The flag is used for tracking if the premaster has
been succesfully generated. Note that when resuming
a session, the flag should not be used when trying to
notice if all the key generation/derivation has been done.
Default flow assumes failure causes multiple issues with
compatibility tests when the return value is initialised
with error value in ssl_in_server_key_exchange_parse.
The function would need a significant change in structure for this.
The verification could be skipped in server, changed the default flow
so that the handshake status is ever updated if the verify
succeeds, and that is checked twice.
Check that the encryption has been done for the outbut buffer.
This is to ensure that glitching out the encryption doesn't
result as a unecrypted buffer to be sent.
This is to enable hardening the security when changing
states in state machine so that the state cannot be changed by bit flipping.
The later commit changes the enumerations so that the states have large
hamming distance in between them to prevent this kind of attack.
-Replace usage of rand() with mbedtls_platform_random_in_range()
-Prevent for-ever loop by hardcoding SCA countermeasure position in
case of used random function is always returning constant number.
-Use separate control bytes for start and final round to get them
randomized separately.
-Remove struct name.
-Fix comments and follow Mbed TLS coding style.
SCA CM implementation caused AES performance drop. For example
AES-CCM-128 calculation speed was dropped from 240 KB/s to 111 KB/s.
(-54%), Similarily AES-CBC-128 calculation speed was dropped from
536 KB/s to 237 KB/s (-56%).
Use functions instead of macros to reduce code indirections and
therefore increase performance. Now the performance is 163 KB/s for
AES-CCM-128 (-32%) and 348 KB/s for AES-CBC-128 (-35%).
When SCA countermeasures are activated the performance is as follows:
122 KB/s for AES-CCM-128 (-49%) and 258 KB/s for AES-CBC-128 (-52%)
compared to the original AES implementation.
Use control bytes to instruct AES calculation rounds. Each
calculation round has a control byte that indicates what data
(real/fake) is used and if any offset is required for AES data
positions.
First and last AES calculation round are calculated with SCA CM data
included. The calculation order is randomized by the control bytes.
Calculations between the first and last rounds contains 3 SCA CMs
in randomized positions.
- Add configuration for AES_SCA_COUNTERMEASURES to config.h. By
default the feature is disabled.
- Add AES_SCA_COUNTERMEASURES configuration check to check_config.h
- Add AES_SCA_COUNTERMEASURES test to all.sh
- 3 additional dummy AES rounds calculated with random data for each
AES encryption/decryption
- additional rounds can be occur in any point in sequence of rounds
- MSVC doesn't like -1u
- We need to include platform.h for MBEDTLS_ERR_PLATFORM_FAULT_DETECTED - in
some configurations it was already included indirectly, but not in all
configurations, so better include it directly.
