MbedTLS 2.9.0 -> 2.16.2 Changelog

mbedtls_2.9.0_2.16.2_changelog.txt

= mbed TLS 2.16.2 branch released 2019-06-11

Security
   * Make mbedtls_ecdh_get_params return an error if the second key
     belongs to a different group from the first. Before, if an application
     passed keys that belonged to different group, the first key's data was
     interpreted according to the second group, which could lead to either
     an error or a meaningless output from mbedtls_ecdh_get_params. In the
     latter case, this could expose at most 5 bits of the private key.

Bugfix
   * Server's RSA certificate in certs.c was SHA-1 signed. In the default
     mbedTLS configuration only SHA-2 signed certificates are accepted.
     This certificate is used in the demo server programs, which lead the
     client programs to fail at the peer's certificate verification
     due to an unacceptable hash signature. The certificate has been
     updated to one that is SHA-256 signed. Fix contributed by
     Illya Gerasymchuk.
   * Fix private key DER output in the key_app_writer example. File contents
     were shifted by one byte, creating an invalid ASN.1 tag. Fixed by
     Christian Walther in #2239.
   * Fix potential memory leak in X.509 self test. Found and fixed by
     Junhwan Park, #2106.
   * Reduce stack usage of hkdf tests. Fixes #2195.
   * Fix 1-byte buffer overflow in mbedtls_mpi_write_string() when
     used with negative inputs. Found by Guido Vranken in #2404. Credit to
     OSS-Fuzz.
   * Fix bugs in the AEAD test suite which would be exposed by ciphers which
     either used both encrypt and decrypt key schedules, or which perform padding.
     GCM and CCM were not affected. Fixed by Jack Lloyd.
   * Fix incorrect default port number in ssl_mail_client example's usage.
     Found and fixed by irwir. #2337
   * Add missing parentheses around parameters in the definition of the
     public macro MBEDTLS_X509_ID_FLAG. This could lead to invalid evaluation
     in case operators binding less strongly than subtraction were used
     for the parameter.
   * Add a check for MBEDTLS_X509_CRL_PARSE_C in ssl_server2, guarding the crl
     sni entry parameter. Reported by inestlerode in #560.
   * Add DER-encoded test CRTs to library/certs.c, allowing
     the example programs ssl_server2 and ssl_client2 to be run
     if MBEDTLS_FS_IO and MBEDTLS_PEM_PARSE_C are unset. Fixes #2254.
   * Fix missing bounds checks in X.509 parsing functions that could
     lead to successful parsing of ill-formed X.509 CRTs. Fixes #2437.
   * Fix multiple X.509 functions previously returning ASN.1 low-level error
     codes to always wrap these codes into X.509 high level error codes before
     returning. Fixes #2431.

Changes
   * Return from various debugging routines immediately if the
     provided SSL context is unset.
   * Remove dead code from bignum.c in the default configuration.
     Found by Coverity, reported and fixed by Peter Kolbus (Garmin). Fixes #2309.
   * Add test for minimal value of MBEDTLS_MPI_WINDOW_SIZE to all.sh.
     Contributed by Peter Kolbus (Garmin).
   * Change wording in the `mbedtls_ssl_conf_max_frag_len()`'s documentation to
     improve clarity. Fixes #2258.
   * Replace multiple uses of MD2 by SHA-256 in X.509 test suite. Fixes #821.

= mbed TLS 2.16.1 branch released 2019-03-19

Features
   * Add MBEDTLS_REMOVE_3DES_CIPHERSUITES to allow removing 3DES ciphersuites
     from the default list (enabled by default). See
     https://sweet32.info/SWEET32_CCS16.pdf.

