First look at the location of the Android 4.x system's certificate store:
AOSP the location of the CA certificate file in the Android system is:/system/etc/security/cacerts/a series of digitally named. 0 files
Method One:
Android 4.0 already supports the user to install the root certificate, only need to put the root certificate to the SDcard root directory, and then to the settings (Settings) – Security – from the storage device installation (install from storage) on it, However, this installation requires a lock screen pin or password to be set.
However, this operation requires a lock screen pin or password each time the phone is turned on, which can cause a lot of trouble for the user.
Method Two: (Note: Root privileges are required)
After the phone has root access, copy the root certificate file in the Base64 text format directly to the Etc/security/cacerts folder, and then to Settings (Settings) – Security – Trusted credentials (Trusted Credentials), the root certificate you want to install at this point should show that it is already installed. After this installation, the root certificate is used as a system certificate, not as a user certificate that is installed as a method.
If you want to delete the root certificate file inside the folder deleted or directly after the certificate of the check out of the line.