| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | OCSP_request_add1_nonce, OCSP_basic_add1_nonce, OCSP_check_nonce, OCSP_copy_nonce - OCSP nonce functions
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/ocsp.h>
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| 10 |
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| 11 | int OCSP_request_add1_nonce(OCSP_REQUEST *req, unsigned char *val, int len);
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| 12 | int OCSP_basic_add1_nonce(OCSP_BASICRESP *resp, unsigned char *val, int len);
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| 13 | int OCSP_copy_nonce(OCSP_BASICRESP *resp, OCSP_REQUEST *req);
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| 14 | int OCSP_check_nonce(OCSP_REQUEST *req, OCSP_BASICRESP *resp);
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| 15 |
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| 16 | =head1 DESCRIPTION
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| 17 |
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| 18 | OCSP_request_add1_nonce() adds a nonce of value B<val> and length B<len> to
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| 19 | OCSP request B<req>. If B<val> is B<NULL> a random nonce is used. If B<len>
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| 20 | is zero or negative a default length will be used (currently 16 bytes).
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| 21 |
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| 22 | OCSP_basic_add1_nonce() is identical to OCSP_request_add1_nonce() except
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| 23 | it adds a nonce to OCSP basic response B<resp>.
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| 24 |
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| 25 | OCSP_check_nonce() compares the nonce value in B<req> and B<resp>.
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| 26 |
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| 27 | OCSP_copy_nonce() copies any nonce value present in B<req> to B<resp>.
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| 28 |
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| 29 | =head1 RETURN VALUES
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| 30 |
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| 31 | OCSP_request_add1_nonce() and OCSP_basic_add1_nonce() return 1 for success
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| 32 | and 0 for failure.
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| 33 |
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| 34 | OCSP_copy_nonce() returns 1 if a nonce was successfully copied, 2 if no nonce
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| 35 | was present in B<req> and 0 if an error occurred.
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| 36 |
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| 37 | OCSP_check_nonce() returns the result of the nonce comparison between B<req>
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| 38 | and B<resp>. The return value indicates the result of the comparison. If
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| 39 | nonces are present and equal 1 is returned. If the nonces are absent 2 is
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| 40 | returned. If a nonce is present in the response only 3 is returned. If nonces
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| 41 | are present and unequal 0 is returned. If the nonce is present in the request
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| 42 | only then -1 is returned.
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| 43 |
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| 44 | =head1 NOTES
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| 45 |
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| 46 | For most purposes the nonce value in a request is set to a random value so
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| 47 | the B<val> parameter in OCSP_request_add1_nonce() is usually NULL.
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| 48 |
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| 49 | An OCSP nonce is typically added to an OCSP request to thwart replay attacks
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| 50 | by checking the same nonce value appears in the response.
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| 51 |
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| 52 | Some responders may include a nonce in all responses even if one is not
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| 53 | supplied.
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| 54 |
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| 55 | Some responders cache OCSP responses and do not sign each response for
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| 56 | performance reasons. As a result they do not support nonces.
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| 57 |
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| 58 | The return values of OCSP_check_nonce() can be checked to cover each case. A
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| 59 | positive return value effectively indicates success: nonces are both present
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| 60 | and match, both absent or present in the response only. A nonzero return
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| 61 | additionally covers the case where the nonce is present in the request only:
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| 62 | this will happen if the responder doesn't support nonces. A zero return value
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| 63 | indicates present and mismatched nonces: this should be treated as an error
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| 64 | condition.
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| 65 |
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| 66 | =head1 SEE ALSO
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| 67 |
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| 68 | L<crypto(7)>,
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| 69 | L<OCSP_cert_to_id(3)>,
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| 70 | L<OCSP_REQUEST_new(3)>,
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| 71 | L<OCSP_resp_find_status(3)>,
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| 72 | L<OCSP_response_status(3)>,
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| 73 | L<OCSP_sendreq_new(3)>
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| 74 |
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| 75 | =head1 COPYRIGHT
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| 76 |
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| 77 | Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
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| 78 |
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| 79 | Licensed under the OpenSSL license (the "License"). You may not use
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| 80 | this file except in compliance with the License. You can obtain a copy
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| 81 | in the file LICENSE in the source distribution or at
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| 82 | L<https://www.openssl.org/source/license.html>.
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| 83 |
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| 84 | =cut
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