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Flash Self-Programming Library
Chapter 4
4.1 Flash Security
4.1.1
R01US0046ED Rev. 1.01
User Manual
FSL Usage
Strategy
In most cases application software contains important intellectual property and/or
data that may not be distributed to others or manipulated by others. In order to
ensure Flash data integrity and to prevent unintended data read-out, Renesas
implements a set of features and mechanisms into Flash devices.
As these mechanisms may also limit the flexibility required for the application and
the programming or reprogramming, it has to be decided carefully what level of
protection is intended.
Two major items to be considered in the protection concept are:
Illegal read-out of Flash content
Illegal or accidental reprogramming of Flash
The following descriptions explain the strategies regarding these items are
described in detail:
Illegal read-out of Flash content
Read-out, legal and illegal, can be done on different ways. The following
describes major ways and the appropriate counter measures against illegal
operations:
Direct read-out via on-chip debug interface
Some devices contain the N-Wire / Nexus debug interface. This allows
full control over all data stored in the device. It can be protected by a
password. As the protection is not directly a Flash feature, it is just
mentioned for reference. Please refer to the device user manual or the
tools description for details.
Direct read-out via programming interface
The standard programming interface (e.g. PG-FP5) supports a command
to read out the Flash contents on all current devices. This feature helps a
lot in the developing and debugging phase and for failure analysis. This
command can be disabled by a protection flag (see chapter 4.1.2
Configuration options for details)
Direct read-out by the application itself (via any interface)
E.g. a debug command in the application can be used to dump memory.
Please ensure that this possibility is not implemented or at least
protected in your application.
Indirect read-out by spy software, programmed into the internal Flash
Software can be programmed into Flash in two different ways:
o
By the application itself using Self-Programming
Please ensure that this possibility is not implemented or at least
protected in your application.
FSL Usage
16
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