#use wml::openssl-macros area=docs page=EVP_PKEY_verify

<title>Documents, EVP_PKEY_verify(3)</title>

<h1>EVP_PKEY_verify(3)</h1>

#use wml::imp::generic

{:
## What's this? [[s|(<STRONG>[^<].+?)</A>(</STRONG><DD>)|$1$2|sg]]
[[s|<P>\s+<P>|<P>|sg]]
[[s|<P>\s+</|</|sg]]
[[s|<DD>\s*<DT>|<DD>&nbsp;<DT>|sg]]
[[s|<DD>\s*</DL>|<DD>&nbsp;</DL>|sg]]
[[s|\[|&#91;|sg]]
[[s|\]|&#93;|sg]]

<!-- INDEX BEGIN -->

<UL>

	<LI><A HREF="#NAME">NAME</A>
	<LI><A HREF="#SYNOPSIS">SYNOPSIS</A>
	<LI><A HREF="#DESCRIPTION">DESCRIPTION</A>
	<LI><A HREF="#NOTES">NOTES</A>
	<LI><A HREF="#RETURN_VALUES">RETURN VALUES</A>
	<LI><A HREF="#EXAMPLE">EXAMPLE</A>
	<LI><A HREF="#SEE_ALSO">SEE ALSO</A>
	<LI><A HREF="#HISTORY">HISTORY</A>
</UL>
<!-- INDEX END -->

<HR>
<P>
<HR>
<H1><A NAME="NAME">NAME</A></H1>
<P>
EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a
public key algorithm

</P>
<P>
<HR>
<H1><A NAME="SYNOPSIS">SYNOPSIS</A></H1>
<PRE> #include &lt;openssl/evp.h&gt;
</PRE>
<PRE> int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
                        const unsigned char *sig, size_t siglen,
                        const unsigned char *tbs, size_t tbslen);
</PRE>
<P>
<HR>
<H1><A NAME="DESCRIPTION">DESCRIPTION</A></H1>
<P>
The <CODE>EVP_PKEY_verify_init()</CODE> function initializes a public key
algorithm context using key <STRONG>pkey</STRONG> for a signature verification operation.

</P>
<P>
The <CODE>EVP_PKEY_verify()</CODE> function performs a public key
verification operation using <STRONG>ctx</STRONG>. The signature is specified using the <STRONG>sig</STRONG> and
<STRONG>siglen</STRONG> parameters. The verified data (i.e. the data believed originally signed) is
specified using the <STRONG>tbs</STRONG> and <STRONG>tbslen</STRONG> parameters.

</P>
<P>
<HR>
<H1><A NAME="NOTES">NOTES</A></H1>
<P>
After the call to <CODE>EVP_PKEY_verify_init()</CODE> algorithm specific
control operations can be performed to set any appropriate parameters for
the operation.

</P>
<P>
The function <CODE>EVP_PKEY_verify()</CODE> can be called more than once on
the same context if several operations are performed using the same
parameters.

</P>
<P>
<HR>
<H1><A NAME="RETURN_VALUES">RETURN VALUES</A></H1>
<P>
<CODE>EVP_PKEY_verify_init()</CODE> and <CODE>EVP_PKEY_verify()</CODE>
return 1 if the verification was successful and 0 if it failed. Unlike
other functions the return value 0 from <CODE>EVP_PKEY_verify()</CODE> only
indicates that the signature did not not verify successfully (that is tbs
did not match the original data or the signature was of invalid form) it is
not an indication of a more serious error.

</P>
<P>
A negative value indicates an error other that signature verification
failure. In particular a return value of -2 indicates the operation is not
supported by the public key algorithm.

</P>
<P>
<HR>
<H1><A NAME="EXAMPLE">EXAMPLE</A></H1>
<P>
Verify signature using PKCS#1 and SHA256 digest:

</P>
<PRE> #include &lt;openssl/evp.h&gt;
 \#include &lt;openssl/rsa.h&gt;
</PRE>
<PRE> EVP_PKEY_CTX *ctx;
 unsigned char *md, *sig;
 size_t mdlen, siglen; 
 EVP_PKEY *verify_key;
 /* NB: assumes verify_key, sig, siglen md and mdlen are already set up
  * and that verify_key is an RSA public key
  */
 ctx = EVP_PKEY_CTX_new(verify_key);
 if (!ctx)
        /* Error occurred */
 if (EVP_PKEY_verify_init(ctx) &lt;= 0)
        /* Error */
 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) &lt;= 0)
        /* Error */
 if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) &lt;= 0)
        /* Error */
</PRE>
<PRE> /* Perform operation */
 ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
</PRE>
<PRE> /* ret == 1 indicates success, 0 verify failure and &lt; 0 for some
  * other error.
  */
</PRE>
<P>
<HR>
<H1><A NAME="SEE_ALSO">SEE ALSO</A></H1>
<P>
<A HREF="../crypto/EVP_PKEY_CTX_new.html#">EVP_PKEY_CTX_new(3)</A>,
<A HREF="../crypto/EVP_PKEY_encrypt.html#">EVP_PKEY_encrypt(3)</A>,
<A HREF="../crypto/EVP_PKEY_decrypt.html#">EVP_PKEY_decrypt(3)</A>,
<A HREF="../crypto/EVP_PKEY_sign.html#">EVP_PKEY_sign(3)</A>,
<A HREF="../crypto/EVP_PKEY_verify_recover.html#">EVP_PKEY_verify_recover(3)</A>,
<A HREF="../crypto/EVP_PKEY_derive.html#">EVP_PKEY_derive(3)</A> 

 

</P>
<P>
<HR>
<H1><A NAME="HISTORY">HISTORY</A></H1>
<P>
These functions were first added to OpenSSL 1.0.0.

</P>
:}