|  | =pod | 
|  |  | 
|  | =head1 NAME | 
|  |  | 
|  | EVP_PKEY_meth_new, EVP_PKEY_meth_free, EVP_PKEY_meth_copy, EVP_PKEY_meth_find, | 
|  | EVP_PKEY_meth_add0, EVP_PKEY_METHOD, | 
|  | EVP_PKEY_meth_set_init, EVP_PKEY_meth_set_copy, EVP_PKEY_meth_set_cleanup, | 
|  | EVP_PKEY_meth_set_paramgen, EVP_PKEY_meth_set_keygen, EVP_PKEY_meth_set_sign, | 
|  | EVP_PKEY_meth_set_verify, EVP_PKEY_meth_set_verify_recover, EVP_PKEY_meth_set_signctx, | 
|  | EVP_PKEY_meth_set_verifyctx, EVP_PKEY_meth_set_encrypt, EVP_PKEY_meth_set_decrypt, | 
|  | EVP_PKEY_meth_set_derive, EVP_PKEY_meth_set_ctrl, | 
|  | EVP_PKEY_meth_set_digestsign, EVP_PKEY_meth_set_digestverify, | 
|  | EVP_PKEY_meth_set_check, | 
|  | EVP_PKEY_meth_set_public_check, EVP_PKEY_meth_set_param_check, | 
|  | EVP_PKEY_meth_set_digest_custom, | 
|  | EVP_PKEY_meth_get_init, EVP_PKEY_meth_get_copy, EVP_PKEY_meth_get_cleanup, | 
|  | EVP_PKEY_meth_get_paramgen, EVP_PKEY_meth_get_keygen, EVP_PKEY_meth_get_sign, | 
|  | EVP_PKEY_meth_get_verify, EVP_PKEY_meth_get_verify_recover, EVP_PKEY_meth_get_signctx, | 
|  | EVP_PKEY_meth_get_verifyctx, EVP_PKEY_meth_get_encrypt, EVP_PKEY_meth_get_decrypt, | 
|  | EVP_PKEY_meth_get_derive, EVP_PKEY_meth_get_ctrl, | 
|  | EVP_PKEY_meth_get_digestsign, EVP_PKEY_meth_get_digestverify, | 
|  | EVP_PKEY_meth_get_check, | 
|  | EVP_PKEY_meth_get_public_check, EVP_PKEY_meth_get_param_check, | 
|  | EVP_PKEY_meth_get_digest_custom, | 
|  | EVP_PKEY_meth_remove | 
|  | - manipulating EVP_PKEY_METHOD structure | 
|  |  | 
|  | =head1 SYNOPSIS | 
|  |  | 
|  | #include <openssl/evp.h> | 
|  |  | 
|  | Deprecated since OpenSSL 3.0, can be hidden entirely by defining | 
|  | B<OPENSSL_API_COMPAT> with a suitable version value, see | 
|  | L<openssl_user_macros(7)>: | 
|  |  | 
|  | typedef struct evp_pkey_method_st EVP_PKEY_METHOD; | 
|  |  | 
|  | EVP_PKEY_METHOD *EVP_PKEY_meth_new(int id, int flags); | 
|  | void EVP_PKEY_meth_free(EVP_PKEY_METHOD *pmeth); | 
|  | void EVP_PKEY_meth_copy(EVP_PKEY_METHOD *dst, const EVP_PKEY_METHOD *src); | 
|  | const EVP_PKEY_METHOD *EVP_PKEY_meth_find(int type); | 
|  | int EVP_PKEY_meth_add0(const EVP_PKEY_METHOD *pmeth); | 
|  | int EVP_PKEY_meth_remove(const EVP_PKEY_METHOD *pmeth); | 
|  |  | 
|  | void EVP_PKEY_meth_set_init(EVP_PKEY_METHOD *pmeth, | 
|  | int (*init) (EVP_PKEY_CTX *ctx)); | 
|  | void EVP_PKEY_meth_set_copy(EVP_PKEY_METHOD *pmeth, | 
|  | int (*copy) (EVP_PKEY_CTX *dst, | 
|  | EVP_PKEY_CTX *src)); | 
|  | void EVP_PKEY_meth_set_cleanup(EVP_PKEY_METHOD *pmeth, | 
|  | void (*cleanup) (EVP_PKEY_CTX *ctx)); | 
|  | void EVP_PKEY_meth_set_paramgen(EVP_PKEY_METHOD *pmeth, | 
|  | int (*paramgen_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*paramgen) (EVP_PKEY_CTX *ctx, | 
|  | EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_set_keygen(EVP_PKEY_METHOD *pmeth, | 
|  | int (*keygen_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*keygen) (EVP_PKEY_CTX *ctx, | 
|  | EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_set_sign(EVP_PKEY_METHOD *pmeth, | 
|  | int (*sign_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*sign) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *sig, size_t *siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_set_verify(EVP_PKEY_METHOD *pmeth, | 
|  | int (*verify_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*verify) (EVP_PKEY_CTX *ctx, | 
|  | const unsigned char *sig, | 
|  | size_t siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_set_verify_recover(EVP_PKEY_METHOD *pmeth, | 
