Step 1: Turn off Wi-Fi
You need to turn off Wi-Fi on your iPhone for a short time.
Step2: Go to VPN Settings
Go to iPhone Settings and select General-> Network-> VPN-> Add VPN Configuration and finally select IPsec Configuration.
Step 3: Input IPsec Configurations
Under the IPsec configuration setting, you have to add the following configuration;
Description- Hotspot Shield
Server- 68.68.107.101
Password- j8adhk
Account- j8adhk
User Certificate- Off
Secret- hss
Group Name- hss
After fixing the above IPsec configuration, you need to save the settings in order to turn on VPN.
Step 4: Turn on Wi-Fi to enable Network Connection
After saving the settings, turn on Wi-Fi network on your iPhone so as to enable connection. The VPN sign should appear next to Wi-Fiindicator on the top left bar of your iPhone.
Step 5: Open Cydia and re-download the package
In order to fix Cydia size mismatch Error, go back to Cydia application and again try to install or download the package resulted to Size mismatch error. This last step takes a lot of time since it becomes slow when you use VPN setting. If the process hangs on the way, click cancel on the download and retry.
Step 6:Turn off VPN Settings
When you are through with your download, turn off the VPN setting following the above steps on iPhone Settings.
By following either of the above two solutions you will be able to fix Cydia size mismatch Error and continue with your Cydia package or App download.