#include <stdio.h>

              #include <openssl/bio.h>

              #include <openssl/rand.h>

              int    main()

              {

                     char                      buf[20],*p;

                     unsigned                charout[20],filename[50];

                     int                         ret,len;

                     BIO                      *print;

             

                     RAND_screen();

                     strcpy(buf,"我的随机数");

                     RAND_add(buf,20,strlen(buf));

                     strcpy(buf,"23424d");

                     RAND_seed(buf,20);

                     while(1)

                     {

                            ret=RAND_status();

                            if(ret==1)

                            {

                                   printf("seeded enough!\n");

                                   break;

                            }

                            else 

                            {

                                   printf("not enough sedded!\n");

                                   RAND_poll();

                            }

                     }

                     p=RAND_file_name(filename,50);

                     if(p==NULL)

                     {

                            printf("can not get rand file\n");

                            return -1;

                     }

                     ret=RAND_write_file(p);

                     len=RAND_load_file(p,1024);

                     ret=RAND_bytes(out, 20);

                     if(ret!=1)

                     {

                            printf("err.\n");

                            return -1;

                     }

                     print=BIO_new(BIO_s_file());

                     BIO_set_fp(print,stdout,BIO_NOCLOSE);

                     BIO_write(print,out,20);

                     BIO_write(print,"\n",2);

                     BIO_free(print);

                     RAND_cleanup();

                     return 0;

              }