EVP_PKEY_ASN1_METHOD(3SSL)
✨ NAME ✨
okay bestie, welcome to the EVP_PKEY_ASN1_METHOD(3SSL) page 💅 — this is the manual for manipulating and registering the EVP_PKEY_ASN1_METHOD structure, and the whole squad is here, no cap 🫶:
EVP_PKEY_ASN1_METHODEVP_PKEY_asn1_newEVP_PKEY_asn1_copyEVP_PKEY_asn1_freeEVP_PKEY_asn1_add0EVP_PKEY_asn1_add_aliasEVP_PKEY_asn1_set_publicEVP_PKEY_asn1_set_privateEVP_PKEY_asn1_set_paramEVP_PKEY_asn1_set_freeEVP_PKEY_asn1_set_ctrlEVP_PKEY_asn1_set_itemEVP_PKEY_asn1_set_siginfEVP_PKEY_asn1_set_checkEVP_PKEY_asn1_set_public_checkEVP_PKEY_asn1_set_param_checkEVP_PKEY_asn1_set_security_bitsEVP_PKEY_asn1_set_set_priv_keyEVP_PKEY_asn1_set_set_pub_keyEVP_PKEY_asn1_set_get_priv_keyEVP_PKEY_asn1_set_get_pub_keyEVP_PKEY_get0_asn1
that's literally the entire NAME cast 💖 if you're looking for one of these, it's on this page, periodt.
🌸 SYNOPSIS 🌸
heads up, bestie: this part is the declarations zone, so every line stays exactly as it appears — no vibes-based edits, no "fixing" the formatting, fr fr 🎀
#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,
const 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);and that's the synopsis, copied with love and zero drift ✨
💅 DESCRIPTION 💅
Okay so picture this: EVP_PKEY_ASN1_METHOD is a struct that is basically the whole personality file for one specific public key algorithm — it holds a set of ASN.1 conversion, printing and information methods for that algorithm. ✨
And there are exactly two places where these EVP_PKEY_ASN1_METHOD objects live:
- one is a built-in array representing the standard methods for different algorithms
- the other is a stack of user-defined application-specific methods, which you can manipulate 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, const 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);pub_decode()andpub_encode()— these get called to decode / encodeX509_PUBKEYASN.1 parameters to / frompk. They MUST return0on error,1on success. They're called byX509_PUBKEY_get0(3)andX509_PUBKEY_set(3). 🫶pub_cmp()— called when two public keys are about to be compared. It MUST return1when the keys are equal,0otherwise. Called byEVP_PKEY_eq(3).pub_print()— called to print a public key in humanly readable text toout, indentedindentspaces. It MUST return0on error,1on success. Called byEVP_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);priv_decode()andpriv_encode()— called to decode / encodePKCS8_PRIV_KEY_INFOform private key to / frompk. They MUST return0on error,1on success. They're called byEVP_PKCS82PKEY(3)andEVP_PKEY2PKCS8(3). 🔐priv_print()— called to print a private key in humanly readable text toout, indentedindentspaces. It MUST return0on error,1on success. Called byEVP_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);pkey_size()— returns the key size in bytes. Called byEVP_PKEY_get_size(3).pkey_bits()— returns the key size in bits. Called byEVP_PKEY_get_bits(3).pkey_security_bits()— the third one in this little trio, sitting right there in the list 🎀
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);param_decode()andparam_encode()— called to decode / encode DER formatted parameters to / frompk. They MUST return0on error,1on success. They're called byPEM_read_bio_Parameters(3)and thefile:OSSL_STORE_LOADER(3). 🌸param_missing()— returns0if a key parameter is missing, otherwise1. Called byEVP_PKEY_missing_parameters(3).param_copy()— copies key parameters fromfromtoto. It MUST return0on error,1on success. Called byEVP_PKEY_copy_parameters(3).param_cmp()— compares the parameters of keysaandb. It MUST return1when the keys are equal,0when not equal, or a negative number on error. Called byEVP_PKEY_parameters_eq(3).param_print()— prints the private key parameters in humanly readable text toout, indentedindentspaces. It MUST return0on error,1on success. Called byEVP_PKEY_print_params(3).
