he amount of data written to <i>routlen</i>.</p>

<h1 id="NOTES">NOTES</h1>

<p>Normally an application is only interested in whether a signature verification operation is successful in those cases the EVP_verify() function should be used.</p>

<p>Sometimes however it is useful to obtain the data originally signed using a signing operation. Only certain public key algorithms can recover a signature in this way (for example RSA in PKCS padding mode).</p>

<p>After the call to EVP_PKEY_verify_recover_init() a