Dear all,
I want to combine OpenMP and RSA_public_encrypt and RSA_private_decrypt
routines. However, I was confused by a weird bug for a few days.
In the attached program, if I generated 2 threads for parallel encryption
and decryption, everything works well. If I generated 3 or more threads, the
RSA_public_encrypt routine works fine. All strings are successfully
encrypted (encrypt_len=256). However, the RSA_private_decrypt routine went
wrong, that is, only one thread works properly, all the other threads failed
to decrypt some of the strings (decrypt_len=-1, rsa_eay_private_decrypt
padding check failed). If there are 1000 strings and 4 threads, the total
number of string failed to decrypt went around 710 (some times as low as
around 200). So as expected, if I use 4 threads for parallel
RSA_public_encrypt and one thread for RSA_private_decrypt, nothing went
wrong.
It would be great if you could give some ideas. Thanks very much.
#include <openssl/rsa.h>
#include <openssl/rand.h>
#include <stdio.h>
#include <string.h>
#include <omp.h>
#define KEY_LENGTH 2048
#define EN_SIZE 200 //number of chars in a string
#define STR_NUM 1000 //number of strings to be encrypted
#define PUB_EXP 3
int main() {
int i, j, k;
int encrypt_len;
int decrypt_len;
char *en_m[STR_NUM]; //array of pointers for the input strings
char *tm_m[STR_NUM]; //array of pointers for the encrypted strings
char *rm_m[STR_NUM]; //array of pointers for the encrypted strings
// rm_m read back tm_m through a .txt file
char *de_m[STR_NUM]; //array of pointers for the decrypted strings
// Generate key pair
RSA *keypair = RSA_generate_key(KEY_LENGTH, PUB_EXP, NULL, NULL);
FILE *f;
f = fopen("message.txt", "r");
if(f==NULL){
perror ("Error in locating the file to be encrypted");
return(-1);
}
for (k=0; k<STR_NUM; k++){
en_m[k] = malloc(sizeof(char)*(EN_SIZE+1));
tm_m[k] = malloc(sizeof(char)*(RSA_size(keypair)));
de_m[k] = malloc(sizeof(char)*(EN_SIZE+1));
fread(en_m[k], 1, EN_SIZE, f);
en_m[k][EN_SIZE] = '\0';
}
fclose(f);
printf("The length of string to be encrypted in each encryption = %d
bytes\n", EN_SIZE);
printf("Total number of the string message to be encrypted = %d\n",
STR_NUM);
omp_set_num_threads(4); //set up 4 threads
kmp_set_defaults("KMP_AFFINITY=scatter");
// Encryption
#pragma omp parallel for shared(en_m, tm_m, keypair) private(i,
encrypt_len) schedule(static)
for(i=0; i<STR_NUM; i++)
encrypt_len = RSA_public_encrypt(EN_SIZE, (unsigned char*)en_m[i],
(unsigned char*)tm_m[i], keypair, RSA_PKCS1_OAEP_PADDING);
printf("Encryption has been finished\n");
f = fopen("en_message.txt", "w");
for (k=0; k<STR_NUM; k++){
fwrite(tm_m[k], sizeof(*tm_m[k]), RSA_size(keypair), f);
}
fclose(f);
/************************************************************************************************/
f = fopen("en_message.txt", "r");
for (k=0; k<STR_NUM; k++){
rm_m[k] = malloc(sizeof(char)*(RSA_size(keypair)));
fread(rm_m[k], 1, RSA_size(keypair), f);
}
fclose(f);
// Decryption
#pragma omp parallel for shared(rm_m, de_m, keypair) private(j,
decrypt_len) schedule(static)
for (j=0; j<STR_NUM; j++)
decrypt_len = RSA_private_decrypt(RSA_size(keypair), (unsigned
char*)rm_m[j], (unsigned char*)de_m[j], keypair, RSA_PKCS1_OAEP_PADDING);
printf("Decryption has been finished.\n");
int temp = 0;
for (k=0; k<STR_NUM; k++){
if (strcmp(en_m[k], de_m[k])!=0)
temp += 1;
}
printf("Total number of dismatch = %d\n", temp);
RSA_free(keypair);
for (k=0; k<STR_NUM; k++){
free(en_m[k]);
free(de_m[k]);
free(tm_m[k]);
free(rm_m[k]);
}
return 0;
}
--
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