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vincent wong
Created November 8, 2019 © GPL3+

IoT Key Vault

IoT Key Vault

IntermediateFull instructions provided15 hours66
IoT Key Vault

Things used in this project

Hardware components

Azure Sphere MT3620 Starter Kit
Avnet Azure Sphere MT3620 Starter Kit
×1

Software apps and online services

Microsoft Azure IoT Hub
Microsoft visual studio 2019

Story

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Code

device_twin.c

C/C++
full device_twin.c
/*
 * Base64 encoding/decoding (RFC1341)
 * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#include <string.h>
#include <stdlib.h>
#include <time.h>

#include "base64.h"

static const unsigned char base64_table[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/**
 * base64_encode - Base64 encode
 * @src: Data to be encoded
 * @len: Length of the data to be encoded
 * @out_len: Pointer to output length variable, or %NULL if not used
 * Returns: Allocated buffer of out_len bytes of encoded data,
 * or %NULL on failure
 *
 * Caller is responsible for freeing the returned buffer. Returned buffer is
 * nul terminated to make it easier to use as a C string. The nul terminator is
 * not included in out_len.
 */
unsigned char* base64_encode(const unsigned char* src, size_t len,
	size_t* out_len)
{
	unsigned char* out, * pos;
	const unsigned char* end, * in;
	size_t olen;
	int line_len;

	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
	olen += olen / 72; /* line feeds */
	olen++; /* nul termination */
	if (olen < len)
		return NULL; /* integer overflow */
	out = malloc(olen);
	if (out == NULL)
		return NULL;

	end = src + len;
	in = src;
	pos = out;
	line_len = 0;
	while (end - in >= 3) {
		*pos++ = base64_table[in[0] >> 2];
		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
		*pos++ = base64_table[in[2] & 0x3f];
		in += 3;
		line_len += 4;
		if (line_len >= 72) {
			*pos++ = '\n';
			line_len = 0;
		}
	}

	if (end - in) {
		*pos++ = base64_table[in[0] >> 2];
		if (end - in == 1) {
			*pos++ = base64_table[(in[0] & 0x03) << 4];
			*pos++ = '=';
		}
		else {
			*pos++ = base64_table[((in[0] & 0x03) << 4) |
				(in[1] >> 4)];
			*pos++ = base64_table[(in[1] & 0x0f) << 2];
		}
		*pos++ = '=';
		line_len += 4;
	}

	if (line_len)
		* pos++ = '\n';

	*pos = '\0';
	if (out_len)
		* out_len = pos - out;
	return out;
}


void base64_encode_inplace(const unsigned char* src, size_t len,
	size_t* out_len)
{
	unsigned char* out, * pos;
	const unsigned char* end, * in;
	size_t olen;
	int line_len;

	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
	olen += olen / 72; /* line feeds */
	olen++; /* nul termination */
	if (olen < len)
		return NULL; /* integer overflow */
	out = malloc(olen);
	if (out == NULL)
		return NULL;

	end = src + len;
	in = src;
	pos = out;
	line_len = 0;
	while (end - in >= 3) {
		*pos++ = base64_table[in[0] >> 2];
		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
		*pos++ = base64_table[in[2] & 0x3f];
		in += 3;
		line_len += 4;
		if (line_len >= 72) {
			*pos++ = '\n';
			line_len = 0;
		}
	}

	if (end - in) {
		*pos++ = base64_table[in[0] >> 2];
		if (end - in == 1) {
			*pos++ = base64_table[(in[0] & 0x03) << 4];
			*pos++ = '=';
		}
		else {
			*pos++ = base64_table[((in[0] & 0x03) << 4) |
				(in[1] >> 4)];
			*pos++ = base64_table[(in[1] & 0x0f) << 2];
		}
		*pos++ = '=';
		line_len += 4;
	}

	if (line_len)
		* pos++ = '\n';

	*pos = '\0';
	if (out_len)
		* out_len = pos - out;
	return out;
}


/**
 * base64_decode - Base64 decode
 * @src: Data to be decoded
 * @len: Length of the data to be decoded
 * @out_len: Pointer to output length variable
 * Returns: Allocated buffer of out_len bytes of decoded data,
 * or %NULL on failure
 *
 * Caller is responsible for freeing the returned buffer.
 */
unsigned char* base64_decode(const unsigned char* src, size_t len,
	size_t* out_len)
{
	unsigned char dtable[256], * out, * pos, block[4], tmp;
	size_t i, count, olen;
	int pad = 0;

	memset(dtable, 0x80, 256);
	for (i = 0; i < sizeof(base64_table) - 1; i++)
		dtable[base64_table[i]] = (unsigned char)i;
	dtable['='] = 0;

	count = 0;
	for (i = 0; i < len; i++) {
		if (dtable[src[i]] != 0x80)
			count++;
	}

	if (count == 0 || count % 4)
		return NULL;

	olen = count / 4 * 3;
	pos = out = malloc(olen);
	if (out == NULL)
		return NULL;

	count = 0;
	for (i = 0; i < len; i++) {
		tmp = dtable[src[i]];
		if (tmp == 0x80)
			continue;

		if (src[i] == '=')
			pad++;
		block[count] = tmp;
		count++;
		if (count == 4) {
			*pos++ = (block[0] << 2) | (block[1] >> 4);
			*pos++ = (block[1] << 4) | (block[2] >> 2);
			*pos++ = (block[2] << 6) | block[3];
			count = 0;
			if (pad) {
				if (pad == 1)
					pos--;
				else if (pad == 2)
					pos -= 2;
				else {
					/* Invalid padding */
					free(out);
					return NULL;
				}
				break;
			}
		}
	}

	*out_len = pos - out;
	return out;
}

Credits

vincent wong
81 projects • 205 followers

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