With curl's options
CURLOPT_SSL_CIPHER_LIST
and
--ciphers
users can control which ciphers to consider when negotiating TLS connections.
TLS 1.3 ciphers are supported since curl 7.61 for OpenSSL 1.1.1+ with options
CURLOPT_TLS13_CIPHERS
and
--tls13-ciphers
. If you are using a different SSL backend you can try setting TLS 1.3 cipher
suites by using the respective regular cipher option.
The names of the known ciphers differ depending on which TLS backend that libcurl was built to use. This is an attempt to list known cipher names.
(based on OpenSSL docs)
When specifying multiple cipher names, separate them with colon (:
).
NULL-MD5
NULL-SHA
RC4-MD5
RC4-SHA
IDEA-CBC-SHA
DES-CBC3-SHA
DH-DSS-DES-CBC3-SHA
DH-RSA-DES-CBC3-SHA
DHE-DSS-DES-CBC3-SHA
DHE-RSA-DES-CBC3-SHA
ADH-RC4-MD5
ADH-DES-CBC3-SHA
NULL-MD5
NULL-SHA
RC4-MD5
RC4-SHA
IDEA-CBC-SHA
DES-CBC3-SHA
DHE-DSS-DES-CBC3-SHA
DHE-RSA-DES-CBC3-SHA
ADH-RC4-MD5
ADH-DES-CBC3-SHA
AES128-SHA
AES256-SHA
DH-DSS-AES128-SHA
DH-DSS-AES256-SHA
DH-RSA-AES128-SHA
DH-RSA-AES256-SHA
DHE-DSS-AES128-SHA
DHE-DSS-AES256-SHA
DHE-RSA-AES128-SHA
DHE-RSA-AES256-SHA
ADH-AES128-SHA
ADH-AES256-SHA
SEED-SHA
DH-DSS-SEED-SHA
DH-RSA-SEED-SHA
DHE-DSS-SEED-SHA
DHE-RSA-SEED-SHA
ADH-SEED-SHA
GOST94-GOST89-GOST89
GOST2001-GOST89-GOST89
GOST94-NULL-GOST94
GOST2001-NULL-GOST94
ECDHE-RSA-NULL-SHA
ECDHE-RSA-RC4-SHA
ECDHE-RSA-DES-CBC3-SHA
ECDHE-RSA-AES128-SHA
ECDHE-RSA-AES256-SHA
ECDHE-ECDSA-NULL-SHA
ECDHE-ECDSA-RC4-SHA
ECDHE-ECDSA-DES-CBC3-SHA
ECDHE-ECDSA-AES128-SHA
ECDHE-ECDSA-AES256-SHA
AECDH-NULL-SHA
AECDH-RC4-SHA
AECDH-DES-CBC3-SHA
AECDH-AES128-SHA
AECDH-AES256-SHA
NULL-SHA256
AES128-SHA256
AES256-SHA256
AES128-GCM-SHA256
AES256-GCM-SHA384
DH-RSA-AES128-SHA256
DH-RSA-AES256-SHA256
DH-RSA-AES128-GCM-SHA256
DH-RSA-AES256-GCM-SHA384
DH-DSS-AES128-SHA256
DH-DSS-AES256-SHA256
DH-DSS-AES128-GCM-SHA256
DH-DSS-AES256-GCM-SHA384
DHE-RSA-AES128-SHA256
DHE-RSA-AES256-SHA256
DHE-RSA-AES128-GCM-SHA256
DHE-RSA-AES256-GCM-SHA384
DHE-DSS-AES128-SHA256
DHE-DSS-AES256-SHA256
DHE-DSS-AES128-GCM-SHA256
DHE-DSS-AES256-GCM-SHA384
ECDHE-RSA-AES128-SHA256
ECDHE-RSA-AES256-SHA384
ECDHE-RSA-AES128-GCM-SHA256
ECDHE-RSA-AES256-GCM-SHA384
ECDHE-ECDSA-AES128-SHA256
ECDHE-ECDSA-AES256-SHA384
ECDHE-ECDSA-AES128-GCM-SHA256
ECDHE-ECDSA-AES256-GCM-SHA384
ADH-AES128-SHA256
ADH-AES256-SHA256
ADH-AES128-GCM-SHA256
