Mobile Examination HW / SW Considerations Pt2

Mobile Examination HW / SW Considerations Pt2

The design of memory allocation and chips in telephones may not follow a prescribed standard. However, memory is an important aspect for communications devices and an example of one telephone memory allocation in 1983 was given in Mobile Examination HW / SW Considerations Pt1 - http://www.trewmte.blogspot.co.uk/2012/10/mobile-examination-hw-sw-considerations.html.

Our interest, of course, is in mobile devices and their memory. Developments have moved us along in technology terms where we have passed through the analogue mobile phone era and into the digital era. It could be laborious for readers to be treated to a discussion about analogue mobile memory given its expiration and therefore we need to fast forward to 1996 to glimpse at memory and chipsets for GSM mobile phones.  Detail from a presentation at Handset '97 Technology Conference by National Semiconductors usefully illustrates memory allocation and chips, as shown in the image below.  

Perhaps of interest is the reference to six chips plus memory. Memory as we may commonly understand it to be can be both EEPROM and Flash. There other memory types but I don't want to stray from the discussion topic as reference to other types of memory would add nothing at this stage. We understand from Mobile Examination HW / SW Considerations Pt1 that E2PROM can be a memory of choice for electronic telephones. We see memory in use back in 1996 as observed by National Semiconductors for GSM using EEPROM and Flash. The relevance of how they were used and what went in them is of historical fact which we need not focus on that. The purpose of the observations in the National Semiconductor 1997 presentation concerned how improvements in silicon technology was enabling the possibility for even smaller scale manufacturing and to forecast how small scale integration would impact on memory and chips for future digital GSM mobile phones (see image below)

The future foreseen by National Semiconductors was the reduction in the number of chips used in mobile phones. Memory sources EEPROM and Flash are still integral requiremengts but remain separate memory allocation; and of course RAM can now be referred to. It was not shown in the earlier material above.

In the decade that followed year 2000 and up-to-date more changes and smaller scale integration has occurred. This will be considered in the next discussion so that the topic can progress towards the objective about considerations relevant to hardware and software and revelation about areas of memory that haven't been fully investigated or explored yet.

Mobile Examination HW / SW Considerations Pt1

Mobile Examination HW / SW Considerations Pt1

Mobile phone forensics requires a level of examiner capability to conduct the examination. The key word 'capability', when analysis is made of what is involved in it, reveals that conducting data acquisition by simply connecting a data reader tool to the target device (mobile phone) today we have significantly moved on from early examination techniques.

The knowledge, skills and experience from my early days telecomms background still serves me well today. When I first started in telecomms type approvals (the procedural path to bringing a telecomms product up to the technical and legal requirements to permit it to connected to the PSTN) the technical standards were important. The technical standards, such as, BS6301 electrical safety, BS6305 network connection, BS6317 apparatus connection and BS6789 apparatus functional features etc provided the grounding to understand what was necessary to succeed. Those standards didn't control how the manufacturer designed to meet each standard's strictures, merely they required to reveal what the product did at the point of, generally speaking, safety, input/output, device specific requirements and functionality and how it met the parameters laid down.

Interestly, designing memory in a device, although seen today as a reference to data storage (ephemeral, tarried or permanent), and thus introduces the notion and prospects of evidence, back then memory was seen as a consumer-friendly feature to create a pyschological attachment between the user and the owned device. Coming from a white goods/brown goods background I had to acquire an understanding/knowledge of not merely the telecomms standards but also the approaches used by manufacturers to meet telecomms standards. Back in 1983 one of the first books I read was Radio Shack "Understanding Telephone Electronics". Electronics, by the way, covered a wide technology design range categorisation including, as a subset of it, computer and computation. Note also that microcomputer was often used in earlier days, to describe manufacturing size and purpose, in comparison today whereas the term 'micro' 'electronic', and 'computer' and used in the term microelectronic computer to describe e.g. a SIM/USIM Card. We also use the term 'smart card' today, as well, but that requires, for discussion at another time, as to what is intended to be communicated by the term 'smart'.

Below are some selected pages discussing ways to create memory storage and access to it from that book which provides, in a nutshell, a useful exemplar how data retention could be created and managed within early electronic telephones. It is worth reading because a mobile phone examiner will see familiar issues that are addressed when considering a methodology for acquiring data from (mobile) devices.