If the key doesn't exist by the time this call is made
then the handle is invalid,
which means that PSA_ERROR_INVALID_HANDLE should be
returned rather than "does not exist"
It may be possible that the implementation runs out of
memory when exporting a key from storage or a secure
element. For example, it may not be possible to directly
move the data from storage to the caller, so the implementation
will have to buffer the material temporarily (an issue if dynamic
memory allocation scheme is used). For a large key
this is more likely to return.
It may be possible that an implementation does not
fetch key material until a command like
this is called and such an error may occur if an
off-chip secure storage dependency may have been wiped.
Note that PSA_ERROR_NOT_PERMITTED is not included
because I can't think of a scenario where you have
a valid key handle but aren't allowed to read the
attributes
Adjust the wording to permit multiple handles to a single key - closing
a handle does not necessarily release volatile memory associated with
the key, that only occurs when the last handle is closed.
- Describe the implementation defined behavior for opening multiple
keys, and provide a reference to the relevant section.
- Describe the use of INSUFFICENT_MEMORY error to indicate additional
implementation resource constaints.
- Clarify the distinction between DOES_NOT_EXIST and INVALID_HANDLE
error conditions.
PSA_KEY_ATTRIBUTES_INIT and psa_key_attributes_init weren't declared
in the API document, only defined in our implementation, but they are
referenced in the API document.
generate_key is a more classical name. The longer name was only
introduced to avoid confusion with getting a key from a generator,
which is key derivation, but we no longer use the generator
terminology so this reason no longer applies.
perl -i -pe 's/psa_generate_random_key/psa_generate_key/g' $(git ls-files)
“Tampering detected” was misleading because in the real world it can
also arise due to a software bug. “Corruption detected” is neutral and
more precisely reflects what can trigger the error.
perl -i -pe 's/PSA_ERROR_TAMPERING_DETECTED/PSA_ERROR_CORRUPTION_DETECTED/gi' $(git ls-files)
Parametrize finite-field Diffie-Hellman key types with a DH group
identifier, in the same way elliptic curve keys are parametrized with
an EC curve identifier.
Define the DH groups from the TLS registry (these are the groups from
RFC 7919).
Replicate the macro definitions and the metadata tests from elliptic
curve identifiers to DH group identifiers.
Define PSA_DH_GROUP_CUSTOM as an implementation-specific extension for
which domain parameters are used to specify the group.
Move psa_get_key_domain_parameters() and
psa_set_key_domain_parameters() out of the official API and declare
them to be implementation-specific extensions.
Expand the documentation of psa_set_key_domain_parameters() a bit to
explain how domain parameters are used.
Remove all mentions of domain parameters from the documentation of API
functions. This leaves DH and DSA effectively unusable.
Generators are mostly about key derivation (currently: only about key
derivation). "Generator" is not a commonly used term in cryptography.
So favor "derivation" as terminology.
This commit updates the function descriptions.
Generators are mostly about key derivation (currently: only about key
derivation). "Generator" is not a commonly used term in cryptography.
So favor "derivation" as terminology. Call a generator a key
derivation operation structure, since it behaves like other multipart
operation structures. Furthermore, the function names are not fully
consistent.
In this commit, I rename the functions to consistently have the prefix
"psa_key_derivation_". I used the following command:
perl -i -pe '%t = (
psa_crypto_generator_t => "psa_key_derivation_operation_t",
psa_crypto_generator_init => "psa_key_derivation_init",
psa_key_derivation_setup => "psa_key_derivation_setup",
psa_key_derivation_input_key => "psa_key_derivation_input_key",
psa_key_derivation_input_bytes => "psa_key_derivation_input_bytes",
psa_key_agreement => "psa_key_derivation_key_agreement",
psa_set_generator_capacity => "psa_key_derivation_set_capacity",
psa_get_generator_capacity => "psa_key_derivation_get_capacity",
psa_generator_read => "psa_key_derivation_output_bytes",
psa_generate_derived_key => "psa_key_derivation_output_key",
psa_generator_abort => "psa_key_derivation_abort",
PSA_CRYPTO_GENERATOR_INIT => "PSA_KEY_DERIVATION_OPERATION_INIT",
PSA_GENERATOR_UNBRIDLED_CAPACITY => "PSA_KEY_DERIVATION_UNLIMITED_CAPACITY",
); s/\b(@{[join("|", keys %t)]})\b/$t{$1}/ge' $(git ls-files)
In psa_import_key, change the order of parameters to pass
the pointer where the newly created handle will be stored last.
This is consistent with most other library functions that put inputs
before outputs.
In psa_generate_derived_key, change the order of parameters to pass
the pointer where the newly created handle will be stored last.
This is consistent with most other library functions that put inputs
before outputs.
Use individual setters for the id and lifetime fields of an attribute
structure, like the other attributes.
This commit updates the specification and adds an implementation of
the new setters.
Define a range of key identifiers for use by the application
(0..2^30-1), a range for use by implementations (2^30..2^31), and a
range that is reserved for future use (2^31..2^32-1).