Bugfix
   * Fix a compilation issue with mbedtls_ecp_restart_ctx not being defined
     when MBEDTLS_ECP_ALT is defined. Reported by jwhui. Fixes #2242.
   * Run the AD too long test only if MBEDTLS_CCM_ALT is not defined.
     Raised as a comment in #1996.
   * Reduce the stack consumption of mbedtls_mpi_fill_random() which could
     previously lead to a stack overflow on constrained targets.
   * Add `MBEDTLS_SELF_TEST` for the mbedtls_self_test functions
     in the header files, which missed the precompilation check. #971
   * Fix clobber list in MIPS assembly for large integer multiplication.
     Previously, this could lead to functionally incorrect assembly being
     produced by some optimizing compilers, showing up as failures in
     e.g. RSA or ECC signature operations. Reported in #1722, fix suggested
     by Aurelien Jarno and submitted by Jeffrey Martin.
   * Fix signed-to-unsigned integer conversion warning
     in X.509 module. Fixes #2212.
   * Reduce stack usage of `mpi_write_hlp()` by eliminating recursion.
     Fixes #2190.
   * Remove a duplicate #include in a sample program. Fixed by Masashi Honma #2326.
   * Remove the mbedtls namespacing from the header file, to fix a "file not found"
     build error. Fixed by Haijun Gu #2319.
   * Fix returning the value 1 when mbedtls_ecdsa_genkey failed.
   * Fix false failure in all.sh when backup files exist in include/mbedtls
     (e.g. config.h.bak). Fixed by Peter Kolbus (Garmin) #2407.
   * Ensure that unused bits are zero when writing ASN.1 bitstrings when using
     mbedtls_asn1_write_bitstring().
   * Fix issue when writing the named bitstrings in KeyUsage and NsCertType
     extensions in CSRs and CRTs that caused these bitstrings to not be encoded
     correctly as trailing zeroes were not accounted for as unused bits in the
     leading content octet. Fixes #1610.

Changes
   * Include configuration file in all header files that use configuration,
     instead of relying on other header files that they include.
     Inserted as an enhancement for #1371
   * Add support for alternative CSR headers, as used by Microsoft and defined
     in RFC 7468. Found by Michael Ernst. Fixes #767.
   * Fix configuration queries in ssl-opt.h. #2030
   * Ensure that ssl-opt.h can be run in OS X. #2029
   * Reduce the complexity of the timing tests. They were assuming more than the
     underlying OS actually guarantees.
   * Re-enable certain interoperability tests in ssl-opt.sh which had previously
     been disabled for lack of a sufficiently recent version of GnuTLS on the CI.
   * Ciphersuites based on 3DES now have the lowest priority by default when
     they are enabled.

= mbed TLS 2.16.0 branch released 2018-12-21

Features
   * Add a new config.h option of MBEDTLS_CHECK_PARAMS that enables validation
     of parameters in the API. This allows detection of obvious misuses of the
     API, such as passing NULL pointers. The API of existing functions hasn't
     changed, but requirements on parameters have been made more explicit in
     the documentation. See the corresponding API documentation for each
     function to see for which parameter values it is defined. This feature is
     disabled by default. See its API documentation in config.h for additional
     steps you have to take when enabling it.

API Changes
   * The following functions in the random generator modules have been
     deprecated and replaced as shown below. The new functions change
     the return type from void to int to allow returning error codes when
     using MBEDTLS_<MODULE>_ALT for the underlying AES or message digest
     primitive. Fixes #1798.
     mbedtls_ctr_drbg_update() -> mbedtls_ctr_drbg_update_ret()
     mbedtls_hmac_drbg_update() -> mbedtls_hmac_drbg_update_ret()
   * Extend ECDH interface to enable alternative implementations.
   * Deprecate error codes of the form MBEDTLS_ERR_xxx_INVALID_KEY_LENGTH for
     ARIA, CAMELLIA and Blowfish. These error codes will be replaced by
     the more generic per-module error codes MBEDTLS_ERR_xxx_BAD_INPUT_DATA.
   * Additional parameter validation checks have been added for the following
     modules - AES, ARIA, Blowfish, CAMELLIA, CCM, GCM, DHM, ECP, ECDSA, ECDH,
     ECJPAKE, SHA, Chacha20 and Poly1305, cipher, pk, RSA, and MPI.
     Where modules have had parameter validation added, existing parameter
     checks may have changed. Some modules, such as Chacha20 had existing
     parameter validation whereas other modules had little. This has now been
     changed so that the same level of validation is present in all modules, and
     that it is now optional with the MBEDTLS_CHECK_PARAMS flag which by default
     is off. That means that checks which were previously present by default
     will no longer be.

New deprecations
   * Deprecate mbedtls_ctr_drbg_update and mbedtls_hmac_drbg_update
     in favor of functions that can return an error code.

