  Cash payment is still king in several markets, accounting for more than 90\
of the payments in almost all the developing countries. The usage of mobile
phones is pretty ordinary in this present era. Mobile phones have become an
inseparable friend for many users, serving much more than just communication
tools. Every subsequent person is heavily relying on them due to multifaceted
usage and affordability. Every person wants to manage his/her daily
transactions and related issues by using his/her mobile phone. With the rise
and advancements of mobile-specific security, threats are evolving as well. In
this paper, we provide a survey of various security models for mobile phones.
We explore multiple proposed models of the mobile payment system (MPS), their
technologies and comparisons, payment methods, different security mechanisms
involved in MPS, and provide analysis of the encryption technologies,
authentication methods, and firewall in MPS. We also present current challenges
and future directions of mobile phone security.