Change the scope of key identifiers to be global, rather than
per lifetime. As a result, you now need to specify the lifetime of a
key only when creating it.
New macros PSA_AEAD_UPDATE_OUTPUT_SIZE, PSA_AEAD_FINISH_OUTPUT_SIZE
and PSA_AEAD_VERIFY_OUTPUT_SIZE to determine the output buffer sizes
for psa_aead_update(), psa_aead_finish() and psa_aead_verify().
Like psa_aead_finish(), psa_aead_verify() needs to produce output from
the last partial block of input if psa_aead_update() cannot produce
output byte by byte.
In psa_import_key and psa_copy_key, some information comes from the
key data (input buffer or source key) rather than from the attributes:
key size for import, key size and type and domain parameters for copy.
If an unused attribute is nonzero in the attribute structure, check
that it matches the correct value. This protects against application
errors.
There was a guarantee that psa_get_key_attributes() does not require a
subsequent psa_reset_key_attributes() to free resources as long as the
key was created with attributes having this property. This requirement
was hard to pin down because if a key is created with default
parameters, there are cases where it is difficult to ensure that the
domain parameters will be reported without allocating memory. So
remove this guarantee. Now the only case psa_reset_key_attributes() is
not required is if the attribute structure has only been modified with
certain specific setters.
Read extra data from the domain parameters in the attribute structure
instead of taking an argument on the function call.
Implement this for RSA key generation, where the public exponent can
be set as a domain parameter.
Add tests that generate RSA keys with various public exponents.
Change psa_get_domain_parameters() and psa_set_domain_parameters() to
access a psa_key_attributes_t structure rather than a key handle.
In psa_get_key_attributes(), treat the RSA public exponent as a domain
parameter and read it out. This is in preparation for removing the
`extra` parameter of psa_generate_key() and setting the RSA public
exponent for key generation via domain parameters.
In this commit, the default public exponent 65537 is not treated
specially, which allows us to verify that test code that should be
calling psa_reset_key_attributes() after retrieving the attributes of
an RSA key is doing so properly (if it wasn't, there would be a memory
leak), even if the test data happens to use an RSA key with the
default public exponent.
Instead of passing a separate parameter for the key size to
psa_generate_key and psa_generator_import_key, set it through the
attributes, like the key type and other metadata.
Types and functions that are not used in the attribute-based key
creation API are now implementation-specific extensions, kept around
until we finish transitioning to the new API.
Implement attribute querying.
Test attribute getters and setters. Use psa_get_key_attributes instead
of the deprecated functions psa_get_key_policy or
psa_get_key_information in most tests.
Implement the new, attribute-based psa_import_key and some basic
functions to access psa_key_attributes_t. Replace
psa_import_key_to_handle by psa_import_key in a few test functions.
This commit does not handle persistence attributes yet.
This commit starts a migration to a new interface for key creation.
Today, the application allocates a handle, then fills its metadata,
and finally injects key material. The new interface fills metadata
into a temporary structure, and a handle is allocated at the same time
it gets filled with both metadata and key material.
This commit was obtained by moving the declaration of the old-style
functions to crypto_extra.h and renaming them with the to_handle
suffix, adding declarations for the new-style functions in crypto.h
under their new name, and running
perl -i -pe 's/\bpsa_(import|copy|generator_import|generate)_key\b/$&_to_handle/g' library/*.c tests/suites/*.function programs/psa/*.c
perl -i -pe 's/\bpsa_get_key_lifetime\b/$&_from_handle/g' library/*.c tests/suites/*.function programs/psa/*.c
Many functions that are specific to the old interface, and which will
not remain under the same name with the new interface, are still in
crypto.h for now.
All functional tests should still pass. The documentation may have
some broken links.
Merge the Mbed Crypto development branch a little after
mbedcrypto-1.0.0 into the PSA Crypto API 1.0 beta branch a little
after beta 2.
Summary of merge conflicts:
* Some features (psa_copy_key, public key format without
SubjectPublicKeyInfo wrapping) went into both sides, but with a few
improvements on the implementation side. For those, take the
implementation side.
* The key derivation API changed considerably on the API side. This
merge commit generally goes with the updated API except in the tests
where it keeps some aspects of the implementation.
Due to the divergence between the two branches on key derivation and
key agreement, test_suite_psa_crypto does not compile. This will be
resolved in subsequent commits.
For DH, ECC (Weierstrass curves) and DSA, specify that the re-drawing
method is the one defined by NIST as
"key-pair generation by testing candidates", and describe it
unambiguously.
Also specify DES explicitly.
psa_generator_import_key() was only specified for "symmetric keys",
and there were some mistakes in the specification. Rewrite the
specification and extend it to other key types.
* For most private key types, specify that the function draws a byte
string repeatedly until the byte string is suitable.
* For DES, despite being a symmetric key type, re-drawing is
necessary.
* For Montgomery curves, despite being asymmetric, no re-drawing is
necessary.
* Specify the behavior for every standard key type other than RSA.
An implementation doesn't have to support all key types, but if it
does, it's better to have a standard.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
