PolarSSL 源码，也许是最小巧的ssl代码库。高效、便于移植和集成。尤其适合嵌入式应用。
目前 PolarSSL 已经被 ARM 公司收购，并改名为 mbed TLS。许可证也由 GPL 改为 Apache。
mbed TLS 1.3.11 发布，此版本修复了一些严重的 bug，解决了一些安全问题。同时也添加了一些优化功能和提升可用性的新特性。
mbed TLS 2.0 将会在几周后发布，首个提供 DTLS 官方支持的版本！
为什么不是 1.5 而是 2.0 版本呢？因为准备从 2.0 分支开始使用语义版本控制，也就是说 2.0.1 将会是第一个 bug 修复版本，2.1.0 是新特性版本，下一个重要版本分支是 3.0.0（API 不兼容）。
mbed TLS 2.0 版本将会重命名所有公共可见的符号 (function names, types, enum constants, macros, global objects) ，这些都会以 MBEDTLS_ (macros, enum constants) 或者 mbedtls_ 开头。
HMAC 函数使用 MD layer 替换，改进 SSL 配置接口，更多 mbed 2.0 特性预览和准备请看这里：https://tls.mbed.org/tech-updates/blog/preparing-2.0-upgrade。
mbed 1.3.11 更新内容
安全修复
此版本解决了 SSL_VERIFY_OPTIONAL authmode 修改，确保 keyUsage 和 extendedKey 能正确调用和使用。 SSL_VERIFY_REQUIRED 是 authmode 推荐安全设置。
新特性
提升 ECC 性能，支持 Diffie-Hellman 参数
重要改进
Remove bias in mpi_gen_prime (contributed by Pascal Junod).
Remove potential sources of timing variations (some contributed by Pascal Junod).
Options POLARSSL_HAVE_INT8 and POLARSSL_HAVE_INT16 are deprecated.
Enabling POLARSSL_NET_C without POLARSSL_HAVE_IPV6 is deprecated.
compat-1.2.h and openssl.h are deprecated.
Adjusting/overriding CFLAGS and LDFLAGS with the make build system is now more flexible (warning: OFLAGS is not used any more) (see the README) (contributed by Alon Bar-Lev).
ssl_set_own_cert() no longer calls pk_check_pair() since the performance impact was bad for some users (this was introduced in 1.3.10).
Move from SHA-1 to SHA-256 in example programs using signatures (suggested by Thorsten Mühlfelder).
Remove some unneeded inclusions of header files from the standard library "minimize" others (e.g. use stddef.h if only size_t is needed).
Change #include lines in test files to use double quotes instead of angle brackets for uniformity with the rest of the code.
Remove dependency on sscanf() in X.509 parsing modules.
Bug 修复
Fix compile errors with PLATFORM_NO_STD_FUNCTIONS.
Fix compile error with PLATFORM_EXIT_ALT (thanks to Rafał Przywara).
Fix bug in entropy.c when THREADING_C is also enabled that caused entropy_free() to crash (thanks to Rafał Przywara).
Fix memory leak when gcm_setkey() and ccm_setkey() are used more than once on the same context.
Fix bug in ssl_mail_client when password is longer that username (found by Bruno Pape).
Fix undefined behaviour (memcmp( NULL, NULL, 0 );) in X.509 modules (detected by Clang's 3.6 UBSan).
mpi_size() and mpi_msb() would segfault when called on an mpi that is initialized but not set (found by pravic).
Fix detection of support for getrandom() on Linux (reported by syzzer) by doing it at runtime (using uname) rather that compile time.
Fix handling of symlinks by "make install" (found by Gaël PORTAY).
Fix potential NULL pointer dereference (not trigerrable remotely) when ssl_write() is called before the handshake is finished (introduced in 1.3.10) (first reported by Martin Blumenstingl).
Fix bug in pk_parse_key() that caused some valid private EC keys to be rejected.
Fix bug in Via Padlock support (found by Nikos Mavrogiannopoulos).
Fix thread safety bug in RSA operations (found by Fredrik Axelsson).
Fix hardclock() (only used in the benchmarking program) with some versions of mingw64 (found by kxjhlele).
Fix warnings from mingw64 in timing.c (found by kxjklele).
Fix potential unintended sign extension in asn1_get_len() on 64-bit platforms.
Fix potential memory leak in ssl_set_psk() (found by Mansour Moufid).
Fix compile error when POLARSSL_SSL_DISABLE_RENEGOTATION and POLARSSL_SSL_SSESSION_TICKETS where both enabled in config.h (introduced in 1.3.10).
Add missing extern "C" guard in aesni.h (reported by amir zamani).
Add missing dependency on SHA-256 in some x509 programs (reported by Gergely Budai).
Fix bug related to ssl_set_curves(): the client didn't check that the curve picked by the server was actually allowed.
软件详情：https://tls.mbed.org/tech-updates/releases/mbedtls-1.3.11-released
下载地址：https://tls.mbed.org/download/mbedtls-1.3.11-gpl.tgz
来自:开源中国社区
