For the situation where the mbedTLS device has limited RAM, but the
other end of the connection doesn't support the max_fragment_length
extension. To be spec-compliant, mbedTLS has to keep a 16384 byte
incoming buffer. However the outgoing buffer can be made smaller without
breaking spec compliance, and we save some RAM.
See comments in include/mbedtls/config.h for some more details.
(The lower limit of outgoing buffer size is the buffer size used during
handshake/cert negotiation. As the handshake is half-duplex it might
even be possible to store this data in the "incoming" buffer during the
handshake, which would save even more RAM - but it would also be a lot
hackier and error-prone. I didn't really explore this possibility, but
thought I'd mention it here in case someone sees this later on a mission
to jam mbedTLS into an even tinier RAM footprint.)
The XTS configuration option MBEDTLS_CIPHER_MODE_XTS currently only enables
XTS for AES. So, don't say it enables XTS for "symmetric ciphers", just
AES. This helps to avoid being misleading.
AES-XEX is a building block for other cryptographic standards and not yet a
standard in and of itself. We'll just provide the standardized AES-XTS
algorithm, and not AES-XEX. The AES-XTS algorithm and interface provided
can be used to perform the AES-XEX algorithm when the length of the input
is a multiple of the AES block size.
XTS mode is fully known as "xor-encrypt-xor with ciphertext-stealing".
This is the generalization of the XEX mode.
This implementation is limited to an 8-bits (1 byte) boundary, which
doesn't seem to be what was thought considering some test vectors [1].
This commit comes with tests, extracted from [1], and benchmarks.
Although, benchmarks aren't really nice here, as they work with a buffer
of a multiple of 16 bytes, which isn't a challenge for XTS compared to
XEX.
[1] http://csrc.nist.gov/groups/STM/cavp/documents/aes/XTSTestVectors.zip
* development: (504 commits)
Fix minor code style issues
Add the uodate to the soversion to the ChangeLog
Fix the ChangeLog for clarity, english and credit
Update version to 2.9.0
ecp: Fix binary compatibility with group ID
Changelog entry
Change accepted ciphersuite versions when parsing server hello
Remove preprocessor directives around platform_util.h include
Fix style for mbedtls_mpi_zeroize()
Improve mbedtls_platform_zeroize() docs
mbedtls_zeroize -> mbedtls_platform_zeroize in docs
Reword config.h docs for MBEDTLS_PLATFORM_ZEROIZE_ALT
Organize CMakeLists targets in alphabetical order
Organize output objs in alfabetical order in Makefile
Regenerate errors after ecp.h updates
Update ecp.h
Change variable bytes_written to header_bytes in record decompression
Update ecp.h
Update ecp.h
Update ecp.h
...
Conflict resolution:
* ChangeLog: put the new entry from my branch in the proper place.
* include/mbedtls/error.h: counted high-level module error codes again.
* include/mbedtls/ssl.h: picked different numeric codes for the
concurrently added errors; made the new error a full sentence per
current standards.
* library/error.c: ran scripts/generate_errors.pl.
* library/ssl_srv.c:
* ssl_prepare_server_key_exchange "DHE key exchanges": the conflict
was due to style corrections in development
(4cb1f4d49cff999d0c853bc696ad7eea68888c35) which I merged with
my refactoring.
* ssl_prepare_server_key_exchange "For key exchanges involving the
server signing", first case, variable declarations: merged line
by line:
* dig_signed_len: added in async
* signature_len: removed in async
* hashlen: type changed to size_t in development
* hash: size changed to MBEDTLS_MD_MAX_SIZE in async
* ret: added in async
* ssl_prepare_server_key_exchange "For key exchanges involving the
server signing", first cae comment: the conflict was due to style
corrections in development (4cb1f4d49cff999d0c853bc696ad7eea68888c35)
which I merged with my comment changes made as part of refactoring
the function.
* ssl_prepare_server_key_exchange "Compute the hash to be signed" if
`md_alg != MBEDTLS_MD_NONE`: conflict between
ebd652fe2dfc2c82d774bfd334398279d9027492
"ssl_write_server_key_exchange: calculate hashlen explicitly" and
46f5a3e9b4d5db3cacfe2ba33480a27317c62d46 "Check return codes from
MD in ssl code". I took the code from commit
ca1d74290439ec9e2723a911657fd96aa320e219 made on top of development
which makes mbedtls_ssl_get_key_exchange_md_ssl_tls return the
hash length.
* programs/ssl/ssl_server2.c: multiple conflicts between the introduction
of MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS and new auxiliary functions and
definitions for async support, and the introduction of idle().
* definitions before main: concurrent additions, kept both.
* main, just after `handshake:`: in the loop around
mbedtls_ssl_handshake(), merge the addition of support for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS and SSL_ASYNC_INJECT_ERROR_CANCEL
with the addition of the idle() call.
* main, if `opt.transport == MBEDTLS_SSL_TRANSPORT_STREAM`: take the
code from development and add a check for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS.
* main, loop around mbedtls_ssl_read() in the datagram case:
take the code from development and add a check for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS; revert to a do...while loop.
* main, loop around mbedtls_ssl_write() in the datagram case:
take the code from development and add a check for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS; revert to a do...while loop.
New compile-time option MBEDTLS_SSL_ASYNC_PRIVATE_C, enabling
callbacks to replace private key operations. These callbacks allow the
SSL stack to make an asynchronous call to an external cryptographic
module instead of calling the cryptography layer inside the library.
The call is asynchronous in that it may return the new status code
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS, in which case the SSL stack returns
and can be later called where it left off.
This commit introduces the configuration option. Later commits will
implement the feature proper.
Add a new macro MBEDTLS_UTILS_ZEROIZE that allows users to configure
mbedtls_zeroize() to an alternative definition when defined. If the
macro is not defined, then mbed TLS will use the default definition of
the function.
MD2, MD4, MD5, DES and SHA-1 are considered weak and their use
constitutes a security risk. If possible, we recommend avoiding
dependencies on them, and considering stronger message digests and
ciphers instead.
This commit allows users to provide alternative implementations of the
ECJPAKE interface through the configuration option MBEDTLS_ECJPAKE_ALT.
When set, the user must add `ecjpake_alt.h` declaring the same
interface as `ecjpake.h`, as well as add some compilation unit which
implements the functionality. This is in line with the preexisting
support for alternative implementations of other modules.
- Adapt the change in all.sh to the new keep-going mode
- Restore alphabetical order of configuration flags for
alternative implementations in config.h and rebuild
library/version_features.c
