Codex

CIPHERS

Section: OpenSSL (1SSL)

Updated: 2015-12-03

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NAME

ciphers - SSL cipher display and cipher list tool.

SYNOPSIS

openssl ciphers [-v] [-V] [-ssl2] [-ssl3] [-tls1] [cipherlist]

DESCRIPTION

The ciphers command converts textual OpenSSL cipher lists into ordered SSL cipher preference lists. It can be used as a test tool to determine the appropriate cipherlist.

COMMAND OPTIONS

-v
Verbose option. List ciphers with a complete description of protocol version (SSLv2 or SSLv3; the latter includes TLS), key exchange, authentication, encryption and mac algorithms used along with any key size restrictions and whether the algorithm is classed as an ``export'' cipher. Note that without the -v option, ciphers may seem to appear twice in a cipher list; this is when similar ciphers are available for SSL v2 and for SSL v3/TLS v1.:
-V
Like -v, but include cipher suite codes in output (hex format).:
-ssl3
only include SSL v3 ciphers.:
-ssl2
only include SSL v2 ciphers.:
-tls1
only include TLS v1 ciphers.:
-h, -?
print a brief usage message.:
cipherlist
a cipher list to convert to a cipher preference list. If it is not included then the default cipher list will be used. The format is described below.:

CIPHER LIST FORMAT

The cipher list consists of one or more cipher strings separated by colons. Commas or spaces are also acceptable separators but colons are normally used.

The actual cipher string can take several different forms.

It can consist of a single cipher suite such as RC4-SHA.

It can represent a list of cipher suites containing a certain algorithm, or cipher suites of a certain type. For example SHA1 represents all ciphers suites using the digest algorithm SHA1 and SSLv3 represents all SSL v3 algorithms.

Lists of cipher suites can be combined in a single cipher string using the + character. This is used as a logical and operation. For example SHA1+DES represents all cipher suites containing the SHA1 and the DES algorithms.

Each cipher string can be optionally preceded by the characters !, - or +.

If ! is used then the ciphers are permanently deleted from the list. The ciphers deleted can never reappear in the list even if they are explicitly stated.

If - is used then the ciphers are deleted from the list, but some or all of the ciphers can be added again by later options.

If + is used then the ciphers are moved to the end of the list. This option doesn't add any new ciphers it just moves matching existing ones.

If none of these characters is present then the string is just interpreted as a list of ciphers to be appended to the current preference list. If the list includes any ciphers already present they will be ignored: that is they will not moved to the end of the list.

Additionally the cipher string @STRENGTH can be used at any point to sort the current cipher list in order of encryption algorithm key length.

CIPHER STRINGS

The following is a list of all permitted cipher strings and their meanings.

DEFAULT
the default cipher list. This is determined at compile time and is normally ALL:!EXPORT:!aNULL:!eNULL:!SSLv2. This must be the firstcipher string specified.:
COMPLEMENTOFDEFAULT
the ciphers included in ALL, but not enabled by default. Currently this is ADH and AECDH. Note that this rule does not cover eNULL, which is not included by ALL (use COMPLEMENTOFALL if necessary).:
ALL
all cipher suites except the eNULL ciphers which must be explicitly enabled; as of OpenSSL, the ALL cipher suites are reasonably ordered by default:
COMPLEMENTOFALL
the cipher suites not enabled by ALL, currently being eNULL.:
HIGH
``high'' encryption cipher suites. This currently means those with key lengths larger than 128 bits, and some cipher suites with 128-bit keys.:
MEDIUM
``medium'' encryption cipher suites, currently some of those using 128 bit encryption.:
LOW
``low'' encryption cipher suites, currently those using 64 or 56 bit encryption algorithms but excluding export cipher suites.:
EXP, EXPORT
export encryption algorithms. Including 40 and 56 bits algorithms.:
EXPORT40
40 bit export encryption algorithms:
EXPORT56
56 bit export encryption algorithms. In OpenSSL 0.9.8c and later the set of 56 bit export ciphers is empty unless OpenSSL has been explicitly configured with support for experimental ciphers.:
eNULL, NULL
the ``NULL'' ciphers that is those offering no encryption. Because these offer no encryption at all and are a security risk they are disabled unless explicitly included.:
aNULL
the cipher suites offering no authentication. This is currently the anonymous DH algorithms and anonymous ECDH algorithms. These cipher suites are vulnerable to a ``man in the middle'' attack and so their use is normally discouraged.:
kRSA, RSA
cipher suites using RSA key exchange.:
kDHr, kDHd, kDH
cipher suites using DH key agreement and DH certificates signed by CAs with RSA and DSS keys or either respectively. Not implemented.:
kEDH
cipher suites using ephemeral DH key agreement, including anonymous cipher suites.:
EDH
cipher suites using authenticated ephemeral DH key agreement.:
ADH
anonymous DH cipher suites, note that this does not include anonymous Elliptic Curve DH (ECDH) cipher suites.:
DH
cipher suites using DH, including anonymous DH, ephemeral DH and fixed DH.:
kECDHr, kECDHe, kECDH
cipher suites using fixed ECDH key agreement signed by CAs with RSA and ECDSA keys or either respectively.:
kEECDH
cipher suites using ephemeral ECDH key agreement, including anonymous cipher suites.:
EECDHE
cipher suites using authenticated ephemeral ECDH key agreement.:
AECDH
anonymous Elliptic Curve Diffie Hellman cipher suites.:
ECDH
cipher suites using ECDH key exchange, including anonymous, ephemeral and fixed ECDH.:
aRSA
cipher suites using RSA authentication, i.e. the certificates carry RSA keys.:
aDSS, DSS
cipher suites using DSS authentication, i.e. the certificates carry DSS keys.:
aDH
cipher suites effectively using DH authentication, i.e. the certificates carry DH keys. Not implemented.:
aECDH
cipher suites effectively using ECDH authentication, i.e. the certificates carry ECDH keys.:
aECDSA, ECDSA
cipher suites using ECDSA authentication, i.e. the certificates carry ECDSA keys.:
kFZA, aFZA, eFZA, FZA
ciphers suites using FORTEZZA key exchange, authentication, encryption or all FORTEZZA algorithms. Not implemented.:
TLSv1.2, TLSv1, SSLv3, SSLv2
TLS v1.2, TLS v1.0, SSL v3.0 or SSL v2.0 cipher suites respectively. Note: there are no ciphersuites specific to TLS v1.1.:
AES128, AES256, AES
cipher suites using 128 bit AES, 256 bit AES or either 128 or 256 bit AES.:
AESGCM
AES in Galois Counter Mode (GCM): these ciphersuites are only supported in TLS v1.2.:
CAMELLIA128, CAMELLIA256, CAMELLIA
cipher suites using 128 bit CAMELLIA, 256 bit CAMELLIA or either 128 or 256 bit CAMELLIA.:
3DES
cipher suites using triple DES.:
DES
cipher suites using DES (not triple DES).:
RC4
cipher suites using RC4.:
RC2
cipher suites using RC2.:
IDEA
cipher suites using IDEA.:
SEED
cipher suites using SEED.:
MD5
cipher suites using MD5.:
SHA1, SHA
cipher suites using SHA1.:
SHA256, SHA384
ciphersuites using SHA256 or SHA384.:
aGOST
cipher suites using GOST R 34.10 (either 2001 or 94) for authenticaction (needs an engine supporting GOST algorithms).:
aGOST01
cipher suites using GOST R 34.10-2001 authentication.:
aGOST94
cipher suites using GOST R 34.10-94 authentication (note that R 34.10-94 standard has been expired so use GOST R 34.10-2001):
kGOST
cipher suites, using VKO 34.10 key exchange, specified in the RFC 4357.:
GOST94
cipher suites, using HMAC based on GOST R 34.11-94.:
GOST89MAC
cipher suites using GOST 28147-89 MAC instead of HMAC.:
PSK
cipher suites using pre-shared keys (PSK).:

