EVP_PKEY_ASN1_METHOD(3)

NAME
EVP_PKEY_asn1_new, EVP_PKEY_asn1_copy, EVP_PKEY_asn1_free, EVP_PKEY_asn1_add0, EVP_PKEY_asn1_add_alias, EVP_PKEY_asn1_set_public, EVP_PKEY_asn1_set_private, EVP_PKEY_asn1_set_param, EVP_PKEY_asn1_set_free, EVP_PKEY_asn1_set_ctrl - manipulating and registering an EVP_PKEY_ASN1_METHOD structure

SYNOPSIS
#include <openssl/evp.h>
EVP_PKEY_ASN1_METHOD *
EVP_PKEY_asn1_new(int id, int flags, const char *pem_str, const char *info);
void
EVP_PKEY_asn1_copy(EVP_PKEY_ASN1_METHOD *dst, const EVP_PKEY_ASN1_METHOD *src);
void
EVP_PKEY_asn1_free(EVP_PKEY_ASN1_METHOD *ameth);
int
EVP_PKEY_asn1_add0(const EVP_PKEY_ASN1_METHOD *ameth);
int
EVP_PKEY_asn1_add_alias(int to, int from);
void
EVP_PKEY_asn1_set_public(EVP_PKEY_ASN1_METHOD *ameth, int (*pub_decode)(EVP_PKEY *pk, X509_PUBKEY *pub), int (*pub_encode)(X509_PUBKEY *pub, const EVP_PKEY *pk), int (*pub_cmp)(const EVP_PKEY *a, const EVP_PKEY *b), int (*pub_print)(BIO *out, const EVP_PKEY *pkey, int indent, ASN1_PCTX *pctx), int (*pkey_size)(const EVP_PKEY *pk), int (*pkey_bits)(const EVP_PKEY *pk));
void
EVP_PKEY_asn1_set_private(EVP_PKEY_ASN1_METHOD *ameth, int (*priv_decode)(EVP_PKEY *pk, const PKCS8_PRIV_KEY_INFO *p8inf), int (*priv_encode)(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pk), int (*priv_print)(BIO *out, const EVP_PKEY *pkey, int indent, ASN1_PCTX *pctx));
void
EVP_PKEY_asn1_set_param(EVP_PKEY_ASN1_METHOD *ameth, int (*param_decode)(EVP_PKEY *pkey, const unsigned char **pder, int derlen), int (*param_encode)(const EVP_PKEY *pkey, unsigned char **pder), int (*param_missing)(const EVP_PKEY *pk), int (*param_copy)(EVP_PKEY *to, const EVP_PKEY *from), int (*param_cmp)(const EVP_PKEY *a, const EVP_PKEY *b), int (*param_print)(BIO *out, const EVP_PKEY *pkey, int indent, ASN1_PCTX *pctx));
void
EVP_PKEY_asn1_set_free(EVP_PKEY_ASN1_METHOD *ameth, void (*pkey_free)(EVP_PKEY *pkey));
void
EVP_PKEY_asn1_set_ctrl(EVP_PKEY_ASN1_METHOD *ameth, int (*pkey_ctrl)(EVP_PKEY *pkey, int op, long arg1, void *arg2));

DESCRIPTION
EVP_PKEY_ASN1_METHOD is a structure which holds a set of ASN.1 conversion, printing and information methods for a specific public key algorithm.

There are two places where the EVP_PKEY_ASN1_METHOD objects are stored: one is a built-in array representing the standard methods for different algorithms, and the other one is a stack of user-defined application-specific methods, which can be manipulated by using EVP_PKEY_asn1_add0().

  Methods
The methods are the underlying implementations of a particular public key algorithm present by the EVP_PKEY object.

    int (*pub_decode)(
    EVP_PKEY *pk
    , X509_PUBKEY *pub
    )
    int (*pub_encode)(
    X509_PUBKEY *pub
    , const EVP_PKEY *pk
    )
    int (*pub_cmp)(
    const EVP_PKEY *a
    , const EVP_PKEY *b
    )
    int (*pub_print)(
    BIO *out
    , const EVP_PKEY *pkey
    , int indent
    , ASN1_PCTX *pctx
    )

The pub_decode() and pub_encode() methods are called to decode and encode X509_PUBKEY ASN.1 parameters to and from pk. They must return 0 on error and 1 on success. They are called by X509_PUBKEY_get(3) and X509_PUBKEY_set(3).

The pub_cmp() method is called when two public keys are compared. It must return 1 when the keys are equal and 0 otherwise. It is called by EVP_PKEY_cmp(3).

