ="

** **

uint8_t bin[32];
size_t bin_len = 0;
if (syn_base64_decode(b64, out_len, bin, sizeof(bin), &bin_len)) {
    // Decoded successfully
}

Public Functions Documentation¶

function syn_base64_decode¶

Decode an RFC 4648 standard Base64 string into binary data.

bool syn_base64_decode (
    const char * src,
    size_t src_len,
    uint8_t * dst,
    size_t dst_size,
    size_t * out_len
)

Automatically skips whitespace characters (spaces, tabs, CR, LF). Rejects invalid non-base64 characters and malformed padding.

Parameters:

src Input Base64 string (null-terminated or bounded by src_len).
src_len Length of input string (or 0 to determine via strlen).
dst [out] Output binary buffer.
dst_size Capacity of output buffer in bytes.
out_len [out] Optional pointer to receive actual binary bytes written.

Returns:

true on success, false if input contains invalid characters or destination is too small.

function syn_base64_encode¶

Encode binary data to standard RFC 4648 Base64 string.

bool syn_base64_encode (
    const uint8_t * src,
    size_t src_len,
    char * dst,
    size_t dst_size,
    size_t * out_len
)

Uses alphabet [A-Za-z0-9+/] and adds = padding when needed. Always null-terminates the output if dst_size > 0.

Parameters:

src Input binary data.
src_len Length of input binary data in bytes.
dst [out] Output string buffer.
dst_size Capacity of output buffer in bytes (must be >= syn_base64_calc_encoded_size(src_len)).
out_len [out] Optional pointer to receive character length written (excluding null).

Returns:

true on success, false if parameters are invalid or buffer is too small.

function syn_base64url_decode¶

Decode an RFC 4648 Base64URL string into binary data.

bool syn_base64url_decode (
    const char * src,
    size_t src_len,
    uint8_t * dst,
    size_t dst_size,
    size_t * out_len
)

Supports both padded (=) and unpadded URL-safe strings.

Parameters:

src Input Base64URL string.
src_len Length of input string (or 0 to determine via strlen).
dst [out] Output binary buffer.
dst_size Capacity of output buffer in bytes.
out_len [out] Optional pointer to receive actual binary bytes written.

Returns:

true on success, false on invalid input or insufficient buffer capacity.

function syn_base64url_encode¶

Encode binary data to RFC 4648 Base64URL string.

bool syn_base64url_encode (
    const uint8_t * src,
    size_t src_len,
    char * dst,
    size_t dst_size,
    bool with_padding,
    size_t * out_len
)

Uses URL-safe alphabet [A-Za-z0-9-_].

Parameters:

src Input binary data.
src_len Length of input binary data in bytes.
dst [out] Output string buffer.
dst_size Capacity of output buffer in bytes.
with_padding If true, appends = padding; if false, omits padding (standard JWT format).
out_len [out] Optional pointer to receive character length written (excluding null).

Returns:

true on success, false if buffer is too small or parameters invalid.

Public Static Functions Documentation¶

function syn_base64_calc_encoded_size¶

Calculate the buffer size needed for standard Base64 encoding.

static inline size_t syn_base64_calc_encoded_size (
    size_t raw_len
)

Includes padding (=) and space for the null terminator.

Parameters:

raw_len Number of raw binary bytes.

Returns:

Total character buffer capacity needed (including null terminator).

function syn_base64_calc_max_decoded_size¶

Calculate the maximum binary buffer size needed to decode a Base64 string.

static inline size_t syn_base64_calc_max_decoded_size (
    size_t b64_len
)

Parameters:

b64_len Number of characters in Base64 string.

Returns:

Maximum number of binary bytes after decoding.

The documentation for this class was generated from the following file src/syntropic/util/syn_base64.h