OCSP_REQUEST_ADD1_NONCE(3) | Library Functions Manual | OCSP_REQUEST_ADD1_NONCE(3)

# NAME

`OCSP_request_add1_nonce`, `OCSP_basic_add1_nonce`, `OCSP_check_nonce`, `OCSP_copy_nonce` — OCSP nonce functions

# SYNOPSIS

library “libcrypto”
`#include <openssl/ocsp.h>`

int
`OCSP_request_add1_nonce`(OCSP_REQUEST *req, unsigned char *val, int len);

int
`OCSP_basic_add1_nonce`(OCSP_BASICRESP *resp, unsigned char *val, int len);

int
`OCSP_check_nonce`(OCSP_REQUEST *req, OCSP_BASICRESP *resp);

int
`OCSP_copy_nonce`(OCSP_BASICRESP *resp, OCSP_REQUEST *req);

# DESCRIPTION

An OCSP nonce is typically added to an OCSP request to thwart replay attacks by checking the same nonce value appears in the response.

`OCSP_request_add1_nonce`() adds a nonce of value val and length len to OCSP request req. If val is `NULL`, a random nonce is used. If len is zero or negative, a default length will be used (currently 16 bytes). For most purposes the nonce value in a request is set to a random value so the val parameter in `OCSP_request_add1_nonce`() is usually NULL.

`OCSP_basic_add1_nonce`() is identical to `OCSP_request_add1_nonce`() except it adds a nonce to OCSP basic response resp.

`OCSP_check_nonce`() compares the nonce value in req and resp.

`OCSP_copy_nonce`() copies any nonce value present in req to resp.

Some responders may include a nonce in all responses even if one is not supplied.

Some responders cache OCSP responses and do not sign each response for performance reasons. As a result they do not support nonces.

# RETURN VALUES

`OCSP_request_add1_nonce`() and `OCSP_basic_add1_nonce`() return 1 for success or 0 for failure.

`OCSP_copy_nonce`() returns 1 if a nonce was successfully copied, 2 if no nonce was present in req, or 0 if an error occurred.

`OCSP_check_nonce`() returns positive values for success: 1 if nonces are present and equal, 2 if both nonces are absent, or 3 if a nonce is present in the response only. A zero return value indicates that both nonces are present but mismatch: this should be treated as an error condition. A return value of -1 indicates that a nonce is present in the request only: this will happen if the responder doesn't support nonces.

# SEE ALSO

OCSP_cert_to_id(3), OCSP_REQUEST_new(3), OCSP_resp_find_status(3), OCSP_response_status(3), OCSP_sendreq_new(3)

# HISTORY

These functions first appeared in OpenSSL 0.9.7 and have been available since OpenBSD 3.2.

June 8, 2025 | Debian