The file oid.c had conditional inclusion of functions based on a config.h
define that belongs to X.509, which is backwards. For now, just include those
functions unconditionally and rely on the linker to garbage-collect them if
not used.
In the longer term X.509-specific functions are likely to be removed from
libmbedcrypto, but at this step the goal is to preserve the API (and even ABI)
of libmbedcrypto for as long as possible while separating the source trees of
Mbed Crypto and Mbed TLS.
As agreed during the workshop, temporarily move definitions to oid.h even if
they might not semantically belong here, as a short-term measure allowing to
build libmbecrypto on its own (without X.509 files present in the source tree)
but still provide all the things Mbed TLS currently expects, and more
specifically preserve the API and ABI exposed by libmbedtls.
Remove front matter from our EC key format, to make it just the contents
of an ECPoint as defined by SEC1 section 2.3.3.
As a consequence of the simplification, remove the restriction on not
being able to use an ECDH key with ECDSA. There is no longer any OID
specified when importing a key, so we can't reject importing of an ECDH
key for the purpose of ECDSA based on the OID.
Remove pkcs-1 and rsaEncryption front matter from RSA public keys. Move
code that was shared between RSA and other key types (like EC keys) to
be used only with non-RSA keys.
New function psa_copy_key().
Conflicts:
* library/psa_crypto.c: trivial conflicts due to consecutive changes.
* tests/suites/test_suite_psa_crypto.data: the same code
was added on both sides, but with a conflict resolution on one side.
* tests/suites/test_suite_psa_crypto_metadata.function: the same code
was added on both sides, but with a conflict resolution on one side.
You can use PSA_ALG_ANY_HASH to build the algorithm value for a
hash-and-sign algorithm in a policy. Then the policy allows usage with
this hash-and-sign family with any hash.
Test that PSA_ALG_ANY_HASH-based policies allow a specific hash, but
not a different hash-and-sign family. Test that PSA_ALG_ANY_HASH is
not valid for operations, only in policies.
Test for a subclass of public-key algorithm: those that perform
full-domain hashing, i.e. algorithms that can be broken down as
sign(key, hash(message)).
Remove the type and bits arguments to psa_allocate_key() and
psa_create_key(). They can be useful if the implementation wants to
know exactly how much space to allocate for the slot, but many
implementations (including ours) don't care, and it's possible to work
around their lack by deferring size-dependent actions to the time when
the key material is created. They are a burden to applications and
make the API more complex, and the benefits aren't worth it.
Change the API and adapt the implementation, the units test and the
sample code accordingly.
Change the key derivation API to take inputs in multiple steps,
instead of a single one-site-fits-poorly function.
Conflicts:
* include/psa/crypto.h: merge independent changes in the documentation
of psa_key_agreement (public_key from the work on public key formats
vs general description and other parameters in the work on key derivation).
* tests/suites/test_suite_psa_crypto.data: update the key agreement
tests from the work on key derivation to the format from the work on
public key formats.
* tests/suites/test_suite_psa_crypto_metadata.function: reconcile the
addition of unrelated ALG_IS_xxx macros
Get rid of "key selection" algorithms (of which there was only one:
raw key selection).
Encode key agreement by combining a raw key agreement with a KDF,
rather than passing the KDF as an argument of a key agreement macro.
The normal way is to pass the shared secret to a key derivation.
Having an ad hoc function will allow us to simplify the possible
behaviors of key agreement and get rid of "key selection" algorithms
which are a hard-to-understand invention of this API.
It isn't a good fit. It's overly complex for what the API can do now,
which is Diffie-Hellman. Consider it again later for more complex use
cases such as authenticated key exchanges.
Use separate step types for a KDF secret and for the private key in a
key agreement.
Determine which key type is allowed from the step type, independently
of the KDF.
Forbid raw inputs for certain steps. They definitely should be
forbidden for asymmetric keys, which are structured. Also forbid them
for KDF secrets: the secrets are supposed to be keys, even if they're
unstructured.
Add the ability to specify Diffie-Hellman key exchange keys. Specify the
import/export format as well, even though importing and exporting isn't
implemented yet.
Remove front matter and DSS parameters from our DSA key formats, both
keypair and public key, to make it just a representation of the integer
private key, `x`, or the public key, `y`, respectively.
DSA and static DH need extra domain parameters. Instead of passing these
in with the keys themselves, add get and set functions to set and
retrieve this information about keys.
Add a new function mbedtls_asn1_write_named_bitstring() that removes
trailing 0s at the end of DER encoded bitstrings. The function is
implemented according to Hanno Becker's suggestions.
This commit also changes the functions x509write_crt_set_ns_cert_type
and crt_set_key_usage to call the new function as the use named
bitstrings instead of the regular bitstrings.
Remove front matter from our EC key format, to make it just the contents
of an ECPoint as defined by SEC1 section 2.3.3.
As a consequence of the simplification, remove the restriction on not
being able to use an ECDH key with ECDSA. There is no longer any OID
specified when importing a key, so we can't reject importing of an ECDH
key for the purpose of ECDSA based on the OID.
You can use PSA_ALG_ANY_HASH to build the algorithm value for a
hash-and-sign algorithm in a policy. Then the policy allows usage with
this hash-and-sign family with any hash.
Test that PSA_ALG_ANY_HASH-based policies allow a specific hash, but
not a different hash-and-sign family. Test that PSA_ALG_ANY_HASH is
not valid for operations, only in policies.
Finish changing "start" to "set up".
Correct the way to set an IV for decryption: it's set_iv(), not
update().
When decrypting, the IV is given, not random.
Test for a subclass of public-key algorithm: those that perform
full-domain hashing, i.e. algorithms that can be broken down as
sign(key, hash(message)).
Remove pkcs-1 and rsaEncryption front matter from RSA public keys. Move
code that was shared between RSA and other key types (like EC keys) to
be used only with non-RSA keys.
Copy the nice and clear documentation from psa_export_key() as to what
implementations are allowed to do regarding key export formats, as the
same applies to public keys.
hash_setup and mac_setup used to be called hash_start and mac_start,
but we've now converged on _setup as names. Finish making the
terminology in the documentation consistent.
We've added documentation for how context objects for multi-part
operations must be initialized consistently for key policy, hash,
cipher, and MAC. Update the generator documentation to be consistent
with how we've documented the other operations.
Add new initializers for cipher operation objects and use them in our
tests and library code. Prefer using the macro initializers due to their
straightforwardness.
The struct psa_cipher_operation_s is built with a
mbedtls_cipher_context_t. The shape of mbedtls_cipher_context_t and an
initializer that works with Clang 5.0 and its
-Wmissing-field-initializers varies based on the configuration of the
library. Instead of making multiple initializers based on a maze of
ifdefs for all combinations of MBEDTLS_CIPHER_MODE_WITH_PADDING,
MBEDTLS_CMAC_C, and MBEDTLS_USE_PSA_CRYPTO, add a dummy variable to
psa_cipher_operation_s's union that encloses mbedtls_cipher_context_t.