|  | int (*verify_recover_init) (EVP_PKEY_CTX | 
|  | *ctx), | 
|  | int (*verify_recover) (EVP_PKEY_CTX | 
|  | *ctx, | 
|  | unsigned char | 
|  | *sig, | 
|  | size_t *siglen, | 
|  | const unsigned | 
|  | char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_set_signctx(EVP_PKEY_METHOD *pmeth, | 
|  | int (*signctx_init) (EVP_PKEY_CTX *ctx, | 
|  | EVP_MD_CTX *mctx), | 
|  | int (*signctx) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *sig, | 
|  | size_t *siglen, | 
|  | EVP_MD_CTX *mctx)); | 
|  | void EVP_PKEY_meth_set_verifyctx(EVP_PKEY_METHOD *pmeth, | 
|  | int (*verifyctx_init) (EVP_PKEY_CTX *ctx, | 
|  | EVP_MD_CTX *mctx), | 
|  | int (*verifyctx) (EVP_PKEY_CTX *ctx, | 
|  | const unsigned char *sig, | 
|  | int siglen, | 
|  | EVP_MD_CTX *mctx)); | 
|  | void EVP_PKEY_meth_set_encrypt(EVP_PKEY_METHOD *pmeth, | 
|  | int (*encrypt_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*encryptfn) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *out, | 
|  | size_t *outlen, | 
|  | const unsigned char *in, | 
|  | size_t inlen)); | 
|  | void EVP_PKEY_meth_set_decrypt(EVP_PKEY_METHOD *pmeth, | 
|  | int (*decrypt_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*decrypt) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *out, | 
|  | size_t *outlen, | 
|  | const unsigned char *in, | 
|  | size_t inlen)); | 
|  | void EVP_PKEY_meth_set_derive(EVP_PKEY_METHOD *pmeth, | 
|  | int (*derive_init) (EVP_PKEY_CTX *ctx), | 
|  | int (*derive) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *key, | 
|  | size_t *keylen)); | 
|  | void EVP_PKEY_meth_set_ctrl(EVP_PKEY_METHOD *pmeth, | 
|  | int (*ctrl) (EVP_PKEY_CTX *ctx, int type, int p1, | 
|  | void *p2), | 
|  | int (*ctrl_str) (EVP_PKEY_CTX *ctx, | 
|  | const char *type, | 
|  | const char *value)); | 
|  | void EVP_PKEY_meth_set_digestsign(EVP_PKEY_METHOD *pmeth, | 
|  | int (*digestsign) (EVP_MD_CTX *ctx, | 
|  | unsigned char *sig, | 
|  | size_t *siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_set_digestverify(EVP_PKEY_METHOD *pmeth, | 
|  | int (*digestverify) (EVP_MD_CTX *ctx, | 
|  | const unsigned char *sig, | 
|  | size_t siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_set_check(EVP_PKEY_METHOD *pmeth, | 
|  | int (*check) (EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_set_public_check(EVP_PKEY_METHOD *pmeth, | 
|  | int (*check) (EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_set_param_check(EVP_PKEY_METHOD *pmeth, | 
|  | int (*check) (EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_set_digest_custom(EVP_PKEY_METHOD *pmeth, | 
|  | int (*digest_custom) (EVP_PKEY_CTX *ctx, | 
|  | EVP_MD_CTX *mctx)); | 
|  |  | 
|  | void EVP_PKEY_meth_get_init(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pinit) (EVP_PKEY_CTX *ctx)); | 
|  | void EVP_PKEY_meth_get_copy(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pcopy) (EVP_PKEY_CTX *dst, | 
|  | EVP_PKEY_CTX *src)); | 
|  | void EVP_PKEY_meth_get_cleanup(const EVP_PKEY_METHOD *pmeth, | 
|  | void (**pcleanup) (EVP_PKEY_CTX *ctx)); | 
|  | void EVP_PKEY_meth_get_paramgen(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pparamgen_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**pparamgen) (EVP_PKEY_CTX *ctx, | 
|  | EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_get_keygen(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pkeygen_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**pkeygen) (EVP_PKEY_CTX *ctx, | 
