BN_mod_mul_montgomery(3) | OpenSSL | BN_mod_mul_montgomery(3) |
BN_MONT_CTX_new() allocates and initializes a BN_MONT_CTX structure. BN_MONT_CTX_init() initializes an existing uninitialized BN_MONT_CTX.
BN_MONT_CTX_set() sets up the mont structure from the modulus m by precomputing its inverse and a value R.
BN_MONT_CTX_copy() copies the BN_MONT_CTX from to to.
BN_MONT_CTX_free() frees the components of the BN_MONT_CTX, and, if it was created by BN_MONT_CTX_new(), also the structure itself.
BN_mod_mul_montgomery() computes Mont(a,b):=a*b*R^-1 and places the result in r.
BN_from_montgomery() performs the Montgomery reduction r = a*R^-1.
BN_to_montgomery() computes Mont(a,R^2), i.e. a*R. Note that a must be non-negative and smaller than the modulus.
For all functions, ctx is a previously allocated BN_CTX used for temporary variables.
The BN_MONT_CTX structure is defined as follows:
typedef struct bn_mont_ctx_st
{
int ri; /* number of bits in R */
BIGNUM RR; /* R^2 (used to convert to Montgomery form) */
BIGNUM N; /* The modulus */
BIGNUM Ni; /* R*(1/R mod N) - N*Ni = 1
* (Ni is only stored for bignum algorithm) */
BN_ULONG n0; /* least significant word of Ni */
int flags;
} BN_MONT_CTX;
BN_to_montgomery() is a macro.
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).
BN_MONT_CTX_init() and BN_MONT_CTX_copy() were added in SSLeay 0.9.1b.
2009-07-19 | 1.0.1u |