diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst index b0cf4ebd83921f..1ad4d618064294 100644 --- a/Doc/library/ssl.rst +++ b/Doc/library/ssl.rst @@ -280,6 +280,12 @@ purposes. RC4 was dropped from the default cipher string. + .. versionchanged:: 3.4.7 + + ChaCha20/Poly1305 was added to the default cipher string. + + 3DES was dropped from the default cipher string. + Random generation ^^^^^^^^^^^^^^^^^ diff --git a/Lib/ssl.py b/Lib/ssl.py index ec42e38d08638c..873aa4798bbc5d 100644 --- a/Lib/ssl.py +++ b/Lib/ssl.py @@ -160,36 +160,42 @@ def _import_symbols(prefix): else: CHANNEL_BINDING_TYPES = [] + # Disable weak or insecure ciphers by default # (OpenSSL's default setting is 'DEFAULT:!aNULL:!eNULL') # Enable a better set of ciphers by default # This list has been explicitly chosen to: # * Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE) # * Prefer ECDHE over DHE for better performance -# * Prefer any AES-GCM over any AES-CBC for better performance and security +# * Prefer AEAD over CBC for better performance and security +# * Prefer AES-GCM over ChaCha20 because most platforms have AES-NI +# (ChaCha20 needs OpenSSL 1.1.0 or patched 1.0.2) +# * Prefer any AES-GCM and ChaCha20 over any AES-CBC for better +# performance and security # * Then Use HIGH cipher suites as a fallback -# * Then Use 3DES as fallback which is secure but slow -# * Disable NULL authentication, NULL encryption, and MD5 MACs for security -# reasons +# * Disable NULL authentication, NULL encryption, 3DES and MD5 MACs +# for security reasons _DEFAULT_CIPHERS = ( - 'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:' - 'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:!aNULL:' - '!eNULL:!MD5' -) + 'ECDH+AESGCM:ECDH+CHACHA20:DH+AESGCM:DH+CHACHA20:ECDH+AES256:DH+AES256:' + 'ECDH+AES128:DH+AES:ECDH+HIGH:DH+HIGH:RSA+AESGCM:RSA+AES:RSA+HIGH:' + '!aNULL:!eNULL:!MD5:!3DES' + ) # Restricted and more secure ciphers for the server side # This list has been explicitly chosen to: # * Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE) # * Prefer ECDHE over DHE for better performance -# * Prefer any AES-GCM over any AES-CBC for better performance and security +# * Prefer AEAD over CBC for better performance and security +# * Prefer AES-GCM over ChaCha20 because most platforms have AES-NI +# * Prefer any AES-GCM and ChaCha20 over any AES-CBC for better +# performance and security # * Then Use HIGH cipher suites as a fallback -# * Then Use 3DES as fallback which is secure but slow -# * Disable NULL authentication, NULL encryption, MD5 MACs, DSS, and RC4 for -# security reasons +# * Disable NULL authentication, NULL encryption, MD5 MACs, DSS, RC4, and +# 3DES for security reasons _RESTRICTED_SERVER_CIPHERS = ( - 'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:' - 'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:!aNULL:' - '!eNULL:!MD5:!DSS:!RC4' + 'ECDH+AESGCM:ECDH+CHACHA20:DH+AESGCM:DH+CHACHA20:ECDH+AES256:DH+AES256:' + 'ECDH+AES128:DH+AES:ECDH+HIGH:DH+HIGH:RSA+AESGCM:RSA+AES:RSA+HIGH:' + '!aNULL:!eNULL:!MD5:!DSS:!RC4:!3DES' ) diff --git a/Misc/NEWS b/Misc/NEWS index 7acaf2fd50e20e..52243983e8d5d6 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -13,6 +13,8 @@ Core and Builtins Library ------- +- Issue #27850: Remove 3DES from ssl module's default cipher list to counter + measure sweet32 attack (CVE-2016-2183). What's New in Python 3.4.6? ===========================