CIPHER SUITE NAMES

The following lists give the SSL or TLS cipher suites names from the relevant specification and their OpenSSL equivalents. It should be noted, that several cipher suite names do not include the authentication used, e.g. DES-CBC3-SHA. In these cases, RSA authentication is used.

SSL v3.0 cipher suites.

TLS v1.0 cipher suites.

AES ciphersuites from RFC3268, extending TLS v1.0

Camellia ciphersuites from RFC4132, extending TLS v1.0

SEED ciphersuites from RFC4162, extending TLS v1.0

GOST ciphersuites from draft-chudov-cryptopro-cptls, extending TLS v1.0

Note: these ciphers require an engine which including GOST cryptographic algorithms, such as the ccgost engine, included in the OpenSSL distribution.

Additional Export 1024 and other cipher suites

Note: these ciphers can also be used in SSL v3.

Elliptic curve cipher suites.

TLS v1.2 cipher suites

Pre shared keying (PSK) cipheruites

Deprecated SSL v2.0 cipher suites.

NOTES

The non-ephemeral DH modes are currently unimplemented in OpenSSL because there is no support for DH certificates.

Some compiled versions of OpenSSL may not include all the ciphers listed here because some ciphers were excluded at compile time.

EXAMPLES

Verbose listing of all OpenSSL ciphers including NULL ciphers:

Include all ciphers except NULL and anonymous DH then sort by strength:

Include all ciphers except ones with no encryption (eNULL) or no authentication (aNULL):

Include only 3DES ciphers and then place RSA ciphers last:

Include all RC4 ciphers but leave out those without authentication:

Include all chiphers with RSA authentication but leave out ciphers without encryption.

SEE ALSO

s_client?(1), s_server?(1), ssl?(3)

HISTORY

The COMPLENTOFALL and COMPLEMENTOFDEFAULT selection options for cipherlist strings were added in OpenSSL 0.9.7. The -V option for the ciphers command was added in OpenSSL 1.0.0.


Index

NAME

SYNOPSIS

DESCRIPTION

COMMAND OPTIONS

CIPHER LIST FORMAT

CIPHER STRINGS

CIPHER SUITE NAMES

SSL v3.0 cipher suites.

TLS v1.0 cipher suites.

AES ciphersuites from RFC3268, extending TLS v1.0

Camellia ciphersuites from RFC4132, extending TLS v1.0

SEED ciphersuites from RFC4162, extending TLS v1.0

GOST ciphersuites from draft-chudov-cryptopro-cptls, extending TLS v1.0

Additional Export 1024 and other cipher suites

Elliptic curve cipher suites.

TLS v1.2 cipher suites

Pre shared keying (PSK) cipheruites

Deprecated SSL v2.0 cipher suites.

NOTES

EXAMPLES

SEE ALSO

HISTORY


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