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compile time warning of 128bit ctr_drbg keys and standardized warnings

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a compile time print was added warning in case of 128bit ctr_drbg keys.
This was don't to avoid an actual warning in these cases
(making build with warnings as errors possible).
Additional warnings on the Changelog/headers were set to use the same phrasing
phrasing was approved by Gilles and Janos.
This commit is contained in:
Nir Sonnenschein 2018-08-29 10:20:12 +03:00
parent ce266e4ca2
commit b7ebbcaa2c
4 changed files with 33 additions and 5 deletions
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18
CMakeLists.txt
View File

@ -36,10 +36,26 @@ set(NULL_ENTROPY_WARNING "${WARNING_BORDER}"
"${NULL_ENTROPY_WARN_L3}"
"${WARNING_BORDER}")
find_package(PythonInterp)
set(CTR_DRBG_128_BIT_KEY_WARN_L1 "**** WARNING! MBEDTLS_CTR_DRBG_USE_128_BIT_KEY defined!\n")
set(CTR_DRBG_128_BIT_KEY_WARN_L2 "**** Using 128-bit keys for CTR_DRBG limits the security of generated\n")
set(CTR_DRBG_128_BIT_KEY_WARN_L3 "**** keys and operations that use random values generated to 128-bit security\n")
set(CTR_DRBG_128_BIT_KEY_WARNING "${WARNING_BORDER}"
"${CTR_DRBG_128_BIT_KEY_WARN_L1}"
"${CTR_DRBG_128_BIT_KEY_WARN_L2}"
"${CTR_DRBG_128_BIT_KEY_WARN_L3}"
"${WARNING_BORDER}")
find_package(Perl)
if(PERL_FOUND)
# If 128-bit keys are configured for CTR_DRBG, display an appropriate warning
execute_process(COMMAND ${PERL_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/config.pl -f ${CMAKE_CURRENT_SOURCE_DIR}/include/mbedtls/config.h get MBEDTLS_CTR_DRBG_USE_128_BIT_KEY
RESULT_VARIABLE result)
if(${result} EQUAL 0)
message(WARNING ${CTR_DRBG_128_BIT_KEY_WARNING})
endif()
# If NULL Entropy is configured, display an appropriate warning
execute_process(COMMAND ${PERL_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/config.pl -f ${CMAKE_CURRENT_SOURCE_DIR}/include/mbedtls/config.h get MBEDTLS_TEST_NULL_ENTROPY
RESULT_VARIABLE result)

4
ChangeLog
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@ -71,8 +71,8 @@ Features
independently contributed again by Paul Sokolovsky.
* Add support for key wrapping modes based on AES as defined by
NIST SP 800-38F algorithms KW and KWP and by RFC 3394 and RFC 5649.
* Add support different keys sizes to CTR_CRBG. Note: using shorter keys
than 256 bit may decrease security.
* Add support for 128-bit keys in CTR_DRBG. Note that using keys shorter
than 256 bits limits the security of generated material to 128 bits.
Bugfix
* Fix the key_app_writer example which was writing a leading zero byte which

12
Makefile
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@ -61,9 +61,21 @@ NULL_ENTROPY_WARN_L3=**** AND IS *NOT* SUITABLE FOR PRODUCTION USE ****\n
NULL_ENTROPY_WARNING=\n$(WARNING_BORDER)$(NULL_ENTROPY_WARN_L1)$(NULL_ENTROPY_WARN_L2)$(NULL_ENTROPY_WARN_L3)$(WARNING_BORDER)
WARNING_BORDER_LONG =**********************************************************************************\n
CTR_DRBG_128_BIT_KEY_WARN_L1=**** WARNING! MBEDTLS_CTR_DRBG_USE_128_BIT_KEY defined! ****\n
CTR_DRBG_128_BIT_KEY_WARN_L2=**** Using 128-bit keys for CTR_DRBG limits the security of generated ****\n
CTR_DRBG_128_BIT_KEY_WARN_L3=**** keys and operations that use random values generated to 128-bit security ****\n
CTR_DRBG_128_BIT_KEY_WARNING=\n$(WARNING_BORDER_LONG)$(CTR_DRBG_128_BIT_KEY_WARN_L1)$(CTR_DRBG_128_BIT_KEY_WARN_L2)$(CTR_DRBG_128_BIT_KEY_WARN_L3)$(WARNING_BORDER_LONG)
# Post build steps
post_build:
ifndef WINDOWS
# If 128-bit keys are configured for CTR_DRBG, display an appropriate warning
-scripts/config.pl get MBEDTLS_CTR_DRBG_USE_128_BIT_KEY && ([ $$? -eq 0 ]) && \
echo '$(CTR_DRBG_128_BIT_KEY_WARNING)'
# If NULL Entropy is configured, display an appropriate warning
-scripts/config.pl get MBEDTLS_TEST_NULL_ENTROPY && ([ $$? -eq 0 ]) && \
echo '$(NULL_ENTROPY_WARNING)'

4
include/mbedtls/ctr_drbg.h
View File

@ -11,8 +11,8 @@
* The Mbed TLS implementation of CTR_DRBG uses AES-256 (default) or AES-128
* as the underlying block cipher.
*
* * \warning ARC4 is considered a weak cipher and its use constitutes a
* security risk. We recommend considering stronger ciphers instead.
* \warning Using 128-bit keys for CTR_DRBG limits the security of generated
* keys and operations that use random values generated to 128-bit security.
*/
/*
* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved