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changeset: 103126:f586742e56cb parent: 103123:4c54d7ab84fa parent: 103124:d2111109fd77 user: Christian Heimes christian@python.org date: Tue Sep 06 20:07:58 2016 +0200 files: Doc/library/ssl.rst Lib/ssl.py Misc/NEWS description: Issues #27850 and #27766: Remove 3DES from ssl default cipher list and add ChaCha20 Poly1305. diff -r 4c54d7ab84fa -r f586742e56cb Doc/library/ssl.rst --- a/Doc/library/ssl.rst Tue Sep 06 10:51:19 2016 -0700 +++ b/Doc/library/ssl.rst Tue Sep 06 20:07:58 2016 +0200 @@ -285,6 +285,12 @@ RC4 was dropped from the default cipher string. + .. versionchanged:: 3.6 + + ChaCha20/Poly1305 was added to the default cipher string. + + 3DES was dropped from the default cipher string. + Random generation ^^^^^^^^^^^^^^^^^ diff -r 4c54d7ab84fa -r f586742e56cb Lib/ssl.py --- a/Lib/ssl.py Tue Sep 06 10:51:19 2016 -0700 +++ b/Lib/ssl.py Tue Sep 06 20:07:58 2016 +0200 @@ -157,36 +157,42 @@ 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 -r 4c54d7ab84fa -r f586742e56cb Misc/NEWS --- a/Misc/NEWS Tue Sep 06 10:51:19 2016 -0700 +++ b/Misc/NEWS Tue Sep 06 20:07:58 2016 +0200 @@ -85,6 +85,12 @@ Library ------- +- Issue #27850: Remove 3DES from ssl module's default cipher list to counter + measure sweet32 attack (CVE-2016-2183). + +- Issue #27766: Add ChaCha20 Poly1305 to ssl module's default ciper list. + (Required OpenSSL 1.1.0 or LibreSSL). + - Issue #25387: Check return value of winsound.MessageBeep. - Issue #27866: Add SSLContext.get_ciphers() method to get a list of all /christian@python.org