The XTS configuration option MBEDTLS_CIPHER_MODE_XTS currently only enables
XTS for AES. So, don't say it enables XTS for "symmetric ciphers", just
AES. This helps to avoid being misleading.
THe function `mbedtls_gf128mul_x_ble()` doesn't multiply by x, x^4, and
x^8. Update the function description to properly describe what the function
does.
mbedtls_aes_crypt_xts() currently takes a `bits_length` parameter, unlike
the other block modes. Change the parameter to accept a bytes length
instead, as the `bits_length` parameter is not actually ever used in the
current implementation.
Add a new context structure for XTS. Adjust the API for XTS to use the new
context structure, including tests suites and the benchmark program. Update
Doxgen documentation accordingly.
AES-XEX is a building block for other cryptographic standards and not yet a
standard in and of itself. We'll just provide the standardized AES-XTS
algorithm, and not AES-XEX. The AES-XTS algorithm and interface provided
can be used to perform the AES-XEX algorithm when the length of the input
is a multiple of the AES block size.
If we're unlucky with memory placement, gf128mul_table_bbe may spread over
two cache lines and this would leak b >> 63 to a cache timing attack.
Instead, take an approach that is less likely to make different memory
loads depending on the value of b >> 63 and is also unlikely to be compiled
to a condition.
XTS mode is fully known as "xor-encrypt-xor with ciphertext-stealing".
This is the generalization of the XEX mode.
This implementation is limited to an 8-bits (1 byte) boundary, which
doesn't seem to be what was thought considering some test vectors [1].
This commit comes with tests, extracted from [1], and benchmarks.
Although, benchmarks aren't really nice here, as they work with a buffer
of a multiple of 16 bytes, which isn't a challenge for XTS compared to
XEX.
[1] http://csrc.nist.gov/groups/STM/cavp/documents/aes/XTSTestVectors.zip
As seen from the first benchmark run, AES-XEX was running pourly (even
slower than AES-CBC). This commit doubles the performances of the
current implementation.
The test cases come from the XTS test vectors given by the CAVP initiative
from NIST (see [1]).
As mentioned in a previous commit, XEX is a simpler case of XTS.
Therefore, to construct the test_suite_aes.xex.data file, extraction of
the XEX-possible cases has been done on the given test vectors.
All of the extracted test vectors pass the tests on a Linux x86_64 machine.
[1] http://csrc.nist.gov/groups/STM/cavp/documents/aes/XTSTestVectors.zip
XEX mode, known as "xor-encrypt-xor", is the simple case of the XTS
mode, known as "XEX with ciphertext stealing". When the buffers to be
encrypted/decrypted have a length divisible by the length of a standard
AES block (16), XTS is exactly like XEX.
It's undesirable to have users of the SSL layer check for an error code
specific to a lower-level layer, both out of general layering principles, and
also because if we later make another crypto module gain resume capabilities,
we would need to change the contract again (checking for a new module-specific
error code).
The way we do negative tests only works if the initial test was positive.
This was not immediately apparent with the set of test data at the time the
code for negative testing was introduced, but it became apparent with the
addition of the "0 private value" / "overlong private value" tests that
happened in development while this branch was developed.
When MBEDTLS_PLATFORM_MEMORY is defined but MBEDTLS_PLATFORM_FREE_MACRO or
MBEDTLS_PLATFORM_CALLOC_MACRO are not defined then the actual functions
used to allocate and free memory are stored in function pointers.
These pointers are exposed to the caller, and it means that the caller
and the library have to share a data section.
In TF-A, we execute in a very constrained environment, where some images
are executed from ROM and other images are executed from SRAM. The
images that are executed from ROM cannot be modified. The SRAM size
is very small and we are moving libraries to the ROM that can be shared
between the different SRAM images. These SRAM images could import all the
symbols used in mbedtls, but it would create an undesirable hard binary
dependency between the different images. For this reason, all the library
functions in ROM are accesed using a jump table whose base address is
known, allowing the images to execute with different versions of the ROM.
This commit changes the function pointers to actual functions,
so that the SRAM images only have to use the new exported symbols
(mbedtls_calloc and mbedtls_free) using the jump table. In
our scenario, mbedtls_platform_set_calloc_free is called from
mbedtls_memory_buffer_alloc_init which initializes the function pointers
to the internal buffer_alloc_calloc and buffer_alloc_free functions.
No functional changes to mbedtls_memory_buffer_alloc_init.
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>
Summary of merge conflicts:
include/mbedtls/ecdh.h -> documentation style
include/mbedtls/ecdsa.h -> documentation style
include/mbedtls/ecp.h -> alt style, new error codes, documentation style
include/mbedtls/error.h -> new error codes
library/error.c -> new error codes (generated anyway)
library/ecp.c:
- code of an extracted function was changed
library/ssl_cli.c:
- code addition on one side near code change on the other side
(ciphersuite validation)
library/x509_crt.c -> various things
- top fo file: helper structure added near old zeroize removed
- documentation of find_parent_in()'s signature: improved on one side,
added arguments on the other side
- documentation of find_parent()'s signature: same as above
- verify_chain(): variables initialised later to give compiler an
opportunity to warn us if not initialised on a code path
- find_parent(): funcion structure completely changed, for some reason git
tried to insert a paragraph of the old structure...
- merge_flags_with_cb(): data structure changed, one line was fixed with a
cast to keep MSVC happy, this cast is already in the new version
- in verify_restratable(): adjacent independent changes (function
signature on one line, variable type on the next)
programs/ssl/ssl_client2.c:
- testing for IN_PROGRESS return code near idle() (event-driven):
don't wait for data in the the socket if ECP_IN_PROGRESS
tests/data_files/Makefile: adjacent independent additions
tests/suites/test_suite_ecdsa.data: adjacent independent additions
tests/suites/test_suite_x509parse.data: adjacent independent additions
* development: (1059 commits)
Change symlink to hardlink to avoid permission issues
Fix out-of-tree testing symlinks on Windows
Updated version number to 2.10.0 for release
Add a disabled CMAC define in the no-entropy configuration
Adapt the ARIA test cases for new ECB function
Fix file permissions for ssl.h
Add ChangeLog entry for PR#1651
Fix MicroBlaze register typo.
Fix typo in doc and copy missing warning
Fix edit mistake in cipher_wrap.c
Update CTR doc for the 64-bit block cipher
Update CTR doc for other 128-bit block ciphers
Slightly tune ARIA CTR documentation
Remove double declaration of mbedtls_ssl_list_ciphersuites
Update CTR documentation
Use zeroize function from new platform_util
Move to new header style for ALT implementations
Add ifdef for selftest in header file
Fix typo in comments
Use more appropriate type for local variable
...
This patch uses grep to search the GDB output for errors as there is
a bug in the tool that causes it to return 0 to the system even though
there was a problem in the script.
This patch also fixes the zeroize test to work with the --keep-going
option in all.sh.
