EVP_PKEY_ASN1_METHOD, 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, EVP_PKEY_asn1_set_item, EVP_PKEY_asn1_set_siginf, EVP_PKEY_asn1_set_check, EVP_PKEY_asn1_set_public_check, EVP_PKEY_asn1_set_param_check, EVP_PKEY_asn1_set_security_bits, EVP_PKEY_asn1_set_set_priv_key, EVP_PKEY_asn1_set_set_pub_key, EVP_PKEY_asn1_set_get_priv_key, EVP_PKEY_asn1_set_get_pub_key, EVP_PKEY_get0_asn1 - manipulating and registering EVP_PKEY_ASN1_METHOD structure #include <openssl/evp.h> typedef struct evp_pkey_asn1_method_st EVP_PKEY_ASN1_METHOD; 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)); void EVP_PKEY_asn1_set_item(EVP_PKEY_ASN1_METHOD *ameth, int (*item_verify) (EVP_MD_CTX *ctx, const ASN1_ITEM *it, void *asn, X509_ALGOR *a, ASN1_BIT_STRING *sig, EVP_PKEY *pkey), int (*item_sign) (EVP_MD_CTX *ctx, const ASN1_ITEM *it, void *asn, X509_ALGOR *alg1, X509_ALGOR *alg2, ASN1_BIT_STRING *sig)); void EVP_PKEY_asn1_set_siginf(EVP_PKEY_ASN1_METHOD *ameth, int (*siginf_set) (X509_SIG_INFO *siginf, const X509_ALGOR *alg, const ASN1_STRING *sig)); void EVP_PKEY_asn1_set_check(EVP_PKEY_ASN1_METHOD *ameth, int (*pkey_check) (const EVP_PKEY *pk)); void EVP_PKEY_asn1_set_public_check(EVP_PKEY_ASN1_METHOD *ameth, int (*pkey_pub_check) (const EVP_PKEY *pk)); void EVP_PKEY_asn1_set_param_check(EVP_PKEY_ASN1_METHOD *ameth, int (*pkey_param_check) (const EVP_PKEY *pk)); void EVP_PKEY_asn1_set_security_bits(EVP_PKEY_ASN1_METHOD *ameth, int (*pkey_security_bits) (const EVP_PKEY *pk)); void EVP_PKEY_asn1_set_set_priv_key(EVP_PKEY_ASN1_METHOD *ameth, int (*set_priv_key) (EVP_PKEY *pk, const unsigned char *priv, size_t len)); void EVP_PKEY_asn1_set_set_pub_key(EVP_PKEY_ASN1_METHOD *ameth, int (*set_pub_key) (EVP_PKEY *pk, const unsigned char *pub, size_t len)); void EVP_PKEY_asn1_set_get_priv_key(EVP_PKEY_ASN1_METHOD *ameth, int (*get_priv_key) (const EVP_PKEY *pk, unsigned char *priv, size_t *len)); void EVP_PKEY_asn1_set_get_pub_key(EVP_PKEY_ASN1_METHOD *ameth, int (*get_pub_key) (const EVP_PKEY *pk, unsigned char *pub, size_t *len)); const EVP_PKEY_ASN1_METHOD *EVP_PKEY_get0_asn1(const EVP_PKEY *pkey); 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(3).

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 / encode X509_PUBKEY ASN.1 parameters to / from pk. They MUST return 0 on error, 1 on success. They're called by X509_PUBKEY_get0(3) and X509_PUBKEY_set(3). The pub_cmp() method is called when two public keys are to be compared. It MUST return 1 when the keys are equal, 0 otherwise. It's 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, 1 on success. It's 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 / encode PKCS8_PRIV_KEY_INFO form private key to / from pk. They MUST return 0 on error, 1 on success. They're called by EVP_PKCS82PKEY(3) and EVP_PKEY2PKCS8(3). 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, 1 on success. It's called by EVP_PKEY_print_private(3). int (*pkey_size) (const EVP_PKEY *pk); int (*pkey_bits) (const EVP_PKEY *pk); int (*pkey_security_bits) (const EVP_PKEY *pk); The pkey_size() method returns the key size in bytes. It's called by EVP_PKEY_size(3). The pkey_bits() method returns the key size in bits. It's called by EVP_PKEY_bits(3). 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 / encode DER formatted parameters to / from pk. They MUST return 0 on error, 1 on success. They're called by PEM_read_bio_Parameters(3) and the file: OSSL_STORE_LOADER(3). The param_missing() method returns 0 if a key parameter is missing, otherwise 1. It's called by EVP_PKEY_missing_parameters(3). The param_copy() method copies key parameters from from to to. It MUST return 0 on error, 1 on success. It's called by EVP_PKEY_copy_parameters(3). The param_cmp() method compares the parameters of keys a and b. It MUST return 1 when the keys are equal, 0 when not equal, or a negative number on error. It's 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, 1 on success. It's called by EVP_PKEY_print_params(3). int (*sig_print) (BIO *out, const X509_ALGOR *sigalg, const ASN1_STRING *sig, int indent, ASN1_PCTX *pctx); The sig_print() method prints a signature in humanly readable text to out, indented indent spaces. sigalg contains the exact signature algorithm. If the signature in sig doesn't correspond to what this method expects, X509_signature_dump() must be used as a last resort. It MUST return 0 on error, 1 on success. It's called by X509_signature_print(3). void (*pkey_free) (EVP_PKEY *pkey); The pkey_free() method helps freeing