diff options
author | Ulf Möller <ulf@openssl.org> | 2000-01-27 01:54:05 +0000 |
---|---|---|
committer | Ulf Möller <ulf@openssl.org> | 2000-01-27 01:54:05 +0000 |
commit | fc58fa8bb8bfd7704079d28c97fccbf875227b83 (patch) | |
tree | 86d6d9b43e5f65ddc70b5b876b8332ec5a451465 /doc/crypto/BN_mod_mul_montgomery.pod | |
parent | e93f9a3284c799bb851afaeddd56ed502ba189b6 (diff) |
New manpage.
Diffstat (limited to 'doc/crypto/BN_mod_mul_montgomery.pod')
-rw-r--r-- | doc/crypto/BN_mod_mul_montgomery.pod | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/doc/crypto/BN_mod_mul_montgomery.pod b/doc/crypto/BN_mod_mul_montgomery.pod new file mode 100644 index 0000000000..7d25dfbac4 --- /dev/null +++ b/doc/crypto/BN_mod_mul_montgomery.pod @@ -0,0 +1,94 @@ +=pod + +=head1 NAME + +BN_mod_mul_montgomery, BN_MONT_CTX_new, BN_MONT_CTX_init, +BN_MONT_CTX_free, BN_MONT_CTX_set, BN_MONT_CTX_copy, +BN_from_montgomery, BN_to_montgomery - Montgomery multiplication + +=head1 SYNOPSIS + + #include <openssl/bn.h> + + BN_MONT_CTX *BN_MONT_CTX_new(void); + void BN_MONT_CTX_init(BN_MONT_CTX *ctx); + void BN_MONT_CTX_free(BN_MONT_CTX *mont); + + int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *m, BN_CTX *ctx); + BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from); + + int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b, + BN_MONT_CTX *mont, BN_CTX *ctx); + + int BN_from_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont, + BN_CTX *ctx); + + int BN_to_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont, + BN_CTX *ctx); + +=head1 DESCRIPTION + +These functions implement Montgomery multiplication. They are used +automatically when BN_mod_exp(3) is called with suitable input, +but they may be useful when several operations are to be perfomed +using the same modulus. + +BN_MONT_CTX_new() allocates and initializes a B<BN_MONT_CTX> structure. +BN_MONT_CTX_init() initializes an existing uninitialized B<BN_MONT_CTX>. + +BN_MONT_CTX_set() sets up the B<mont> structure from the modulus B<m> +by precomputing its inverse and a value R. + +BN_MONT_CTX_copy() copies the B<N_MONT_CTX> B<from> to B<to>. + +BN_MONT_CTX_free() frees the components of the B<BN_MONT_CTX>, and, if +it was created by BN_MONT_CTX_new(), also the structure itself. + +BN_mod_mul_mont() computes Mont(B<a>,B<b>):=B<a>*B<b>*R^-1 and places +the result in B<r>. + +BN_from_montgomery() performs the Montgomery reduction B<r> = B<a>*R^-1. + +BN_to_montgomery() computes Mont(B<a>,R^2). + +For all functions, B<ctx> is a previously allocated B<BN_CTX> used for +temporary variables. + +The B<BN_MONT_CTX> structure is defined as follows: + + typedef struct bn_mont_ctx_st + { + int use_word; /* 0 for word form, 1 for bignum form */ + int ri; /* number of bits in R */ + BIGNUM RR; /* R^2 (used to convert to Montgomery form) */ + BIGNUM N; /* The modulus */ + BIGNUM Ni; /* The inverse of N (bignum form) */ + BN_ULONG n0; /* The inverse of N in word form */ + int flags; + } BN_MONT_CTX; + +BN_to_montgomery() is a macro. + +=head1 RETURN VALUES + +BN_MONT_CTX_new() returns the newly allocated B<BN_MONT_CTX>, and NULL +on error. + +BN_MONT_CTX_init() and BN_MONT_CTX_free() have no return values. + +For the other functions, 1 is returned for success, 0 on error. +The error codes can be obtained by ERR_get_error(3). + +=head1 SEE ALSO + +bn(3), err(3), BN_add(3), BN_CTX_new(3) + +=head1 HISTORY + +BN_MONT_CTX_new(), BN_MONT_CTX_free(), BN_MONT_CTX_set(), +BN_mod_mul_montgomery(), BN_from_montgomery() and BN_to_montgomery() +are available in all versions of SSLeay and OpenSSL. + +BN_MONT_CTX_init() and BN_MONT_CTX_copy() were added in SSLeay 0.9.1b. + +=cut |