The pub_print() method is called to print a public key in humanly readable text to out, indented indent spaces. It must return 0 on error and 1 on success. It is called by EVP_PKEY_print_public(3).

    int (*priv_decode)(
    EVP_PKEY *pk
    , const PKCS8_PRIV_KEY_INFO *p8inf
    )
    int (*priv_encode)(
    PKCS8_PRIV_KEY_INFO *p8
    , const EVP_PKEY *pk
    )
    int (*priv_print)(
    BIO *out
    , const EVP_PKEY *pkey
    , int indent
    , ASN1_PCTX *pctx
    )

The priv_decode() and priv_encode() methods are called to decode and encode PKCS8_PRIV_KEY_INFO form private key to and from pk. They must return 0 on error, 1 on success. They are called by EVP_PKCS82PKEY() and EVP_PKEY2PKCS8().

The priv_print() method is called to print a private key in humanly readable text to out, indented indent spaces. It must return 0 on error and 1 on success. It is called by EVP_PKEY_print_private(3).

    int (*pkey_size)(const EVP_PKEY *pk)
    int (*pkey_bits)(const EVP_PKEY *pk);

The pkey_size() method returns the key size in bytes. It is called by EVP_PKEY_size(3).

The pkey_bits() method returns the key size in bits. It's called by EVP_PKEY_bits().

    int (*param_decode)(
    EVP_PKEY *pkey
    , const unsigned char **pder
    , int derlen
    )
    int (*param_encode)(
    const EVP_PKEY *pkey
    , unsigned char **pder
    )
    int (*param_missing)(
    const EVP_PKEY *pk
    )
    int (*param_copy)(
    EVP_PKEY *to
    , const EVP_PKEY *from
    )
    int (*param_cmp)(
    const EVP_PKEY *a
    , const EVP_PKEY *b
    )
    int (*param_print)(
    BIO *out
    , const EVP_PKEY *pkey
    , int indent
    , ASN1_PCTX *pctx
    )

The param_decode() and param_encode() methods are called to decode and encode DER formatted parameters to and from pk. They must return 0 on error and 1 on success. They are called by PEM_read_bio_Parameters().

The param_missing() method returns 0 if a key parameter is missing or otherwise 1. It is called by EVP_PKEY_missing_parameters(3).

The param_copy() method copies key parameters from from to to. It must return 0 on error and 1 on success. It is called by EVP_PKEY_copy_parameters(3).

The param_cmp() method compares the parameters of the keys a and b. It must return 1 when the keys are equal, 0 when not equal, and a negative number on error. It is called by EVP_PKEY_cmp_parameters(3).

The param_print() method prints the private key parameters in humanly readable text to out, indented indent spaces. It must return 0 on error and 1 on success. It is called by EVP_PKEY_print_params(3).

    void (*pkey_free)(EVP_PKEY *pkey)

The pkey_free() method helps freeing the internals of pkey. It is called by EVP_PKEY_free(3), EVP_PKEY_set_type(), EVP_PKEY_set_type_str(), and EVP_PKEY_assign().

    int (*pkey_ctrl)(
    EVP_PKEY *pkey
    , int op
    , long arg1
    , void *arg2
    )

The pkey_ctrl() method adds extra algorithm specific control. It is called by EVP_PKEY_get_default_digest_nid(3), PKCS7_SIGNER_INFO_set(), PKCS7_RECIP_INFO_set(), and other functions.

  Functions
EVP_PKEY_asn1_new() creates and returns a new EVP_PKEY_ASN1_METHOD object, and associates the given id, flags, pem_str and info. id is a NID, pem_str is the PEM type string, info is a descriptive string. If ASN1_PKEY_SIGPARAM_NULL is set in flags, the signature algorithm parameters are given the type V_ASN1_NULL by default, otherwise they will be given the type V_ASN1_UNDEF (i.e. the parameter is omitted). See X509_ALGOR_set0(3) for more information.

EVP_PKEY_asn1_copy() copies an EVP_PKEY_ASN1_METHOD object from src to dst. This function is not thread safe, it is recommended to only use this when initializing the application.

EVP_PKEY_asn1_free() frees an existing EVP_PKEY_ASN1_METHOD pointed by ameth.

EVP_PKEY_asn1_add0() adds ameth to the user defined stack of methods unless another EVP_PKEY_ASN1_METHOD with the same NID is already there. This function is not thread safe, it is recommended to only use this when initializing the application.

EVP_PKEY_asn1_add_alias() creates an alias with the NID to for the EVP_PKEY_ASN1_METHOD with NID from unless another EVP_PKEY_ASN1_METHOD with the same NID is already added. This function is not thread safe, it's recommended to only use this when initializing the application.

EVP_PKEY_asn1_set_public(), EVP_PKEY_asn1_set_private(), EVP_PKEY_asn1_set_param(), EVP_PKEY_asn1_set_free(), and EVP_PKEY_asn1_set_ctrl() set the diverse methods of the given EVP_PKEY_ASN1_METHOD object.

RETURN VALUES
EVP_PKEY_asn1_new() returns a pointer to an EVP_PKEY_ASN1_METHOD object or NULL on error.

EVP_PKEY_asn1_add0() and EVP_PKEY_asn1_add_alias() return 0 on error or 1 on success.

HISTORY
These functions first appeared in OpenSSL 1.0.0 and have been available since OpenBSD 4.9.