This allows us to initialize the dummy with a Clang-approved initializer
and have it properly initialize the entire object.
Add new initializers for MAC operation objects and use them in our tests
and library code. Prefer using the macro initializers due to their
straightforwardness.
Add new initializers for hash operation objects and use them in our
tests and library code. Prefer using the macro initializers due to their
straightforwardness.
Add new initializers for key policies and use them in our docs, example
programs, tests, and library code. Prefer using the macro initializers
due to their straightforwardness.
As there are some definitions that are defined regardless of
whether MBEDTLS_ECP_RESTARTABLE is defined or not, these definitions
need to be moved outside the MBEDTLS_ECP_ALT guards. This is a simple
move as MBEDTLS_ECP_ALT and MBEDTLS_ECP_RESTARTABLE are mutually
exclusive options.
Split crypto_driver.h into 4:
* crypto_driver_common.h for common definitions, not meant to be
included directly by driver code.
* crypto_accel_driver.h for drivers that work with transparent
key material.
* crypto_se_driver.h for drivers that work with opaque key
material.
* crypto_entropy_driver.h for drivers of entropy sources.
There is no code change in this commit, I only moved some code around.
Now that the type definitions that are useful for driver are in a
separate header file from the application interface function
declarations, include that header file in crypto_driver.h.
Some parts of the library, and crypto drivers, need to see key types,
algorithms, policies, etc. but not API functions. Move portable
integral types and macros to build and analyze values of these types
to a separate headers crypto_types.h and crypto_values.h.
No functional changes, code was only moved from crypto.h to the new headers.
Define psa_status_t to int32_t unconditionally. There's no reason to
refer to psa_error_t here: psa_error_t is int32_t if it's present. We
would only need a conditional definition if psa_defs.h and
psa_crypto.h used the same type name.
Keep the conditional definition of PSA_SUCCESS. Although the C
preprocessor allows a duplicate definition for a macro, it has to be
the exact same token sequence, not merely an equivalent way to build
the same value.
Document when a context must be initialized or not, when it must be
set up or not, and whether it needs a private key or a public key will
do.
The implementation is sometimes more liberal than the documentation,
accepting a non-set-up context as a context that can't perform the
requested information. This preserves backward compatibility.
For mbedtls_pk_parse_key and mbedtls_pk_parse_keyfile, the password is
optional. Clarify what this means: NULL is ok and means no password.
Validate parameters and test accordingly.
A 0-length buffer for the key is a legitimate edge case. Ensure that
it works, even with buf=NULL. Document the key and keylen parameters.
There are already test cases for parsing an empty buffer. A subsequent
commit will add tests for writing to an empty buffer.
The previous introduction of constant deprecation macros
in platform_util.h lead to failure of tests/scrips/check-names.sh
because the regular expressions in the latter choked on the brackets
in the part `__attribute__((deprecated))` of the definition of the
helper type `mbedtls_deprecated_{numeric|string}_constant_t`.
Postponing any further study and potential robustness improvements
in check-names.sh to another time, this commit circumvents this
problem by temporarily abbreviating `__attribute__((deprecated))`
as `MBEDTLS_DEPRECATED`, which doesn't lead to problems with
check-names.sh.
This commit introduces macros
* MBEDTLS_DEPRECATED_STRING_CONSTANT
* MBEDTLS_DEPRECATED_NUMERIC_CONSTANT
to platform_util.h which can be used to deprecate public macro constants.
Their definition is essentially taken from dhm.h where the
MBEDTLS_DEPRECATED_STRING_CONSTANT was used to deprecate
insecure hardcoded DHM primes.
Add inclusion to configration file in header files,
instead of relying on other header files to include
the configuration file. This issue resolves#1371
- Be specific about the constraints: be a readable/writable buffer of length
X, be an initialized context, be a context initialized and bound to a key...
- Always use full sentences with all the required pronouns.
Some of the documentation is obsolete in its reference to key slots
when it should discuss key handles. This may require a further pass,
possibly with some reorganization of error codes.
Update the documentation of functions that modify key slots (key
material creation and psa_set_key_policy()) to discuss how they affect
storage.
This commit marks the beginning of the removal of support for direct
access to key slots. From this commit on, programs that use
psa_key_slot_t will no longer compile.
Subsequent commits will remove the now-unused legacy support in
psa_crypto.c.
Replace `psa_key_slot_t key` by `psa_key_handle_t` in function
declarations.
This is a transition period during which handles are key slot numbers
and the whole library can still be used by accessing a key slot number
without allocating a handle.
It's better if the macro receives the condition as an expression rather than a
string - that way it can choose to use it as is or stringify it. Also, the
documentation states that the parameter is an expression, not a string.
The test framework for validation of parameters depends on the macro
MBEDTLS_PARAM_FAILED() being set to its default value when building the
library. So far the test framework attempted to define this macro but this was
the wrong place - this definition wouldn't be picked by the library.
Instead, a different approach is taken: skip those tests when the macro is
defined in config.h, as in that case we have no way to know if it will indeed
end up calling mbedtls_param_failed() as we need it to.
This commit was tested by manually ensuring that aes_invalid_params:
- passes (and is not skipped) in the default configuration
- is skipped when MBEDTLS_PARAM_FAILED() is defined in config.h
The previous prototype gave warnings are the strings produced by #cond and
__FILE__ are const, so we shouldn't implicitly cast them to non-const.
While at it modifying most example programs:
- include the header that has the function declaration, so that the definition
can be checked to match by the compiler
- fix whitespace
- make it work even if PLATFORM_C is not defined:
- CHECK_PARAMS is not documented as depending on PLATFORM_C and there is
no reason why it should
- so, remove the corresponding #if defined in each program...
- and add missing #defines for mbedtls_exit when needed
The result has been tested (make all test with -Werror) with the following
configurations:
- full with CHECK_PARAMS with PLATFORM_C
- full with CHECK_PARAMS without PLATFORM_C
- full without CHECK_PARAMS without PLATFORM_C
- full without CHECK_PARAMS with PLATFORM_C
Additionally, it has been manually tested that adding
mbedtls_aes_init( NULL );
near the normal call to mbedtls_aes_init() in programs/aes/aescrypt2.c has the
expected effect when running the program.
It was inconsistent between files: sometimes 3 arguments, sometimes one.
Align to 1 argument for the macro and 3 for the function, because:
- we don't need 3 arguments for the macro, it can add __FILE__ and __LINE__
in its expansion, while the function needs them as parameters to be correct;
- people who re-defined the macro should have flexibility, and 3 arguments
can give the impression they they don't have as much as they actually do;
- the design document has the macro with 1 argument, so let's stick to that.
