TLS Cipher String Cheat Sheet

Last revision (mm/dd/yy): 09/28/2017

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Introduction

This article is focused on providing clear and simple examples for the cipher string. They are based on different scenarios where you use the Transport Layer Security (TLS) protocol.

Recommendations for a cipher string

Secenarios

The cipher strings are based on the recommendation to setup your policy to get a whitelist for yours ciphers as described in the Transport Layer Protection Cheat Sheet (Rule - Only Support Strong Cryptographic Ciphers). The latest and strongest ciphers are solely available with TLSv1.2, older protocols don't support them.
We have not included any ChaCha20-Poly1305 ciphers, yet. One reason is that we haven't found various assessments yet, the other is that implementations of new ciphers may be more buggy.

The recommened cipher strings are based on the different scenarios:

• OWASP Cipher String 'A+' (Advanced+, limited compatibility, e.g. to more recent browser versions)

• Recommended if you control the server and the clients (e.g. by approvement) and if you check the compatibility before using it
• Includes solely the strongest perfect forward secrecy (PFS) ciphers
• Protocols: TLSv1.2 (and newer or better)

• OWASP Cipher String 'A' (Advanced, wider compatibility, e.g. to most newer browser versions)

• Recommended if you control the server and the clients (e.g. by approvement) if the 'A+' string does not work, make sure to check the compatibility before using it
• includes solely the strongest and stronger PFS ciphers
• Protocols: TLSv1.2 (and newer or better)

• OWASP Cipher String 'B' (Broad compatibility to browsers, check the compatibility to other protocols before using it, e.g. IMAPS)

• Recommended if you solely control the server, the clients use their browsers and if you check the compatibility before using it for other protocols than https
• Includes solely PFS ciphers
• Be aware of additional risks and of new vulnerabilities that may appear are more likely than above
• Plan to phase out SHA-1 and TLSv1/TLSv1.1 for https in middle-term
• Protocols: TLSv1.2, TLSv1.1, TLSv1 (and newer or better)

• OWASP Cipher String 'C' (Widest Compatibility, compatibility to most legacy browsers, legacy libraries (still patched) and other application protocols besides https, e.g. IMAPS)

• You may use this if you solely control the server, your clients use elder browsers and other elder libraries or if you use other protocols than https
• Be aware of the existing risks and of new vulnerabilities that may appear more likely
• PFS ciphers are preferred, except all DHE ciphers that use SHA-1 (to prevent possible incompatibility issues caused by the length of the DHparameter)
• Plan to move to 'A' for https or at least 'B' otherwise in middle-term
• Protocols: TLSv1.2, TLSv1.1, TLSv1 (and newer or better)

• OWASP Cipher String 'C-' (Legacy, widest compatibility to real old browsers and legacy libraries and other application protocols like SMTP)

• Take care, use this cipher string only if you are forced to support 3DES(=TLS_RSA_WITH_3DES_EDE_CBC_SHA, =DES-CBC3-SHA) for real old clients with very old libraries or old libraries for other protocols besides https
• Be aware of the existing risks (e.g. ciphers without PFS, ciphers with 3DES) and of new vulnerabilities that may appear the most likely
• Never use even more INSECURE or elder ciphers based on RC2, RC4, DES, MD4, MD5, EXP, EXP1024, AH, ADH, aNULL, eNULL, SEED nor IDEA
• PFS ciphers are preferred, except all DHE ciphers that use SHA-1 (to prevent possible incompatibility issues caused by the length of the DHparameter)
• Plan to move at least to 'C' in a short-term
• Protocols: TLSv1.2, TLSv1.1, TLSv1 (and newer or better)

Table of the ciphers (and their priority from high (1) to low (e.g. 19))

IANA, OpenSSL and other crypto libraries use slightly different names for the same ciphers. This table lists the names used by IANA and by openssl in brackets []. Additional you can find the unambiguously hex values defined by IANA. Mozilla offers a larger cipher names correspondence table.

