1X509_VERIFY_CERT(3ossl) OpenSSL X509_VERIFY_CERT(3ossl)
2
6 X509_build_chain, X509_verify_cert, X509_STORE_CTX_verify - build and
7 verify X509 certificate chain
8
10 #include <openssl/x509_vfy.h>
11 STACK_OF(X509) *X509_build_chain(X509 *target, STACK_OF(X509) *certs,
13 X509_STORE *store, int with_self_signed,
14 OSSL_LIB_CTX *libctx, const char *propq);
15 int X509_verify_cert(X509_STORE_CTX *ctx);
16 int X509_STORE_CTX_verify(X509_STORE_CTX *ctx);
17
19 X509_build_chain() builds a certificate chain starting from target
20 using the optional list of intermediate CA certificates certs. If
21 store is NULL it builds the chain as far down as possible, ignoring
22 errors. Else the chain must reach a trust anchor contained in store.
23 It internally uses a X509_STORE_CTX structure associated with the
24 library context libctx and property query string propq, both of which
25 may be NULL. In case there is more than one possibility for the chain,
26 only one is taken.
27 On success it returns a pointer to a new stack of (up_ref'ed)
29 certificates starting with target and followed by all available
30 intermediate certificates. A self-signed trust anchor is included only
31 if target is the trust anchor of with_self_signed is 1. If a non-NULL
32 stack is returned the caller is responsible for freeing it.
33 The X509_verify_cert() function attempts to discover and validate a
35 certificate chain based on parameters in ctx. The verification
36 context, of type X509_STORE_CTX, can be constructed using
37 X509_STORE_CTX_new(3) and X509_STORE_CTX_init(3). It usually includes
38 a target certificate to be verified, a set of certificates serving as
39 trust anchors, a list of non-trusted certificates that may be helpful
40 for chain construction, flags such as X509_V_FLAG_X509_STRICT, and
41 various other optional components such as a callback function that
42 allows customizing the verification outcome. A complete description of
43 the certificate verification process is contained in the
44 openssl-verification-options(1) manual page.
45 Applications rarely call this function directly but it is used by
47 OpenSSL internally for certificate validation, in both the S/MIME and
48 SSL/TLS code.
49 A negative return value from X509_verify_cert() can occur if it is
51 invoked incorrectly, such as with no certificate set in ctx, or when it
52 is called twice in succession without reinitialising ctx for the second
53 call. A negative return value can also happen due to internal resource
54 problems or because an internal inconsistency has been detected.
55 Applications must interpret any return value <= 0 as an error.
56 The X509_STORE_CTX_verify() behaves like X509_verify_cert() except that
58 its target certificate is the first element of the list of untrusted
59 certificates in ctx unless a target certificate is set explicitly.
60
62 X509_build_chain() returns NULL on error, else a stack of certificates.
63 Both X509_verify_cert() and X509_STORE_CTX_verify() return 1 if a
65 complete chain can be built and validated, otherwise they return 0, and
66 in exceptional circumstances (such as malloc failure and internal
67 errors) they can also return a negative code.
68 If a complete chain can be built and validated both functions return 1.
70 If the certificate must be rejected on the basis of the data available
71 or any required certificate status data is not available they return 0.
72 If no definite answer possible they usually return a negative code.
73 On error or failure additional error information can be obtained by
75 examining ctx using, for example, X509_STORE_CTX_get_error(3). Even if
76 verification indicated success, the stored error code may be different
77 from X509_V_OK, likely because a verification callback function has
78 waived the error.
79
81 X509_STORE_CTX_new(3), X509_STORE_CTX_init(3),
82 X509_STORE_CTX_get_error(3)
83
85 X509_build_chain() and X509_STORE_CTX_verify() were added in OpenSSL
86 3.0.
87
89 Copyright 2009-2022 The OpenSSL Project Authors. All Rights Reserved.
90 Licensed under the Apache License 2.0 (the "License"). You may not use
92 this file except in compliance with the License. You can obtain a copy
93 in the file LICENSE in the source distribution or at
94 <https://www.openssl.org/source/license.html>.
953.1.1 2023-08-31 X509_VERIFY_CERT(3ossl)