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Merge pull request #209 from ejohnstown/aesctr-example 

Add a crypto example for AES-CTR encrypt/decrypt
pull/212/head
JacobBarthelmeh 2020-06-10 10:22:57 -06:00 committed by GitHub
parent 8dbdcac3a9 5e460127d0
commit c080ea89f5
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 333 additions and 2 deletions
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7
crypto/aes/Makefile
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@ -2,7 +2,7 @@ CC=gcc
CFLAGS=-Wall CFLAGS=-Wall
LIBS= -lwolfssl LIBS= -lwolfssl
all: aes-file-encrypt aescfb-file-encrypt all: aes-file-encrypt aescfb-file-encrypt aesctr-file-encrypt
aes-file-encrypt: aes-file-encrypt.o aes-file-encrypt: aes-file-encrypt.o
$(CC) -o $@ $^ $(CFLAGS) $(LIBS) $(CC) -o $@ $^ $(CFLAGS) $(LIBS)
@ -10,7 +10,10 @@ aes-file-encrypt: aes-file-encrypt.o
aescfb-file-encrypt: aescfb-file-encrypt.o aescfb-file-encrypt: aescfb-file-encrypt.o
$(CC) -o $@ $^ $(CFLAGS) $(LIBS) $(CC) -o $@ $^ $(CFLAGS) $(LIBS)
aesctr-file-encrypt: aesctr-file-encrypt.o
$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
.PHONY: clean .PHONY: clean
clean: clean:
rm -f *.o aes-file-encrypt aescfb-file-encrypt rm -f *.o aes-file-encrypt aescfb-file-encrypt aesctr-file-encrypt

328
crypto/aes/aesctr-file-encrypt.c 100644
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@ -0,0 +1,328 @@
/* aesctr-file-encrypt.c
*
* Copyright (C) 2006-2020 wolfSSL Inc.
*
* This file is part of wolfSSL. (formerly known as CyaSSL)
*
* wolfSSL is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* wolfSSL is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include <stdio.h>
#include <unistd.h>
#include <termios.h>
#include <wolfssl/options.h>
#include <wolfssl/wolfcrypt/aes.h>
#include <wolfssl/wolfcrypt/sha256.h>
#include <wolfssl/wolfcrypt/random.h>
#include <wolfssl/wolfcrypt/pwdbased.h>
#if defined(HAVE_PBKDF2) && !defined(NO_PWDBASED) && \
defined(WOLFSSL_AES_COUNTER)
#define SALT_SIZE 8
/*
* Makes a cryptographically secure key by stretching a user entered key
*/
int GenerateKey(WC_RNG* rng, byte* key, int size, byte* salt)
{
int ret;
ret = wc_RNG_GenerateBlock(rng, salt, SALT_SIZE);
if (ret != 0)
return -1020;
/* stretches key */
ret = wc_PBKDF2(key, key, strlen((const char*)key), salt, SALT_SIZE, 4096,
size, WC_SHA256);
if (ret != 0)
return -1030;
return 0;
}
/*
* Encrypts a file using AES-CTR
*/
int AesCtrEncrypt(Aes* aes, byte* key, int size, FILE* inFile, FILE* outFile)
{
WC_RNG rng;
byte iv[AES_BLOCK_SIZE];
byte* input;
byte* output;
byte salt[SALT_SIZE] = {0};
int ret = 0;
int length;
fseek(inFile, 0, SEEK_END);
length = ftell(inFile);
fseek(inFile, 0, SEEK_SET);
input = malloc(length);
output = malloc(length);
ret = wc_InitRng(&rng);
if (ret != 0) {
printf("Failed to initialize random number generator\n");
return -1030;
}
/* reads from inFile and writes whatever is there to the input array */
ret = fread(input, 1, length, inFile);
if (ret == 0) {
printf("Input file does not exist.\n");
return -1010;
}
ret = wc_RNG_GenerateBlock(&rng, iv, AES_BLOCK_SIZE);
if (ret != 0)
return -1020;
/* stretches key to fit size */
ret = GenerateKey(&rng, key, size, salt);
if (ret != 0)
return -1040;
/* sets key */
ret = wc_AesSetKey(aes, key, AES_BLOCK_SIZE, iv, AES_ENCRYPTION);
if (ret != 0)
return -1001;
/* encrypts the message to the output based on input length + padding */
ret = wc_AesCtrEncrypt(aes, output, input, length);
if (ret != 0)
return -1005;
/* writes to outFile */
fwrite(salt, 1, SALT_SIZE, outFile);
fwrite(iv, 1, AES_BLOCK_SIZE, outFile);
fwrite(output, 1, length, outFile);
/* closes the opened files and frees the memory*/
memset(input, 0, length);
memset(output, 0, length);
memset(key, 0, size);
free(input);
free(output);
free(key);
fclose(inFile);
fclose(outFile);
wc_FreeRng(&rng);
return ret;
}
/*
* Decrypts a file using AES-CTR
*/
int AesCtrDecrypt(Aes* aes, byte* key, int size, FILE* inFile, FILE* outFile)
