Update the documentation to mention that calling it with zero
as an argument will result in an undefined behavior.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
Place smallest items first, as this makes them most easily addressable
in Thumb architecture. 16-bit access instructions have a 5-bit offset
field, which is interpreted as bytes, halfwords, or words depending
on access size, so smaller fields have smaller range. Range is 0-31
times the access size.
The mbedtls_ssl_context structure is too large to be fully easily
accessed even for words, so reorder functional blocks to put more
frequently-referenced fields in the first 128 bytes, reducing
total code size.
Signed-off-by: Kevin Bracey <kevin.bracey@arm.com>
Bitfields in context structures do not have sufficient (if any) RAM
payoff for the ROM complexity to manipulate them. Replace with
plain uint8_t.
On the smallest targets, the configuration options mean that there
are 4 or fewer members anyway, so a bitfield saves no RAM compared
to uint8_t.
ROM saving will be further increased if the uint8_t members are at the
start of the structure (when compiling for Thumb).
Signed-off-by: Kevin Bracey <kevin.bracey@arm.com>
Follow the model of `MBEDTLS_SSL_CONF_ENDPOINT`. This saves a small
amount - most of the saving was already acheived via`
MBEDTLS_SSL_TRANSPORT_IS_TLS` but we can scrape out a little more by
totally eliminating `ssl->conf->transport` references.
Signed-off-by: Kevin Bracey <kevin.bracey@arm.com>
Optimize the key switching mechanism to set the key only if
a different operation is performed with the context.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
Store the raw encryption and decryption keys in transforms
to set them before each cipher operation. Add a config option
for this - MBEDTLS_SSL_TRANSFORM_OPTIMIZE_CIPHERS.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
Thanks to this change the produced ASM does not need an additional instruction
to place the constant value in a register, but can compare it directly.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
The earlier implementation had two problems: the random generator always
returned 0 if the MBEDTLS_ENTROPY_HARDWARE_ALT flag was not defined and there
was no protection needed if the HW RNG was malfunctioning. Both these problems
have been solved in this commit by adding the linear congruential generator algorithm.
Signed-off-by: Piotr Nowicki <piotr.nowicki@arm.com>
CRC is calculated when the key is set. This commit also adds new tests
for ecb encryption and decryption, simulating a fault injection after the key is set.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
Add a new CRC module along with some tests for it.
The table and the CRC function body is generated using pycrc v0.9.2.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