ADH-AES256-GCM-SHA384
AES128-CCM
AES256-CCM
DHE-RSA-AES128-CCM
DHE-RSA-AES256-CCM
AES128-CCM8
AES256-CCM8
DHE-RSA-AES128-CCM8
DHE-RSA-AES256-CCM8
ECDHE-ECDSA-AES128-CCM
ECDHE-ECDSA-AES256-CCM
ECDHE-ECDSA-AES128-CCM8
ECDHE-ECDSA-AES256-CCM8
ECDHE-ECDSA-CAMELLIA128-SHA256
ECDHE-ECDSA-CAMELLIA256-SHA384
ECDHE-RSA-CAMELLIA128-SHA256
ECDHE-RSA-CAMELLIA256-SHA384
(Note these ciphers are set with CURLOPT_TLS13_CIPHERS
and --tls13-ciphers
)
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_GCM_SHA256
TLS_AES_128_CCM_8_SHA256
TLS_AES_128_CCM_SHA256
rc4
rc4-md5
rc4export
rc2
rc2export
des
desede3
rsa_rc4_128_md5
rsa_rc4_128_sha
rsa_3des_sha
rsa_des_sha
rsa_rc4_40_md5
rsa_rc2_40_md5
rsa_null_md5
rsa_null_sha
fips_3des_sha
fips_des_sha
fortezza
fortezza_rc4_128_sha
fortezza_null
rsa_des_56_sha
rsa_rc4_56_sha
dhe_dss_aes_128_cbc_sha
dhe_dss_aes_256_cbc_sha
dhe_rsa_aes_128_cbc_sha
dhe_rsa_aes_256_cbc_sha
rsa_aes_128_sha
rsa_aes_256_sha
ecdh_ecdsa_null_sha
ecdh_ecdsa_rc4_128_sha
ecdh_ecdsa_3des_sha
ecdh_ecdsa_aes_128_sha
ecdh_ecdsa_aes_256_sha
ecdhe_ecdsa_null_sha
ecdhe_ecdsa_rc4_128_sha
ecdhe_ecdsa_3des_sha
ecdhe_ecdsa_aes_128_sha
ecdhe_ecdsa_aes_256_sha
ecdh_rsa_null_sha
ecdh_rsa_128_sha
ecdh_rsa_3des_sha
ecdh_rsa_aes_128_sha
ecdh_rsa_aes_256_sha
ecdhe_rsa_null
ecdhe_rsa_rc4_128_sha
ecdhe_rsa_3des_sha
ecdhe_rsa_aes_128_sha
ecdhe_rsa_aes_256_sha
ecdh_anon_null_sha
ecdh_anon_rc4_128sha
ecdh_anon_3des_sha
ecdh_anon_aes_128_sha
ecdh_anon_aes_256_sha
rsa_null_sha_256
rsa_aes_128_cbc_sha_256
rsa_aes_256_cbc_sha_256
dhe_rsa_aes_128_cbc_sha_256
dhe_rsa_aes_256_cbc_sha_256
ecdhe_ecdsa_aes_128_cbc_sha_256
ecdhe_rsa_aes_128_cbc_sha_256
rsa_aes_128_gcm_sha_256
dhe_rsa_aes_128_gcm_sha_256
dhe_dss_aes_128_gcm_sha_256
ecdhe_ecdsa_aes_128_gcm_sha_256
ecdh_ecdsa_aes_128_gcm_sha_256
ecdhe_rsa_aes_128_gcm_sha_256
ecdh_rsa_aes_128_gcm_sha_256
rsa_aes_256_gcm_sha_384
dhe_rsa_aes_256_gcm_sha_384
dhe_dss_aes_256_gcm_sha_384
ecdhe_ecdsa_aes_256_sha_384
ecdhe_rsa_aes_256_sha_384
ecdhe_ecdsa_aes_256_gcm_sha_384
ecdhe_rsa_aes_256_gcm_sha_384
ecdhe_rsa_chacha20_poly1305_sha_256
ecdhe_ecdsa_chacha20_poly1305_sha_256
dhe_rsa_chacha20_poly1305_sha_256
aes_128_gcm_sha_256
aes_256_gcm_sha_384
chacha20_poly1305_sha_256
Ciphers are internally defined as numeric codes. libcurl maps them to the following case-insensitive names.
