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# Kconfig - Cryptography primitive options for mbed TLS
# Copyright (c) 2016 Intel Corporation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
menuconfig MBEDTLS
bool "mbedTLS Support"
help
This option enables the mbedTLS cryptography library.
if MBEDTLS
choice
prompt "Select implementation"
default MBEDTLS_BUILTIN
config MBEDTLS_BUILTIN
bool "Enable mbedTLS integrated sources"
help
Link with local mbedTLS sources instead of external library.
config MBEDTLS_LIBRARY
bool "Enable mbedTLS external library"
help
This option enables mbedTLS library.
endchoice
config MBEDTLS_CFG_FILE
string "mbed TLS configuration file"
depends on MBEDTLS_BUILTIN
default "config-tls-generic.h"
help
Use a specific mbed TLS configuration file. The default config file
file can be tweaked with Kconfig. The default configuration is
suitable to communicate with majority of HTTPS servers on the Internet,
but has relatively many features enabled. To optimize resources for
special TLS usage, use available Kconfig options, or select an
alternative config.
if MBEDTLS_BUILTIN && MBEDTLS_CFG_FILE = "config-tls-generic.h"
rsource "Kconfig.tls-generic"
endif
config MBEDTLS_SSL_MAX_CONTENT_LEN
int "Max payload size for TLS protocol message"
default 1500
depends on MBEDTLS_BUILTIN
help
The TLS standards mandate max payload size of 16384 bytes. So, for
maximum operability and for general-purpose usage, that value must
be used. For specific usages, that value can be largely decreased.
E.g. for DTLS, payload size is limited by UDP datagram size, and
even for HTTPS REST API, the payload can be limited to max size of
(REST request, REST response, server certificate(s)).
mbedTLS uses this value separate for input and output buffers, so
twice this value will be allocated (on mbedTLS own heap, so the
value of MBEDTLS_HEAP_SIZE should accommodate that).
config MBEDTLS_DEBUG
bool "mbed TLS debug activation"
depends on MBEDTLS_BUILTIN
help
Enable debugging activation for mbed TLS configuration. If you use
mbedTLS/Zephyr integration (e.g. net_app), this will activate debug
logging (of the level configured by MBEDTLS_DEBUG_LEVEL).
If you use mbedTLS directly instead, you will need to perform
additional configuration yourself: call
mbedtls_ssl_conf_dbg(&mbedtls.conf, my_debug, NULL);
mbedtls_debug_set_threshold(level);
functions in your application, and create the my_debug() function to
actually print something useful.
config MBEDTLS_DEBUG_LEVEL
int "mbed TLS default debug level"
depends on MBEDTLS_DEBUG
default 0
range 0 4
help
Default mbed TLS debug logging level for Zephyr integration code
(from ext/lib/crypto/mbedtls/include/mbedtls/debug.h):
0 No debug
1 Error
2 State change
3 Information
4 Verbose
config MBEDTLS_TEST
bool "Compile internal self test functions"
depends on MBEDTLS_BUILTIN
help
Enable self test function for the crypto algorithms
config MBEDTLS_INSTALL_PATH
string "mbedTLS install path"
depends on MBEDTLS_LIBRARY
help
This option holds the path where the mbedTLS libraries and headers are
installed. Make sure this option is properly set when MBEDTLS_LIBRARY
is enabled otherwise the build will fail.
config MBEDTLS_ENABLE_HEAP
bool "Enable global heap for mbed TLS"
help
This option enables the mbedtls to use the heap. This setting must
be global so that various applications and libraries in Zephyr do not
try to do this themselves as there can be only one heap defined
in mbedtls. If this is enabled, then the Zephyr will, during the device
startup, initialize the heap automatically.
config MBEDTLS_HEAP_SIZE
int "Heap size for mbed TLS"
default 512
depends on MBEDTLS_ENABLE_HEAP
help
The mbedtls routines will use this heap if enabled.
See ext/lib/crypto/mbedtls/include/mbedtls/config.h and
MBEDTLS_MEMORY_BUFFER_ALLOC_C option for details. That option is not
enabled by default.
Default value for the heap size is not set as it depends on the
application. For streaming communication with arbitrary (HTTPS)
servers on the Internet, 32KB + overheads (up to another 20KB) may
be needed. For some dedicated and specific usage of mbedtls API, the
1000 bytes might be ok.
config APP_LINK_WITH_MBEDTLS
bool "Link 'app' with MBEDTLS"
default y
help
Add MBEDTLS header files to the 'app' include path. It may be
disabled if the include paths for MBEDTLS are causing aliasing
issues for 'app'.
endif # MBEDTLS