Manual Pages for UNIX Operating System command usage for man BN_RECP_CTX_init

OpenSSL                           BN_mod_mul_reciprocal(3openssl)



NNNNAAAAMMMMEEEE
     BN_mod_mul_reciprocal,  BN_div_recp, BN_RECP_CTX_new,
     BN_RECP_CTX_init, BN_RECP_CTX_free, BN_RECP_CTX_set -
     modular multiplication using reciprocal

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      BN_RECP_CTX *BN_RECP_CTX_new(void);
      void BN_RECP_CTX_init(BN_RECP_CTX *recp);
      void BN_RECP_CTX_free(BN_RECP_CTX *recp);

      int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *m, BN_CTX *ctx);

      int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *a, BN_RECP_CTX *recp,
             BN_CTX *ctx);

      int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *a, BIGNUM *b,
             BN_RECP_CTX *recp, BN_CTX *ctx);


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     BN_mod_mul_reciprocal() can be used to perform an efficient
     BN_mod_mul(3) operation when the operation will be performed
     repeatedly with the same modulus. It computes rrrr=(aaaa*bbbb)%mmmm
     using rrrreeeeccccpppp=1/mmmm, which is set as described below.  ccccttttxxxx is a
     previously allocated BBBBNNNN_CCCCTTTTXXXX used for temporary variables.

     BN_RECP_CTX_new() allocates and initializes a BBBBNNNN_RRRREEEECCCCPPPP
     structure.  BN_RECP_CTX_init() initializes an existing
     uninitialized BBBBNNNN_RRRREEEECCCCPPPP.

     BN_RECP_CTX_free() frees the components of the BBBBNNNN_RRRREEEECCCCPPPP, and,
     if it was created by BN_RECP_CTX_new(), also the structure
     itself.

     BN_RECP_CTX_set() stores mmmm in rrrreeeeccccpppp and sets it up for
     computing 1/mmmm and shifting it left by BN_num_bits(mmmm)+1 to
     make it an integer. The result and the number of bits it was
     shifted left will later be stored in rrrreeeeccccpppp.

     BN_div_recp() divides aaaa by mmmm using rrrreeeeccccpppp. It places the
     quotient in ddddvvvv and the remainder in rrrreeeemmmm.

     The BBBBNNNN_RRRREEEECCCCPPPP_CCCCTTTTXXXX structure is defined as follows:










25/Sep/2002            Last change: 0.9.8o                      1






OpenSSL                           BN_mod_mul_reciprocal(3openssl)



      typedef struct bn_recp_ctx_st
             {
             BIGNUM N;       /* the divisor */
             BIGNUM Nr;      /* the reciprocal */
             int num_bits;
             int shift;
             int flags;
             } BN_RECP_CTX;

     It cannot be shared between threads.

RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     BN_RECP_CTX_new() returns the newly allocated BBBBNNNN_RRRREEEECCCCPPPP_CCCCTTTTXXXX,
     and NULL on error.

     BN_RECP_CTX_init() and BN_RECP_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).

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     bn(3), ERR_get_error(3), BN_add(3), BN_CTX_new(3)

HHHHIIIISSSSTTTTOOOORRRRYYYY
     BBBBNNNN_RRRREEEECCCCPPPP_CCCCTTTTXXXX was added in SSLeay 0.9.0. Before that, the
     function BN_reciprocal() was used instead, and the
     BN_mod_mul_reciprocal() arguments were different.



























25/Sep/2002            Last change: 0.9.8o                      2