Bugfix
   * Fix for Clang, which was reporting a warning for the bignum.c inline
     assembly for AMD64 targets creating string literals greater than those
     permitted by the ISO C99 standard. Found by Aaron Jones. Fixes #482.
   * Fix runtime error in `mbedtls_platform_entropy_poll()` when run
     through qemu user emulation. Reported and fix suggested by randombit
     in #1212. Fixes #1212.
   * Fix an unsafe bounds check when restoring an SSL session from a ticket.
     This could lead to a buffer overflow, but only in case ticket authentication
     was broken. Reported and fix suggested by Guido Vranken in #659.
   * Add explicit integer to enumeration type casts to example program
     programs/pkey/gen_key which previously led to compilation failure
     on some toolchains. Reported by phoenixmcallister. Fixes #2170.
   * Fix double initialization of ECC hardware that made some accelerators
     hang.
   * Clarify documentation of mbedtls_ssl_set_own_cert() regarding the absence
     of check for certificate/key matching. Reported by Attila Molnar, #507.

= mbed TLS 2.14.1 branch released 2018-11-30

Security
   * Fix timing variations and memory access variations in RSA PKCS#1 v1.5
     decryption that could lead to a Bleichenbacher-style padding oracle
     attack. In TLS, this affects servers that accept ciphersuites based on
     RSA decryption (i.e. ciphersuites whose name contains RSA but not
     (EC)DH(E)). Discovered by Eyal Ronen (Weizmann Institute),  Robert Gillham
     (University of Adelaide), Daniel Genkin (University of Michigan),
     Adi Shamir (Weizmann Institute), David Wong (NCC Group), and Yuval Yarom
     (University of Adelaide, Data61). The attack is described in more detail
     in the paper available here: http://cat.eyalro.net/cat.pdf  CVE-2018-19608
   * In mbedtls_mpi_write_binary(), don't leak the exact size of the number
     via branching and memory access patterns. An attacker who could submit
     a plaintext for RSA PKCS#1 v1.5 decryption but only observe the timing
     of the decryption and not its result could nonetheless decrypt RSA
     plaintexts and forge RSA signatures. Other asymmetric algorithms may
     have been similarly vulnerable. Reported by Eyal Ronen, Robert Gillham,
     Daniel Genkin, Adi Shamir, David Wong and Yuval Yarom.
   * Wipe sensitive buffers on the stack in the CTR_DRBG and HMAC_DRBG
     modules.

API Changes
   * The new functions mbedtls_ctr_drbg_update_ret() and
     mbedtls_hmac_drbg_update_ret() are similar to mbedtls_ctr_drbg_update()
     and mbedtls_hmac_drbg_update() respectively, but the new functions
     report errors whereas the old functions return void. We recommend that
     applications use the new functions.

= mbed TLS 2.14.0 branch released 2018-11-19

Security
   * Fix overly strict DN comparison when looking for CRLs belonging to a
     particular CA. This previously led to ignoring CRLs when the CRL's issuer
     name and the CA's subject name differed in their string encoding (e.g.,
     one using PrintableString and the other UTF8String) or in the choice of
     upper and lower case. Reported by Henrik Andersson of Bosch GmbH in issue
     #1784.
   * Fix a flawed bounds check in server PSK hint parsing. In case the
     incoming message buffer was placed within the first 64KiB of address
     space and a PSK-(EC)DHE ciphersuite was used, this allowed an attacker
     to trigger a memory access up to 64KiB beyond the incoming message buffer,
     potentially leading to an application crash or information disclosure.
   * Fix mbedtls_mpi_is_prime() to use more rounds of probabilistic testing. The
     previous settings for the number of rounds made it practical for an
     adversary to construct non-primes that would be erroneously accepted as
     primes with high probability. This does not have an impact on the
     security of TLS, but can matter in other contexts with numbers chosen
     potentially by an adversary that should be prime and can be validated.
     For example, the number of rounds was enough to securely generate RSA key
     pairs or Diffie-Hellman parameters, but was insufficient to validate
     Diffie-Hellman parameters properly.
     See "Prime and Prejudice" by by Martin R. Albrecht and Jake Massimo and
     Kenneth G. Paterson and Juraj Somorovsky.

