Any easy way to disable the RC4 stream cipher in Iron?

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vmq6695
Posts: 25
Joined: Mon Feb 27, 2012 2:43 am

Any easy way to disable the RC4 stream cipher in Iron?

Postby vmq6695 » Fri Mar 27, 2015 11:24 am

Password Recovery Attacks against RC4 in TLS (see http://www.isg.rhul.ac.uk/tls/RC4passwords.pdf) suggests that the RC4 stream cipher is not yet broken but its effectiveness is weakened and being further weakened by the day.

Does Iron have any easy way to exclude the use of RC4?

Or will Iron users have to wait for the next Chrome version to exclude the use of RC4?

Reportedly, Firefox configuration allows RC4 to be excluded. And Firefox 37 (or some builds of it) supposedly excludes it by default.

If you point your browser to https://cc.dcsec.uni-hannover.de/ the response is the cipher suites supported by your browser.

For Iron/41.0.2200.0, that response is shows that RC4 is lowest in order of preference. For example:

Cipher Suites Supported by Your Browser (ordered by preference):

SpecCipher Suite NameKey SizeDescription
(c0,2b)ECDHE-ECDSA-AES128-GCM-SHA256128 BitKey exchange: ECDH, encryption: AES, MAC: SHA256.
(c0,2f)ECDHE-RSA-AES128-GCM-SHA256128 BitKey exchange: ECDH, encryption: AES, MAC: SHA256.
(00,9e)DHE-RSA-AES128-GCM-SHA256128 BitKey exchange: DH, encryption: AES, MAC: SHA256.
(cc,14)ECDHE-ECDSA-CHACHA20-POLY1305-SHA256128 BitKey exchange: ECDH, encryption: ChaCha20 Poly1305, MAC: SHA256.
(cc,13)ECDHE-RSA-CHACHA20-POLY1305-SHA256128 BitKey exchange: ECDH, encryption: ChaCha20 Poly1305, MAC: SHA256.
(cc,15)DHE-RSA-CHACHA20-POLY1305-SHA256128 BitKey exchange: DH, encryption: ChaCha20 Poly1305, MAC: SHA256.
(c0,0a)ECDHE-ECDSA-AES256-SHA256 BitKey exchange: ECDH, encryption: AES, MAC: SHA1.
(c0,14)ECDHE-RSA-AES256-SHA256 BitKey exchange: ECDH, encryption: AES, MAC: SHA1.
(00,39)DHE-RSA-AES256-SHA256 BitKey exchange: DH, encryption: AES, MAC: SHA1.
(c0,09)ECDHE-ECDSA-AES128-SHA128 BitKey exchange: ECDH, encryption: AES, MAC: SHA1.
(c0,13)ECDHE-RSA-AES128-SHA128 BitKey exchange: ECDH, encryption: AES, MAC: SHA1.
(00,33)DHE-RSA-AES128-SHA128 BitKey exchange: DH, encryption: AES, MAC: SHA1.
(c0,07)ECDHE-ECDSA-RC4128-SHA128 BitKey exchange: ECDH, encryption: RC4, MAC: SHA1.
(c0,11)ECDHE-RSA-RC4128-SHA128 BitKey exchange: ECDH, encryption: RC4, MAC: SHA1.
(00,9c)RSA-AES128-GCM-SHA256128 BitKey exchange: RSA, encryption: AES, MAC: SHA256.
(00,35)RSA-AES256-SHA256 BitKey exchange: RSA, encryption: AES, MAC: SHA1.
(00,2f)RSA-AES128-SHA128 BitKey exchange: RSA, encryption: AES, MAC: SHA1.
(00,05)RSA-RC4128-SHA128 BitKey exchange: RSA, encryption: RC4, MAC: SHA1.
(00,04)RSA-RC4128-MD5128 BitKey exchange: RSA, encryption: RC4, MAC: MD5.
(00,0a)RSA-3DES-EDE-SHA168 BitKey exchange: RSA, encryption: 3DES, MAC: SHA1.
(00,ff)EMPTY-RENEGOTIATION-INFO-SCSV0 BitUsed for secure renegotation.


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