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BN_CTX_start(3)
NAME
  BN_CTX_start, BN_CTX_get, BN_CTX_end - Use temporary BIGNUM variables

SYNOPSIS
   #include <openssl/bn.h>

  void BN_CTX_start(
	  BN_CTX *ctx );

  BIGNUM *BN_CTX_get(
	  BN_CTX *ctx );

  void BN_CTX_end(
	  BN_CTX *ctx );

DESCRIPTION
  These functions are used to obtain temporary BIGNUM variables from a BN_CTX
  (which can been created by using the BN_CTX_new() function) in order to
  save the overhead of repeatedly creating and freeing BIGNUMs in functions
  that are called from inside a loop.

  A function must call BN_CTX_start() first. Then, BN_CTX_get() may be called
  repeatedly to obtain temporary BIGNUMs. All BN_CTX_get() calls must be made
  before calling any other functions that use the ctx as an argument.

  Finally, BN_CTX_end() must be called before returning from the function.
  When BN_CTX_end() is called, the BIGNUM pointers obtained from BN_CTX_get()
  become invalid.

RETURN VALUES
  The BN_CTX_start() and BN_CTX_end() functions return no values.

  The BN_CTX_get() function returns a pointer to the BIGNUM, or NULL on
  error. Once BN_CTX_get() has failed, the subsequent calls will return NULL
  as well, so it is sufficient to check the return value of the last
  BN_CTX_get() call. In case of an error, an error code is set, which can be
  obtained by ERR_get_error().

HISTORY
  The BN_CTX_start(), BN_CTX_get(), and BN_CTX_end() functions were added in
  OpenSSL 0.9.5.

SEE ALSO
  Functions: BN_CTX_new(3)

Index for Section 3

Alphabetical listing for B

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