|  | EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_get_sign(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**psign_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**psign) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *sig, size_t *siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_get_verify(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pverify_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**pverify) (EVP_PKEY_CTX *ctx, | 
|  | const unsigned char *sig, | 
|  | size_t siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_get_verify_recover(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pverify_recover_init) (EVP_PKEY_CTX | 
|  | *ctx), | 
|  | int (**pverify_recover) (EVP_PKEY_CTX | 
|  | *ctx, | 
|  | unsigned char | 
|  | *sig, | 
|  | size_t *siglen, | 
|  | const unsigned | 
|  | char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_get_signctx(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**psignctx_init) (EVP_PKEY_CTX *ctx, | 
|  | EVP_MD_CTX *mctx), | 
|  | int (**psignctx) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *sig, | 
|  | size_t *siglen, | 
|  | EVP_MD_CTX *mctx)); | 
|  | void EVP_PKEY_meth_get_verifyctx(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pverifyctx_init) (EVP_PKEY_CTX *ctx, | 
|  | EVP_MD_CTX *mctx), | 
|  | int (**pverifyctx) (EVP_PKEY_CTX *ctx, | 
|  | const unsigned char *sig, | 
|  | int siglen, | 
|  | EVP_MD_CTX *mctx)); | 
|  | void EVP_PKEY_meth_get_encrypt(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pencrypt_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**pencryptfn) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *out, | 
|  | size_t *outlen, | 
|  | const unsigned char *in, | 
|  | size_t inlen)); | 
|  | void EVP_PKEY_meth_get_decrypt(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pdecrypt_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**pdecrypt) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *out, | 
|  | size_t *outlen, | 
|  | const unsigned char *in, | 
|  | size_t inlen)); | 
|  | void EVP_PKEY_meth_get_derive(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pderive_init) (EVP_PKEY_CTX *ctx), | 
|  | int (**pderive) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *key, | 
|  | size_t *keylen)); | 
|  | void EVP_PKEY_meth_get_ctrl(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pctrl) (EVP_PKEY_CTX *ctx, int type, int p1, | 
|  | void *p2), | 
|  | int (**pctrl_str) (EVP_PKEY_CTX *ctx, | 
|  | const char *type, | 
|  | const char *value)); | 
|  | void EVP_PKEY_meth_get_digestsign(EVP_PKEY_METHOD *pmeth, | 
|  | int (**digestsign) (EVP_MD_CTX *ctx, | 
|  | unsigned char *sig, | 
|  | size_t *siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_get_digestverify(EVP_PKEY_METHOD *pmeth, | 
|  | int (**digestverify) (EVP_MD_CTX *ctx, | 
|  | const unsigned char *sig, | 
|  | size_t siglen, | 
|  | const unsigned char *tbs, | 
|  | size_t tbslen)); | 
|  | void EVP_PKEY_meth_get_check(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pcheck) (EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_get_public_check(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pcheck) (EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_get_param_check(const EVP_PKEY_METHOD *pmeth, | 
|  | int (**pcheck) (EVP_PKEY *pkey)); | 
|  | void EVP_PKEY_meth_get_digest_custom(EVP_PKEY_METHOD *pmeth, | 
|  | int (**pdigest_custom) (EVP_PKEY_CTX *ctx, | 
|  | EVP_MD_CTX *mctx)); | 
|  |  | 
|  | =head1 DESCRIPTION | 
