Erreur de segmentation

void
enCrypt(void) {
    char keyFile[MAX_FILENAME+EXTENSION_LENGTH+1], encryptFile[MAX_FILENAME+1];
    char outFile[MAX_FILENAME+1];
    FILE *PK,*OF;
    mpz_t e,n,m,c;
    int blockSize, *block, i, j;
    char *cBlock, scratch[4];

    /* initialize our integers */
    mpz_init(e);
    mpz_init(n);
    mpz_init(m);
    mpz_init(c);

    /* grab name of file to encrypt */
    printf("Enter filename to encrypt\n");
    fgets(encryptFile,MAX_FILENAME+1,stdin);
    encryptFile[strlen(encryptFile)-1] = NULL;
getchar();

    /* grab name of ciphertext */
    printf("Enter filename to store ciphertext in\n");
fgets(outFile,MAX_FILENAME+1,stdin);
    outFile[strlen(outFile)-1] = NULL;
getchar();

    /* grab name of keyfile */
    printf("Enter filename for the public key to encrypt this file with\n");
    printf("WITHOUT the .public extension\n");
    fgets(keyFile,MAX_FILENAME+1,stdin);
    keyFile[strlen(keyFile)-1] = NULL;

    strcat(keyFile,".public");

    /* read in key */
    PK=fopen(keyFile,"r");
    mpz_inp_str(e,PK,10);
    mpz_inp_str(n,PK,10);
    fclose(PK);

#if 0
    printf("e      = %s\n",mpz_get_str(NULL,10,e));
    printf("n      = %s\n",mpz_get_str(NULL,10,n));
#endif

/* compute blocksize */
    blockSize = (strlen(mpz_get_str(NULL,10,n)) - 1) / 3;
    block = calloc(blockSize+1, sizeof(int));
    cBlock = calloc(3 * blockSize + 1, sizeof(char));

#if 0
    printf("blockSize = %d\n",blockSize);
#endif

    PK=fopen(encryptFile,"r");
    OF=fopen(outFile,"w+");

    /* loop thru plaintext, reading in blocks */
    while(!feof(PK)) {

        /* read in enough chars for block */
        for(i=0;i<blockSize && !feof(PK);i++) {
            block[i] = fgetc(PK);

            if(block[i] == EOF) {
                block[i] = 0;
                break;
            }
 else if((block[i] < 32) || (block[i] > 127))
                block[i] = ' ';

            block[i+1]=0;
        }

        /* concat decimal representations */
        for(j=0;j<i;j++) {
            sprintf(scratch,"%d",block[j]);
            strcat(cBlock,scratch);
        }

        /* put string into integer type */
        mpz_set_str(m,cBlock,10);

        /* c = (m^e) % n ... RSA encryption */
        mpz_powm(c,m,e,n);

        /* write out encrypted block */
        mpz_out_str(OF,10,c);
        fprintf(OF,"\n");
        cBlock[0]='\0';

 fclose(PK);
    fclose(OF);

    mpz_clear(e);
    mpz_clear(n);
    mpz_clear(m);
    mpz_clear(c);
    free(cBlock);
    free(block);
}   }