{
byte* input;
byte* output;
byte* salt;
byte* iv;
byte* c;
int ret = 0;
int bufSz;
int cSz;
fseek(inFile, 0, SEEK_END);
bufSz = ftell(inFile);
fseek(inFile, 0, SEEK_SET);
input = malloc(bufSz);
output = malloc(bufSz);
/* reads from inFile and writes whatever is there to the input array */
ret = fread(input, 1, bufSz, inFile);
if (ret == 0) {
printf("Input file does not exist.\n");
return -1010;
}
salt = input;
iv = input + SALT_SIZE;
c = input + SALT_SIZE + AES_BLOCK_SIZE;
cSz = bufSz - SALT_SIZE - AES_BLOCK_SIZE;
/* replicates old key if keys match */
ret = wc_PBKDF2(key, key, strlen((const char*)key), salt, SALT_SIZE, 4096,
size, WC_SHA256);
if (ret != 0)
return -1050;
/* sets key */
ret = wc_AesSetKey(aes, key, AES_BLOCK_SIZE, iv, AES_ENCRYPTION);
if (ret != 0)
return -1002;
ret = wc_AesCtrEncrypt(aes, output, c, cSz);
if (ret != 0)
return -1006;
/* writes output to the outFile based on shortened length */
fwrite(output, 1, cSz, outFile);
/* closes the opened files and frees the memory*/
memset(input, 0, bufSz);
memset(output, 0, bufSz);
memset(key, 0, size);
free(input);
free(output);
free(key);
fclose(inFile);
fclose(outFile);
return 0;
}
/*
* help message
*/
void help()
{
printf("\n~~~~~~~~~~~~~~~~~~~~|Help|~~~~~~~~~~~~~~~~~~~~~\n\n");
printf("Usage: ./aesctr-file-encrypt <-option> <KeySize> <-i file.in> "
"<-o file.out>\n\n");
printf("Options\n");
printf("-d Decryption\n-e Encryption\n-h Help\n");
}
/*
* temporarily disables echoing in terminal for secure key input
*/
int NoEcho(char* key, int size)
{
struct termios oflags, nflags;
/* disabling echo */
tcgetattr(fileno(stdin), &oflags);
nflags = oflags;
nflags.c_lflag &= ~ECHO;
nflags.c_lflag |= ECHONL;
if (tcsetattr(fileno(stdin), TCSANOW, &nflags) != 0) {
printf("Error: tcsetattr failed to disable terminal echo\n");
return -1060;
}
printf("Unique Password: ");
if (fgets(key, size, stdin) == NULL) {
printf("Error: fgets failed to retrieve secure key input\n");
return -1070;
}
key[strlen(key) - 1] = 0;
/* restore terminal */
if (tcsetattr(fileno(stdin), TCSANOW, &oflags) != 0) {
printf("Error: tcsetattr failed to enable terminal echo\n");
return -1080;
}
return 0;
}
int SizeCheck(int size)
{
int ret = 0;
if (size != 128 && size != 192 && size != 256) {
/* if the entered size does not match acceptable size */
printf("Invalid AES key size\n");
ret = -1080;
}
return ret;
}
int main(int argc, char** argv)
{
Aes aes;
byte* key; /* user entered key */
FILE* inFile = NULL;
FILE* outFile = NULL;
const char* in;
const char* out;
int option; /* choice of how to run program */
int ret = 0; /* return value */
int size = 0;
int inCheck = 0;
int outCheck = 0;
char choice = 'n';
while ((option = getopt(argc, argv, "d:e:i:o:h")) != -1) {
switch (option) {
case 'd': /* if entered decrypt */
size = atoi(optarg);
ret = SizeCheck(size);
choice = 'd';
break;
case 'e': /* if entered encrypt */
size = atoi(optarg);
ret = SizeCheck(size);
choice = 'e';
break;
case 'h': /* if entered 'help' */
help();
break;
case 'i': /* input file */
in = optarg;
inCheck = 1;
inFile = fopen(in, "r");
break;
case 'o': /* output file */
out = optarg;
outCheck = 1;
outFile = fopen(out, "w");
break;
case '?':
if (optopt) {
printf("Ending Session\n");
return -111;
}
default:
abort();
}
}
if (inCheck == 0 || outCheck == 0) {
printf("Must have both input and output file");
printf(": -i filename -o filename\n");
}
else if (ret == 0 && choice != 'n' && inFile != NULL) {
key = malloc(size); /* sets size memory of key */
ret = NoEcho((char*)key, size);
if (choice == 'e')
AesCtrEncrypt(&aes, key, size, inFile, outFile);
else if (choice == 'd')
AesCtrDecrypt(&aes, key, size, inFile, outFile);
}
else if (choice == 'n') {
printf("Must select either -e or -d for encryption and decryption\n");
ret = -110;
}
return ret;
}
#else
int main()
{
printf("Missing pwdbased, pbkdf2, or aes-ctr from wolfSSL\n");
return 0;
}
#endif