Cipher name: IANA, [openssl]	Cipher hex value	Advanced+ (A+)	Advanced (A)	Broad Compatibility (B)	Widest Compatibility (C)	Legacy (C-)
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384, [DHE-RSA-AES256-GCM-SHA384]	0x009f	1	1	1	1	1
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256, [DHE-RSA-AES128-GCM-SHA256]	0x009e	2	2	2	2	2
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, [ECDHE-RSA-AES256-GCM-SHA384]	0xc030	3	3	3	3	3
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, [ECDHE-RSA-AES128-GCM-SHA256]	0xc02f	4	4	4	4	4
TLS_DHE_RSA_WITH_AES_256_CBC_SHA256, [DHE-RSA-AES256-SHA256]	0x006b		5	5	5	5
TLS_DHE_RSA_WITH_AES_128_CBC_SHA256, [DHE-RSA-AES128-SHA256]	0x0067		6	6	6	6
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384, [ECDHE-RSA-AES256-SHA384]	0xc028		7	7	7	7
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, [ECDHE-RSA-AES128-SHA256]	0xc027		8	8	8	8
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, [ECDHE-RSA-AES256-SHA]	0xc014			9	9	9
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, [ECDHE-RSA-AES128-SHA]	0xc013			10	10	10
TLS_RSA_WITH_AES_256_GCM_SHA384, [AES256-GCM-SHA384]	0x009d				11	11
TLS_RSA_WITH_AES_128_GCM_SHA256, [AES128-GCM-SHA256]	0x009c				12	12
TLS_RSA_WITH_AES_256_CBC_SHA256, [AES256-SHA256]	0x003d				13	13
TLS_RSA_WITH_AES_128_CBC_SHA256, [AES128-SHA256]	0x003c				14	14
TLS_RSA_WITH_AES_256_CBC_SHA, [AES256-SHA]	0x0035				15	15
TLS_RSA_WITH_AES_128_CBC_SHA, [AES128-SHA]	0x002f				16	16
TLS_RSA_WITH_3DES_EDE_CBC_SHA, [DES-CBC3-SHA]	0x000a					17
TLS_DHE_RSA_WITH_AES_256_CBC_SHA, [DHE-RSA-AES256-SHA]	0x0039			11	17	18
TLS_DHE_RSA_WITH_AES_128_CBC_SHA, [DHE-RSA-AES128-SHA]	0x0033			12	18	19

Remarks:
- Elder versions of Internet-Explorer and Java do not support Diffie-Hellman parameters >1024 bit. So the ciphers 'TLS_DHE_RSA_WITH_AES_256_CBC_SHA' and 'TLS_DHE_RSA_WITH_AES_128_CBC_SHA' were moved to the end to prevent possible incompatibility issues. Other option: Delete this two ciphers from your list.

Examples for cipher strings

• OpenSSL

Cipher-String	OpenSSL-Syntax
Advanced+ (A+)	DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256
Advanced (A)	DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256
Broad Compatibility (B)	DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA
Widest Compatibility (C)	DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA
Legacy (C-)	DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA

At a glance: Hardening of other parts of the configuration of TLS/SSL for web servers

• Use solely secure and server initiated renegotiation
• Disable compression on TLS/SSL level
• Check the configuration for all virtual hosts
• If you use 'Server Name Indication' (SNI), configure one virtual server is your default server (often this is the first virtual serever). Ancient browsers, OSs or runtime environments without SNI support connect solely to this server
• Use only the TLS/SSL extensions that you really need, e.g. deactivate heart beat (see Heartbleed), do not activate insecure or untested drafts for extensions e.g. additional random, opaque PRF input (see. DualECTLS)
• Set reasonable HTML headers, e.g. HTTP Strict Transport Security (HSTS)

Example configs

Apache

• Cipher String 'A':

SSLProtocol +TLSv1.2                  # for Cipher-String 'A+', 'A'
#SSLProtocol +TLSv1.2 +TLSv1.1 +TLSv1 # for Cipher-String 'B', 'C', 'C-'
SSLCompression off
SSLHonorCipherOrder on
SSLCipherSuite 'DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256'
#add optionally ':!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:!ADH:!IDEA:!3DES'

Remarks:
- The cipher string is compiled as a whitelist of individual ciphers to get a better compatibility even with old versions of OpenSSL.
- Monitor the performance of your server, e.g. the TLS handshake with DHE hinders the CPU about 2.4 times more than ECDHE, cf. Vincent Bernat, 2011, nmav's Blog, 2011.

• Verify your cipher string using your crypto library, e.g. openssl using cipher string 'A':

openssl ciphers -V "DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256"
#add optionally ':!aNULL:!eNULL:!LOW:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:!ADH:!IDEA' to protect older Versions of OpenSSL
#use openssl ciphers -v "..." for openssl < 1.0.1:

0x00,0x9F - DHE-RSA-AES256-GCM-SHA384   TLSv1.2 Kx=DH     Au=RSA  Enc=AESGCM(256) Mac=AEAD
0x00,0x9E - DHE-RSA-AES128-GCM-SHA256   TLSv1.2 Kx=DH     Au=RSA  Enc=AESGCM(128) Mac=AEAD
0xC0,0x30 - ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH   Au=RSA  Enc=AESGCM(256) Mac=AEAD
0xC0,0x2F - ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH   Au=RSA  Enc=AESGCM(128) Mac=AEAD
0x00,0x6B - DHE-RSA-AES256-SHA256       TLSv1.2 Kx=DH     Au=RSA  Enc=AES(256)    Mac=SHA256
0x00,0x67 - DHE-RSA-AES128-SHA256       TLSv1.2 Kx=DH     Au=RSA  Enc=AES(128)    Mac=SHA256
0xC0,0x28 - ECDHE-RSA-AES256-SHA384     TLSv1.2 Kx=ECDH   Au=RSA  Enc=AES(256)    Mac=SHA384
0xC0,0x27 - ECDHE-RSA-AES128-SHA256     TLSv1.2 Kx=ECDH   Au=RSA  Enc=AES(128)    Mac=SHA256

CAUTION: You need a newer version of OpenSSL to use this cipher string!

Related Articles

• OWASP: Transport Layer Protection Cheat Sheet

Authors and Primary Editors

Torsten Gigler @
Achim Hoffmann @