BN_mod_inverse 3 2003-07-24 0.9.9-dev OpenSSL

### NAME

BN_mod_inverse - compute inverse modulo n

### LIBRARY

libcrypto, -lcrypto

### SYNOPSIS

     #include

     BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
               BN_CTX *ctx);

### DESCRIPTION

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 or 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).

### SEE ALSO

openssl_bn(3), ERR_get_error(3), BN_add(3)

### HISTORY

BN_mod_inverse() is available in all versions of SSLeay and OpenSSL.