|  |  | 
|  | All of the functions described on this page are deprecated. | 
|  | Applications should instead use the OSSL_PROVIDER APIs. | 
|  |  | 
|  | B<EVP_PKEY_METHOD> is a structure which holds a set of methods for a | 
|  | specific public key cryptographic algorithm. Those methods are usually | 
|  | used to perform different jobs, such as generating a key, signing or | 
|  | verifying, encrypting or decrypting, etc. | 
|  |  | 
|  | There are two places where the B<EVP_PKEY_METHOD> objects are stored: one | 
|  | is a built-in static 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 L<EVP_PKEY_meth_add0(3)>. | 
|  |  | 
|  | The B<EVP_PKEY_METHOD> objects are usually referenced by B<EVP_PKEY_CTX> | 
|  | objects. | 
|  |  | 
|  | =head2 Methods | 
|  |  | 
|  | The methods are the underlying implementations of a particular public key | 
|  | algorithm present by the B<EVP_PKEY_CTX> object. | 
|  |  | 
|  | int (*init) (EVP_PKEY_CTX *ctx); | 
|  | int (*copy) (EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src); | 
|  | void (*cleanup) (EVP_PKEY_CTX *ctx); | 
|  |  | 
|  | The init() method is called to initialize algorithm-specific data when a new | 
|  | B<EVP_PKEY_CTX> is created. As opposed to init(), the cleanup() method is called | 
|  | when an B<EVP_PKEY_CTX> is freed. The copy() method is called when an B<EVP_PKEY_CTX> | 
|  | is being duplicated. Refer to L<EVP_PKEY_CTX_new(3)>, L<EVP_PKEY_CTX_new_id(3)>, | 
|  | L<EVP_PKEY_CTX_free(3)> and L<EVP_PKEY_CTX_dup(3)>. | 
|  |  | 
|  | int (*paramgen_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*paramgen) (EVP_PKEY_CTX *ctx, EVP_PKEY *pkey); | 
|  |  | 
|  | The paramgen_init() and paramgen() methods deal with key parameter generation. | 
|  | They are called by L<EVP_PKEY_paramgen_init(3)> and L<EVP_PKEY_paramgen(3)> to | 
|  | handle the parameter generation process. | 
|  |  | 
|  | int (*keygen_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*keygen) (EVP_PKEY_CTX *ctx, EVP_PKEY *pkey); | 
|  |  | 
|  | The keygen_init() and keygen() methods are used to generate the actual key for | 
|  | the specified algorithm. They are called by L<EVP_PKEY_keygen_init(3)> and | 
|  | L<EVP_PKEY_keygen(3)>. | 
|  |  | 
|  | int (*sign_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*sign) (EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen, | 
|  | const unsigned char *tbs, size_t tbslen); | 
|  |  | 
|  | The sign_init() and sign() methods are used to generate the signature of a | 
|  | piece of data using a private key. They are called by L<EVP_PKEY_sign_init(3)> | 
|  | and L<EVP_PKEY_sign(3)>. | 
|  |  | 
|  | int (*verify_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*verify) (EVP_PKEY_CTX *ctx, | 
|  | const unsigned char *sig, size_t siglen, | 
|  | const unsigned char *tbs, size_t tbslen); | 
|  |  | 
|  | The verify_init() and verify() methods are used to verify whether a signature is | 
|  | valid. They are called by L<EVP_PKEY_verify_init(3)> and L<EVP_PKEY_verify(3)>. | 
|  |  | 
|  | int (*verify_recover_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*verify_recover) (EVP_PKEY_CTX *ctx, | 
|  | unsigned char *rout, size_t *routlen, | 
|  | const unsigned char *sig, size_t siglen); | 
|  |  | 
|  | The verify_recover_init() and verify_recover() methods are used to verify a | 
|  | signature and then recover the digest from the signature (for instance, a | 
|  | signature that was generated by RSA signing algorithm). They are called by | 
