.\" $OpenBSD: ASN1_item_verify.3,v 1.3 2021/12/18 17:47:44 schwarze Exp $
.\"
.\" Copyright (c) 2021 Ingo Schwarze <schwarze@openbsd.org>
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.Dd $Mdocdate: December 18 2021 $
.Dt ASN1_ITEM_VERIFY 3
.Os
.Sh NAME
.Nm ASN1_item_verify
.Nd signature verification for ASN.1 values
.Sh SYNOPSIS
.In openssl/x509.h
.Ft int
.Fo ASN1_item_verify
.Fa "const ASN1_ITEM *it"
.Fa "X509_ALGOR *algor1"
.Fa "ASN1_BIT_STRING *sig_in"
.Fa "void *val_in"
.Fa "EVP_PKEY *pkey"
.Fc
.Sh DESCRIPTION
.Fn ASN1_item_verify
assumes that
.Fa val_in
is an
.Ft ASN1_VALUE
of the type specified by
.Fa it ,
encodes it into DER format by calling
.Xr ASN1_item_i2d 3 ,
and verifies in a way similar to
.Xr EVP_DigestVerify 3
that
.Fa sig_in
contains a valid signature of the resulting byte array,
a signature that was created with the signature algorithm
.Fa algor1
and the private key corresponding to the public key
.Fa pkey .
.Sh RETURN VALUES
.Fn ASN1_item_verify
returns 1 if signature verification succeeds, 0 if signature verification
fails, or \-1 if
.Fa pkey
is
.Dv NULL ,
if
.Fa sig_in
contains invalid flags, or if
.Fa algor1
requests an invalid or unsupported digest algorithm
or does not work with the given
.Fa pkey .
.Sh SEE ALSO
.Xr ASN1_BIT_STRING_new 3 ,
.Xr ASN1_item_i2d 3 ,
.Xr ASN1_item_sign 3 ,
.Xr EVP_DigestVerify 3 ,
.Xr EVP_PKEY_new 3 ,
.Xr OBJ_find_sigid_algs 3 ,
.Xr X509_ALGOR_new 3
.Sh HISTORY
.Fn ASN1_item_verify
first appeared in OpenSSL 0.9.7 and has been available since
.Ox 3.1 .