EVP_PKEY_get0_asn1 (3)

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NAME

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_security_bits, EVP_PKEY_get0_asn1 - manipulating and registering EVP_PKEY_ASN1_METHOD structure

SYNOPSIS

 #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_security_bits(EVP_PKEY_ASN1_METHOD *ameth,
                                      int (*pkey_security_bits) (const EVP_PKEY
                                                                 *pk));

 const EVP_PKEY_ASN1_METHOD *EVP_PKEY_get0_asn1(const EVP_PKEY *pkey);

DESCRIPTION

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

There are two places where the

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 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

parameters to / from pk. They 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

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

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

form private key to / from pk. They return 0 on error, 1 on success. They're called by (3) and (3).

The priv_print() method is called to print a private key in humanly readable text to out, indented indent spaces. It

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

formatted parameters to / from pk. They return 0 on error, 1 on success. They're called by PEM_read_bio_Parameters(3) and the file: (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

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

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

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

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

formatted array. These are exclusively used to help decoding / encoding older (pre PKCS#8) formatted encrypted private keys. old_priv_decode() return 0 on error, 1 on success. old_priv_encode() 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()

return one of:

<=0

error

1

item_sign() did everything, OpenSSL internals just needs to pass the signature length back.

2

item_sign() did nothing, OpenSSL internal standard routines are expected to continue with the default signature production.

3

item_sign() set the algorithm identifier algor1 and algor2, OpenSSL internals should just sign using those algorithms.

item_verify()

return one of:

<=0

error

1

item_sign() did everything, OpenSSL internals just needs to pass the signature length back.

2

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), ...

Functions

EVP_PKEY_asn1_new() creates and returns a new object, and associates the given id, flags, pem_str and info. id is a pem_str is the type string, info is a descriptive string. The following flags are supported:

 ASN1_PKEY_SIGPARAM_NULL

If

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

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

pointed by ameth.

EVP_PKEY_asn1_add0() adds ameth to the user defined stack of methods unless another

with the same 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

to for the with from unless another with the same 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(), and EVP_PKEY_asn1_set_security_bits() set the diverse methods of the given

object.

EVP_PKEY_get0_asn1() finds the

associated with the key pkey.

RETURN VALUES

EVP_PKEY_asn1_new() returns on error, or a pointer to an 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

on error, or a pointer to a constant object otherwise.

COPYRIGHT

Copyright 2017 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

in the source distribution or at <www.openssl.org/source/license.html>.