the internals of pkey. It's called by EVP_PKEY_free(3), EVP_PKEY_set_type(3), EVP_PKEY_set_type_str(3), and EVP_PKEY_assign(3). int (*pkey_ctrl) (EVP_PKEY *pkey, int op, long arg1, void *arg2); The pkey_ctrl() method adds extra algorithm specific control. It's called by EVP_PKEY_get_default_digest_nid(3), EVP_PKEY_set1_tls_encodedpoint(3), EVP_PKEY_get1_tls_encodedpoint(3), PKCS7_SIGNER_INFO_set(3), PKCS7_RECIP_INFO_set(3), ... int (*old_priv_decode) (EVP_PKEY *pkey, const unsigned char **pder, int derlen); int (*old_priv_encode) (const EVP_PKEY *pkey, unsigned char **pder); The old_priv_decode() and old_priv_encode() methods decode / encode they private key pkey from / to a DER formatted array. These are exclusively used to help decoding / encoding older (pre PKCS#8) PEM formatted encrypted private keys. old_priv_decode() MUST return 0 on error, 1 on success. old_priv_encode() MUST the return same kind of values as i2d_PrivateKey(). They're called by d2i_PrivateKey(3) and i2d_PrivateKey(3). int (*item_verify) (EVP_MD_CTX *ctx, const ASN1_ITEM *it, void *asn, X509_ALGOR *a, ASN1_BIT_STRING *sig, EVP_PKEY *pkey); int (*item_sign) (EVP_MD_CTX *ctx, const ASN1_ITEM *it, void *asn, X509_ALGOR *alg1, X509_ALGOR *alg2, ASN1_BIT_STRING *sig); The item_sign() and item_verify() methods make it possible to have algorithm specific signatures and verification of them. item_sign() MUST return one of: error item_sign() did everything, OpenSSL internals just needs to pass the signature length back. item_sign() did nothing, OpenSSL internal standard routines are expected to continue with the default signature production. item_sign() set the algorithm identifier algor1 and algor2, OpenSSL internals should just sign using those algorithms. item_verify() MUST return one of: error item_sign() did everything, OpenSSL internals just needs to pass the signature length back. item_sign() did nothing, OpenSSL internal standard routines are expected to continue with the default signature production. item_verify() and item_sign() are called by ASN1_item_verify(3) and ASN1_item_sign(3), and by extension, X509_verify(3), X509_REQ_verify(3), X509_sign(3), X509_REQ_sign(3), ... int (*siginf_set) (X509_SIG_INFO *siginf, const X509_ALGOR *alg, const ASN1_STRING *sig); The siginf_set() method is used to set custom X509_SIG_INFO parameters. It MUST return 0 on error, or 1 on success. It's called as part of X509_check_purpose(3), X509_check_ca(3) and X509_check_issued(3). int (*pkey_check) (const EVP_PKEY *pk); int (*pkey_public_check) (const EVP_PKEY *pk); int (*pkey_param_check) (const EVP_PKEY *pk); The pkey_check(), pkey_public_check() and pkey_param_check() methods are used to check the validity of pk for key-pair, public component and parameters, respectively. They MUST return 0 for an invalid key, or 1 for a valid key. They are called by EVP_PKEY_check(3), EVP_PKEY_public_check(3) and EVP_PKEY_param_check(3) respectively. int (*set_priv_key) (EVP_PKEY *pk, const unsigned char *priv, size_t len); int (*set_pub_key) (EVP_PKEY *pk, const unsigned char *pub, size_t len); The set_priv_key() and set_pub_key() methods are used to set the raw private and public key data for an EVP_PKEY. They MUST return 0 on error, or 1 on success. They are called by EVP_PKEY_new_raw_private_key(3), and EVP_PKEY_new_raw_public_key(3) respectively.

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. The following flags are supported: ASN1_PKEY_SIGPARAM_NULL If ASN1_PKEY_SIGPARAM_NULL is set, then 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's 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's 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(), EVP_PKEY_asn1_set_ctrl(), EVP_PKEY_asn1_set_item(), EVP_PKEY_asn1_set_siginf(), EVP_PKEY_asn1_set_check(), EVP_PKEY_asn1_set_public_check(), EVP_PKEY_asn1_set_param_check(), EVP_PKEY_asn1_set_security_bits(), EVP_PKEY_asn1_set_set_priv_key(), EVP_PKEY_asn1_set_set_pub_key(), EVP_PKEY_asn1_set_get_priv_key() and EVP_PKEY_asn1_set_get_pub_key() set the diverse methods of the given EVP_PKEY_ASN1_METHOD object. EVP_PKEY_get0_asn1() finds the EVP_PKEY_ASN1_METHOD associated with the key pkey. EVP_PKEY_asn1_new() returns NULL on error, or a pointer to an EVP_PKEY_ASN1_METHOD object otherwise. EVP_PKEY_asn1_add0() and EVP_PKEY_asn1_add_alias() return 0 on error, or 1 on success. EVP_PKEY_get0_asn1() returns NULL on error, or a pointer to a constant EVP_PKEY_ASN1_METHOD object otherwise. Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.