This commit modifies the PKCS1 v1.5 signature verification function `mbedtls_rsa_rsassa_pkcs1_v15_verify` to prepare the
expected PKCS1-v1.5-encoded hash using the function also used by the signing routine `mbedtls_rsa_rsassa_pkcs1_v15_sign`
and comparing it to the provided byte-string afterwards. This comes at the benefits of (1) avoiding any error-prone
parsing, (2) removing the dependency of the RSA module on the ASN.1 parsing module, and (3) reducing code size.
This commit moves the code preparing PKCS1 v1.5 encoded hashes from `mbedtls_rsa_rsassa_pkcs1_v15_sign` to a separate
non-public function `rsa_rsassa_pkcs1_v15_encode`. This code-path will then be re-used by the signature verification function
`mbetls_rsa_rsassa_pkcs1_v15_verify` in a later commit.
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.
This commit changes the implementation of `mbedtls_rsa_get_len` to return
`ctx->len` instead of always re-computing the modulus' byte-size via
`mbedtls_mpi_size`.
If CRT is not used, the helper fields CRT are not assumed to be present in the
RSA context structure, so do the verification directly in this case. If CRT is
used, verification could be done using CRT, but we're sticking to ordinary
verification for uniformity.
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.
Primality testing is guarded by the configuration flag MBEDTLS_GENPRIME and used in the new RSA helper functions. This
commit adds a corresponding preprocessor directive.
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.
The RSA private key functions rsa_rsaes_pkcs1_v15_decrypt and
rsa_rsaes_oaep_decrypt put sensitive data (decryption results) on the
stack. Wipe it before returning.
Thanks to Laurent Simon for reporting this issue.
The sliding window exponentiation algorithm is vulnerable to
side-channel attacks. As a countermeasure we add exponent blinding in
order to prevent combining the results of different measurements.
This commit handles the case when the Chinese Remainder Theorem is used
to accelerate the computation.
The sliding window exponentiation algorithm is vulnerable to
side-channel attacks. As a countermeasure we add exponent blinding in
order to prevent combining the results of fifferent measurements.
This commits handles the case when the Chinese Remainder Theorem is NOT
used to accelerate computations.
The test case was generated by modifying our signature code so that it
produces a 7-byte long padding (which also means garbage at the end, so it is
essential in to check that the error that is detected first is indeed the
padding rather than the final length check).
The PKCS#1 standard says nothing about the relation between P and Q
but many libraries guarantee P>Q and mbed TLS did so too in earlier
versions.
This commit restores this behaviour.
Once the mutex is acquired, we must goto cleanup rather that return.
Since cleanup adjusts the return value, adjust that in test cases.
Also, at cleanup we don't want to overwrite 'ret', or we'll loose track of
errors.
see #257
* commit 'ce60fbe':
Fix potential timing difference with RSA PMS
Update Changelog for recent merge
Added more constant-time code and removed biases in the prime number generation routines.
Conflicts:
library/bignum.c
library/ssl_srv.c
* mbedtls-1.3:
Add missing depends in x509 programs
Simplify ifdef checks in programs/x509
Fix thread safety issue in RSA operations
Add test certificate for bitstring in DN
Add support for X.520 uniqueIdentifier
Accept bitstrings in X.509 names
The race was due to mpi_exp_mod storing a Montgomery coefficient in the
context (RM, RP, RQ).
The fix was verified with -fsanitize-thread using ssl_pthread_server and two
concurrent clients.
A more fine-grained fix should be possible, locking just enough time to check
if those values are OK and set them if not, rather than locking for the whole
mpi_exp_mod() operation, but it will be for later.