The function called through the macro MBEDTLS_PARAM_FAILED() must be supplied by
users and makes no sense as a library function, apart from debug and test.
The SSL module accesses ECDH context members directly to print debug
information. This can't work with the new context, where we can't make
assumptions about the implementation of the context. This commit adds
new debug functions to complete the encapsulation of the ECDH context
and work around the problem.
We want to support alternative software implementations and we extend
the ECDH context to enable this. The actual functional change that makes
use of the new context is out of scope for this commit.
Changing the context breaks the API and therefore it has to be
excluded from the default configuration by a compile time flag.
We add the compile time flag to the module header instead of
`config.h`, because this is not a standalone feature, it only
enables adding new implementations in the future.
The new context features a union of the individual implementations
and a selector that chooses the implementation in use. An alternative
is to use an opaque context and function pointers, like for example the
PK module does it, but it is more dangerous, error prone and tedious to
implement.
We leave the group ID and the point format at the top level of the
structure, because they are very simple and adding an abstraction
layer around them away does not come with any obvious benefit.
Other alternatives considered:
- Using the module level replacement mechanism in the ECP module. This
would have made the use of the replacement feature more difficult and
the benefit limited.
- Replacing our Montgomery implementations with a new one directly. This
would have prevented using Montgomery curves across implementations.
(For example use implementation A for Curve448 and implementation B for
Curve22519.) Also it would have been inflexible and limited to
Montgomery curves.
- Encoding the implementation selector and the alternative context in
`mbedtls_ecp_point` somehow and rewriting `mbedtls_ecp_mul()` to
dispatch between implementations. This would have been a dangerous and
ugly hack, and very likely to break legacy applications.
- Same as above just with hardcoding the selector and using a compile
time option to make the selection. Rejected for the same reasons as
above.
- Using the PK module to provide to provide an entry point for
alternative implementations. Like most of the above options this
wouldn't have come with a new compile time option, but conceptually
would have been very out of place and would have meant much more work to
complete the abstraction around the context.
In retrospect:
- We could have used the group ID as the selector, but this would have
made the code less flexible and only marginally simpler. On the other
hand it would have allowed to get rid of the compile time option if a
tight integration of the alternative is possible. (It does not seem
possible at this point.)
- We could have used the same approach we do in this commit to the
`mbedtls_ecp_point` structure. Completing the abstraction around this
structure would have been a much bigger and much riskier code change
with increase in memory footprint, potential decrease in performance
and no immediate benefit.
In the future we want to support alternative ECDH implementations. We
can't make assumptions about the structure of the context they might
use, and therefore shouldn't access the members of
`mbedtls_ecdh_context`.
Currently the lifecycle of the context can't be done without direct
manipulation. This commit adds `mbedtls_ecdh_setup()` to complete
covering the context lifecycle with functions.
`mbedtls_ecp_tls_read_group()` both parses the group ID and loads the
group into the structure provided. We want to support alternative
implementations of ECDH in the future and for that we need to parse the
group ID without populating an `mbedtls_ecp_group` structure (because
alternative implementations might not use that).
This commit moves the part that parses the group ID to a new function.
There is no need to test the new function directly, because the tests
for `mbedtls_ecp_tls_read_group()` are already implicitly testing it.
There is no intended change in behaviour in this commit.
Revived from a previous PR by Gilles, see:
https://github.com/ARMmbed/mbedtls/pull/1293/files#diff-568ef321d275f2035b8b26a70ee9af0bR71
This will be useful in eliminating temporary stack buffers for transcoding the
signature: in order to do that in place we need to be able to make assumptions
about the size of the output buffer, which this macro will provide. (See next
commit.)
It's better for names in the API to describe the "what" (opaque keys) rather
than the "how" (using PSA), at least since we don't intend to have multiple
function doing the same "what" in different ways in the foreseeable future.
Unfortunately the can_do wrapper does not receive the key context as an
argument, so it cannot check psa_get_key_information(). Later we might want to
change our internal structures to fix this, but for now we'll just restrict
opaque PSA keys to be ECDSA keypairs, as this is the only thing we need for
now. It also simplifies testing a bit (no need to test each key type).
While at it, clarify who's responsible for destroying the underlying key. That
can't be us because some keys cannot be destroyed and we wouldn't know. So
let's leave that up to the caller.
The sanity checking script tests/scripts/check-names.sh uses a
simple state machine paired with a sequence of `sed` commands to
extract enumeration constants from the code. This code, however,
doesn't work properly when using multiline comments in enumerations
such as recently done in the constants MBEDTLS_CIPHER_PSA_KEY_XXX.
This commit doesn't attempt to make check-names.sh more robust
but instead uses /* ... */ comment indicators in each comment line,
while silences check-names.sh.
Increasing the robustness of check-names.sh is instead tracked
in #2210.
For AEAD ciphers, the information contained in mbedtls_cipher_info
is not enough to deduce a PSA algorithm value of type psa_algorithm_t.
This is because mbedtls_cipher_info doesn't contain the AEAD tag
length, while values of type psa_algorithm_t do.
This commit adds the AEAD tag length as a separate parameter
to mbedtls_cipher_setup_psa(). For Non-AEAD ciphers, the value
must be 0.
This approach is preferred over passing psa_algorithm_t directly
in order to keep the changes in existing code using the cipher layer
small.
This commit implements the internal key slot management performed
by PSA-based cipher contexts. Specifically, `mbedtls_cipher_setkey()`
wraps the provided raw key material into a key slot, and
`mbedtls_cipher_free()` destroys that key slot.
This field determines whether a cipher context should
use an external implementation of the PSA Crypto API for
cryptographic operations, or Mbed TLS' own crypto library.
The commit also adds dummy implementations for the cipher API.
This commit adds a field `psk_opaque` to the handshake parameter
struct `mbedtls_ssl_handshake_params` which indicates if the user
has configured the use of an opaque PSK.
This commit adds two public API functions
mbedtls_ssl_conf_psk_opaque()
mbedtls_ssl_set_hs_psk_opaque()
which allow to configure the use of opaque, PSA-maintained PSKs
at configuration time or run time.
In case of AEAD ciphers, the cipher mode (and not even the entire content
of mbedtls_cipher_info_t) doesn't uniquely determine a psa_algorithm_t
because it doesn't specify the AEAD tag length, which however is included
in psa_algorithm_t identifiers.
This commit adds a tag length value to mbedtls_psa_translate_cipher_mode()
to account for that ambiguity.
This commit adds the header file mbedtls/psa_util.h which contains
static utility functions `mbedtls_psa_xxx()` used in the integration
of PSA Crypto into Mbed TLS.
Warning: These functions are internal only and may change at any time.
The sanity checking script tests/scripts/check-names.sh uses a
simple state machine paired with a sequence of `sed` commands to
extract enumeration constants from the code. This code, however,
doesn't work properly when using multiline comments in enumerations
such as recently done in the constants MBEDTLS_CIPHER_PSA_KEY_XXX.
