.\" $OpenBSD: EVP_PKEY_meth_new.3,v 1.6 2023/09/09 14:35:23 schwarze Exp $
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.\" The original file was written by Paul Yang <yang.yang@baishancloud.com>.
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.Dd $Mdocdate: September 9 2023 $
.Dt EVP_PKEY_METH_NEW 3
.Os
.Sh NAME
.Nm EVP_PKEY_meth_new ,
.Nm EVP_PKEY_meth_free ,
.Nm EVP_PKEY_meth_copy ,
.Nm EVP_PKEY_meth_find ,
.Nm EVP_PKEY_meth_add0 ,
.Nm EVP_PKEY_meth_set_init ,
.Nm EVP_PKEY_meth_set_copy ,
.Nm EVP_PKEY_meth_set_cleanup ,
.Nm EVP_PKEY_meth_set_paramgen ,
.Nm EVP_PKEY_meth_set_keygen ,
.Nm EVP_PKEY_meth_set_sign ,
.Nm EVP_PKEY_meth_set_verify ,
.Nm EVP_PKEY_meth_set_verify_recover ,
.Nm EVP_PKEY_meth_set_signctx ,
.Nm EVP_PKEY_meth_set_verifyctx ,
.Nm EVP_PKEY_meth_set_encrypt ,
.Nm EVP_PKEY_meth_set_decrypt ,
.Nm EVP_PKEY_meth_set_derive ,
.Nm EVP_PKEY_meth_set_ctrl ,
.Nm EVP_PKEY_meth_set_check ,
.Nm EVP_PKEY_meth_set_public_check ,
.Nm EVP_PKEY_meth_set_param_check ,
.Nm EVP_PKEY_CTX_get_data ,
.Nm EVP_PKEY_CTX_set_data
.Nd manipulate an EVP_PKEY_METHOD structure
.Sh SYNOPSIS
.In openssl/evp.h
.Ft EVP_PKEY_METHOD *
.Fo EVP_PKEY_meth_new
.Fa "int id"
.Fa "int flags"
.Fc
.Ft void
.Fo EVP_PKEY_meth_free
.Fa "EVP_PKEY_METHOD *pmeth"
.Fc
.Ft void
.Fo EVP_PKEY_meth_copy
.Fa "EVP_PKEY_METHOD *dst"
.Fa "const EVP_PKEY_METHOD *src"
.Fc
.Ft const EVP_PKEY_METHOD *
.Fo EVP_PKEY_meth_find
.Fa "int type"
.Fc
.Ft int
.Fo EVP_PKEY_meth_add0
.Fa "const EVP_PKEY_METHOD *pmeth"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_init
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*init)(EVP_PKEY_CTX *ctx)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_copy
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*copy)(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_cleanup
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "void (*cleanup)(EVP_PKEY_CTX *ctx)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_paramgen
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*paramgen_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*paramgen)(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_keygen
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*keygen_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*keygen)(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_sign
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*sign_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*sign)(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,\
 const unsigned char *tbs, size_t tbslen)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_verify
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*verify_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*verify)(EVP_PKEY_CTX *ctx, const unsigned char *sig,\
 size_t siglen, const unsigned char *tbs, size_t tbslen)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_verify_recover
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*verify_recover_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*verify_recover)(EVP_PKEY_CTX *ctx, unsigned char *sig,\
 size_t *siglen, const unsigned char *tbs, size_t tbslen)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_signctx
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*signctx_init)(EVP_PKEY_CTX *ctx, EVP_MD_CTX *mctx)"
.Fa "int (*signctx)(EVP_PKEY_CTX *ctx, unsigned char *sig,\
 size_t *siglen, EVP_MD_CTX *mctx)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_verifyctx
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*verifyctx_init)(EVP_PKEY_CTX *ctx, EVP_MD_CTX *mctx)"
.Fa "int (*verifyctx)(EVP_PKEY_CTX *ctx, const unsigned char *sig,\
 int siglen, EVP_MD_CTX *mctx)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_encrypt
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*encrypt_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*encryptfn)(EVP_PKEY_CTX *ctx, unsigned char *out,\
 size_t *outlen, const unsigned char *in, size_t inlen)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_decrypt
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*decrypt_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*decrypt)(EVP_PKEY_CTX *ctx, unsigned char *out,\
 size_t *outlen, const unsigned char *in, size_t inlen)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_derive
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*derive_init)(EVP_PKEY_CTX *ctx)"
.Fa "int (*derive)(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_ctrl
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*ctrl)(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)"
.Fa "int (*ctrl_str)(EVP_PKEY_CTX *ctx, const char *type, const char *value)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_check
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*check)(EVP_PKEY *pkey)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_public_check
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*public_check)(EVP_PKEY *pkey)"
.Fc
.Ft void
.Fo EVP_PKEY_meth_set_param_check
.Fa "EVP_PKEY_METHOD *pmeth"
.Fa "int (*param_check)(EVP_PKEY *pkey)"
.Fc
.Ft void *
.Fo EVP_PKEY_CTX_get_data
.Fa "EVP_PKEY_CTX *ctx"
.Fc
.Ft void
.Fo EVP_PKEY_CTX_set_data
.Fa "EVP_PKEY_CTX *ctx"
.Fa "void *data"
.Fc
.Sh DESCRIPTION
The
.Vt EVP_PKEY_METHOD
structure holds a set of methods
for a specific public key cryptographic algorithm.
