The privacy of calls, messages and emails has been a media focus in recent months with enterprises and governments around the world seeking better protection from hackers and illegal surveillance. Enterprise digital data represents an economic asset and whilst perfect security isn’t possible, there are steps that organisations can take to protect their mobile communications.
Securing mobile communications
When looking at securing mobile communications, be it voice or data, it is important for any solution to deliver three key outcomes. The first is confidentiality, i.e. ensuring no unauthorised person or machine can access the content of any data exchange The second is integrity, ensuring that information, messages, attachments have not been tampered with; and third is authentication of identity, i.e. ensuring that the parties exchanging data – whether persons or machines – are doing so with the individual or the machine with which they believe they are exchanging data.
Protecting data confidentiality
Encryption of data passed between two parties requires an encryption key. However, the challenging part of a cryptographic protocol is deciding on a key to use for encrypting a particular set of data (for example, a voice call between two users). One method is called asymmetric cryptography, also known as public key cryptography: this uses the concept of a public and private key pair, encrypting the data with the public key, such that only the owner of the private key can decrypt it (thus also proving the recipient’s identity if they are the only holder of that private key). Each user’s application holds a private key within it which remains secret whilst their public key is made available to any other users who wish to encrypt a call or message to them.
However, there are disadvantages with typical implementations of public key cryptography in that it is cumbersome to scale in large organisations as public keys need to be distributed to all the users before encrypted communications can take place. To ease administration, organisations can use a central trusted server to store the public keys and users can then ‘look-up’ the public key of another user whenever needed. However, this requires the server to be always available 24×7 and fully secure, so no one can maliciously insert fraudulent keys.
Alternatives include one-time asymmetric encryption also known as ephemeral Diffie-Hellman. This method establishes a one-time key between two users; however, a disadvantage of this method is that it doesn’t prove the other user’s identity (so could be spoofed by a malicious hacker posing as the recipient, or acting as a man-in-the-middle between the two users) and is therefore reliant on another layer of complexity to prove authenticity of the end points.
MIKEY-SAKKE protocol – Secure multimedia communications
Secure communications are needed across government and within many industries; to this end the UK government has a policy of encouraging the development of security solutions. MIKEY-SAKKE was defined in 2012 by the UK’s National Technical Authority for Information and Assurance (CESG) – now the National Cyber Security Centre (NCSC) – using recognised Internet standards (e.g. RFC6809).
The MIKEY-SAKKE protocol uses identity-based cryptography and is designed to enable secure, cross-platform communications by identifying and authenticating the end points. It is an efficient and effective protocol for building a wide range of secure multimedia services for government and enterprise organisations.
Identity-based encryption
Identity-based encryption uses the publicly known identity of the communicating parties to determine the encryption keys to use. For example, a trusted domain manager provides a domain certificate giving any user the ability to take an input ‘identity’ and create a public key to encrypt data to the user with that unique ‘identity’. The identity could be a phone number, email address or other similar identifier.
This identity needs to be centrally verified, so that everyone in the system knows the identity is associated with a particular user. Using an existing unique identity (such as a mobile phone number) provides a ready source for these identities. The recipient, provisioned with the private key for their unique identity, can then decrypt the calls and message sent to their identity. As a result, anyone can securely communicate with any user in the domain without having to individually exchange any prior information between the users.
Scalable, flexible and complete control
Armour’s identity-based encryption solution delivers the flexibility, convenience and security required in today’s world of modern communications. As secure registration is established using only a single message, the Armour identity-based encryption solution is highly scalable and flexible.
It supports both real-time communications such as one-to-one and conference calls (both voice and video), and deferred delivery such as messaging and voicemail. It is designed to be centrally-managed, providing domain managers with full control of the security of the system whilst maintaining high availability.
Features of the Armour solution include the ability to build a validity period into the user identity. This is ideal for organisations that may regularly employee contractors or utilise third parties. Encryption keys can be generated for a limited period of a month, week or even just minutes. After the time has lapsed the key is rendered inactive and a new key would need to be generated. This reduces the risk of keys remaining valid after a team member leaves (or a mobile device is lost or stolen), reducing the risk of accidental data loss.
A new approach
Securing modern methods of communication requires a new approach. Various forms of public key infrastructure have attempted to provide usable and scalable, client-to-client security. However, processes have often been cumbersome and the driving factor behind frustrated users adopting less than secure practices in order to ‘get their job done’, thus creating a weak link in the security chain. Identity-based encryption avoids having to tie a user to a hard-to-remember-and-identify public key, instead the user’s identity ‘becomes’ their public key.
Security should not be seen as a hindrance but as a significant component of the overall culture of an organisation and as a business enabler that can allow innovation by supporting modern working practices.
For more information about MIKEY-SAKKE visit: https://www.ncsc.gov.uk/articles/using-mikey-sakke-building-secure-multimedia-services
