X509v3(3) - phpMan

X509V3_add1_i2d (3ssl) - X509 extension decode and encode functions
X509v3_add_ext (3ssl) - extension stack utility functions
x509v3_config (5ssl) - X509 V3 certificate extension configuration format
X509v3_delete_ext (3ssl) - extension stack utility functions
X509V3_EXT_d2i (3ssl) - X509 extension decode and encode functions
X509V3_EXT_i2d (3ssl) - X509 extension decode and encode functions
X509V3_get_d2i (3ssl) - X509 extension decode and encode functions
X509v3_get_ext (3ssl) - extension stack utility functions
X509v3_get_ext_by_critical (3ssl) - extension stack utility functions
X509v3_get_ext_by_NID (3ssl) - extension stack utility functions
X509v3_get_ext_by_OBJ (3ssl) - extension stack utility functions
X509v3_get_ext_count (3ssl) - extension stack utility functions