This commit doesn't attempt to make check-names.sh more robust
but instead uses /* ... */ comment indicators in each comment line,
while silences check-names.sh.
Increasing the robustness of check-names.sh is instead tracked
in #2210.
For AEAD ciphers, the information contained in mbedtls_cipher_info
is not enough to deduce a PSA algorithm value of type psa_algorithm_t.
This is because mbedtls_cipher_info doesn't contain the AEAD tag
length, while values of type psa_algorithm_t do.
This commit adds the AEAD tag length as a separate parameter
to mbedtls_cipher_setup_psa(). For Non-AEAD ciphers, the value
must be 0.
This approach is preferred over passing psa_algorithm_t directly
in order to keep the changes in existing code using the cipher layer
small.
This commit implements the internal key slot management performed
by PSA-based cipher contexts. Specifically, `mbedtls_cipher_setkey()`
wraps the provided raw key material into a key slot, and
`mbedtls_cipher_free()` destroys that key slot.
This field determines whether a cipher context should
use an external implementation of the PSA Crypto API for
cryptographic operations, or Mbed TLS' own crypto library.
The commit also adds dummy implementations for the cipher API.
Revived from a previous PR by Gilles, see:
https://github.com/ARMmbed/mbedtls/pull/1293/files#diff-568ef321d275f2035b8b26a70ee9af0bR71
This will be useful in eliminating temporary stack buffers for transcoding the
signature: in order to do that in place we need to be able to make assumptions
about the size of the output buffer, which this macro will provide. (See next
commit.)
It's better for names in the API to describe the "what" (opaque keys) rather
than the "how" (using PSA), at least since we don't intend to have multiple
function doing the same "what" in different ways in the foreseeable future.
Unfortunately the can_do wrapper does not receive the key context as an
argument, so it cannot check psa_get_key_information(). Later we might want to
change our internal structures to fix this, but for now we'll just restrict
opaque PSA keys to be ECDSA keypairs, as this is the only thing we need for
now. It also simplifies testing a bit (no need to test each key type).
While at it, clarify who's responsible for destroying the underlying key. That
can't be us because some keys cannot be destroyed and we wouldn't know. So
let's leave that up to the caller.
This commit adds a field `psk_opaque` to the handshake parameter
struct `mbedtls_ssl_handshake_params` which indicates if the user
has configured the use of an opaque PSK.
This commit adds two public API functions
mbedtls_ssl_conf_psk_opaque()
mbedtls_ssl_set_hs_psk_opaque()
which allow to configure the use of opaque, PSA-maintained PSKs
at configuration time or run time.
In case of AEAD ciphers, the cipher mode (and not even the entire content
of mbedtls_cipher_info_t) doesn't uniquely determine a psa_algorithm_t
because it doesn't specify the AEAD tag length, which however is included
in psa_algorithm_t identifiers.
This commit adds a tag length value to mbedtls_psa_translate_cipher_mode()
to account for that ambiguity.
This commit adds the header file mbedtls/psa_util.h which contains
static utility functions `mbedtls_psa_xxx()` used in the integration
of PSA Crypto into Mbed TLS.
Warning: These functions are internal only and may change at any time.
Allow use of persistent keys, including configuring them, importing and
exporting them, and destroying them.
When getting a slot using psa_get_key_slot, there are 3 scenarios that
can occur if the keys lifetime is persistent:
1. Key type is PSA_KEY_TYPE_NONE, no persistent storage entry:
- The key slot is treated as a standard empty key slot
2. Key type is PSA_KEY_TYPE_NONE, persistent storage entry exists:
- Attempt to load the key from persistent storage
3. Key type is not PSA_KEY_TYPE_NONE:
- As checking persistent storage on every use of the key could
be expensive, the persistent key is assumed to be saved in
persistent storage, the in-memory key is continued to be used.
Add new functions, psa_load_persistent_key(),
psa_free_persistent_key_data(), and psa_save_persistent_key(), for
managing persistent keys. These functions load to or save from our
internal representation of key slots. Serialization is a concern of the
storage backend implementation and doesn't abstraction-leak into the
lifetime management code.
An initial implementation for files is provided. Additional storage
backends can implement this interface for other storage types.
Mbed TLS version 2.14.0
Resolved conflicts in include/mbedtls/config.h,
tests/scripts/check-files.py, and yotta/create-module.sh by removing yotta.
Resolved conflicts in tests/.jenkins/Jenkinsfile by continuing to run
mbedtls-psa job.
Add missing checks for defined(MBEDTLS_MD_C) around types and
functions that require it (HMAC, HKDF, TLS12_PRF).
Add missing checks for defined(MBEDTLS_ECDSA_DETERMINISTIC) around
code that calls mbedtls_ecdsa_sign_det().
Add missing checks for defined(MBEDTLS_ECDH_C) around ECDH-specific
functions.
This commit adds KDF algorithm identifiers `PSA_ALG_TLS12_PRF(HASH)`
to the PSA crypto API. They represent the key derivation functions
used by TLS 1.2 for the PreMasterSecret->MasterSecret and
MasterSecret->KeyBlock conversions.
Use m for the bit size of the field order, not q which is
traditionally the field order.
Correct and clarify the private key representation format as has been
done for the private key and ECDH shared secret formats.
The endianness actually depends on the curve type.
Correct the terminology around "curve size" and "order of the curve".
I tried to find a formulation that is comprehensible to programmers
who do not know the underlying mathematics, but nonetheless correct
and precise.
Use similar terminology in other places that were using "order of the
curve" to describe the bit size associated with the curve.
psa_key_derivation requires the caller to specify a maximum capacity.
This commit adds a special value that indicates that the maximum
capacity should be the maximum supported by the algorithm. This is
currently meant only for selection algorithms used on the shared
secret produced by a key agreement.
A key selection algorithm is similar to a key derivation algorithm in
that it takes a secret input and produces a secret output stream.
However, unlike key derivation algorithms, there is no expectation
that the input cannot be reconstructed from the output. Key selection
algorithms are exclusively meant to be used on the output of a key
agreement algorithm to select chunks of the shared secret.
Deprecate the module-specific XXX_HW_ACCEL_FAILED and
XXX_FEATURE_UNAVAILABLE errors, as alternative implementations should now
return `MBEDTLS_ERR_PLATFORM_HW_FAILED` and
`MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED`.
Change the import/export format of private elliptic curve keys from
RFC 5915 to the raw secret value. This commit updates the format
specification and the import code, but not the export code.
Context:
The macro `MBEDTLS_ECP_BUDGET()` is called before performing a
number of potentially time-consuming ECC operations. If restartable
ECC is enabled, it wraps a call to `mbedtls_ecp_check_budget()`
which in turn checks if the requested number of operations can be
performed without exceeding the maximum number of consecutive ECC
operations.