Those methods perform tasks such as generating keys, signing, verifying,
encrypting, decrypting, and so on.
.Pp
There are two places where the
.Vt 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
with
.Fn EVP_PKEY_meth_add0 .
.Pp
The
.Vt EVP_PKEY_METHOD
objects are usually referenced by
.Vt EVP_PKEY_CTX
objects.
.Ss Methods
The methods implement the particular public key algorithm represented by the
.Vt EVP_PKEY_CTX
object.
.Bd -unfilled
.Ft int Fn (*init) "EVP_PKEY_CTX *ctx"
.Ft int Fn (*copy) "EVP_PKEY_CTX *dst" "EVP_PKEY_CTX *src"
.Ft void Fn (*cleanup) "EVP_PKEY_CTX *ctx"
.Ed
.Pp
The
.Fn init
method is called by
.Xr EVP_PKEY_CTX_new 3
and
.Xr EVP_PKEY_CTX_new_id 3
to initialize the algorithm-specific data when a new
.Vt EVP_PKEY_CTX
is created.
The
.Fn cleanup
method is called by
.Xr EVP_PKEY_CTX_free 3
when an
.Vt EVP_PKEY_CTX
is freed.
The
.Fn copy
method is called by
.Xr EVP_PKEY_CTX_dup 3
when an
.Vt EVP_PKEY_CTX
is duplicated.
.Bd -unfilled
.Ft int Fn (*paramgen_init) "EVP_PKEY_CTX *ctx"
.Ft int Fn (*paramgen) "EVP_PKEY_CTX *ctx" "EVP_PKEY *pkey"
.Ed
.Pp
The
.Fn paramgen_init
and
.Fn paramgen
methods deal with key parameter generation.
They are called by
.Xr EVP_PKEY_paramgen_init 3
and
.Xr EVP_PKEY_paramgen 3
to handle the parameter generation process.
.Bd -unfilled
.Ft int Fn (*keygen_init) "EVP_PKEY_CTX *ctx"
.Ft int Fn (*keygen) "EVP_PKEY_CTX *ctx" "EVP_PKEY *pkey"
.Ed
.Pp
The
.Fn keygen_init
and
.Fn keygen
methods are used to generate a key for the specified algorithm.
They are called by
.Xr EVP_PKEY_keygen_init 3
and
.Xr EVP_PKEY_keygen 3 .
.Bd -unfilled
.Ft int Fn (*sign_init) "EVP_PKEY_CTX *ctx"
.Ft int Fo (*sign)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "unsigned char *sig"
.Fa "size_t *siglen"
.Fa "const unsigned char *tbs"
.Fa "size_t tbslen"
.Fc
.Ed
.Pp
The
.Fn sign_init
and
.Fn sign
methods are used to generate the signature of a piece of data using a
private key.
They are called by
.Xr EVP_PKEY_sign_init 3
and
.Xr EVP_PKEY_sign 3 .
.Bd -unfilled
.Ft int Fn (*verify_init) "EVP_PKEY_CTX *ctx"
.Ft int Fo (*verify)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "const unsigned char *sig"
.Fa "size_t siglen"
.Fa "const unsigned char *tbs"
.Fa "size_t tbslen"
.Fc
.Ed
.Pp
The
.Fn verify_init
and
.Fn verify
methods are used to verify whether a signature is valid.
They are called by
.Xr EVP_PKEY_verify_init 3
and
.Xr EVP_PKEY_verify 3 .
