From 7cdde735604de3d1be54fc535df3985b89eebd0a Mon Sep 17 00:00:00 2001 From: Mark Haines Date: Mon, 15 Jun 2015 17:48:09 +0100 Subject: Add base64 encoders and decoders --- src/base64.cpp | 118 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 src/base64.cpp (limited to 'src/base64.cpp') diff --git a/src/base64.cpp b/src/base64.cpp new file mode 100644 index 0000000..6428424 --- /dev/null +++ b/src/base64.cpp @@ -0,0 +1,118 @@ +#include "axolotl/base64.hh" + + +namespace { + +static const std::uint8_t ENCODE_BASE64[64] = { + 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, + 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, + 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, + 0x59, 0x5A, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, + 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, + 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, + 0x77, 0x78, 0x79, 0x7A, 0x30, 0x31, 0x32, 0x33, + 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x2B, 0x2F, +}; + +static const std::uint8_t E = -1; + +static const std::uint8_t DECODE_BASE64[128] = { +/* 0x0 0x1 0x2 0x3 0x4 0x5 0x6 0x7 0x8 0x9 0xA 0xB 0xC 0xD 0xE 0xF */ + E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, + E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, + E, E, E, E, E, E, E, E, E, E, E, 62, E, E, E, 63, + 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, E, E, E, E, E, E, + E, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, + 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, E, E, E, E, E, + E, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, + 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, E, E, E, E, E, +}; + +} // namespace + + +std::size_t axolotl::encode_base64_length( + std::size_t input_length +) { + return 4 * ((input_length + 2) / 3) + (input_length + 2) % 3 - 2; +} + + +void axolotl::encode_base64( + std::uint8_t const * input, std::size_t input_length, + std::uint8_t * output +) { + std::uint8_t const * end = input + (input_length / 3) * 3; + std::uint8_t const * pos = input; + while (pos != end) { + unsigned value = pos[0]; + value <<= 8; value |= pos[1]; + value <<= 8; value |= pos[2]; + pos += 3; + output[3] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; output[2] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; output[1] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; output[0] = ENCODE_BASE64[value]; + output += 4; + } + unsigned remainder = input + input_length - pos; + if (remainder) { + unsigned value = pos[0]; + if (remainder == 2) { + value <<= 8; value |= pos[1]; + value <<= 2; + output[2] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; + } else { + value <<= 4; + } + output[1] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; + output[0] = ENCODE_BASE64[value]; + } +} + + +std::size_t axolotl::decode_base64_length( + std::size_t input_length +) { + if (input_length % 4 == 1) { + return std::size_t(-1); + } else { + return 3 * ((input_length + 2) / 4) + (input_length + 2) % 4 - 2; + } +} + + +void axolotl::decode_base64( + std::uint8_t const * input, std::size_t input_length, + std::uint8_t * output +) { + std::uint8_t const * end = input + (input_length / 4) * 4; + std::uint8_t const * pos = input; + while (pos != end) { + unsigned value = DECODE_BASE64[pos[0] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[1] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[2] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[3] & 0x7F]; + pos += 4; + output[2] = value; + value >>= 8; output[1] = value; + value >>= 8; output[0] = value; + output += 3; + } + unsigned remainder = input + input_length - pos; + if (remainder) { + unsigned value = DECODE_BASE64[pos[0] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[1] & 0x7F]; + if (remainder == 3) { + value <<= 6; value |= DECODE_BASE64[pos[2] & 0x7F]; + value >>= 2; + output[1] = value; + value >>= 8; + } else { + value >>= 4; + } + output[0] = value; + } +} -- cgit v1.2.3