Features
   * Add support for temporarily suspending expensive ECC computations after
     some configurable amount of operations. This is intended to be used in
     constrained, single-threaded systems where ECC is time consuming and can
     block other operations until they complete. This is disabled by default,
     but can be enabled by MBEDTLS_ECP_RESTARTABLE at compile time and
     configured by mbedtls_ecp_set_max_ops() at runtime. It applies to the new
     xxx_restartable functions in ECP, ECDSA, PK and X.509 (CRL not supported
     yet), and to existing functions in ECDH and SSL (currently only
     implemented client-side, for ECDHE-ECDSA ciphersuites in TLS 1.2,
     including client authentication).
   * Add support for Arm CPU DSP extensions to accelerate asymmetric key
     operations. On CPUs where the extensions are available, they can accelerate
     MPI multiplications used in ECC and RSA cryptography. Contributed by
     Aurelien Jarno.
   * Extend RSASSA-PSS signature to allow a smaller salt size. Previously, PSS
     signature always used a salt with the same length as the hash, and returned
     an error if this was not possible. Now the salt size may be up to two bytes
     shorter. This allows the library to support all hash and signature sizes
     that comply with FIPS 186-4, including SHA-512 with a 1024-bit key.
   * 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.

API Changes
   * Add a common error code of `MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED` for
     a feature that is not supported by underlying alternative
     implementations implementing cryptographic primitives. This is useful for
     hardware accelerators that don't implement all options or features.

New deprecations
   * All module specific errors following the form
     MBEDTLS_ERR_XXX_FEATURE_UNAVAILABLE that indicate a feature is not
     supported are deprecated and are now replaced by the new equivalent
     platform error.
   * All module specific generic hardware acceleration errors following the
     form MBEDTLS_ERR_XXX_HW_ACCEL_FAILED that are deprecated and are replaced
     by the equivalent plaform error.
   * Deprecate the function mbedtls_mpi_is_prime() in favor of
     mbedtls_mpi_is_prime_ext() which allows specifying the number of
     Miller-Rabin rounds.

Bugfix
   * Fix wrong order of freeing in programs/ssl/ssl_server2 example
     application leading to a memory leak in case both
     MBEDTLS_MEMORY_BUFFER_ALLOC_C and MBEDTLS_MEMORY_BACKTRACE are set.
     Fixes #2069.
   * Fix a bug in the update function for SSL ticket keys which previously
     invalidated keys of a lifetime of less than a 1s. Fixes #1968.
   * Fix failure in hmac_drbg in the benchmark sample application, when
     MBEDTLS_THREADING_C is defined. Found by TrinityTonic, #1095
   * Fix a bug in the record decryption routine ssl_decrypt_buf()
     which lead to accepting properly authenticated but improperly
     padded records in case of CBC ciphersuites using Encrypt-then-MAC.
   * Fix memory leak and freeing without initialization in the example
     program programs/x509/cert_write. Fixes #1422.
   * Ignore IV in mbedtls_cipher_set_iv() when the cipher mode is
     MBEDTLS_MODE_ECB. Found by ezdevelop. Fixes #1091.
   * Zeroize memory used for buffering or reassembling handshake messages
     after use.
   * Use `mbedtls_platform_zeroize()` instead of `memset()` for zeroization
     of sensitive data in the example programs aescrypt2 and crypt_and_hash.
   * Change the default string format used for various X.509 DN attributes to
     UTF8String. Previously, the use of the PrintableString format led to
     wildcards and non-ASCII characters being unusable in some DN attributes.
     Reported by raprepo in #1860 and by kevinpt in #468. Fix contributed by
     Thomas-Dee.
   * Fix compilation failure for configurations which use compile time
     replacements of standard calloc/free functions through the macros
     MBEDTLS_PLATFORM_CALLOC_MACRO and MBEDTLS_PLATFORM_FREE_MACRO.
     Reported by ole-de and ddhome2006. Fixes #882, #1642 and #1706.

Changes
   * Removed support for Yotta as a build tool.
   * Add tests for session resumption in DTLS.
   * Close a test gap in (D)TLS between the client side and the server side:
     test the handling of large packets and small packets on the client side
     in the same way as on the server side.
   * Change the dtls_client and dtls_server samples to work by default over
     IPv6 and optionally by a build option over IPv4.
   * Change the use of Windows threading to use Microsoft Visual C++ runtime
     calls, rather than Win32 API calls directly. This is necessary to avoid
     conflict with C runtime usage. Found and fixed by irwir.
   * Remember the string format of X.509 DN attributes when replicating
     X.509 DNs. Previously, DN attributes were always written in their default
     string format (mostly PrintableString), which could lead to CRTs being
     created which used PrintableStrings in the issuer field even though the
     signing CA used UTF8Strings in its subject field; while X.509 compliant,
     such CRTs were rejected in some applications, e.g. some versions of
     Firefox, curl and GnuTLS. Reported in #1033 by Moschn. Fix contributed by
     Thomas-Dee.
   * Improve documentation of mbedtls_ssl_get_verify_result().
     Fixes #517 reported by github-monoculture.
   * Add MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR flag to mbedtls_mpi_gen_prime() and
     use it to reduce error probability in RSA key generation to levels mandated
     by FIPS-186-4.