|  | L<EVP_PKEY_verify_recover_init(3)> and L<EVP_PKEY_verify_recover(3)>. | 
|  |  | 
|  | int (*signctx_init) (EVP_PKEY_CTX *ctx, EVP_MD_CTX *mctx); | 
|  | int (*signctx) (EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen, | 
|  | EVP_MD_CTX *mctx); | 
|  |  | 
|  | The signctx_init() and signctx() methods are used to sign a digest present by | 
|  | a B<EVP_MD_CTX> object. They are called by the EVP_DigestSign functions. See | 
|  | L<EVP_DigestSignInit(3)> for details. | 
|  |  | 
|  | int (*verifyctx_init) (EVP_PKEY_CTX *ctx, EVP_MD_CTX *mctx); | 
|  | int (*verifyctx) (EVP_PKEY_CTX *ctx, const unsigned char *sig, int siglen, | 
|  | EVP_MD_CTX *mctx); | 
|  |  | 
|  | The verifyctx_init() and verifyctx() methods are used to verify a signature | 
|  | against the data in a B<EVP_MD_CTX> object. They are called by the various | 
|  | EVP_DigestVerify functions. See L<EVP_DigestVerifyInit(3)> for details. | 
|  |  | 
|  | int (*encrypt_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*encrypt) (EVP_PKEY_CTX *ctx, unsigned char *out, size_t *outlen, | 
|  | const unsigned char *in, size_t inlen); | 
|  |  | 
|  | The encrypt_init() and encrypt() methods are used to encrypt a piece of data. | 
|  | They are called by L<EVP_PKEY_encrypt_init(3)> and L<EVP_PKEY_encrypt(3)>. | 
|  |  | 
|  | int (*decrypt_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*decrypt) (EVP_PKEY_CTX *ctx, unsigned char *out, size_t *outlen, | 
|  | const unsigned char *in, size_t inlen); | 
|  |  | 
|  | The decrypt_init() and decrypt() methods are used to decrypt a piece of data. | 
|  | They are called by L<EVP_PKEY_decrypt_init(3)> and L<EVP_PKEY_decrypt(3)>. | 
|  |  | 
|  | int (*derive_init) (EVP_PKEY_CTX *ctx); | 
|  | int (*derive) (EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen); | 
|  |  | 
|  | The derive_init() and derive() methods are used to derive the shared secret | 
|  | from a public key algorithm (for instance, the DH algorithm). They are called by | 
|  | L<EVP_PKEY_derive_init(3)> and L<EVP_PKEY_derive(3)>. | 
|  |  | 
|  | int (*ctrl) (EVP_PKEY_CTX *ctx, int type, int p1, void *p2); | 
|  | int (*ctrl_str) (EVP_PKEY_CTX *ctx, const char *type, const char *value); | 
|  |  | 
|  | The ctrl() and ctrl_str() methods are used to adjust algorithm-specific | 
|  | settings. See L<EVP_PKEY_CTX_ctrl(3)> and related functions for details. | 
|  |  | 
|  | int (*digestsign) (EVP_MD_CTX *ctx, unsigned char *sig, size_t *siglen, | 
|  | const unsigned char *tbs, size_t tbslen); | 
|  | int (*digestverify) (EVP_MD_CTX *ctx, const unsigned char *sig, | 
|  | size_t siglen, const unsigned char *tbs, | 
|  | size_t tbslen); | 
|  |  | 
|  | The digestsign() and digestverify() methods are used to generate or verify | 
|  | a signature in a one-shot mode. They could be called by L<EVP_DigestSign(3)> | 
|  | and L<EVP_DigestVerify(3)>. | 
|  |  | 
|  | int (*check) (EVP_PKEY *pkey); | 
|  | int (*public_check) (EVP_PKEY *pkey); | 
|  | int (*param_check) (EVP_PKEY *pkey); | 
|  |  | 
|  | The check(), public_check() and param_check() methods are used to validate a | 
|  | key-pair, the public component and parameters respectively for a given B<pkey>. | 
|  | They could be called by L<EVP_PKEY_check(3)>, L<EVP_PKEY_public_check(3)> and | 
|  | L<EVP_PKEY_param_check(3)> respectively. | 
|  |  | 
|  | int (*digest_custom) (EVP_PKEY_CTX *ctx, EVP_MD_CTX *mctx); | 
|  |  | 
|  | The digest_custom() method is used to generate customized digest content before | 