Issue:
The function `mbedtls_ecp_check_budget()` expects a the number
of requested operations to be given as a value of type `unsigned`,
while some calls of the wrapper macro `MBEDTLS_ECP_BUDGET()` use
expressions of type `size_t`.
This rightfully leads to warnings about implicit truncation
from `size_t` to `unsigned` on some compilers.
Fix:
This commit makes the truncation explicit by adding an explicit cast
to `unsigned` in the expansion of the `MBEDTLS_ECP_BUDGET()` macro.
Justification:
Functionally, the new version is equivalent to the previous code.
The warning about truncation can be discarded because, as can be
inferred from `ecp.h`, the number of requested operations is never
larger than 1000.
Add extern "C" wrappers around type and function declarations to enable C++
interoperability of the driver header. This is done so that the driver
functions and types can be used or implmented by C++ code.
Convert PSA Crypto driver model structs to typedefs so that the `struct`
name doesn't need to be used and for consistent style with other PSA
structures.
The file crypto_driver.h was not using the header guard style as other PSA
Crypto header files. Remove the `__` prefix and suffix. Use C-style
comments for the end-of-guard comment.
The driver model's "encrypt or decrypt" type, encrypt_or_decrypt_t, is
publicly exposed and needs to have a `psa_` prefix in order to properly
communicate that it is part of the PSA driver model.
The `pcd_` prefix is ambiguous and does not make it clear that the types
and symbols are standardized by PSA. Replace `pcd_` with a prefix that can
be shared with all PSA drivers, `psa_drv_`.
"Driver APIs" can be interpreted to mean APIs used when you want to write a
driver, not the set of functions you implement to make a driver. See
https://www.kernel.org/doc/html/latest/driver-api/index.html "The kernel
offers a wide variety of interfaces to support the development of device
drivers."
As such, we are renaming "Driver API" to "Driver Model" and updating our
work so far to reflect this change.
It turns out that in some environments MinGW esposes a non-conforming
(v)snprintf behavior despite the tests against the MSVC runtime pass.
Therefore it has been included in the "non-conforming" scope alongide
older MSVC rungime environments.
Add comments noting that the maximum length of a MAC must fit in
PSA_ALG_MAC_TRUNCATION_MASK. Add a unit test that verifies that the
maximum MAC size fits.
Previously, mbedtls_pkcs5_pbes2() was unconditionally declared
in `pkcs5.h` but defined as a stub returning
`MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE` in case
MBEDTLS_ASN1_PARSE_C was not defined.
In line with the previous commits, this commit removes declaration
and definition from both `pkcs5.h` and `pkcs5.c` in case
MBEDTLS_ASN1_PARSE_C is not defined.
Rename the PLATFORM HW error, to avoid ABI breakage with Mbed OS.
The value changed as well, as previous value was not in the range of
Mbed TLS low level error codes.
The previous comment in ecp.h that only functions that take a "restart
context" argument can restart was wrong due to ECDH and SSL functions.
Changing that criterion to "document says if can return IN PROGRESS".
This requires updating the documentation of the SSL functions to mention this
explicitly, but it's something we really ought to do anyway, a bit
embarrassing that this wasn't done already - callers need to know what
`MBEDTLS_ERR_SSL_xxx` error codes to special-case. Note that the documentation
of the relevant functions was in a suboptimal state, so it was improved in the
process - it could use some more improvement, but only the changes that helped
cleanly insert the info about the IN_PROGRESS part were done here.
Also, while updating the ecp.h comment, I noticed several functions in the
ECDH module were wrongfully documented as restartable, which is probably a
left-over from the days before `mbedtls_ecdh_enable_restart()` was introduced.
Fixing that as well, to make the criterion used in ecp.h correct.
When using a primality testing function the tolerable error rate depends
on the scheme in question, the required security strength and wether it
is used for key generation or parameter validation. To support all use
cases we need more flexibility than what the old API provides.
The FIPS 186-4 RSA key generation prescribes lower failure probability
in primality testing and this makes key generation slower. We enable the
caller to decide between compliance/security and performance.
This python script calculates the base two logarithm of the formulas in
HAC Fact 4.48 and was used to determine the breakpoints and number of
rounds:
def mrpkt_log_2(k, t):
if t <= k/9.0:
return 3*math.log(k,2)/2+t-math.log(t,2)/2+4-2*math.sqrt(t*k)
elif t <= k/4.0:
c1 = math.log(7.0*k/20,2)-5*t
c2 = math.log(1/7.0,2)+15*math.log(k,2)/4.0-k/2.0-2*t
c3 = math.log(12*k,2)-k/4.0-3*t
return max(c1, c2, c3)
else:
return math.log(1/7.0)+15*math.log(k,2)/4.0-k/2.0-2*t
The Cortex M4, M7 MCUs and the Cortex A CPUs support the ARM DSP
instructions, and especially the umaal instruction which greatly
speed up MULADDC code. In addition the patch switched the ASM
constraints to registers instead of memory, giving the opportunity
for the compiler to load them the best way.
The speed improvement is variable depending on the crypto operation
and the CPU. Here are the results on a Cortex M4, a Cortex M7 and a
Cortex A8. All tests have been done with GCC 6.3 using -O2. RSA uses a
RSA-4096 key. ECDSA uses a secp256r1 curve EC key pair.
+--------+--------+--------+
| M4 | M7 | A8 |
+----------------+--------+--------+--------+
| ECDSA signing | +6.3% | +7.9% | +4.1% |
+----------------+--------+--------+--------+
| RSA signing | +43.7% | +68.3% | +26.3% |
+----------------+--------+--------+--------+
| RSA encryption | +3.4% | +9.7% | +3.6% |
+----------------+--------+--------+--------+
| RSA decryption | +43.0% | +67.8% | +22.8% |
+----------------+--------+--------+--------+
I ran the whole testsuite on the Cortex A8 Linux environment, and it
all passes.
Remove the trailing whitespace from the inline assembly for AMD64 target, to
overcome a warning in Clang, which was objecting to the string literal
generated by the inline assembly being greater than 4096 characters specified
by the ISO C99 standard. (-Woverlength-strings)
This is a cosmetic change and doesn't change the logic of the code in any way.
This change only fixes the problem for AMD64 target, and leaves other targets as
they are.
Fixes#482.
It should be valid to RSASSA-PSS sign a SHA-512 hash with a 1024-bit or
1032-bit RSA key, but with the salt size being always equal to the hash
size, this isn't possible: the key is too small.
To enable use of hashes that are relatively large compared to the key
size, allow reducing the salt size to no less than the hash size minus 2
bytes. We don't allow salt sizes smaller than the hash size minus 2
bytes because that too significantly changes the security guarantees the
library provides compared to the previous implementation which always
used a salt size equal to the hash size. The new calculated salt size
remains compliant with FIPS 186-4.