rc2-md5
rc4-md5
exp-rc2-md5
exp-rc4-md5
des-cbc-md5
des-cbc3-md5
null-md5
null-sha
rc4-md5
rc4-sha
exp-rc2-cbc-md5
exp-rc4-md5
exp-des-cbc-sha
des-cbc3-sha
null-md5
null-sha
rc4-md5
rc4-sha
exp-rc2-cbc-md5
exp-rc4-md5
exp-des-cbc-sha
des-cbc3-sha
aes128-sha
aes256-sha
null-md5
null-sha
rc4-md5
rc4-sha
exp-des-cbc-sha
des-cbc3-sha
aes128-sha
aes256-sha
null-md5
null-sha
null-sha256
rc4-md5
rc4-sha
des-cbc3-sha
aes128-sha
aes256-sha
aes128-sha256
aes256-sha256
aes128-gcm-sha256
aes256-gcm-sha384
RC4-SHA
,
RC4-MD5
,
DES-CBC3-SHA
,
AES128-SHA
,
AES256-SHA
,
NULL-SHA
,
NULL-SHA256
,
DHE-RSA-AES128-SHA
,
DHE-RSA-AES256-SHA
,
DHE-PSK-AES256-GCM-SHA384
,
DHE-PSK-AES128-GCM-SHA256
,
PSK-AES256-GCM-SHA384
,
PSK-AES128-GCM-SHA256
,
DHE-PSK-AES256-CBC-SHA384
,
DHE-PSK-AES128-CBC-SHA256
,
PSK-AES256-CBC-SHA384
,
PSK-AES128-CBC-SHA256
,
PSK-AES128-CBC-SHA
,
PSK-AES256-CBC-SHA
,
DHE-PSK-AES128-CCM
,
DHE-PSK-AES256-CCM
,
PSK-AES128-CCM
,
PSK-AES256-CCM
,
PSK-AES128-CCM-8
,
PSK-AES256-CCM-8
,
DHE-PSK-NULL-SHA384
,
DHE-PSK-NULL-SHA256
,
PSK-NULL-SHA384
,
PSK-NULL-SHA256
,
PSK-NULL-SHA
,
HC128-MD5
,
HC128-SHA
,
HC128-B2B256
,
AES128-B2B256
,
AES256-B2B256
,
RABBIT-SHA
,
NTRU-RC4-SHA
,
NTRU-DES-CBC3-SHA
,
NTRU-AES128-SHA
,
NTRU-AES256-SHA
,
AES128-CCM-8
,
AES256-CCM-8
,
ECDHE-ECDSA-AES128-CCM
,
ECDHE-ECDSA-AES128-CCM-8
,
ECDHE-ECDSA-AES256-CCM-8
,
ECDHE-RSA-AES128-SHA
,
ECDHE-RSA-AES256-SHA
,
ECDHE-ECDSA-AES128-SHA
,
ECDHE-ECDSA-AES256-SHA
,
ECDHE-RSA-RC4-SHA
,
ECDHE-RSA-DES-CBC3-SHA
,
ECDHE-ECDSA-RC4-SHA
,
ECDHE-ECDSA-DES-CBC3-SHA
,
AES128-SHA256
,
AES256-SHA256
,
DHE-RSA-AES128-SHA256
,
DHE-RSA-AES256-SHA256
,
ECDH-RSA-AES128-SHA
,
ECDH-RSA-AES256-SHA
,
ECDH-ECDSA-AES128-SHA
,
ECDH-ECDSA-AES256-SHA
,
ECDH-RSA-RC4-SHA
,
ECDH-RSA-DES-CBC3-SHA
,
ECDH-ECDSA-RC4-SHA
,
ECDH-ECDSA-DES-CBC3-SHA
,
AES128-GCM-SHA256
,
AES256-GCM-SHA384
,
DHE-RSA-AES128-GCM-SHA256
,
DHE-RSA-AES256-GCM-SHA384
,
ECDHE-RSA-AES128-GCM-SHA256
,
ECDHE-RSA-AES256-GCM-SHA384
,
ECDHE-ECDSA-AES128-GCM-SHA256
,
ECDHE-ECDSA-AES256-GCM-SHA384
,
ECDH-RSA-AES128-GCM-SHA256
,
ECDH-RSA-AES256-GCM-SHA384
,
ECDH-ECDSA-AES128-GCM-SHA256
,
ECDH-ECDSA-AES256-GCM-SHA384
,
CAMELLIA128-SHA
,
DHE-RSA-CAMELLIA128-SHA
,
CAMELLIA256-SHA
,
DHE-RSA-CAMELLIA256-SHA
,
CAMELLIA128-SHA256
,
DHE-RSA-CAMELLIA128-SHA256
,
CAMELLIA256-SHA256
,
DHE-RSA-CAMELLIA256-SHA256
,
ECDHE-RSA-AES128-SHA256
,
ECDHE-ECDSA-AES128-SHA256
,
ECDH-RSA-AES128-SHA256
,
ECDH-ECDSA-AES128-SHA256
,
ECDHE-RSA-AES256-SHA384
,
ECDHE-ECDSA-AES256-SHA384
,
ECDH-RSA-AES256-SHA384
,
ECDH-ECDSA-AES256-SHA384
,
ECDHE-RSA-CHACHA20-POLY1305
,
ECDHE-ECDSA-CHACHA20-POLY1305
,
DHE-RSA-CHACHA20-POLY1305
,
ECDHE-RSA-CHACHA20-POLY1305-OLD
,
ECDHE-ECDSA-CHACHA20-POLY1305-OLD
,
DHE-RSA-CHACHA20-POLY1305-OLD
,
ADH-AES128-SHA
,
QSH
,
RENEGOTIATION-INFO
,
IDEA-CBC-SHA
,
ECDHE-ECDSA-NULL-SHA
,
ECDHE-PSK-NULL-SHA256
,
ECDHE-PSK-AES128-CBC-SHA256
,
PSK-CHACHA20-POLY1305
,
ECDHE-PSK-CHACHA20-POLY1305
,
DHE-PSK-CHACHA20-POLY1305
,
EDH-RSA-DES-CBC3-SHA
,
Schannel allows the enabling and disabling of encryption algorithms, but not specific ciphersuites. They are defined by Microsoft.