= mbed TLS 2.13.1 branch released 2018-09-06

API Changes
   * Extend the platform module with an abstraction mbedtls_platform_gmtime_r()
     whose implementation should behave as a thread-safe version of gmtime().
     This allows users to configure such an implementation at compile time when
     the target system cannot be deduced automatically, by setting the option
     MBEDTLS_PLATFORM_GMTIME_R_ALT. At this stage Mbed TLS is only able to
     automatically select implementations for Windows and POSIX C libraries.

Bugfix
   * Fix build failures on platforms where only gmtime() is available but
     neither gmtime_r() nor gmtime_s() are present. Fixes #1907.

= mbed TLS 2.13.0 branch released 2018-08-31

Security
   * Fix an issue in the X.509 module which could lead to a buffer overread
     during certificate extensions parsing. In case of receiving malformed
     input (extensions length field equal to 0), an illegal read of one byte
     beyond the input buffer is made. Found and analyzed by Nathan Crandall.

Features
   * Add support for fragmentation of outgoing DTLS handshake messages. This
     is controlled by the maximum fragment length as set locally or negotiated
     with the peer, as well as by a new per-connection MTU option, set using
     mbedtls_ssl_set_mtu().
   * Add support for auto-adjustment of MTU to a safe value during the
     handshake when flights do not get through (RFC 6347, section 4.1.1.1,
     last paragraph).
   * Add support for packing multiple records within a single datagram,
     enabled by default.
   * Add support for buffering out-of-order handshake messages in DTLS.
     The maximum amount of RAM used for this can be controlled by the
     compile-time constant MBEDTLS_SSL_DTLS_MAX_BUFFERING defined
     in mbedtls/config.h.

API Changes
   * Add function mbedtls_ssl_set_datagram_packing() to configure
     the use of datagram packing (enabled by default).

Bugfix
   * Fix a potential memory leak in mbedtls_ssl_setup() function. An allocation
     failure in the function could lead to other buffers being leaked.
   * Fixes an issue with MBEDTLS_CHACHAPOLY_C which would not compile if
     MBEDTLS_ARC4_C and MBEDTLS_CIPHER_NULL_CIPHER weren't also defined. #1890
   * Fix a memory leak in ecp_mul_comb() if ecp_precompute_comb() fails.
     Fix contributed by Espressif Systems.
   * Add ecc extensions only if an ecc based ciphersuite is used.
     This improves compliance to RFC 4492, and as a result, solves
     interoperability issues with BouncyCastle. Raised by milenamil in #1157.
   * Replace printf with mbedtls_printf in the ARIA module. Found by
     TrinityTonic in #1908.
   * Fix potential use-after-free in mbedtls_ssl_get_max_frag_len()
     and mbedtls_ssl_get_record_expansion() after a session reset. Fixes #1941.
   * Fix a bug that caused SSL/TLS clients to incorrectly abort the handshake
     with TLS versions 1.1 and earlier when the server requested authentication
     without providing a list of CAs. This was due to an overly strict bounds
     check in parsing the CertificateRequest message,
     introduced in Mbed TLS 2.12.0. Fixes #1954.
   * Fix a miscalculation of the maximum record expansion in
     mbedtls_ssl_get_record_expansion() in case of ChachaPoly ciphersuites,
     or CBC ciphersuites in (D)TLS versions 1.1 or higher. Fixes #1913, #1914.
   * Fix undefined shifts with negative values in certificates parsing
     (found by Catena cyber using oss-fuzz)
   * Fix memory leak and free without initialization in pk_encrypt
     and pk_decrypt example programs. Reported by Brace Stout. Fixes #1128.
   * Remove redundant else statement. Raised by irwir. Fixes #1776.

