BN_is_prime_fasttest(3ssl)

1BN_generate_prime(3)                OpenSSL               BN_generate_prime(3)
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NAME

6       BN_generate_prime_ex, BN_is_prime_ex, BN_is_prime_fasttest_ex,
7       BN_GENCB_call, BN_GENCB_set_old, BN_GENCB_set, BN_generate_prime,
8       BN_is_prime, BN_is_prime_fasttest - generate primes and test for
9       primality
10

SYNOPSIS

12        #include <openssl/bn.h>
13
14        int BN_generate_prime_ex(BIGNUM *ret,int bits,int safe, const BIGNUM *add,
15            const BIGNUM *rem, BN_GENCB *cb);
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17        int BN_is_prime_ex(const BIGNUM *p,int nchecks, BN_CTX *ctx, BN_GENCB *cb);
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19        int BN_is_prime_fasttest_ex(const BIGNUM *p,int nchecks, BN_CTX *ctx,
20            int do_trial_division, BN_GENCB *cb);
21
22        int BN_GENCB_call(BN_GENCB *cb, int a, int b);
23
24        #define BN_GENCB_set_old(gencb, callback, cb_arg) ...
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26        #define BN_GENCB_set(gencb, callback, cb_arg) ...
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28       Deprecated:
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30        BIGNUM *BN_generate_prime(BIGNUM *ret, int num, int safe, BIGNUM *add,
31            BIGNUM *rem, void (*callback)(int, int, void *), void *cb_arg);
32
33        int BN_is_prime(const BIGNUM *a, int checks, void (*callback)(int, int,
34            void *), BN_CTX *ctx, void *cb_arg);
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36        int BN_is_prime_fasttest(const BIGNUM *a, int checks,
37            void (*callback)(int, int, void *), BN_CTX *ctx, void *cb_arg,
38            int do_trial_division);
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DESCRIPTION

41       BN_generate_prime_ex() generates a pseudo-random prime number of bit
42       length bits.  If ret is not NULL, it will be used to store the number.
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44       If cb is not NULL, it is used as follows:
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46       ·   BN_GENCB_call(cb, 0, i) is called after generating the i-th
47           potential prime number.
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49       ·   While the number is being tested for primality, BN_GENCB_call(cb,
50           1, j) is called as described below.
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52       ·   When a prime has been found, BN_GENCB_call(cb, 2, i) is called.
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54       The prime may have to fulfill additional requirements for use in
55       Diffie-Hellman key exchange:
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57       If add is not NULL, the prime will fulfill the condition p % add == rem
58       (p % add == 1 if rem == NULL) in order to suit a given generator.
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60       If safe is true, it will be a safe prime (i.e. a prime p so that
61       (p-1)/2 is also prime).
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63       The PRNG must be seeded prior to calling BN_generate_prime_ex().  The
64       prime number generation has a negligible error probability.
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66       BN_is_prime_ex() and BN_is_prime_fasttest_ex() test if the number p is
67       prime.  The following tests are performed until one of them shows that
68       p is composite; if p passes all these tests, it is considered prime.
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70       BN_is_prime_fasttest_ex(), when called with do_trial_division == 1,
71       first attempts trial division by a number of small primes; if no
72       divisors are found by this test and cb is not NULL, BN_GENCB_call(cb,
73       1, -1) is called.  If do_trial_division == 0, this test is skipped.
74
75       Both BN_is_prime_ex() and BN_is_prime_fasttest_ex() perform a Miller-
76       Rabin probabilistic primality test with nchecks iterations. If nchecks
77       == BN_prime_checks, a number of iterations is used that yields a false
78       positive rate of at most 2^-80 for random input.
79
80       If cb is not NULL, BN_GENCB_call(cb, 1, j) is called after the j-th
81       iteration (j = 0, 1, ...). ctx is a pre-allocated BN_CTX (to save the
82       overhead of allocating and freeing the structure in a loop), or NULL.
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84       BN_GENCB_call calls the callback function held in the BN_GENCB
85       structure and passes the ints a and b as arguments. There are two types
86       of BN_GENCB structure that are supported: "new" style and "old" style.
87       New programs should prefer the "new" style, whilst the "old" style is
88       provided for backwards compatibility purposes.
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90       For "new" style callbacks a BN_GENCB structure should be initialised
91       with a call to BN_GENCB_set, where gencb is a BN_GENCB *, callback is
92       of type int (*callback)(int, int, BN_GENCB *) and cb_arg is a void *.
93       "Old" style callbacks are the same except they are initialised with a
94       call to BN_GENCB_set_old and callback is of type void (*callback)(int,
95       int, void *).
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97       A callback is invoked through a call to BN_GENCB_call. This will check
98       the type of the callback and will invoke callback(a, b, gencb) for new
99       style callbacks or callback(a, b, cb_arg) for old style.
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101       BN_generate_prime (deprecated) works in the same way as
102       BN_generate_prime_ex but expects an old style callback function
103       directly in the callback parameter, and an argument to pass to it in
104       the cb_arg. Similarly BN_is_prime and BN_is_prime_fasttest are
105       deprecated and can be compared to BN_is_prime_ex and
106       BN_is_prime_fasttest_ex respectively.
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RETURN VALUES

109       BN_generate_prime_ex() return 1 on success or 0 on error.
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111       BN_is_prime_ex(), BN_is_prime_fasttest_ex(), BN_is_prime() and
112       BN_is_prime_fasttest() return 0 if the number is composite, 1 if it is
113       prime with an error probability of less than 0.25^nchecks, and -1 on
114       error.
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116       BN_generate_prime() returns the prime number on success, NULL
117       otherwise.
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119       Callback functions should return 1 on success or 0 on error.
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121       The error codes can be obtained by ERR_get_error(3).
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HISTORY

127       The cb_arg arguments to BN_generate_prime() and to BN_is_prime() were
128       added in SSLeay 0.9.0. The ret argument to BN_generate_prime() was
129       added in SSLeay 0.9.1.  BN_is_prime_fasttest() was added in OpenSSL
130       0.9.5.
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1341.0.2o                            2018-03-27              BN_generate_prime(3)

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUES

SEE ALSO

HISTORY