Move fields around to have fewer accesses outside the 128-element Thumb
direct access window.
In psa_crypto.c's global_data, put the state fields first (-20).
In psa_crypto_slot_management.c's global_data, keep the key slots first
(otherwise it's +24).
In mbedtls_psa_random_context_t, swapping entropy and drbg makes no
difference (at least when the DRBG is mbedtls_ctr_drbg_context).
Results (arm-none-eabi-gcc 7.3.1, build_arm_none_eabi_gcc_m0plus build):
library/psa_crypto.o: 16166 -> 16146 (diff: 20)
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Move fields around to have fewer accesses outside the 128-element Thumb
direct access window.
In psa_hkdf_key_derivation_t, move the large fields (output_block, prk,
hmac) after the state bit-fields. Experimentally, it's slightly better
to put hmac last.
In aead_operation_t, tag_length was outside the window. The details depend
on the sizes of contexts included in ctx. Make the large ctx be the last
field.
In mbedtls_psa_hmac_operation_t, the opad field is outside the window when
SHA-512 is enabled. Moving opad before hash_ctx only saves 4 bytes and made
the structure clumsy, so I left it alone.
Results (arm-none-eabi-gcc 7.3.1, build_arm_none_eabi_gcc_m0plus build):
library/psa_crypto.o: 16246 -> 16166 (diff: 80)
library/psa_crypto_aead.o: 952 -> 928 (diff: 24)
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This comment is about how the functions are implemented, not about their
public interface, so it doesn't belong in the header file.
It applies to everything in constant_time.c so moved there.
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
The equality checker functions always return 0 or 1 value,
thus the type of return value can be the same dispite of the
size of the parameters.
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
Tne unpadding part of `mbedtls_rsa_rsaes_pkcs1_v15_decrypt` function is
contant-time therefore it moved to a separate function to be prepared
for moving to the contant-time module.
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
Add a constant-time function with size_t parameter for choosing
between two integer values, like the ?: ternary operator.
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
All function declaration provided by ssl_invasive.h is needed only for
testing purposes and all of them are provided by constant_time.h as well.
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
