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Module: OpenSSL::Random

Relationships & Source Files
Namespace Children
Exceptions:
RandomError
Defined in: ext/openssl/ossl_rand.c

Class Attribute Summary

  • .status? ⇒ Boolean readonly mod_func

    Return true if the PRNG has been seeded with enough data, false otherwise.

Class Method Summary

Class Attribute Details

.status? ⇒ Boolean (readonly, mod_func)

Return true if the PRNG has been seeded with enough data, false otherwise.

[ GitHub ] 

  


# File 'ext/openssl/ossl_rand.c', line 166



static VALUE
ossl_rand_status(VALUE self)
{
    return RAND_status() ? Qtrue : Qfalse;
}


  







Class Method Details



  

    .egd(filename)  ⇒ true  (mod_func)  



  

    

Same as .egd_bytes but queries 255 bytes by default.


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 130



static VALUE
ossl_rand_egd(VALUE self, VALUE filename)
{
    if (RAND_egd(StringValueCStr(filename)) == -1) {
	ossl_raise(eRandomError, NULL);
    }
    return Qtrue;
}


  








  

    .egd_bytes(filename, length)  ⇒ true  (mod_func)  



  

    

Queries the entropy gathering daemon EGD on socket path given by filename.



Fetches length number of bytes and uses .add to seed the ::OpenSSL built-in PRNG.


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 148



static VALUE
ossl_rand_egd_bytes(VALUE self, VALUE filename, VALUE len)
{
    int n = NUM2INT(len);

    if (RAND_egd_bytes(StringValueCStr(filename), n) == -1) {
	ossl_raise(eRandomError, NULL);
    }
    return Qtrue;
}


  








  

    .load_random_file(filename)  ⇒ true  (mod_func)  



  

    

Reads bytes from filename and adds them to the PRNG.


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 67



static VALUE
ossl_rand_load_file(VALUE self, VALUE filename)
{
    if(!RAND_load_file(StringValueCStr(filename), -1)) {
	ossl_raise(eRandomError, NULL);
    }
    return Qtrue;
}


  








  

    .add(str, entropy)  ⇒ self  (mod_func)  



  

    

Mixes the bytes from str into the Pseudo Random Number Generator(PRNG) state.



Thus, if the data from str are unpredictable to an adversary, this increases the uncertainty about the state and makes the PRNG output less predictable.



The entropy argument is (the lower bound of) an estimate of how much randomness is contained in str, measured in bytes.



Example



pid = $$
now = Time.now
ary = [now.to_i, now.nsec, 1000, pid]
OpenSSL::Random.add(ary.join, 0.0)
OpenSSL::Random.seed(ary.join)


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 52



static VALUE
ossl_rand_add(VALUE self, VALUE str, VALUE entropy)
{
    StringValue(str);
    RAND_add(RSTRING_PTR(str), RSTRING_LENINT(str), NUM2DBL(entropy));

    return self;
}


  








  

    .random_bytes(length)  ⇒ String  (mod_func)  



  

    

Generates a String with length number of cryptographically strong pseudo-random bytes.



Example



OpenSSL::Random.random_bytes(12)
#=> "..."


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 105



static VALUE
ossl_rand_bytes(VALUE self, VALUE len)
{
    VALUE str;
    int n = NUM2INT(len);
    int ret;

    str = rb_str_new(0, n);
    ret = RAND_bytes((unsigned char *)RSTRING_PTR(str), n);
    if (ret == 0) {
	ossl_raise(eRandomError, "RAND_bytes");
    } else if (ret == -1) {
	ossl_raise(eRandomError, "RAND_bytes is not supported");
    }

    return str;
}


  








  

    .seed(str)  ⇒ String  (mod_func)  



  

    

.seed is equivalent to .add where entropy is length of str.


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 21



static VALUE
ossl_rand_seed(VALUE self, VALUE str)
{
    StringValue(str);
    RAND_seed(RSTRING_PTR(str), RSTRING_LENINT(str));

    return str;
}


  








  

    .write_random_file(filename)  ⇒ true  (mod_func)  



  

    

Writes a number of random generated bytes (currently 1024) to filename which can be used to initialize the PRNG by calling .load_random_file in a later session.


  



  [ GitHub ]


  

  


# File 'ext/openssl/ossl_rand.c', line 84



static VALUE
ossl_rand_write_file(VALUE self, VALUE filename)
{
    if (RAND_write_file(StringValueCStr(filename)) == -1) {
	ossl_raise(eRandomError, NULL);
    }
    return Qtrue;
}