|  | the real message is passed to functions like L<EVP_DigestSignUpdate(3)> or | 
|  | L<EVP_DigestVerifyInit(3)>. This is usually required by some public key | 
|  | signature algorithms like SM2 which requires a hashed prefix to the message to | 
|  | be signed. The digest_custom() function will be called by L<EVP_DigestSignInit(3)> | 
|  | and L<EVP_DigestVerifyInit(3)>. | 
|  |  | 
|  | =head2 Functions | 
|  |  | 
|  | EVP_PKEY_meth_new() creates and returns a new B<EVP_PKEY_METHOD> object, | 
|  | and associates the given B<id> and B<flags>. The following flags are | 
|  | supported: | 
|  |  | 
|  | EVP_PKEY_FLAG_AUTOARGLEN | 
|  | EVP_PKEY_FLAG_SIGCTX_CUSTOM | 
|  |  | 
|  | If an B<EVP_PKEY_METHOD> is set with the B<EVP_PKEY_FLAG_AUTOARGLEN> flag, the | 
|  | maximum size of the output buffer will be automatically calculated or checked | 
|  | in corresponding EVP methods by the EVP framework. Thus the implementations of | 
|  | these methods don't need to care about handling the case of returning output | 
|  | buffer size by themselves. For details on the output buffer size, refer to | 
|  | L<EVP_PKEY_sign(3)>. | 
|  |  | 
|  | The B<EVP_PKEY_FLAG_SIGCTX_CUSTOM> is used to indicate the signctx() method | 
|  | of an B<EVP_PKEY_METHOD> is always called by the EVP framework while doing a | 
|  | digest signing operation by calling L<EVP_DigestSignFinal(3)>. | 
|  |  | 
|  | EVP_PKEY_meth_free() frees an existing B<EVP_PKEY_METHOD> pointed by | 
|  | B<pmeth>. | 
|  |  | 
|  | EVP_PKEY_meth_copy() copies an B<EVP_PKEY_METHOD> object from B<src> | 
|  | to B<dst>. | 
|  |  | 
|  | EVP_PKEY_meth_find() finds an B<EVP_PKEY_METHOD> object with the B<id>. | 
|  | This function first searches through the user-defined method objects and | 
|  | then the built-in objects. | 
|  |  | 
|  | EVP_PKEY_meth_add0() adds B<pmeth> to the user defined stack of methods. | 
|  |  | 
|  | EVP_PKEY_meth_remove() removes an B<EVP_PKEY_METHOD> object added by | 
|  | EVP_PKEY_meth_add0(). | 
|  |  | 
|  | The EVP_PKEY_meth_set functions set the corresponding fields of | 
|  | B<EVP_PKEY_METHOD> structure with the arguments passed. | 
|  |  | 
|  | The EVP_PKEY_meth_get functions get the corresponding fields of | 
|  | B<EVP_PKEY_METHOD> structure to the arguments provided. | 
|  |  | 
|  | =head1 RETURN VALUES | 
|  |  | 
|  | EVP_PKEY_meth_new() returns a pointer to a new B<EVP_PKEY_METHOD> | 
|  | object or returns NULL on error. | 
|  |  | 
|  | EVP_PKEY_meth_free() and EVP_PKEY_meth_copy() do not return values. | 
|  |  | 
|  | EVP_PKEY_meth_find() returns a pointer to the found B<EVP_PKEY_METHOD> | 
|  | object or returns NULL if not found. | 
|  |  | 
|  | EVP_PKEY_meth_add0() returns 1 if method is added successfully or 0 | 
|  | if an error occurred. | 
|  |  | 
|  | EVP_PKEY_meth_remove() returns 1 if method is removed successfully or | 
|  | 0 if an error occurred. | 
|  |  | 
|  | All EVP_PKEY_meth_set and EVP_PKEY_meth_get functions have no return | 
|  | values. For the 'get' functions, function pointers are returned by | 
|  | arguments. | 
|  |  | 
|  | =head1 HISTORY | 
|  |  | 
|  | All of these functions were deprecated in OpenSSL 3.0. | 
|  |  | 
|  | =head1 COPYRIGHT | 
|  |  | 
|  | Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved. | 
|  |  | 
|  | Licensed under the Apache License 2.0 (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 | 
|  | L<https://www.openssl.org/source/license.html>. | 
|  |  | 
|  | =cut |