Changes
   * Copy headers preserving timestamps when doing a "make install".
     Contributed by xueruini.
   * Allow the forward declaration of public structs. Contributed by Dawid
     Drozd. Fixes #1215 raised by randombit.
   * Improve compatibility with some alternative CCM implementations by using
     CCM test vectors from RAM.
   * Add support for buffering of out-of-order handshake messages.
   * Add warnings to the documentation of the HKDF module to reduce the risk
     of misusing the mbedtls_hkdf_extract() and mbedtls_hkdf_expand()
     functions. Fixes #1775. Reported by Brian J. Murray.

= mbed TLS 2.12.0 branch released 2018-07-25

Security
   * Fix a vulnerability in TLS ciphersuites based on CBC and using SHA-384,
     in (D)TLS 1.0 to 1.2, that allowed an active network attacker to
     partially recover the plaintext of messages under some conditions by
     exploiting timing measurements. With DTLS, the attacker could perform
     this recovery by sending many messages in the same connection. With TLS
     or if mbedtls_ssl_conf_dtls_badmac_limit() was used, the attack only
     worked if the same secret (for example a HTTP Cookie) has been repeatedly
     sent over connections manipulated by the attacker. Connections using GCM
     or CCM instead of CBC, using hash sizes other than SHA-384, or using
     Encrypt-then-Mac (RFC 7366) were not affected. The vulnerability was
     caused by a miscalculation (for SHA-384) in a countermeasure to the
     original Lucky 13 attack. Found by Kenny Paterson, Eyal Ronen and Adi
     Shamir.
   * Fix a vulnerability in TLS ciphersuites based on CBC, in (D)TLS 1.0 to
     1.2, that allowed a local attacker, able to execute code on the local
     machine as well as manipulate network packets, to partially recover the
     plaintext of messages under some conditions by using a cache attack
     targetting an internal MD/SHA buffer. With TLS or if
     mbedtls_ssl_conf_dtls_badmac_limit() was used, the attack only worked if
     the same secret (for example a HTTP Cookie) has been repeatedly sent over
     connections manipulated by the attacker. Connections using GCM or CCM
     instead of CBC or using Encrypt-then-Mac (RFC 7366) were not affected.
     Found by Kenny Paterson, Eyal Ronen and Adi Shamir.
   * Add a counter-measure against a vulnerability in TLS ciphersuites based
     on CBC, in (D)TLS 1.0 to 1.2, that allowed a local attacker, able to
     execute code on the local machine as well as manipulate network packets,
     to partially recover the plaintext of messages under some conditions (see
     previous entry) by using a cache attack targeting the SSL input record
     buffer. Connections using GCM or CCM instead of CBC or using
     Encrypt-then-Mac (RFC 7366) were not affected. Found by Kenny Paterson,
     Eyal Ronen and Adi Shamir.

Features
   * Add new crypto primitives from RFC 7539: stream cipher Chacha20, one-time
     authenticator Poly1305 and AEAD construct Chacha20-Poly1305. Contributed
     by Daniel King.
   * Add support for CHACHA20-POLY1305 ciphersuites from RFC 7905.
   * Add platform support for the Haiku OS. (https://www.haiku-os.org).
     Contributed by Augustin Cavalier.
   * Make the receive and transmit buffers independent sizes, for situations
     where the outgoing buffer can be fixed at a smaller size than the incoming
     buffer, which can save some RAM. If buffer lengths are kept equal, there
     is no functional difference. Contributed by Angus Gratton, and also
     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.