.Bd -unfilled
.Ft int Fn (*verify_recover_init) "EVP_PKEY_CTX *ctx"
.Ft int Fo (*verify_recover)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "unsigned char *rout"
.Fa "size_t *routlen"
.Fa "const unsigned char *sig"
.Fa "size_t siglen"
.Fc
.Ed
.Pp
The
.Fn verify_recover_init
and
.Fn 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 the RSA
signing algorithm).
They are called by
.Xr EVP_PKEY_verify_recover_init 3
and
.Xr EVP_PKEY_verify_recover 3 .
.Bd -unfilled
.Ft int Fn (*signctx_init) "EVP_PKEY_CTX *ctx" "EVP_MD_CTX *mctx"
.Ft int Fo (*signctx)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "unsigned char *sig"
.Fa "size_t *siglen"
.Fa "EVP_MD_CTX *mctx"
.Fc
.Ed
.Pp
The
.Fn signctx_init
and
.Fn signctx
methods are used to sign a digest represented by an
.Vt EVP_MD_CTX
object.
They are called by the
.Xr EVP_DigestSignInit 3
functions.
.Bd -unfilled
.Ft int Fn (*verifyctx_init) "EVP_PKEY_CTX *ctx" "EVP_MD_CTX *mctx"
.Ft int Fo (*verifyctx)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "const unsigned char *sig"
.Fa "int siglen"
.Fa "EVP_MD_CTX *mctx"
.Fc
.Ed
.Pp
The
.Fn verifyctx_init
and
.Fn verifyctx
methods are used to verify a signature against the data in an
.Vt EVP_MD_CTX
object.
They are called by the
.Xr EVP_DigestVerifyInit 3
functions.
.Bd -unfilled
.Ft int Fn (*encrypt_init) "EVP_PKEY_CTX *ctx"
.Ft int Fo (*encrypt)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "unsigned char *out"
.Fa "size_t *outlen"
.Fa "const unsigned char *in"
.Fa "size_t inlen"
.Fc
.Ed
.Pp
The
.Fn encrypt_init
and
.Fn encrypt
methods are used to encrypt a piece of data.
They are called by
.Xr EVP_PKEY_encrypt_init 3
and
.Xr EVP_PKEY_encrypt 3 .
.Bd -unfilled
.Ft int Fn (*decrypt_init) "EVP_PKEY_CTX *ctx"
.Ft int Fo (*decrypt)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "unsigned char *out"
.Fa "size_t *outlen"
.Fa "const unsigned char *in"
.Fa "size_t inlen"
.Fc
.Ed
.Pp
The
.Fn decrypt_init
and
.Fn decrypt
methods are used to decrypt a piece of data.
They are called by
.Xr EVP_PKEY_decrypt_init 3
and
.Xr EVP_PKEY_decrypt 3 .
.Bd -unfilled
.Ft int Fn (*derive_init) "EVP_PKEY_CTX *ctx"
.Ft int Fo (*derive)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "unsigned char *key"
.Fa "size_t *keylen"
.Fc
.Ed
.Pp
The
.Fn derive_init
and
.Fn derive
methods are used to derive the shared secret from a public key algorithm
(for instance, the DH algorithm).
They are called by
.Xr EVP_PKEY_derive_init 3
and
.Xr EVP_PKEY_derive 3 .
.Bd -unfilled
.Ft int Fo (*ctrl)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "int type"
.Fa "int p1"
.Fa "void *p2"
.Fc
.Ft int Fo (*ctrl_str)
.Fa "EVP_PKEY_CTX *ctx"
.Fa "const char *type"
.Fa "const char *value"
.Fc
.Ed
.Pp
The
.Fn ctrl
and
.Fn ctrl_str
methods are used to adjust algorithm-specific settings.
See
.Xr EVP_PKEY_CTX_ctrl 3
for details.
.Bd -unfilled
.Ft int Fn (*check) "EVP_PKEY *pkey"
.Ft int Fn (*public_check) "EVP_PKEY *pkey"
.Ft int Fn (*param_check) "EVP_PKEY *pkey"
.Ed
These methods are used to validate a key pair, the public component,
and the parameters for the given
.Fa pkey ,
respectively.
They are called by
.Xr EVP_PKEY_check 3 ,
.Xr EVP_PKEY_public_check 3 ,
and
.Xr EVP_PKEY_param_check 3 ,
respectively.
