I tried using:
keytool -exportcert -alias <RELEASE_KEY_ALIAS> -keystore <RELEASE_KEY_PATH> | PATH_TO_OPENSSL_LIBRARY\bin\openssl sha1 -binary | PATH_TO_OPENSSL_LIBRARY\bin\openssl base64
This didn't seem to work for me as it said:
What do it do?
Use the following command to get SHA-1 hash of your signing key.
keytool -list -v -keystore KEYSTORE_PATH -alias ALIAS_NAME