BN_mod_inverse(3ssl)

BN_mod_inverse3ssl

Compute inverse modulo n

Usage

 #include <openssl/bn.h>
 BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
                        BN_CTX *ctx);

Overview

BN_mod_inverse() computes the inverse of a modulo n places the result in r ("(a*r)%n==1"). If r is NULL, a new BIGNUM is created.

ctx is a previously allocated BN_CTX used for temporary variables. r may be the same BIGNUM as a.

Notes

It is an error to use the same BIGNUM as n.

Return values

BN_mod_inverse() returns the BIGNUM containing the inverse, and NULL on error. The error codes can be obtained by ERR_get_error(3).

Releases

13 releases since Debian 3.0 (Woody); the text changed 12 times.

  1. 3.0
  2. 3.1
  3. 4.0
  4. 5.0
  5. 6.0
  6. 7
  7. 8
  8. 9
  9. 10
  10. 11
  11. 12
  12. 13
  13. Arch

From openssl 3.6.5-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.