We also need to update the "hash too large" test, since we now reduce
the salt size when certain key sizes are used. We used to not support
1024-bit keys with SHA-512, but now we support this by reducing the salt
size to 62. Update the "hash too large" test to use a 1016-bit RSA key
with SHA-512, which still has too large of a hash because we will not
reduce the salt size further than 2 bytes shorter than the hash size.
The RSA private key used for the test was generated using "openssl
genrsa 1016" using OpenSSL 1.1.1-pre8.
$ openssl genrsa 1016
Generating RSA private key, 1016 bit long modulus (2 primes)
..............++++++
....++++++
e is 65537 (0x010001)
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
Yotta is no longer supported by Mbed TLS, so has been removed. Specifically, the
following changes have been made:
* references to yotta have been removed from the main readme and build
instructions
* the yotta module directory and build script has been removed
* yotta has been removed from test scripts such as all.sh and check-names.sh
* yotta has been removed from other files that that referenced it such as the
doxyfile and the bn_mul.h header
* yotta specific configurations and references have been removed from config.h
Setting the dh_flag to 1 used to indicate that the caller requests safe
primes from mbedtls_mpi_gen_prime. We generalize the functionality to
make room for more flags in that parameter.
None of the currently defined MAC algorithms have a MAC size that
depends on the key size, so the key_bits parameter is unused. The
key_type parameter may be unused on an implementation where there is
no block cipher MAC. Declare the key_type and key_bits parameters as
used so that callers who define a variable just for this don't risk
getting "unused variable" warnings.
The macro was used under the name PSA_ALG_IS_BLOCK_CIPHER_MAC but
defined as PSA_ALG_IS_CIPHER_MAC. That wouldn't have worked if we used
this macro (we currently don't but it may become useful).
TLS now defines named curves in the "TLS Supported Groups registry",
but we're using the encoding only for elliptic curves, so don't
include values that aren't named curve.
While we're at it, upgrade the reference to the shiny new RFC 8422.
OFB and CFB are streaming modes. XTS is a not a cipher mode but it
doesn't use a separate padding step. This leaves only CBC as a block
cipher mode that needs a padding step.
Since CBC is the only mode that uses a separate padding step, and is
likely to remain the only mode in the future, encode the padding mode
directly in the algorithm constant, rather than building up an
algorithm value from a chaining mode and a padding mode. This greatly
simplifies the interface as well as some parts of the implementation.
There were only 5 categories (now 4). Reduce the category mask from 7
bits to 3.
Combine unformatted, not-necessarily-uniform keys (HMAC, derivation)
with raw data.
Reintroduce a KEY_TYPE_IS_UNSTRUCTURED macro (which used to exist
under the name KEY_TYPE_IS_RAW_DATA macro) for key types that don't
have any structure, including both should-be-uniform keys (such as
block cipher and stream cipher keys) and not-necessarily-uniform
keys (such as HMAC keys and secrets for key derivation).
These structs are using bitfields of length one, which can only represent 0 and -1 for signed ints.
Changing these to unsigned int lets them represent 0 and 1, which is what we want.
MBEDTLS_PK_WRITE_C only requires either MBEDTLS_RSA_C or MBEDTLS_ECP_C to be defined.
Added wrappers to handle the cases where only one has been defined.
Moved mbedtls_pk_init to be within the ifdefs, so it's only called if appropriate.
* Broken link #PSA_ALG_SHA_256
* Duplicate group name "generators"
* Missing documentation in psa_generate_key_extra_rsa due to bad magic
comment marker
New key type PSA_KEY_TYPE_DERIVE. New usage flag PSA_KEY_USAGE_DERIVE.
New function psa_key_derivation.
No key derivation algorithm is implemented yet. The code may not
compile with -Wunused.
Write some unit test code for psa_key_derivation. Most of it cannot be
used yet due to the lack of a key derivation algorithm.
Add an API for byte generators: psa_crypto_generator_t,
PSA_CRYPTO_GENERATOR_INIT, psa_crypto_generator_init,
psa_get_generator_capacity, psa_generator_read,
psa_generator_import_key, psa_generator_abort.
This commit does not yet implement any generator algorithm, it only
provides the framework. This code may not compile with -Wunused.
This is the most common mode and the only mode that Mbed TLS functions
fully supports (mbedtls_rsa_rsassa_pss_verify_ext can verify
signatures with a different salt length).
Explicitly state that calling abort is safe after initializing to
zero.
Explicitly state that calling abort on an inactive operation is safe,
and replace "active" by "initialized" in the description of the
parameter.
Get rid of the recommendation for implementers to try to handle
uninitialized structures safely. It's good advice in principle but
cannot be achieved in a robust way and the wording was confusing.
No common signature algorithm uses a salt (RSA-PKCS#1v1.5, RSA-PSS,
DSA, ECDSA, EdDSA). We don't even take an IV for MAC whereas MAC
algorithms with IV are uncommon but heard of. So remove the salt
parameter from psa_asymmetric_sign and psa_asymmetric_verify.
We failed check-names.sh due to using a define which wasn't described or
defined anywhere. Even though we won't realistically enable
MBEDTLS_PSA_CRYPTO_SPM via the configuration system (and will do it from
PSA Crypto SPM tooling instead), add a description of the configuration to
config.h as good practice. Exclude MBEDTLS_PSA_CRYPTO_SPM from the "full"
configuration as well.
Make function names for multipart operations more consistent (cipher
edition).
Rename symmetric cipher multipart operation functions so that they all
start with psa_cipher_:
* psa_encrypt_setup -> psa_cipher_encrypt_setup
* psa_decrypt_setup -> psa_cipher_decrypt_setup
* psa_encrypt_set_iv -> psa_cipher_set_iv
* psa_encrypt_generate_iv -> psa_cipher_generate_iv
Make function names for multipart operations more consistent (MAC
setup edition).
Split psa_mac_setup into two functions psa_mac_sign_setup and
psa_mac_verify_setup. These functions behave identically except that
they require different usage flags on the key. The goal of the split
is to enforce the key policy during setup rather than at the end of
the operation (which was a bit of a hack).
In psa_mac_sign_finish and psa_mac_verify_finish, if the operation is
of the wrong type, abort the operation before returning BAD_STATE.
This requires defining a maximum RSA key size, since the RSA key size
is the signature size. Enforce the maximum RSA key size when importing
or generating a key.
Macros such as PSA_HASH_SIZE whose definitions can be the same
everywhere except in implementations that support non-standard
algorithms remain in crypto.h, at least for the time being.
This header will contain macros that calculate buffer sizes, whose
semantics are standardized but whose definitions are
implementation-specific because they depend on the available algorithms
and on some permitted buffer size tolerances.
Move size macros from crypto_struct.h to crypto_sizes.h, because these
definitions need to be available both in the frontend and in the
backend, whereas structures have different contents.
