X509_GET_PUBKEY(3)         Library Functions Manual         X509_GET_PUBKEY(3)

NAME
     X509_get_pubkey, X509_get0_pubkey, X509_set_pubkey, X509_get_X509_PUBKEY,
     X509_get0_pubkey_bitstr, X509_REQ_get_pubkey, X509_REQ_get0_pubkey,
     X509_REQ_set_pubkey, X509_extract_key, X509_REQ_extract_key - get or set
     certificate or certificate request public key

SYNOPSIS
     #include <openssl/x509.h>

     EVP_PKEY *
     X509_get_pubkey(X509 *x);

     EVP_PKEY *
     X509_get0_pubkey(const X509 *x);

     int
     X509_set_pubkey(X509 *x, EVP_PKEY *pkey);

     X509_PUBKEY *
     X509_get_X509_PUBKEY(const X509 *x);

     ASN1_BIT_STRING *
     X509_get0_pubkey_bitstr(const X509 *x);

     EVP_PKEY *
     X509_REQ_get_pubkey(X509_REQ *req);

     EVP_PKEY *
     X509_REQ_get0_pubkey(X509_REQ *req);

     int
     X509_REQ_set_pubkey(X509_REQ *x, EVP_PKEY *pkey);

     EVP_PKEY *
     X509_extract_key(X509 *x);

     EVP_PKEY *
     X509_REQ_extract_key(X509_REQ *req);

DESCRIPTION
     X509_get_pubkey() attempts to decode the public key for certificate x.
     If successful, it returns the public key as an EVP_PKEY pointer with its
     reference count incremented: this means the returned key must be freed up
     after use.  X509_get0_pubkey() is similar except that it does not
     increment the reference count of the returned EVP_PKEY, so it must not be
     freed up after use.

     X509_get_X509_PUBKEY() returns an internal pointer to the
     SubjectPublicKeyInfo structure contained in x.  The returned value must
     not be freed up after use.

     X509_get0_pubkey_bitstr() returns an internal pointer to just the public
     key contained in this SubjectPublicKeyInfo structure, without the
     information about the algorithm used.

     X509_set_pubkey() attempts to set the public key for certificate x to
     pkey.  The key pkey should be freed up after use.

     X509_REQ_get_pubkey(), X509_REQ_get0_pubkey(), and X509_REQ_set_pubkey()
     are similar but operate on certificate request req.

     The first time a public key is decoded, the EVP_PKEY structure is cached
     in the certificate or certificate request itself.  Subsequent calls
     return the cached structure with its reference count incremented to
     improve performance.

     X509_extract_key() and X509_REQ_extract_key() are deprecated aliases for
     X509_get_pubkey() and X509_REQ_get_pubkey(), respectively, implemented as
     macros.

RETURN VALUES
     X509_get_pubkey(), X509_get0_pubkey(), X509_get_X509_PUBKEY(),
     X509_get0_pubkey_bitstr(), X509_REQ_get_pubkey(), X509_REQ_get0_pubkey(),
     X509_extract_key(), and X509_REQ_extract_key() return a public key or
     NULL if an error occurred.

     X509_set_pubkey() and X509_REQ_set_pubkey() return 1 for success or 0 for
     failure.

     In some cases of failure of X509_get0_pubkey(), X509_set_pubkey(),
     X509_REQ_get_pubkey(), X509_REQ_get0_pubkey(), and X509_REQ_set_pubkey(),
     the reason can be determined with ERR_get_error(3).

ERRORS
     X509_get_pubkey(), X509_get0_pubkey(), X509_REQ_get_pubkey(),
     X509_extract_key(), and X509_REQ_extract_key() provide diagnostics as
     documented for X509_PUBKEY_get(3).  If x or req is NULL or contains no
     certificate information, they fail without pushing an error onto the
     stack.

     X509_get_X509_PUBKEY() provides no diagnostics and crashes by accessing a
     NULL pointer if x is NULL or contains no certificate information,

     X509_get0_pubkey_bitstr() provides no diagnostics and fails without
     pushing an error onto the stack if x is NULL, but it crashes by accessing
     a NULL pointer if x contains no certificate information.

SEE ALSO
     d2i_X509(3), X509_CRL_get0_by_serial(3), X509_NAME_add_entry_by_txt(3),
     X509_NAME_ENTRY_get_object(3), X509_NAME_get_index_by_NID(3),
     X509_NAME_print_ex(3), X509_new(3), X509_PUBKEY_new(3), X509_REQ_new(3),
     X509_sign(3), X509_verify_cert(3), X509V3_get_d2i(3)

STANDARDS
     RFC 5280, Internet X.509 Public Key Infrastructure Certificate and
     Certificate Revocation List (CRL) Profile, section 4.1 Basic Certificate
     Fields

     RFC 2986: PKCS #10: Certification Request Syntax Specification, section
     4.1 CertificationRequestInfo

HISTORY
     X509_extract_key() and X509_REQ_extract_key() first appeared in SSLeay
     0.5.1 but returned a pointer to an RSA object before SSLeay 0.6.0.
     X509_get_pubkey(), X509_set_pubkey(), X509_REQ_get_pubkey(), and
     X509_REQ_set_pubkey() first appeared in SSLeay 0.6.5.
     X509_get_X509_PUBKEY() first appeared in SSLeay 0.8.0.  These functions
     have been available since OpenBSD 2.4.

     X509_get0_pubkey_bitstr() first appeared in OpenSSL 0.9.7 and has been
     available since OpenBSD 3.4.

     X509_get0_pubkey() first appeared in OpenSSL 1.1.0 and has been available
     since OpenBSD 6.3.  X509_REQ_get0_pubkey() first appeared in OpenSSL
     1.1.0 and has been available since OpenBSD 7.1.

Linux 6.8.2-arch2-1             March 31, 2022             Linux 6.8.2-arch2-1