Generic Base64 codec. More...

#include <base64.h>

Public Types
using	alphabet_type = std::array< char, 64 >
	type of all alphabet. More...

using	inverse_alphabet_type = std::array< int8_t, 256 >
	type of all inverse mappings of alphabets. More...

Static Public Member Functions
template<Base64Endianess endianess, bool PaddingMandatory, char PaddingChar>
static std::vector< uint8_t >	decode (const std::string &encoded, const inverse_alphabet_type &inverse_alphabet)

template<Base64Endianess endianess, bool PaddingMandatory, char PaddingChar>
static std::string	encode (const std::vector< uint8_t > &data, const alphabet_type &alphabet)

template<Base64Endianess endianess, bool PaddingMandatory, char PaddingChar>
static std::string	encode (const std::string &data, const alphabet_type &alphabet)

template<Base64Endianess endianess, bool PaddingMandatory, char PaddingChar>
static std::string	encode (const std::string_view &data, const alphabet_type &alphabet)

template<Base64Endianess endianess, bool PaddingMandatory, char PaddingChar>
static std::string	encode (const char *data, const alphabet_type &alphabet)

Static Private Member Functions
template<Base64Endianess endianess, bool PaddingMandatory, char PaddingChar, typename T >
static std::string	encode_impl (const T &data, const alphabet_type &alphabet)

Detailed Description

Generic Base64 codec.

Base64 comes in many flavours:

RFC4648 used by HTTP
crypt
bcrypt
pbkdf2 in MCF
UUencode

they differ by

alphabet
endianness
padding

Base64Impl provides generic encode and decode methods which are parametrized by Endianness, Padding.

Parametrization with templates allows to provide:

one implementation for all combinations
without extra runtime overhead as dead code is removed by the compiler

Endianness

Little Endian

using Alphabet=Crypt

octet(hex):        55
uint32:      ........ ........  01010101 (LSB)
uint32:      ...... ...... ....01 010101 (LSB)
sextet(hex):                    1     15
Alphabet:                       /      J

Out: J/

Big Endian

using Alphabet=Crypt

octet(hex):        55
uint32:      01010101 ........  ........ (LSB)
uint32:      010101 01.... ...... ...... (LSB)
sextet(hex):     15     10
Alphabet:         J      E

Out: JE

Padding

If padding is defined mandatory,

at encode() each group of 4 sextets is filled by with the padding character.
at decode() input must have padding.

If padding is not mandatory,

at encode() no padding is added.
at decode() padding is accepted, but not required.

Member Typedef Documentation

◆ alphabet_type

using Base64Impl::alphabet_type = std::array<char, 64>

type of all alphabet.

◆ inverse_alphabet_type

using Base64Impl::inverse_alphabet_type = std::array<int8_t, 256>

type of all inverse mappings of alphabets.

-1 invalid
0-63 position into alphabet