Change the representation of an ECDSA signature from the ASN.1 DER
encoding used in TLS and X.509, to the concatenation of r and s
in big-endian order with a fixed size. A fixed size helps memory and
buffer management and this representation is generally easier to use
for anything that doesn't require the ASN.1 representation. This is
the same representation as PKCS#11 (Cryptoki) except that PKCS#11
allows r and s to be truncated (both to the same length), which
complicates the implementation and negates the advantage of a
fixed-size representation.
* Distinguish randomized ECDSA from deterministic ECDSA.
* Deterministic ECDSA needs to be parametrized by a hash.
* Randomized ECDSA only uses the hash for the initial hash step,
but add ECDSA(hash) algorithms anyway so that all the signature
algorithms encode the initial hashing step.
* Add brief documentation for the ECDSA signature mechanisms.
* Also define DSA signature mechanisms while I'm at it. There were
already key types for DSA.
* PSS needs to be parametrized by a hash.
* Don't use `_MGF1` in the names of macros for OAEP and PSS. No one
ever uses anything else.
* Add brief documentation for the RSA signature mechanisms.
Doxygen interprets `\param` as starting documentation for a new param, or
to extend a previously started `\param` documentation when the same
reference is used. The intention here was to reference the function
parameter, not extend the previous documentation. Use `\p` to refer to
function parameters.
It isn't used to define other macros and it doesn't seem that useful
for users. Remove it, we can reintroduce it if needed.
Define a similar function key_type_is_raw_bytes in the implementation
with a clear semantics: it's a key that's represented as a struct
raw_data.
When calling psa_generate_key, pass the size of the parameters buffer
explicitly. This makes calls more verbose but less error-prone. This
also has the benefit that in an implementation with separation, the
frontend knows how many bytes to send to the backend without needing
to know about each key type.
Switch the default config.h back to the upstream version, plus the new
feature from this branch MBEDTLS_PSA_CRYPTO_C, plus MBEDTLS_CMAC_C
because it's a features we're using to explore the API design but
that's off by default in Mbed TLS.
Having a crypto-only version saved a bit of developer time, and it's
something we want to ship, but we also need a full build with TLS to
work, and the CI scripts assume that the default build includes TLS.
As a consequence, list-macros.sh no longer needs a special case to
pass check-names.sh.
The default config.h omits non-crypto features. Remove some features
that had been accidentally left in but have dependencies that had been
removed.
Also update configs/config-psa-crypto.h to match
include/mbedtls/config.h. They were historically identical but started
diverging when the feature-psa branch was rebased on top of a more
recent upstream.
Now the code builds with the "full" config.
Instead of rolling our own list of elliptic curve identifiers, use one
from somewhere. Pick TLS because it's the right size (16 bits) and
it's as good as any.
* development-restricted: (578 commits)
Update library version number to 2.13.1
Don't define _POSIX_C_SOURCE in header file
Don't declare and define gmtime()-mutex on Windows platforms
Correct preprocessor guards determining use of gmtime()
Correct documentation of mbedtls_platform_gmtime_r()
Correct typo in documentation of mbedtls_platform_gmtime_r()
Correct POSIX version check to determine presence of gmtime_r()
Improve documentation of mbedtls_platform_gmtime_r()
platform_utils.{c/h} -> platform_util.{c/h}
Don't include platform_time.h if !MBEDTLS_HAVE_TIME
Improve wording of documentation of MBEDTLS_PLATFORM_GMTIME_R_ALT
Fix typo in documentation of MBEDTLS_PLATFORM_GMTIME_R_ALT
Replace 'thread safe' by 'thread-safe' in the documentation
Improve documentation of MBEDTLS_HAVE_TIME_DATE
ChangeLog: Add missing renamings gmtime -> gmtime_r
Improve documentation of MBEDTLS_HAVE_TIME_DATE
Minor documentation improvements
Style: Add missing period in documentation in threading.h
Rename mbedtls_platform_gmtime() to mbedtls_platform_gmtime_r()
Guard decl and use of gmtime mutex by HAVE_TIME_DATE and !GMTIME_ALT
...
Previous commits attempted to use `gmtime_s()` for IAR systems; however,
this attempt depends on the use of C11 extensions which lead to incompatibility
with other pieces of the library, such as the use of `memset()` which is
being deprecated in favor of `memset_s()` in C11.
Conflicts:
library/psa_crypto.c
tests/suites/test_suite_psa_crypto.data
tests/suites/test_suite_psa_crypto.function
All the conflicts are concurrent additions where the order doesn't
matter. I put the code from feature-psa (key policy) before the code
from PR #13 (key lifetime).
psa_get_key_lifetime() behavior changed regarding empty slots, now
it return the lifetime of and empty slots. Documentation in header
file updated accordingly.
Conflict resolution:
* `tests/suites/test_suite_psa_crypto.data`: in the new tests from PR #14,
rename `PSA_ALG_RSA_PKCS1V15_RAW` to `PSA_ALG_RSA_PKCS1V15_SIGN_RAW` as
was done in PR #15 in the other branch.
When no algorithms are present in a category (e.g. no AEAD algorithm),
the union in the corresponding operation structure was empty, which is
not valid C. Add a dummy field to avoid this.
Document key import/export functions, hash functions, and asymmetric
sign/verify, as well as some related macros and types.
Nicer formatting for return values: use \retval.
New header file crypto_struct.h. The main file crypto.sh declares
structures which are implementation-defined. These structures must be
defined in crypto_struct.h, which is included at the end so that the
structures can use types defined in crypto.h.
Implement psa_hash_start, psa_hash_update and psa_hash_final. This
should work for all hash algorithms supported by Mbed TLS, but has
only been smoke-tested for SHA-256, and only in the nominal case.
Define psa_key_type_t and a first stab at a few values.
New functions psa_import_key, psa_export_key, psa_destroy_key,
psa_get_key_information. Implement them for raw data and RSA.
Under the hood, create an in-memory, fixed-size keystore with room
for MBEDTLS_PSA_KEY_SLOT_COUNT - 1 keys.
Add a new function mbedtls_rsa_get_bitlen which returns the RSA key
size, i.e. the bit size of the modulus. In the pk module, call
mbedtls_rsa_get_bitlen instead of mbedtls_rsa_get_len, which gave the
wrong result for key sizes that are not a multiple of 8.
This commit adds one non-regression test in the pk suite. More tests
are needed for RSA key sizes that are a multiple of 8.
This commit does not address RSA alternative implementations, which
only provide an interface that return the modulus size in bytes.
New module psa_crypto.c (MBEDTLS_PSA_CRYPTO_C):
Platform Security Architecture compatibility layer on top of
libmedcrypto.
Implement psa_crypto_init function which sets up a RNG.
Add a mbedtls_psa_crypto_free function which deinitializes the
library.
