    ,    ,    
,    .   -
   ,    - SHA  
.  SHA (Secure Hash Algorithm,    -
)       ( ,
message digest),      
(National Security Agency, NSA)       
     (NIST) ( 
  , FIPS 186).    -
    ,    -
  (  )     - -
  (  128  160 ).    
  .      
  -.  ,     (-
,   )     -.
      -,
     .   -
    MD4  MD5.   - SHA
,       . ,
  -       .
      ,      -
     .      
       ,   
 .        ,   -
.    ,       .

<-       ->



  
 

|      10110001->

  
  
 
   
  
add_keyboard_randomness()



11100101100000110101

01111010101110100010
00100010110101011000

 

1111010000->

  
    
/dev/random  /dev/urandom

. .1.      

     ,      -
  .       -
 ,      .   -
      ,     

    425