path: root/lib/libcrypto/man/X509_ALGOR_dup.3

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.Dd $Mdocdate: October 13 2023 $
.Dt X509_ALGOR_DUP 3
.Os
.Sh NAME
.Nm X509_ALGOR_new ,
.Nm X509_ALGOR_free ,
.Nm X509_ALGOR_dup ,
.Nm X509_ALGOR_set0 ,
.Nm X509_ALGOR_get0 ,
.Nm X509_ALGOR_set_md ,
.Nm X509_ALGOR_cmp
.Nd create, change, and inspect algorithm identifiers
.Sh SYNOPSIS
.In openssl/x509.h
.Ft X509_ALGOR *
.Fn X509_ALGOR_new void
.Ft void
.Fn X509_ALGOR_free "X509_ALGOR *alg"
.Ft X509_ALGOR *
.Fo X509_ALGOR_dup
.Fa "X509_ALGOR *alg"
.Fc
.Ft int
.Fo X509_ALGOR_set0
.Fa "X509_ALGOR *alg"
.Fa "ASN1_OBJECT *aobj"
.Fa "int ptype"
.Fa "void *pval"
.Fc
.Ft void
.Fo X509_ALGOR_get0
.Fa "const ASN1_OBJECT **paobj"
.Fa "int *pptype"
.Fa "const void **ppval"
.Fa "const X509_ALGOR *alg"
.Fc
.Ft void
.Fo X509_ALGOR_set_md
.Fa "X509_ALGOR *alg"
.Fa "const EVP_MD *md"
.Fc
.Ft int
.Fo X509_ALGOR_cmp
.Fa "const X509_ALGOR *a"
.Fa "const X509_ALGOR *b"
.Fc
.Sh DESCRIPTION
An
.Vt X509_ALGOR
object represents an ASN.1
.Vt AlgorithmIdentifier
structure defined in RFC 5280 section 4.1.1.2.
It specifies a cryptographic
.Fa algorithm
by an ASN.1 object identifier (OID) that can be obtained from
.Xr OBJ_nid2obj 3 ,
together with optional algorithm-specific
.Fa parameters
of the type
.Vt ASN1_TYPE ,
see
.Xr ASN1_TYPE_set 3 .
.Vt X509_ALGOR
objects are used by many other objects, for example certificates,
certificate revocation lists, and certificate requests.
.Pp
.Fn X509_ALGOR_new
allocates a new
.Vt X509_ALGOR
object containing the object that
.Xr OBJ_nid2obj 3
returns for
.Dv NID_undef
as the
.Fa algorithm
and a
.Dv NULL
pointer as the
.Fa parameters .
.Pp
.Fn X509_ALGOR_free
frees
.Fa alg
and any data contained in it.
If
.Fa alg
is
.Dv NULL ,
no action occurs.
.Pp
.Fn X509_ALGOR_dup
creates a deep copy of
.Fa alg .
It is implemented by calling
.Xr ASN1_item_dup 3
with arguments of
.Dv X509_ALGOR_it
and
.Fa alg ,
which is equivalent to calling
.Xr i2d_X509_ALGOR 3
and
.Xr d2i_X509_ALGOR 3 .
.Pp
.Fn X509_ALGOR_set0
sets the algorithm OID of
.Fa alg
to
.Fa aobj
and the associated parameter type to
.Fa ptype
with value
.Fa pval .
If
.Fa ptype
is
.Dv V_ASN1_UNDEF ,
the parameter is omitted and
.Fa pval
is ignored.
If
.Fa ptype
is zero,
.Fa pval
is ignored and the existing parameter is left unchanged, or if
.Fa alg
does not contain a parameter, a new, empty parameter of type
.Dv V_ASN1_UNDEF
is added.
Otherwise
.Fa ptype
and
.Fa pval
have the same meaning as the
.Fa type
and
.Fa value
parameters to
.Xr ASN1_TYPE_set 3 .
Ownership of
.Fa aobj
and, unless it is ignored, of
.Fa pval
is transferred to
.Fa alg
on success.
.Pp
.Fn X509_ALGOR_get0
returns
.Fa alg Ns 's
algorithm OID in
.Pf * Fa paobj ,
its parameter type in
.Pf * Fa pptype ,
and its parameter value in
.Pf * Fa ppval .
Any of
.Fa paobj ,
.Fa pptype ,
and
.Fa ppval
can be
.Dv NULL .
If
.Fa pptype is
.Dv NULL
or if
.Pf * Fa pptype
is
.Dv V_ASN1_UNDEF
then
.Pf * Fa ppval Ns 's
value is undefined.
.Pp
.Fn X509_ALGOR_set_md
sets
.Fa alg
to appropriate values for the message digest
.Fa md .
If the
.Dv EVP_MD_FLAG_DIGALGID_ABSENT
flag is not set on
.Fa md ,
.Fn X509_ALGOR_set_md
can leave
.Fa alg
in a corrupted state due to memory allocation failure.
This problem can be avoided by preallocating with an error-checked call to
.Fn X509_ALGOR_set0 alg NULL 0 NULL .
.Pp
.Fn X509_ALGOR_cmp
compares
.Fa a
and
.Fa b .
.Sh RETURN VALUES
.Fn X509_ALGOR_new
and
.Fn X509_ALGOR_dup
return a new
.Vt X509_ALGOR
object or
.Dv NULL
if an error occurs.
.Pp
.Fn X509_ALGOR_set0
returns 1 for success or 0 if
.Fa alg
is
.Dv NULL
or memory allocation fails.
.Pp
.Fn X509_ALGOR_cmp
returns 0 if
.Fa a
and
.Fa b
have identical encodings or non-zero otherwise.
.Sh SEE ALSO
.Xr ASN1_TYPE_set 3 ,
.Xr d2i_X509_ALGOR 3 ,
.Xr EVP_DigestInit 3 ,
.Xr OBJ_nid2obj 3 ,
.Xr X509_get0_signature 3 ,
.Xr X509_new 3 ,
.Xr X509_PUBKEY_get0_param 3 ,
.Xr X509_signature_dump 3
.Sh STANDARDS
RFC 5280: Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile
.Sh HISTORY
.Fn X509_ALGOR_new
and
.Fn X509_ALGOR_free
appeared in SSLeay 0.4 or earlier and have been available since
.Ox 2.4 .
.Pp
.Fn X509_ALGOR_dup
first appeared in SSLeay 0.9.1 and has been available since
.Ox 2.6 .
.Pp
.Fn X509_ALGOR_set0
and
.Fn X509_ALGOR_get0
first appeared in OpenSSL 0.9.8h and have been available since
.Ox 4.5 .
.Pp
.Fn X509_ALGOR_cmp
first appeared in OpenSSL 0.9.8zd, 1.0.0p, and 1.0.1k
and has been available since
.Ox 4.9 .
.Pp
.Fn X509_ALGOR_set_md
first appeared in OpenSSL 1.0.1 and has been available since
.Ox 5.3 .
.Sh BUGS
.Fn X509_ALGOR_set_md
can fail but cannot communicate failure to the caller.