openssl rsa+sha

//openssl genrsa -out test.key 1024
//openssl rsa -in test.key -pubout -out test_pub.key

#include <sys/wait.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <pthread.h>
#include <semaphore.h>
#include <openssl/sha.h>
#include <openssl/aes.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>

#define PUBKEYFILE "test_pub.key"
#define OPENSSLKEY "test.key"

int pipefd[2];

void *server()
{
    int len, i;
    char sha256[32];
    char buf[1024];
    char buf2[1024];
    
    RSA *p_rsa;
    FILE *file;
    int rsa_len;

    if((file = fopen(OPENSSLKEY, "r")) == NULL){
        perror("open key file error");
        return NULL;
    }

    if((p_rsa = PEM_read_RSAPrivateKey(file, NULL, NULL, NULL))== NULL){
        ERR_print_errors_fp(stdout);
        return NULL;
    }

    rsa_len = RSA_size(p_rsa);	

    while(1){
	count = 0;
	memset(buf,0,sizeof(buf));
        len = read(pipefd[0],buf,sizeof(buf));
		
	int packsize = *(int *)buf;
	for(i=0; i < len; i += rsa_len){
	    if(RSA_private_decrypt(rsa_len,buf + 4 + i,buf2 + i, p_rsa, RSA_NO_PADDING) < 0){
                return NULL;
    	    }
	}

        SHA256(buf2, packsize - sizeof(sha256), sha256);
        for(i=0; i < 32; i++){
            printf("%02X", sha256[i]);
        }
        printf("\n");
        if(memcmp(sha256, buf2 + packsize - sizeof(sha256), sizeof(sha256)) == 0){
            printf("~~~i ,server read %d bytes :\n%s\n",len,buf2);
        }
    }
    RSA_free(p_rsa);
    fclose(file);
}

int
main(int argc, char *argv[])
{
    int i;

    if (pipe(pipefd) == -1) {
       perror("pipe");
       exit(EXIT_FAILURE);
    }

    pthread_t threadid;
    pthread_create(&threadid, NULL, server, NULL);

    RSA *p_rsa;
    FILE *file;
    int flen,rsa_len;
    
    if((file = fopen(PUBKEYFILE, "r")) == NULL){
        perror("open key file error");
        return NULL;    
    }   

    if((p_rsa = PEM_read_RSA_PUBKEY(file, NULL, NULL, NULL)) == NULL){
	ERR_print_errors_fp(stdout);
        return NULL;
    }

    rsa_len = RSA_size(p_rsa);

    char buf[1024];
    char buf2[1024];
    char sha256[32];
    while(1){

        memset(buf,0,sizeof(buf));
        gets(buf);
        int len = strlen(buf);

        SHA256(buf, len + 1, sha256);
        for(i=0; i < 32; i++){
            printf("%02X", sha256[i]);
        }
        printf("\n");

	memcpy(buf+len+1, sha256, sizeof(sha256));

	int packsize = len + 1 + sizeof(sha256);
	int hole = rsa_len - ((packsize % rsa_len == 0) ? 16 : rsa_len % 16);
		
	*(int *)buf2 = packsize;
	packsize = packsize + hole;		

	for(i=0; i < packsize; i += rsa_len){
	    if(RSA_public_encrypt(rsa_len, buf + i, buf2 + sizeof(int) + i, p_rsa, RSA_NO_PADDING) < 0){
		return NULL;
	    }
	}

        write(pipefd[1], buf2, packsize + sizeof(int));
    }

    RSA_free(p_rsa);
    fclose(file);
}