 returns the maximum length signature or 0 on error.</p>

<p>ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful or 0 on error.</p>

<p>ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated <b>ECDSA_SIG</b> structure or NULL on error.</p>

<p>ECDSA_verify() and ECDSA_do_verify() return 1 for a valid signature, 0 for an invalid signature and -1 on error. The error codes can be obtained by <a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>.</p>

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