Bugfix
   * Fix the key_app_writer example which was writing a leading zero byte which
     was creating an invalid ASN.1 tag. Found by Aryeh R. Fixes #1257.
   * Fix compilation error on C++, because of a variable named new.
     Found and fixed by Hirotaka Niisato in #1783.
   * Fix "no symbols" warning issued by ranlib when building on Mac OS X. Fix
     contributed by tabascoeye.
   * Clarify documentation for mbedtls_ssl_write() to include 0 as a valid
     return value. Found by @davidwu2000. #839
   * Fix a memory leak in mbedtls_x509_csr_parse(), found by catenacyber,
     Philippe Antoine. Fixes #1623.
   * Remove unused headers included in x509.c. Found by Chris Hanson and fixed
     by Brendan Shanks. Part of a fix for #992.
   * Fix compilation error when MBEDTLS_ARC4_C is disabled and
     MBEDTLS_CIPHER_NULL_CIPHER is enabled. Found by TrinityTonic in #1719.
   * Added length checks to some TLS parsing functions. Found and fixed by
     Philippe Antoine from Catena cyber. #1663.
   * Fix the inline assembly for the MPI multiply helper function for i386 and
     i386 with SSE2. Found by László Langó. Fixes #1550
   * Fix namespacing in header files. Remove the `mbedtls` namespacing in
     the `#include` in the header files. Resolves #857
   * Fix compiler warning of 'use before initialisation' in
     mbedtls_pk_parse_key(). Found by Martin Boye Petersen and fixed by Dawid
     Drozd. #1098
   * Fix decryption for zero length messages (which contain all padding) when a
     CBC based ciphersuite is used together with Encrypt-then-MAC. Previously,
     such a message was wrongly reported as an invalid record and therefore lead
     to the connection being terminated. Seen most often with OpenSSL using
     TLS 1.0. Reported by @kFYatek and by Conor Murphy on the forum. Fix
     contributed by Espressif Systems. Fixes #1632
   * Fix ssl_client2 example to send application data with 0-length content
     when the request_size argument is set to 0 as stated in the documentation.
     Fixes #1833.
   * Correct the documentation for `mbedtls_ssl_get_session()`. This API has
     deep copy of the session, and the peer certificate is not lost. Fixes #926.
   * Fix build using -std=c99. Fixed by Nick Wilson.

Changes
   * Fail when receiving a TLS alert message with an invalid length, or invalid
     zero-length messages when using TLS 1.2. Contributed by Espressif Systems.
   * Change the default behaviour of mbedtls_hkdf_extract() to return an error
     when calling with a NULL salt and non-zero salt_len. Contributed by
     Brian J Murray
   * Change the shebang line in Perl scripts to look up perl in the PATH.
     Contributed by fbrosson.
   * Allow overriding the time on Windows via the platform-time abstraction.
     Fixed by Nick Wilson.
   * Use gmtime_r/gmtime_s for thread-safety. Fixed by Nick Wilson.

= mbed TLS 2.11.0 branch released 2018-06-18

Features
   * Add additional block mode, OFB (Output Feedback), to the AES module and
     cipher abstraction module.
   * Implement the HMAC-based extract-and-expand key derivation function
     (HKDF) per RFC 5869. Contributed by Thomas Fossati.
   * Add support for the CCM* block cipher mode as defined in IEEE Std. 802.15.4.
   * Add support for the XTS block cipher mode with AES (AES-XTS).
     Contributed by Aorimn in pull request #414.
   * In TLS servers, support offloading private key operations to an external
     cryptoprocessor. Private key operations can be asynchronous to allow
     non-blocking operation of the TLS server stack.

Bugfix
   * Fix the cert_write example to handle certificates signed with elliptic
     curves as well as RSA. Fixes #777 found by dbedev.
   * Fix for redefinition of _WIN32_WINNT to avoid overriding a definition
     used by user applications. Found and fixed by Fabio Alessandrelli.
   * Fix compilation warnings with IAR toolchain, on 32 bit platform.
     Reported by rahmanih in #683
   * Fix braces in mbedtls_memory_buffer_alloc_status(). Found by sbranden, #552.

Changes
   * Changed CMake defaults for IAR to treat all compiler warnings as errors.
   * Changed the Clang parameters used in the CMake build files to work for
     versions later than 3.6. Versions of Clang earlier than this may no longer
     work. Fixes #1072

= mbed TLS 2.10.0 branch released 2018-06-06

Features
   * Add support for ARIA cipher (RFC 5794) and associated TLS ciphersuites
     (RFC 6209). Disabled by default, see MBEDTLS_ARIA_C in config.h

API Changes
   * Extend the platform module with a util component that contains
     functionality shared by multiple Mbed TLS modules. At this stage
     platform_util.h (and its associated platform_util.c) only contain
     mbedtls_platform_zeroize(), which is a critical function from a security
     point of view. mbedtls_platform_zeroize() needs to be regularly tested
     against compilers to ensure that calls to it are not removed from the
     output binary as part of redundant code elimination optimizations.
     Therefore, mbedtls_platform_zeroize() is moved to the platform module to
     facilitate testing and maintenance.

Bugfix
   * Fix an issue with MicroBlaze support in bn_mul.h which was causing the
     build to fail. Found by zv-io. Fixes #1651.

Changes
   * Support TLS testing in out-of-source builds using cmake. Fixes #1193.
   * Fix redundant declaration of mbedtls_ssl_list_ciphersuites. Raised by
     TrinityTonic. #1359.