int (*sig_print) (BIO *out,
const X509_ALGOR *sigalg, const ASN1_STRING *sig,
int indent, ASN1_PCTX *pctx);sig_print() 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);pkey_free() 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);pkey_ctrl() adds extra algorithm specific control. It's called by EVP_PKEY_get_default_digest_nid(3), EVP_PKEY_set1_encoded_public_key(3), EVP_PKEY_get1_encoded_public_key(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);old_priv_decode() and old_priv_encode() decode / encode the 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 return the 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:
<=0— error1—item_sign()did everything, OpenSSL internals just needs to pass the signature length back2—item_sign()did nothing, OpenSSL internal standard routines are expected to continue with the default signature production3—item_sign()set the algorithm identifieralgor1andalgor2, OpenSSL internals should just sign using those algorithms
item_verify() MUST return one of:
<=0— error1—item_sign()did everything, OpenSSL internals just needs to pass the signature length back2—item_sign()did nothing, OpenSSL internal standard routines are expected to continue with the default signature production
Yeah bestie, thoseitem_verify()entries do sayitem_sign()— that's literally what the page says, not me being chaotic 🙈
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);siginf_set() 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);pkey_check(), pkey_public_check() and pkey_param_check() 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);set_priv_key() and set_pub_key() 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.
size_t (*dirty) (const EVP_PKEY *pk);
void *(*export_to) (const EVP_PKEY *pk, EVP_KEYMGMT *keymgmt);dirty_cnt()— returns the internal key's dirty count. This can be used to synchronise different copies of the same keys.export_to()— exports the key material from the given key to a provider, through theEVP_KEYMGMT(3)interface, if that provider supports importing key material. 🔄
✨ 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 this is set, then the signature algorithm parameters are given the typeV_ASN1_NULLby default, otherwise they will be given the typeV_ASN1_UNDEF(i.e. the parameter is omitted). SeeX509_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. If the argument is NULL, nothing is done. 🧚
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.
⚠️ Also not thread safe, fr — 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.
⚠️ Not thread safe either, same deal — recommend using it only during application initialization.
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. 🔍
🫶 RETURN VALUES 🫶
EVP_PKEY_asn1_new()returnsNULLon error, or a pointer to anEVP_PKEY_ASN1_METHODobject otherwise.EVP_PKEY_asn1_add0()andEVP_PKEY_asn1_add_alias()return0on error, or1on success.EVP_PKEY_get0_asn1()returnsNULLon error, or a pointer to a constantEVP_PKEY_ASN1_METHODobject otherwise. 👑
✨ HISTORY ✨
Okay so bestie, there's been a glow-up and you need to know about it 💅
The signature of the pub_decode functional argument of EVP_PKEY_asn1_set_public() has changed in OpenSSL 3.0 so its pub parameter is now constified.
That's it, that's the tea ☕ — the pub param got that const treatment in 3.0, so if you're staring at old code wondering why the types don't line up, that's your answer, no cap 🫶
🎀 COPYRIGHT 🎀
Copyright 2017-2024 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 <https://www.openssl.org/source/license.html>.
fr fr read the license before you go wild with it — it's giving "legal but make it cute," and the terms are the terms 💖
And that's a wrap on EVP_PKEY_ASN1_METHOD(3SSL) 🦋 this whole page is from 3.5.7, dated 2026-06-09 — screenshot it, bookmark it, tattoo it on your forearm, whatever helps you remember 😭✨ go forth and ASN.1 responsibly, queen 👑
📦 where this page comes from
- debian trixie: libssl-doc 3.5.7-1~deb13u2 · Apache-2.0
- debian trixie: libssl-doc 3.5.7-1~deb13u3 · Apache-2.0
- 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on : a language model's rewrite of the original, under its terms