BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables
#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);
These functions are used to obtain temporary BIGNUM variables from a BN_CTX (which can been created by using RETURN VALUES
BN_CTX_start() and BN_CTX_end() return no values. BN_CTX_get() 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 SEE ALSO
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