.Ss Functions
.Fn EVP_PKEY_meth_new
creates a new
.Vt EVP_PKEY_METHOD
object with the given
.Fa id
and
.Fa flags .
The following flags are supported:
.Bl -tag -width Ds
.It Dv EVP_PKEY_FLAG_AUTOARGLEN
Automatically calculate the maximum size of the output buffer
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
.Xr EVP_PKEY_sign 3 .
.It Dv EVP_PKEY_FLAG_SIGCTX_CUSTOM
Indicate that the
.Fn signctx
method of an
.Vt EVP_PKEY_METHOD
is always called by the EVP framework while doing a digest signing
operation by calling
.Xr EVP_DigestSignFinal 3 .
.El
.Pp
.Fn EVP_PKEY_meth_free
frees
.Fa pmeth .
.Pp
.Fn EVP_PKEY_meth_copy
copies
.Fa src
to
.Fa dst .
.Pp
.Fn EVP_PKEY_meth_find
finds an
.Vt EVP_PKEY_METHOD
object with the given
.Fa id .
This function first searches through the user-defined method objects and
then through the built-in objects.
.Pp
.Fn EVP_PKEY_meth_add0
adds
.Fa pmeth
to the stack of user defined methods.
.Pp
The
.Fn EVP_PKEY_meth_set_*
functions set the corresponding fields of
.Fa pmeth
to the arguments passed.
.Pp
.Fn EVP_PKEY_CTX_get_data
retrieves algorithm- and implementation-specific private key data from
.Fa ctx .
Public key algorithm implementations typically allocate and initialize
this data automatically in their
.Fn init
function.
.Pp
.Fn EVP_PKEY_CTX_set_data
transfers ownership of the given
.Fa data
to
.Fa ctx ,
replacing the existing algorithm- and implementation-specific
private key data.
It is the responsibility of the caller to free the existing data
before calling this function.
.Sh RETURN VALUES
.Fn EVP_PKEY_meth_new
returns a pointer to a new
.Vt EVP_PKEY_METHOD
object or
.Dv NULL
on error.
.Pp
.Fn EVP_PKEY_meth_find
returns a pointer to the found
.Vt EVP_PKEY_METHOD
object or
.Dv NULL
if no matching object is found.
.Pp
.Fn EVP_PKEY_meth_add0
returns 1 if the method is added successfully or 0 if an error occurred.
.Pp
.Fn EVP_PKEY_CTX_get_data
returns an internal pointer owned by
.Fa ctx .
.Sh SEE ALSO
.Xr EVP_DigestInit 3 ,
.Xr EVP_PKEY_meth_get0_info 3 ,
.Xr EVP_PKEY_new 3
.Sh HISTORY
.Fn EVP_PKEY_meth_new ,
.Fn EVP_PKEY_meth_free ,
.Fn EVP_PKEY_meth_find ,
.Fn EVP_PKEY_meth_add0 ,
.Fn EVP_PKEY_meth_set_init ,
.Fn EVP_PKEY_meth_set_copy ,
.Fn EVP_PKEY_meth_set_cleanup ,
.Fn EVP_PKEY_meth_set_paramgen ,
.Fn EVP_PKEY_meth_set_keygen ,
.Fn EVP_PKEY_meth_set_sign ,
.Fn EVP_PKEY_meth_set_verify ,
.Fn EVP_PKEY_meth_set_verify_recover ,
.Fn EVP_PKEY_meth_set_signctx ,
.Fn EVP_PKEY_meth_set_verifyctx ,
.Fn EVP_PKEY_meth_set_encrypt ,
.Fn EVP_PKEY_meth_set_decrypt ,
.Fn EVP_PKEY_meth_set_derive ,
.Fn EVP_PKEY_meth_set_ctrl ,
.Fn EVP_PKEY_CTX_get_data ,
and
.Fn EVP_PKEY_CTX_set_data
first appeared in OpenSSL 1.0.0 and have been available since
.Ox 4.9 .
.Pp
.Fn EVP_PKEY_meth_copy
first appeared in OpenSSL 1.0.1 and has been available since
.Ox 5.3 .
.Pp
.Fn EVP_PKEY_meth_set_check ,
.Fn EVP_PKEY_meth_set_public_check ,
and
.Fn EVP_PKEY_meth_set_param_check
first appeared in OpenSSL 1.1.1 and have been available since
.Ox 7.1 .