Without this parameter, it would be hard for callers to know how many bytes
of output the function wrote into the output buffer. It would be possible,
since the cumulated output must have the same length as the cumulated input,
but it would be cumbersome for the caller to keep track.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Hashes used in RSA-PSS encoding (EMSA-PSS-ENCODE, see §9.1.1 in RFC
8017):
- H1: Hashing the message (step 2)
- H2: Hashing in the salt (step 6)
- H3: Mask generation function (step 9)
According to the standard:
- H1 and H2 MUST be done by the same hash function
- H3 is RECOMMENDED to be the same as the hash used for H1 and H2.
According to the implementation:
- H1 happens outside of the function call. It might or might not happen
and the implementation might or might not be aware of the hash used.
- H2 happens inside the function call, consistency with H1 is not
enforced and might not even be possible to detect.
- H3 is done with the same hash as H2 (with the exception of
mbedtls_rsassa_pss_verify_ext(), which takes a dedicated parameter for
the hash used in the MGF).
Issues with the documentation:
- The comments weren't always clear about the three hashes involved and
often only mentioned two of them (which two varied from function to
function).
- The documentation was giving the impression that the standard
recommends aligning H2 and H1 (which is not a recommendation but a
must).
Signed-off-by: Janos Follath <janos.follath@arm.com>
This saves some code when compiling for Thumb, where access to
fields with offset index > 127 requires intermediate address
computations. Frequently used fields should therefore be located
at the top of the structure, while less frequently used ones --
such as the export callback -- can be moved to the back.
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
Reverting some deleted tests and changing the deprecated algo
Deleting deprecated headers from /alt-dummy dir
Corrections to the comments
Removal of deleted functions from compat-2.x.h
Corrections to tests/data_files/Makefile
Signed-off-by: TRodziewicz <tomasz.rodziewicz@mobica.com>
For TLS, secp256k1 is deprecated by RFC 8422 §5.1.1. For X.509,
secp256k1 is not deprecated, but it isn't used in practice, especially
in the context of TLS where there isn't much point in having an X.509
certificate which most peers do not support. So remove it from the
default profile. We can add it back later if there is demand.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
TLS used to prefer larger curves, under the idea that a larger curve has a
higher security strength and is therefore harder to attack. However, brute
force attacks are not a practical concern, so this was not particularly
meaningful. If a curve is considered secure enough to be allowed, then we
might as well use it.
So order curves by resource usage. The exact definition of what this means
is purposefully left open. It may include criteria such as performance and
memory usage. Risk of side channels could be a factor as well, although it
didn't affect the current choice.
The current list happens to exactly correspond to the numbers reported by
one run of the benchmark program for "full handshake/s" on my machine.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
We stated that curves were listed "in order of preference", but we never
explained what the preference was, so this was not meaningful.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
MBEDTLS_ECP_WINDOW_SIZE is a compromise between memory usage (growing based
on the value) and performance (faster with larger values). There are
disminishing returns as the value grows larger. Based on Manuel's benchmarks
recorded in https://github.com/ARMmbed/mbedtls/issues/4127, 4 is a good
compromise point, with larger values bringing little advantage. So reduce
the default from 6 to 4.
Document the default value as in optimized for performance mostly, but don't
document the specific value, so we may change it later or make it
platform-dependent.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Upgrade the default list of hashes and curves allowed for TLS. The list is
now aligned with X.509 certificate verification: hashes and curves with at
least 255 bits (Curve25519 included), and RSA 2048 and above.
Remove MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE which would no
longer do anything.
Document more precisely what is allowed by default.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Upgrade the default X.509 certificate verification profile
mbedtls_x509_crt_profile_default to the former value of
mbedtls_x509_crt_profile_next, which is hashes and curves with at least 255
bits (Curve25519 included), and RSA 2048 and above.
Document more precisely what goes into the default profile.
Keep the "next" profile unchanged for now.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This makes it easier to ensure that crypto_spe.h is included everywhere it
needs to be, and that it's included early enough to do its job (it must be
included before any mention of psa_xxx() functions with external linkage,
because it defines macros to rename these functions).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
These fields are supposed to be manipulated directly, that's how people
create custom profiles.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
It was used to remove the code used when mbedtls_ecp_mul() received a
NULL RNG parameter. This code is no longer relevant (as the RNG may no
longer be NULL) and will be unconditionally removed in the next commit.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
This is necessary for the case where the public part of an EC keypair
needs to be computed from the private part - either because it was not
included (it's an optional component) or because it was compressed (a
format we can't parse).
This changes the API of two public functions: mbedtls_pk_parse_key() and
mbedtls_pk_parse_keyfile().
Tests and programs have been adapted. Some programs use a non-secure RNG
(from the test library) just to get things to compile and run; in a
future commit this should be improved in order to demonstrate best
practice.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
- mbedtls_ecp_check_pub_priv() because it calls ecp_mul()
- mbedtls_pk_check_pair() because it calls the former
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
