c-libp2p/crypto/encoding/base64.c

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2016-11-03 16:15:18 +00:00
//
// base64.c
// c-ipfs
//
// Created by John Jones on 10/31/16.
// Copyright © 2016 JMJAtlanta. All rights reserved.
//
#include <stdio.h>
#include <math.h>
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#include "mbedtls/base64.h"
/**
* encode using base64
* @param input_data the data to be encoded
* @param input_length the length of the input data
* @param output_data where the data is to be stored
* @param max_output_length the max size of the output_data
* @param bytes_written the number of bytes written to output_data
* @returns true(1) on success, otherwise false
*/
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int libp2p_crypto_encoding_base64_encode(const unsigned char* input_data, size_t input_length, unsigned char* output_data, size_t max_output_length, size_t* bytes_written) {
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int retVal = mbedtls_base64_encode(output_data, max_output_length, bytes_written, input_data, input_length);
return retVal == 0;
}
/**
* decode something that was encoded as base64
* @param input_data the data to decode
* @param input_length the length of the input data
* @param output_data the buffer to store the output
* @param max_output_length the length of the output buffer
* @param bytes_written the number of bytes written to output_data
* @returns a pointer to the decoded data
*/
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int libp2p_crypto_encoding_base64_decode(const unsigned char* input_data, size_t input_length, unsigned char* output_data, size_t max_output_length, size_t* bytes_written) {
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int retVal = mbedtls_base64_decode(output_data, max_output_length, bytes_written, input_data, input_length);
return retVal == 0;
}
/**
* calculate the max length in bytes of an encoding of n source bytes
* @param encoded_size the size of the encoded string
* @returns the maximum size in bytes had the string been decoded
*/
size_t libp2p_crypto_encoding_base64_decode_size(size_t encoded_size) {
size_t radix = 64;
double bits_per_digit = log2(radix); // each char represents about 6 bits
return ceil(encoded_size * bits_per_digit / 8);
}
/**
* calculate the max length in bytes of a decoding of n source bytes
* @param decoded_size the size of the incoming string to be encoded
* @returns the maximum size in bytes had the string been encoded
*/
size_t libp2p_crypto_encoding_base64_encode_size(size_t decoded_size) {
/*
size_t radix = 64;
double bits_per_digit = log2(radix);
return ceil( (8 / bits_per_digit * decoded_size) + 1);
*/
return (decoded_size / 3 + (decoded_size % 3 != 0)) * 4 + 1;
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}