"You understand and agree that Apple may, in its sole discretion, [...] reject Your Application for distribution for any reason, even if Your Application meets the Documentation and Program Requirements".
-- Apple developer documentation
"The certificate does not need to be signed by a certificate authority: it is perfectly allowable, and typical, for Android applications to use self-signed certificates. The certificate is used only to establish trust relationships between applications, not for wholesale control over whether an application can be installed."
-- Android developer documentation