There is also the case that the selected algorithm is not supported by the
protocol or does not match the ciphers offered by the server during the SSL
negotiation. In this case curl will return error
CURLE_SSL_CONNECT_ERROR (35) SEC_E_ALGORITHM_MISMATCH
and the request will fail.
CALG_MD2
,
CALG_MD4
,
CALG_MD5
,
CALG_SHA
,
CALG_SHA1
,
CALG_MAC
,
CALG_RSA_SIGN
,
CALG_DSS_SIGN
,
CALG_NO_SIGN
,
CALG_RSA_KEYX
,
CALG_DES
,
CALG_3DES_112
,
CALG_3DES
,
CALG_DESX
,
CALG_RC2
,
CALG_RC4
,
CALG_SEAL
,
CALG_DH_SF
,
CALG_DH_EPHEM
,
CALG_AGREEDKEY_ANY
,
CALG_HUGHES_MD5
,
CALG_SKIPJACK
,
CALG_TEK
,
CALG_CYLINK_MEK
,
CALG_SSL3_SHAMD5
,
CALG_SSL3_MASTER
,
CALG_SCHANNEL_MASTER_HASH
,
CALG_SCHANNEL_MAC_KEY
,
CALG_SCHANNEL_ENC_KEY
,
CALG_PCT1_MASTER
,
CALG_SSL2_MASTER
,
CALG_TLS1_MASTER
,
CALG_RC5
,
CALG_HMAC
,
CALG_TLS1PRF
,
CALG_HASH_REPLACE_OWF
,
CALG_AES_128
,
CALG_AES_192
,
CALG_AES_256
,
CALG_AES
,
CALG_SHA_256
,
CALG_SHA_384
,
CALG_SHA_512
,
CALG_ECDH
,
CALG_ECMQV
,
CALG_ECDSA
,
CALG_ECDH_EPHEM
,
As of curl 7.77.0, you can also pass SCH_USE_STRONG_CRYPTO
as a cipher name
to constrain the set of available ciphers as specified in the schannel
documentation.
Note that the supported ciphers in this case follow the OS version, so if you
are running an outdated OS you might still be supporting weak ciphers.
BearSSL ciphers can be specified by either the OpenSSL name (ECDHE-RSA-AES128-GCM-SHA256
) or the IANA name (TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
).
Since BearSSL 0.1:
DES-CBC3-SHA
AES128-SHA
AES256-SHA
AES128-SHA256
AES256-SHA256
AES128-GCM-SHA256
AES256-GCM-SHA384
ECDH-ECDSA-DES-CBC3-SHA
ECDH-ECDSA-AES128-SHA
ECDH-ECDSA-AES256-SHA
ECDHE-ECDSA-DES-CBC3-SHA
ECDHE-ECDSA-AES128-SHA
ECDHE-ECDSA-AES256-SHA
ECDH-RSA-DES-CBC3-SHA
ECDH-RSA-AES128-SHA
ECDH-RSA-AES256-SHA
ECDHE-RSA-DES-CBC3-SHA
ECDHE-RSA-AES128-SHA
ECDHE-RSA-AES256-SHA
ECDHE-ECDSA-AES128-SHA256
ECDHE-ECDSA-AES256-SHA384
ECDH-ECDSA-AES128-SHA256
ECDH-ECDSA-AES256-SHA384
ECDHE-RSA-AES128-SHA256
ECDHE-RSA-AES256-SHA384
ECDH-RSA-AES128-SHA256
ECDH-RSA-AES256-SHA384
ECDHE-ECDSA-AES128-GCM-SHA256
ECDHE-ECDSA-AES256-GCM-SHA384
ECDH-ECDSA-AES128-GCM-SHA256
ECDH-ECDSA-AES256-GCM-SHA384
ECDHE-RSA-AES128-GCM-SHA256
ECDHE-RSA-AES256-GCM-SHA384
ECDH-RSA-AES128-GCM-SHA256
ECDH-RSA-AES256-GCM-SHA384
Since BearSSL 0.2:
ECDHE-RSA-CHACHA20-POLY1305
ECDHE-ECDSA-CHACHA20-POLY1305
Since BearSSL 0.6:
AES128-CCM
AES256-CCM
AES128-CCM8
AES256-CCM8
ECDHE-ECDSA-AES128-CCM
ECDHE-ECDSA-AES256-CCM
ECDHE-ECDSA-AES128-CCM8
ECDHE-ECDSA-AES256-CCM8