This commit splits off the RSA helper functions into separate headers and
compilation units to have a clearer separation of the public RSA interface,
intended to be used by end-users, and the helper functions which are publicly
provided only for the benefit of designers of alternative RSA implementations.
1) move the change into Features from Changes, in the changLog
2) Change the feature alternative configuration MBEDTLS_ECDH_ALT
definition to function alternative defintions
MBEDTLS_ECDH_COMPUTE_SHARED_ALT and MBEDTLS_ECDH_GEN_PUBLIC_ALT
1) update ChangLog to have new feature in Features instead of Changes
2) Change MBEDTLS_ECDSA_ALT to function specific alternative definitions:
MBEDTLS_ECDSA_SIGN_ALT, MBEDTLS_ECDSA_VERIFY_ALT and MBEDTLS_ECDSA_GENKEY_ALT
It is not necessary to pass a CSPRNG to `mbedtls_rsa_deduce_moduli`, as there
exist well-working static strategies, and even if a PRNG is preferred, a
non-secure one would be sufficient.
Further, the implementation is changed to use a static strategy for the choice
of candidates which according to some benchmarks even performs better than the
previous one using random candidate choices.
Further, state explicitly that wrong key types need not be supported by alternative RSA implementations, and that those
may instead return the newly introduced error code MBEDTLS_ERR_RSA_UNSUPPORTED_OPERATION.
Original intention was to be allowed to perform in-place operations like changing the byte-order before importing
parameters into an HSM. Now a copy is needed in this case, but there's no more danger of a user expecting the arguments
to be left untouched.
Document explicitly that `mbedtls_rsa_check_privkey` and `mbedtls_rsa_complete` succeeding does not guarantee the
consistency of the underlying RSA private key but only that enough information is present to perform a private key
operation.
This commit adds the function mbedtls_rsa_validate_crt for validating a set of CRT parameters. The function
mbedtls_rsa_check_crt is simplified accordingly.
Alternative RSA implementations can be provided by defining MBEDTLS_RSA_ALT in
config.h, defining an mbedtls_rsa_context struct in a new file rsa_alt.h and
re-implementing the RSA interface specified in rsa.h.
Through the previous reworkings, the adherence to the interface is the only
implementation obligation - in particular, implementors are free to use a
different layout for the RSA context structure.
This commit extends the RSA interface by import/export calls that can be used to
setup an RSA context from a subset of the core RSA parameters (N,P,Q,D,E).
The intended workflow is the following:
1. Call mbedtls_rsa_import one or multiple times to import the core parameters.
2. Call mbedtls_rsa_complete to deduce remaining core parameters as well as any
implementation-defined internal helper variables.
The RSA context is ready for use after this call.
The import function comes in two variants mbedtls_rsa_import and
mbedtls_rsa_import_raw, the former taking pointers to MPI's as input, the latter
pointers buffers holding to big-endian encoded MPI's.
The reason for this splitting is the following: When only providing an import
function accepting const MPI's, a user trying to import raw binary data into an
RSA context has to convert these to MPI's first which before passing them to the
import function, introducing an unnecessary copy of the data in memory. The
alternative would be to have another MPI-based import-function with
move-semantics, but this would be in contrast to the rest of the library's
interfaces.
Similarly, there are functions mbedtls_rsa_export and mbedtls_rsa_export_raw for
exporting the core RSA parameters, either as MPI's or in big-endian binary
format.
The main import/export functions deliberately do not include the additional
helper values DP, DQ and QP present in ASN.1-encoded RSA private keys. To
nonetheless be able to check whether given parameters DP, DQ and QP are in
accordance with a given RSA private key, the interface is extended by a function
mbedtls_rsa_check_opt (in line with mbedtls_rsa_check_privkey,
mbedtls_rsa_check_pubkey and mbedtls_rsa_check_pub_priv). Exporting the optional
parameters is taken care of by mbedtls_export_opt (currently MPI format only).
This commit adds convenience functions to the RSA module for computing a
complete RSA private key (with fields N, P, Q, D, E, DP, DQ, QP) from a subset
of core parameters, e.g. (N, D, E).
As noted in #557, several functions use 'index' resp. 'time'
as parameter names in their declaration and/or definition, causing name
conflicts with the functions in the C standard library of the same
name some compilers warn about.
This commit renames the arguments accordingly.
Allow forcing 64-bit integer type for bignum operations. Also introduce
the macro MBEDTLS_TYPE_UDBL to allow configuration of the double length
integer in unknown compilers.
