5 BN_mod_mul_montgomery, BN_MONT_CTX_new, BN_MONT_CTX_init,
6 BN_MONT_CTX_free, BN_MONT_CTX_set, BN_MONT_CTX_copy,
7 BN_from_montgomery, BN_to_montgomery - Montgomery multiplication
11 #include <openssl/bn.h>
13 BN_MONT_CTX *BN_MONT_CTX_new(void);
14 void BN_MONT_CTX_free(BN_MONT_CTX *mont);
16 int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *m, BN_CTX *ctx);
17 BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from);
19 int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
20 BN_MONT_CTX *mont, BN_CTX *ctx);
22 int BN_from_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
25 int BN_to_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
30 These functions implement Montgomery multiplication. They are used
31 automatically when L<BN_mod_exp(3)> is called with suitable input,
32 but they may be useful when several operations are to be performed
33 using the same modulus.
35 BN_MONT_CTX_new() allocates and initializes a B<BN_MONT_CTX> structure.
37 BN_MONT_CTX_set() sets up the I<mont> structure from the modulus I<m>
38 by precomputing its inverse and a value R.
40 BN_MONT_CTX_copy() copies the B<BN_MONT_CTX> I<from> to I<to>.
42 BN_MONT_CTX_free() frees the components of the B<BN_MONT_CTX>, and, if
43 it was created by BN_MONT_CTX_new(), also the structure itself.
44 If B<mont> is NULL, nothing is done.
46 BN_mod_mul_montgomery() computes Mont(I<a>,I<b>):=I<a>*I<b>*R^-1 and places
49 BN_from_montgomery() performs the Montgomery reduction I<r> = I<a>*R^-1.
51 BN_to_montgomery() computes Mont(I<a>,R^2), i.e. I<a>*R.
52 Note that I<a> must be non-negative and smaller than the modulus.
54 For all functions, I<ctx> is a previously allocated B<BN_CTX> used for
59 BN_MONT_CTX_new() returns the newly allocated B<BN_MONT_CTX>, and NULL
62 BN_MONT_CTX_free() has no return value.
64 For the other functions, 1 is returned for success, 0 on error.
65 The error codes can be obtained by L<ERR_get_error(3)>.
69 The inputs must be reduced modulo B<m>, otherwise the result will be
70 outside the expected range.
72 =head1 REMOVED FUNCTIONALITY
74 void BN_MONT_CTX_init(BN_MONT_CTX *c);
76 BN_MONT_CTX_init() is no longer available as of OpenSSL 1.1.0. It was used to
77 initialize an existing uninitialized B<BN_MONT_CTX>. Typically this would be
81 BN_MONT_CTX_init(&ctx);
83 Instead applications should create a BN_MONT_CTX structure using
87 ctx = BN_MONT_CTX_new();
88 if(!ctx) /* handle error */
90 BN_MONT_CTX_free(ctx);
94 L<bn(3)>, L<ERR_get_error(3)>, L<BN_add(3)>,
99 BN_MONT_CTX_new(), BN_MONT_CTX_free(), BN_MONT_CTX_set(),
100 BN_mod_mul_montgomery(), BN_from_montgomery() and BN_to_montgomery()
101 are available in all versions of SSLeay and OpenSSL.
103 BN_MONT_CTX_init() and BN_MONT_CTX_copy() were added in SSLeay 0.9.1b.
104 BN_MONT_CTX_init was removed in OpenSSL 1.1.0