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797a89a1 DSH |
1 | =pod |
2 | ||
3 | OCSP_request_add1_nonce, OCSP_basic_add1_nonce, OCSP_check_nonce, OCSP_copy_nonce - OCSP nonce functions. | |
4 | ||
5 | =head1 SYNOPSIS | |
6 | ||
7 | #include <openssl/ocsp.h> | |
8 | ||
9 | int OCSP_request_add1_nonce(OCSP_REQUEST *req, unsigned char *val, int len); | |
10 | int OCSP_basic_add1_nonce(OCSP_BASICRESP *resp, unsigned char *val, int len); | |
11 | int OCSP_copy_nonce(OCSP_BASICRESP *resp, OCSP_REQUEST *req); | |
12 | int OCSP_check_nonce(OCSP_REQUEST *req, OCSP_BASICRESP *resp); | |
13 | ||
14 | =head1 DESCRIPTION | |
15 | ||
16 | OCSP_request_add1_nonce() adds a nonce of value B<val> and length B<len> to | |
17 | OCSP request B<req>. If B<val> is B<NULL> a random nonce is used. If B<len> | |
18 | is zero or negative a default length will be used (currently 16 bytes). | |
19 | ||
20 | OCSP_basic_add1_nonce() is identical to OCSP_request_add1_nonce() except | |
21 | it adds a nonce to OCSP basic response B<resp>. | |
22 | ||
23 | OCSP_check_nonce() compares the nonce value in B<req> and B<resp>. | |
24 | ||
25 | OCSP_copy_nonce() copys any nonce value present in B<req> to B<resp>. | |
26 | ||
27 | =head1 RETURN VALUES | |
28 | ||
29 | OCSP_request_add1_nonce() and OCSP_basic_add1_nonce() return 1 for success | |
30 | and 0 for failure. | |
31 | ||
32 | OCSP_copy_nonce() returns 1 if a nonce was successfully copied, 2 if no nonce | |
33 | was present in B<req> and 0 if an error occurred. | |
34 | ||
35 | OCSP_check_nonce() returns the result of the nonce comparison between B<req> | |
36 | and B<resp>. The return value indicates the result of the comparison. If | |
37 | nonces are present and equal 1 is returned. If the nonces are absent 2 is | |
38 | returned. If a nonce is present in the response only 3 is returned. If nonces | |
39 | are present and unequal 0 is returned. If the nonce is present in the request | |
40 | only then -1 is returned. | |
41 | ||
42 | =head1 NOTES | |
43 | ||
44 | For most purposes the nonce value in a request is set to a random value so | |
45 | the B<val> parameter in OCSP_request_add1_nonce() is usually NULL. | |
46 | ||
47 | An OCSP nonce is typically added to an OCSP request to thwart replay attacks | |
48 | by checking the same nonce value appears in the response. | |
49 | ||
50 | Some responders may include a nonce in all responses even if one is not | |
51 | supplied. | |
52 | ||
53 | Some responders cache OCSP responses and do not sign each response for | |
54 | performance reasons. As a result they do not support nonces. | |
55 | ||
56 | The return values of OCSP_check_nonce() can be checked to cover each case. A | |
57 | positive return value effectively indicates success: nonces are both present | |
58 | and match, both absent or present in the response only. A non-zero return | |
59 | additionally covers the case where the nonce is present in the request only: | |
60 | this will happen if the responder doesn't support nonces. A zero return value | |
61 | indicates present and mismatched nonces: this should be treated as an error | |
62 | condition. | |
63 | ||
64 | =head1 SEE ALSO | |
65 | ||
66 | L<crypto(3)|crypto(3)>, | |
67 | L<OCSP_cert_to_id(3)|OCSP_cert_to_id(3)>, | |
68 | L<OCSP_REQUEST_new(3)|OCSP_REQUEST_new(3)>, | |
69 | L<OCSP_response_find_status(3)|OCSP_response_find_status(3)>, | |
70 | L<OCSP_response_status(3)|OCSP_response_status(3)>, | |
71 | L<OCSP_sendreq_new(3)|OCSP_sendreq_new(3)> | |
72 | ||
73 | =cut |