1=pod
2
3=head1 NAME
4
5BN_BLINDING_new, BN_BLINDING_free, BN_BLINDING_update, BN_BLINDING_convert, 
6BN_BLINDING_invert, BN_BLINDING_convert_ex, BN_BLINDING_invert_ex, 
7BN_BLINDING_get_thread_id, BN_BLINDING_set_thread_id, BN_BLINDING_get_flags,
8BN_BLINDING_set_flags, BN_BLINDING_create_param - blinding related BIGNUM
9functions.
10
11=head1 SYNOPSIS
12
13 #include <openssl/bn.h>
14
15 BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai,
16	BIGNUM *mod);
17 void BN_BLINDING_free(BN_BLINDING *b);
18 int BN_BLINDING_update(BN_BLINDING *b,BN_CTX *ctx);
19 int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx);
20 int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx);
21 int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b,
22	BN_CTX *ctx);
23 int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
24	BN_CTX *ctx);
25 unsigned long BN_BLINDING_get_thread_id(const BN_BLINDING *);
26 void BN_BLINDING_set_thread_id(BN_BLINDING *, unsigned long);
27 unsigned long BN_BLINDING_get_flags(const BN_BLINDING *);
28 void BN_BLINDING_set_flags(BN_BLINDING *, unsigned long);
29 BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
30	const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
31	int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
32			  const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx),
33	BN_MONT_CTX *m_ctx);
34
35=head1 DESCRIPTION
36
37BN_BLINDING_new() allocates a new B<BN_BLINDING> structure and copies
38the B<A> and B<Ai> values into the newly created B<BN_BLINDING> object.
39
40BN_BLINDING_free() frees the B<BN_BLINDING> structure.
41
42BN_BLINDING_update() updates the B<BN_BLINDING> parameters by squaring
43the B<A> and B<Ai> or, after specific number of uses and if the
44necessary parameters are set, by re-creating the blinding parameters.
45
46BN_BLINDING_convert_ex() multiplies B<n> with the blinding factor B<A>.
47If B<r> is not NULL a copy the inverse blinding factor B<Ai> will be
48returned in B<r> (this is useful if a B<RSA> object is shared amoung
49several threads). BN_BLINDING_invert_ex() multiplies B<n> with the
50inverse blinding factor B<Ai>. If B<r> is not NULL it will be used as
51the inverse blinding.
52
53BN_BLINDING_convert() and BN_BLINDING_invert() are wrapper
54functions for BN_BLINDING_convert_ex() and BN_BLINDING_invert_ex()
55with B<r> set to NULL.
56
57BN_BLINDING_set_thread_id() and BN_BLINDING_get_thread_id()
58set and get the "thread id" value of the B<BN_BLINDING> structure,
59a field provided to users of B<BN_BLINDING> structure to help them
60provide proper locking if needed for multi-threaded use. The 
61"thread id" of a newly allocated B<BN_BLINDING> structure is zero.
62
63BN_BLINDING_get_flags() returns the BN_BLINDING flags. Currently
64there are two supported flags: B<BN_BLINDING_NO_UPDATE> and
65B<BN_BLINDING_NO_RECREATE>. B<BN_BLINDING_NO_UPDATE> inhibits the
66automatic update of the B<BN_BLINDING> parameters after each use
67and B<BN_BLINDING_NO_RECREATE> inhibits the automatic re-creation
68of the B<BN_BLINDING> parameters after a fixed number of uses (currently
6932). In newly allocated B<BN_BLINDING> objects no flags are set.
70BN_BLINDING_set_flags() sets the B<BN_BLINDING> parameters flags.
71
72BN_BLINDING_create_param() creates new B<BN_BLINDING> parameters
73using the exponent B<e> and the modulus B<m>. B<bn_mod_exp> and
74B<m_ctx> can be used to pass special functions for exponentiation
75(normally BN_mod_exp_mont() and B<BN_MONT_CTX>).
76
77=head1 RETURN VALUES
78
79BN_BLINDING_new() returns the newly allocated B<BN_BLINDING> structure
80or NULL in case of an error.
81
82BN_BLINDING_update(), BN_BLINDING_convert(), BN_BLINDING_invert(),
83BN_BLINDING_convert_ex() and BN_BLINDING_invert_ex() return 1 on
84success and 0 if an error occured.
85
86BN_BLINDING_get_thread_id() returns the thread id (a B<unsigned long>
87value) or 0 if not set.
88
89BN_BLINDING_get_flags() returns the currently set B<BN_BLINDING> flags
90(a B<unsigned long> value).
91
92BN_BLINDING_create_param() returns the newly created B<BN_BLINDING> 
93parameters or NULL on error.
94
95=head1 SEE ALSO
96
97L<bn(3)|bn(3)>
98
99=head1 HISTORY
100
101BN_BLINDING_convert_ex, BN_BLINDIND_invert_ex, BN_BLINDING_get_thread_id,
102BN_BLINDING_set_thread_id, BN_BLINDING_set_flags, BN_BLINDING_get_flags
103and BN_BLINDING_create_param were first introduced in OpenSSL 0.9.8
104
105=head1 AUTHOR
106
107Nils Larsch for the OpenSSL project (http://www.openssl.org).
108
109=cut
110