227 lines
8.3 KiB
Plaintext
227 lines
8.3 KiB
Plaintext
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=pod
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=head1 NAME
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ASN1_item_sign, ASN1_item_sign_ex, ASN1_item_sign_ctx,
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ASN1_item_verify, ASN1_item_verify_ex, ASN1_item_verify_ctx -
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ASN1 sign and verify
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=head1 SYNOPSIS
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#include <openssl/x509.h>
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int ASN1_item_sign_ex(const ASN1_ITEM *it, X509_ALGOR *algor1,
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X509_ALGOR *algor2, ASN1_BIT_STRING *signature,
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const void *data, const ASN1_OCTET_STRING *id,
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EVP_PKEY *pkey, const EVP_MD *md, OSSL_LIB_CTX *libctx,
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const char *propq);
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int ASN1_item_sign(const ASN1_ITEM *it, X509_ALGOR *algor1, X509_ALGOR *algor2,
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ASN1_BIT_STRING *signature, const void *data,
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EVP_PKEY *pkey, const EVP_MD *md);
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int ASN1_item_sign_ctx(const ASN1_ITEM *it, X509_ALGOR *algor1,
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X509_ALGOR *algor2, ASN1_BIT_STRING *signature,
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const void *data, EVP_MD_CTX *ctx);
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int ASN1_item_verify_ex(const ASN1_ITEM *it, const X509_ALGOR *alg,
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const ASN1_BIT_STRING *signature, const void *data,
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const ASN1_OCTET_STRING *id, EVP_PKEY *pkey,
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OSSL_LIB_CTX *libctx, const char *propq);
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int ASN1_item_verify(const ASN1_ITEM *it, const X509_ALGOR *alg,
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const ASN1_BIT_STRING *signature, const void *data,
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EVP_PKEY *pkey);
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int ASN1_item_verify_ctx(const ASN1_ITEM *it, const X509_ALGOR *alg,
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const ASN1_BIT_STRING *signature, const void *data,
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EVP_MD_CTX *ctx);
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=head1 DESCRIPTION
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ASN1_item_sign_ex() is used to sign arbitrary ASN1 data using a data object
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I<data>, the ASN.1 structure I<it>, private key I<pkey> and message digest I<md>.
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The data that is signed is formed by taking the data object in I<data> and
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converting it to der format using the ASN.1 structure I<it>.
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The I<data> that will be signed, and a structure containing the signature may
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both have a copy of the B<X509_ALGOR>. The ASN1_item_sign_ex() function will
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write the correct B<X509_ALGOR> to the structs based on the algorithms and
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parameters that have been set up. If one of I<algor1> or I<algor2> points to the
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B<X509_ALGOR> of the I<data> to be signed, then that B<X509_ALGOR> will first be
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written before the signature is generated.
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Examples of valid values that can be used by the ASN.1 structure I<it> are
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ASN1_ITEM_rptr(X509_CINF), ASN1_ITEM_rptr(X509_REQ_INFO) and
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ASN1_ITEM_rptr(X509_CRL_INFO).
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The B<OSSL_LIB_CTX> specified in I<libctx> and the property query string
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specified in I<props> are used when searching for algorithms in providers.
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The generated signature is set into I<signature>.
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The optional parameter I<id> can be NULL, but can be set for special key types.
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See EVP_PKEY_CTX_set1_id() for further info. The output parameters <algor1> and
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I<algor2> are ignored if they are NULL.
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ASN1_item_sign() is similar to ASN1_item_sign_ex() but uses default values of
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NULL for the I<id>, I<libctx> and I<propq>.
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ASN1_item_sign_ctx() is similar to ASN1_item_sign() but uses the parameters
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contained in digest context I<ctx>.
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ASN1_item_verify_ex() is used to verify the signature I<signature> of internal
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data I<data> using the public key I<pkey> and algorithm identifier I<alg>.
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The data that is verified is formed by taking the data object in I<data> and
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converting it to der format using the ASN.1 structure I<it>.
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The B<OSSL_LIB_CTX> specified in I<libctx> and the property query string
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specified in I<props> are used when searching for algorithms in providers.
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The optional parameter I<id> can be NULL, but can be set for special key types.
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See EVP_PKEY_CTX_set1_id() for further info.
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ASN1_item_verify() is similar to ASN1_item_verify_ex() but uses default values of
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NULL for the I<id>, I<libctx> and I<propq>.
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ASN1_item_verify_ctx() is similar to ASN1_item_verify() but uses the parameters
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contained in digest context I<ctx>.
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=head1 RETURN VALUES
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All sign functions return the size of the signature in bytes for success and
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zero for failure.
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All verify functions return 1 if the signature is valid and 0 if the signature
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check fails. If the signature could not be checked at all because it was
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ill-formed or some other error occurred then -1 is returned.
