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    Command:

    RAND_add

    
    
    
    

    SYNOPSIS

            #include <openssl/rand.h>
    
            void RAND_seed(const void *buf, int num);
    
            void RAND_add(const void *buf, int num, double entropy);
    
            int  RAND_status(void);
    
            int  RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam);
            void RAND_screen(void);
    
    
    

    DESCRIPTION

           RAND_add() mixes the num bytes at buf into the PRNG state. Thus, if the
           data at buf are unpredictable to an adversary, this increases the
           uncertainty about the state and makes the PRNG output less predictable.
           Suitable input comes from user interaction (random key presses, mouse
           movements) and certain hardware events. The entropy argument is (the
           lower bound of) an estimate of how much randomness is contained in buf,
           measured in bytes. Details about sources of randomness and how to
           estimate their entropy can be found in the literature, e.g. RFC 1750.
    
           RAND_add() may be called with sensitive data such as user entered
           passwords. The seed values cannot be recovered from the PRNG output.
    
           OpenSSL makes sure that the PRNG state is unique for each thread. On
           systems that provide "/dev/urandom", the randomness device is used to
           seed the PRNG transparently. However, on all other systems, the
           application is responsible for seeding the PRNG by calling RAND_add(),
           RAND_egd(3) or RAND_load_file(3).
    
           RAND_seed() is equivalent to RAND_add() when num == entropy.
    
           RAND_event() collects the entropy from Windows events such as mouse
           movements and other user interaction. It should be called with the
           iMsg, wParam and lParam arguments of all messages sent to the window
           procedure. It will estimate the entropy contained in the event message
           (if any), and add it to the PRNG. The program can then process the
           messages as usual.
    
           The RAND_screen() function is available for the convenience of Windows
           programmers. It adds the current contents of the screen to the PRNG.
           For applications that can catch Windows events, seeding the PRNG by
           calling RAND_event() is a significantly better source of randomness. It
           should be noted that both methods cannot be used on servers that run
           without user interaction.
    
    
    

    RETURN VALUES

           RAND_status() and RAND_event() return 1 if the PRNG has been seeded
           with enough data, 0 otherwise.
    
    
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