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encrypt.cpp
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encrypt.cpp
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#include <emp-tool/emp-tool.h>
#include <gcrypt.h>
// function taken from the Metal project
void aesgcm_encrypt(emp::PRG prg, unsigned char *input, unsigned char *output, const int input_len, int *output_len, uint8_t *key){
uint8_t iv[16];
prg.random_block((emp::block*)iv);
gcry_cipher_hd_t handle;
gcry_cipher_open(&handle, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_GCM, 0);
gcry_cipher_setkey(handle, key, 16);
gcry_cipher_setctr(handle, iv, 16);
int blocks = input_len / 16;
if(input_len % 16 != 0) blocks ++;
memcpy(output, iv, 16);
gcry_cipher_encrypt(handle, &output[16], 16 * blocks, input, 16 * blocks);
uint8_t tag[16];
gcry_cipher_gettag(handle, tag, 16);
memcpy(&output[16 + 16 * blocks], tag, 16);
*output_len = 16 /*IV*/ + 16 * blocks /*data*/ + 16 /*tag*/;
gcry_cipher_close(handle);
}
void load_public_key(eb_t eb, int party){
char filename[100];
sprintf(filename, "pk_%d", party);
FILE *fp;
fp = fopen(filename, "rb");
int eb_size;
if(fp == NULL){
printf("cannot open the public key file.\n");
exit(1);
}
fread(&eb_size, sizeof(int), 1, fp);
uint8_t eb_buffer[EB_SIZE];
memset(eb_buffer, 0, EB_SIZE * sizeof(uint8_t));
fread(eb_buffer, eb_size, sizeof(uint8_t), fp);
eb_read_bin(eb, eb_buffer, eb_size);
}
int main(int argc, char **argv){
if(argc != 3){
printf("format: encrypt <filename_in> <filename_out>\n");
return 0;
}
FILE *fp;
int filesize_in;
fp = fopen(argv[1], "rb");
if(fp == NULL){
printf("cannot open the input file.\n");
return 0;
}
fseek(fp, 0, SEEK_END);
filesize_in = ftell(fp);
fseek(fp, 0, SEEK_SET);
unsigned char *message = (unsigned char*) calloc(16 + filesize_in, 1);
unsigned char *message_encrypted = (unsigned char*) calloc(16 + 16 + 16 + filesize_in, 1);
fread(message, filesize_in, 1, fp);
fclose(fp);
emp::block s;
emp::block k;
emp::PRG prg;
prg.random_block(&s);
emp::PRG prg_s(&s);
prg_s.random_block(&k);
bn_t q;
eb_t g;
const eb_t *gTbl;
emp::initialize_relic();
eb_curve_get_gen(g);
eb_curve_get_ord(q);
gTbl = eb_curve_get_tab();
bn_t r_1;
bn_t r_2;
bn_t r_3;
emp::bn_newl(r_1, r_2, r_3);
prg.random_bn(r_1);
prg_s.random_bn(r_2);
prg_s.random_bn(r_3);
eb_t pk_1;
eb_t pk_2;
eb_t pk_3;
emp::eb_newl(pk_1, pk_2, pk_3);
load_public_key(pk_1, 1);
load_public_key(pk_2, 2);
load_public_key(pk_3, 3);
int output_len;
aesgcm_encrypt(prg, message, message_encrypted, filesize_in, &output_len, (uint8_t*)&k);
eb_t c_1_part_1;
eb_t c_1_part_2_num;
emp::block c_1_part_2;
eb_t c_2_part_1;
eb_t c_2_part_2_num;
emp::block c_2_part_2;
eb_t c_3_part_1;
eb_t c_3_part_2_num;
emp::block c_3_part_2;
emp::eb_newl(c_1_part_1, c_1_part_2_num, c_2_part_1, c_2_part_2_num, c_3_part_1, c_3_part_2_num);
emp::eb_mul_fix_norm(c_1_part_1, gTbl, r_1);
emp::eb_mul_fix_norm(c_2_part_1, gTbl, r_2);
emp::eb_mul_fix_norm(c_3_part_1, gTbl, r_3);
emp::eb_mul_norm(c_1_part_2_num, pk_1, r_1);
emp::eb_mul_norm(c_2_part_2_num, pk_2, r_2);
emp::eb_mul_norm(c_3_part_2_num, pk_3, r_3);
c_1_part_2 = emp::KDF(c_1_part_2_num);
c_2_part_2 = emp::KDF(c_2_part_2_num);
c_3_part_2 = emp::KDF(c_3_part_2_num);
c_1_part_2 = emp::xorBlocks(c_1_part_2, s);
c_2_part_2 = emp::xorBlocks(c_2_part_2, k);
c_3_part_2 = emp::xorBlocks(c_3_part_2, k);
// output file format
// size for c_1_part_1, c_2_part_1, c_3_part_1, message_encrypted, message_original_size
// c_1_part_1, c_2_part_1, c_3_part_1 (stored in EB_SIZE!)
// c_1_part_2, c_2_part_2, c_3_part_2
// message_encrypted
int c_1_part_1_size;
int c_2_part_1_size;
int c_3_part_1_size;
c_1_part_1_size = eb_size_bin(c_1_part_1, ECC_PACK);
c_2_part_1_size = eb_size_bin(c_2_part_1, ECC_PACK);
c_3_part_1_size = eb_size_bin(c_3_part_1, ECC_PACK);
uint8_t c_1_part_1_buffer[EB_SIZE];
uint8_t c_2_part_1_buffer[EB_SIZE];
uint8_t c_3_part_1_buffer[EB_SIZE];
memset(c_1_part_1_buffer, 0, sizeof(uint8_t) * EB_SIZE);
memset(c_2_part_1_buffer, 0, sizeof(uint8_t) * EB_SIZE);
memset(c_3_part_1_buffer, 0, sizeof(uint8_t) * EB_SIZE);
eb_write_bin(c_1_part_1_buffer, c_1_part_1_size, c_1_part_1, ECC_PACK);
eb_write_bin(c_2_part_1_buffer, c_2_part_1_size, c_2_part_1, ECC_PACK);
eb_write_bin(c_3_part_1_buffer, c_3_part_1_size, c_3_part_1, ECC_PACK);
fp = fopen(argv[2], "wb");
if(fp == NULL){
printf("cannot open the output file.\n");
exit(1);
}
fwrite(&c_1_part_1_size, sizeof(int), 1, fp);
fwrite(&c_2_part_1_size, sizeof(int), 1, fp);
fwrite(&c_3_part_1_size, sizeof(int), 1, fp);
fwrite(&output_len, sizeof(int), 1, fp);
fwrite(&filesize_in, sizeof(int), 1, fp);
fwrite(c_1_part_1_buffer, sizeof(uint8_t), EB_SIZE, fp);
fwrite(c_2_part_1_buffer, sizeof(uint8_t), EB_SIZE, fp);
fwrite(c_3_part_1_buffer, sizeof(uint8_t), EB_SIZE, fp);
fwrite(&c_1_part_2, sizeof(emp::block), 1, fp);
fwrite(&c_2_part_2, sizeof(emp::block), 1, fp);
fwrite(&c_3_part_2, sizeof(emp::block), 1, fp);
fwrite(message_encrypted, sizeof(unsigned char), output_len, fp);
fclose(fp);
emp::bn_freel(r_1, r_2, r_3);
emp::eb_freel(pk_1, pk_2, pk_3);
free(message);
free(message_encrypted);
emp::eb_freel(c_1_part_1, c_1_part_2_num, c_2_part_1, c_2_part_2_num, c_3_part_1, c_3_part_2_num);
return 0;
}