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=head1 EXAMPLES
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In the following example a 'MyObject' object is signed using the key contained
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in an EVP_MD_CTX. The signature is written to MyObject.signature. The object is
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then output in DER format and then loaded back in and verified.
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#include <openssl/x509.h>
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#include <openssl/asn1t.h>
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/* An object used to store the ASN1 data fields that will be signed */
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typedef struct MySignInfoObject_st
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{
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ASN1_INTEGER *version;
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X509_ALGOR sig_alg;
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} MySignInfoObject;
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DECLARE_ASN1_FUNCTIONS(MySignInfoObject)
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/*
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* A higher level object containing the ASN1 fields, signature alg and
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* output signature.
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*/
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typedef struct MyObject_st
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{
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MySignInfoObject info;
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X509_ALGOR sig_alg;
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ASN1_BIT_STRING *signature;
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} MyObject;
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DECLARE_ASN1_FUNCTIONS(MyObject)
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/* The ASN1 definition of MySignInfoObject */
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ASN1_SEQUENCE_cb(MySignInfoObject, NULL) = {
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ASN1_SIMPLE(MySignInfoObject, version, ASN1_INTEGER)
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ASN1_EMBED(MySignInfoObject, sig_alg, X509_ALGOR),
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} ASN1_SEQUENCE_END_cb(MySignInfoObject, MySignInfoObject)
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/* new, free, d2i & i2d functions for MySignInfoObject */
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IMPLEMENT_ASN1_FUNCTIONS(MySignInfoObject)
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/* The ASN1 definition of MyObject */
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ASN1_SEQUENCE_cb(MyObject, NULL) = {
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ASN1_EMBED(MyObject, info, MySignInfoObject),
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ASN1_EMBED(MyObject, sig_alg, X509_ALGOR),
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ASN1_SIMPLE(MyObject, signature, ASN1_BIT_STRING)
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} ASN1_SEQUENCE_END_cb(MyObject, MyObject)
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/* new, free, d2i & i2d functions for MyObject */
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IMPLEMENT_ASN1_FUNCTIONS(MyObject)
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int test_asn1_item_sign_verify(const char *mdname, EVP_PKEY *pkey, long version)
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{
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int ret = 0;
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unsigned char *obj_der = NULL;
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const unsigned char *p = NULL;
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MyObject *obj = NULL, *loaded_obj = NULL;
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const ASN1_ITEM *it = ASN1_ITEM_rptr(MySignInfoObject);
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EVP_MD_CTX *sctx = NULL, *vctx = NULL;
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int len;
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/* Create MyObject and set its version */
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obj = MyObject_new();
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if (obj == NULL)
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goto err;
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if (!ASN1_INTEGER_set(obj->info.version, version))
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goto err;
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/* Set the key and digest used for signing */
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sctx = EVP_MD_CTX_new();
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if (sctx == NULL
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|| !EVP_DigestSignInit_ex(sctx, NULL, mdname, NULL, NULL, pkey))
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goto err;
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/*
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* it contains the mapping between ASN.1 data and an object MySignInfoObject
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* obj->info is the 'MySignInfoObject' object that will be
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* converted into DER data and then signed.
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* obj->signature will contain the output signature.
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* obj->sig_alg is filled with the private key's signing algorithm id.
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* obj->info.sig_alg is another copy of the signing algorithm id that sits
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* within MyObject.
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*/
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len = ASN1_item_sign_ctx(it, &obj->sig_alg, &obj->info.sig_alg,
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obj->signature, &obj->info, sctx);
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if (len <= 0
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|| X509_ALGOR_cmp(&obj->sig_alg, &obj->info.sig_alg) != 0)
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goto err;
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/* Output MyObject in der form */
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len = i2d_MyObject(obj, &obj_der);
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if (len <= 0)
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goto err;
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/* Set the key and digest used for verifying */
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vctx = EVP_MD_CTX_new();
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if (vctx == NULL
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goto err;
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/* Load the der data back into an object */
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p = obj_der;
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loaded_obj = d2i_MyObject(NULL, &p, len);
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if (loaded_obj == NULL)
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goto err;
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/* Verify the loaded object */
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ret = ASN1_item_verify_ctx(it, &loaded_obj->sig_alg, loaded_obj->signature,
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&loaded_obj->info, vctx);
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err:
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OPENSSL_free(obj_der);
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MyObject_free(loaded_obj);
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MyObject_free(obj);
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EVP_MD_CTX_free(sctx);
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EVP_MD_CTX_free(vctx);
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return ret;
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}
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=head1 SEE ALSO
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L<X509_sign(3)>,
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L<X509_verify(3)>
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=head1 HISTORY
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ASN1_item_sign_ex() and ASN1_item_verify_ex() were added in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2020-2022 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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