关于生成协商密钥的长度问题 about gmobjc HOT 6 CLOSED

// 根据椭圆曲线密钥长度，计算签名长度
size_t outlen = (EC_GROUP_get_degree(group) + 7) / 8;
uint8_t *ecdh_text = (uint8_t *)OPENSSL_zalloc(outlen + 1);
int ret = ECDH_compute_key(ecdh_text, outlen, pub_point, key, 0);
if (ret <= 0) {
    break;
}
NSData *ecdhData = [NSData dataWithBytes:ecdh_text length:ret];
ecdhStr = [GMUtils dataToHex:ecdhData];