Define a first batch of error codes.
a compile time print was added warning in case of 128bit ctr_drbg keys.
This was don't to avoid an actual warning in these cases
(making build with warnings as errors possible).
Additional warnings on the Changelog/headers were set to use the same phrasing
phrasing was approved by Gilles and Janos.
the change is designed to make configuring 128bit keys for ctr_drbg more similar to other configuration options. Tests have been updated accordingly.
also clarified test naming.
This commit introduces a compile time constant MBEDTLS_SSL_DTLS_MAX_BUFFERING
to mbedtls/config.h which allows the user to control the cumulative size of
all heap buffer allocated for the purpose of reassembling and buffering
handshake messages.
It is put to use by introducing a new field `total_bytes_buffered` to
the buffering substructure of `mbedtls_ssl_handshake_params` that keeps
track of the total size of heap allocated buffers for the purpose of
reassembly and buffering at any time. It is increased whenever a handshake
message is buffered or prepared for reassembly, and decreased when a
buffered or fully reassembled message is copied into the input buffer
and passed to the handshake logic layer.
This commit does not yet include future epoch record buffering into
account; this will be done in a subsequent commit.
Also, it is now conceivable that the reassembly of the next expected
handshake message fails because too much buffering space has already
been used up for future messages. This case currently leads to an
error, but instead, the stack should get rid of buffered messages
to be able to buffer the next one. This will need to be implemented
in one of the next commits.
This setting belongs to the individual connection, not to a configuration
shared by many connections. (If a default value is desired, that can be handled
by the application code that calls mbedtls_ssl_set_mtu().)
There are at least two ways in which this matters:
- per-connection settings can be adjusted if MTU estimates become available
during the lifetime of the connection
- it is at least conceivable that a server might recognize restricted clients
based on range of IPs and immediately set a lower MTU for them. This is much
easier to do with a per-connection setting than by maintaining multiple
near-duplicated ssl_config objects that differ only by the MTU setting.
This commit implements the buffering of a record from the next epoch.
- The buffering substructure of mbedtls_ssl_handshake_params
gets another field to hold a raw record (incl. header) from
a future epoch.
- If ssl_parse_record_header() sees a record from the next epoch,
it signals that it might be suitable for buffering by returning
MBEDTLS_ERR_SSL_EARLY_MESSAGE.
- If ssl_get_next_record() finds this error code, it passes control
to ssl_buffer_future_record() which may or may not decide to buffer
the record; it does so if
- a handshake is in progress,
- the record is a handshake record
- no record has already been buffered.
If these conditions are met, the record is backed up in the
aforementioned buffering substructure.
- If the current datagram is fully processed, ssl_load_buffered_record()
is called to check if a record has been buffered, and if yes,
if by now the its epoch is the current one; if yes, it copies
the record into the (empty! otherwise, ssl_load_buffered_record()
wouldn't have been called) input buffer.
This commit returns the error code MBEDTLS_ERR_SSL_EARLY_MESSAGE
for proper handshake fragments, forwarding their treatment to
the buffering function ssl_buffer_message(); currently, though,
this function does not yet buffer or reassembly HS messages, so:
! This commit temporarily disables support for handshake reassembly !
This commit introduces, but does not yet put to use, a sub-structure
of mbedtls_ssl_handshake_params::buffering that will be used for the
buffering and/or reassembly of handshake messages with handshake
sequence numbers that are greater or equal to the next expected
sequence number.
This commit introduces a sub-structure `buffering` within
mbedtls_ssl_handshake_params that shall contain all data
related to the reassembly and/or buffering of handshake
messages.
Currently, only buffering of CCS messages is implemented,
so the only member of this struct is the previously introduced
`seen_ccs` field.
This commit implements support for remembering out-of-order
CCS messages. Specifically, a flag is set whenever a CCS message
is read which remains until the end of a flight, and when a
CCS message is expected and a CCS message has been seen in the
current flight, a synthesized CCS record is created.
This function was previously global because it was
used directly within ssl_parse_certificate_verify()
in library/ssl_srv.c. The previous commit removed
this dependency, replacing the call by a call to
the global parent function mbedtls_ssl_read_record().
This renders mbedtls_ssl_read_record_layer() internal
and therefore allows to make it static, and accordingly
rename it as ssl_read_record_layer().
Previously, mbedtls_ssl_read_record() always updated the handshake
checksum in case a handshake record was received. While desirable
most of the time, for the CertificateVerify message the checksum
update must only happen after the message has been fully processed,
because the validation requires the handshake digest up to but
excluding the CertificateVerify itself. As a remedy, the bulk
of mbedtls_ssl_read_record() was previously duplicated within
ssl_parse_certificate_verify(), hardening maintenance in case
mbedtls_ssl_read_record() is subject to changes.
This commit adds a boolean parameter to mbedtls_ssl_read_record()
indicating whether the checksum should be updated in case of a
handshake message or not. This allows using it also for
ssl_parse_certificate_verify(), manually updating the checksum
after the message has been processed.
This commit adds a public function
`mbedtls_ssl_conf_datagram_packing()`
that allows to allow / forbid the packing of multiple
records within a single datagram.
This commit finally enables datagram packing by modifying the
record preparation function ssl_write_record() to not always
calling mbedtls_ssl_flush_output().
This commit is another step towards supporting the packing of
multiple records within a single datagram.
Previously, the incremental outgoing record sequence number was
statically stored within the record buffer, at its final place
within the record header. This slightly increased efficiency
as it was not necessary to copy the sequence number when writing
outgoing records.
When allowing multiple records within a single datagram, it is
necessary to allow the position of the current record within the
datagram buffer to be flexible; in particular, there is no static
address for the record sequence number field within the record header.
This commit introduces an additional field `cur_out_ctr` within
the main SSL context structure `mbedtls_ssl_context` to keep track
of the outgoing record sequence number independent of the buffer used
for the current record / datagram. Whenever a new record is written,
this sequence number is copied to the the address `out_ctr` of the
sequence number header field within the current outgoing record.
This will allow fragmentation to always happen in the same place, always from
a buffer distinct from ssl->out_msg, and with the same way of resuming after
returning WANT_WRITE
The standard HKDF security guarantees only hold if `mbedtls_hkdf()` is
used or if `mbedtls_hkdf_extract()` and `mbedtls_hkdf_expand()` are
called in succession carefully and an equivalent way.
Making `mbedtls_hkdf_extract()` and `mbedtls_hkdf_expand()` static would
prevent any misuse, but doing so would require the TLS 1.3 stack to
break abstraction and bypass the module API.
To reduce the risk of misuse we add warnings to the function
descriptions.
When MBEDTLS_ARC4_C and MBEDTLS_CIPHER_NULL_CIPHER were disabled, the stream
cipher function wasn't being include in the cipher struct, yet Chacha20 requires
it.
