ssl(3erl) Erlang Module Definition ssl(3erl)
NAME
ssl - Interface Functions for Secure Socket Layer
DESCRIPTION
This module contains interface functions for the TLS/DTLS protocol. For
detailed information about the supported standards see ssl(7).
DATA TYPES
Types used in TLS/DTLS
socket() = gen_tcp:socket()
sslsocket() = any()
An opaque reference to the TLS/DTLS connection, may be used for
equality matching.
tls_option() = tls_client_option() | tls_server_option()
tls_client_option() =
client_option() |
common_option() |
socket_option() |
transport_option()
tls_server_option() =
server_option() |
common_option() |
socket_option() |
transport_option()
socket_option() =
gen_tcp:connect_option() |
gen_tcp:listen_option() |
gen_udp:option()
The default socket options are [{mode,list},{packet, 0},{header,
0},{active, true}].
For valid options, see the inet(3erl), gen_tcp(3erl) and
gen_udp(3erl) manual pages in Kernel. Note that stream oriented
options such as packet are only relevant for TLS and not DTLS
active_msgs() =
{ssl, sslsocket(), Data :: binary() | list()} |
{ssl_closed, sslsocket()} |
{ssl_error, sslsocket(), Reason :: any()} |
{ssl_passive, sslsocket()}
When a TLS/DTLS socket is in active mode (the default), data
from the socket is delivered to the owner of the socket in the
form of messages as described above.
The ssl_passive message is sent only when the socket is in {ac-
tive, N} mode and the counter dropped to 0. It indicates that
the socket has transitioned to passive ({active, false}) mode.
transport_option() =
{cb_info,
{CallbackModule :: atom(),
DataTag :: atom(),
ClosedTag :: atom(),
ErrTag :: atom()}} |
{cb_info,
{CallbackModule :: atom(),
DataTag :: atom(),
ClosedTag :: atom(),
ErrTag :: atom(),
PassiveTag :: atom()}}
Defaults to {gen_tcp, tcp, tcp_closed, tcp_error, tcp_passive}
for TLS (for backward compatibility a four tuple will be con-
verted to a five tuple with the last element "second_ele-
ment"_passive) and {gen_udp, udp, udp_closed, udp_error} for
DTLS (might also be changed to five tuple in the future). Can be
used to customize the transport layer. The tag values should be
the values used by the underlying transport in its active mode
messages. For TLS the callback module must implement a reliable
transport protocol, behave as gen_tcp, and have functions corre-
sponding to inet:setopts/2, inet:getopts/2, inet:peername/1,
inet:sockname/1, and inet:port/1. The callback gen_tcp is
treated specially and calls inet directly. For DTLS this feature
must be considered exprimental.
host() = hostname() | ip_address()
hostname() = string()
ip_address() = inet:ip_address()
protocol_version() = tls_version() | dtls_version()
tls_version() = 'tlsv1.2' | 'tlsv1.3' | tls_legacy_version()
dtls_version() = 'dtlsv1.2' | dtls_legacy_version()
tls_legacy_version() = tlsv1 | 'tlsv1.1'
dtls_legacy_version() = dtlsv1
prf_random() = client_random | server_random
verify_type() = verify_none | verify_peer
ciphers() = [erl_cipher_suite()] | string()
erl_cipher_suite() =
#{key_exchange := kex_algo(),
cipher := cipher(),
mac := hash() | aead,
prf := hash() | default_prf}
cipher() =
aes_128_cbc | aes_256_cbc | aes_128_gcm | aes_256_gcm |
aes_128_ccm | aes_256_ccm | aes_128_ccm_8 | aes_256_ccm_8 |
chacha20_poly1305 |
legacy_cipher()
legacy_cipher() = rc4_128 | des_cbc | '3des_ede_cbc'
cipher_filters() =
[{key_exchange | cipher | mac | prf, algo_filter()}]
hash() = sha | sha2() | legacy_hash()
sha2() = sha224 | sha256 | sha384 | sha512
legacy_hash() = md5
old_cipher_suite() =
{kex_algo(), cipher(), hash()} |
{kex_algo(), cipher(), hash() | aead, hash()}
signature_algs() = [{hash(), sign_algo()}]
sign_algo() = rsa | dsa | ecdsa
sign_scheme() =
rsa_pkcs1_sha256 | rsa_pkcs1_sha384 | rsa_pkcs1_sha512 |
ecdsa_secp256r1_sha256 | ecdsa_secp384r1_sha384 |
ecdsa_secp521r1_sha512 | rsa_pss_rsae_sha256 |
rsa_pss_rsae_sha384 | rsa_pss_rsae_sha512 |
rsa_pss_pss_sha256 | rsa_pss_pss_sha384 | rsa_pss_pss_sha512 |
rsa_pkcs1_sha1 | ecdsa_sha1
group() =
secp256r1 | secp384r1 | secp521r1 | ffdhe2048 | ffdhe3072 |
ffdhe4096 | ffdhe6144 | ffdhe8192
kex_algo() =
rsa | dhe_rsa | dhe_dss | ecdhe_ecdsa | ecdh_ecdsa |
ecdh_rsa | srp_rsa | srp_dss | psk | dhe_psk | rsa_psk |
dh_anon | ecdh_anon | srp_anon | any
algo_filter() =
fun((kex_algo() | cipher() | hash() | aead | default_prf) ->
true | false)
named_curve() =
sect571r1 | sect571k1 | secp521r1 | brainpoolP512r1 |
sect409k1 | sect409r1 | brainpoolP384r1 | secp384r1 |
sect283k1 | sect283r1 | brainpoolP256r1 | secp256k1 |
secp256r1 | sect239k1 | sect233k1 | sect233r1 | secp224k1 |
secp224r1 | sect193r1 | sect193r2 | secp192k1 | secp192r1 |
sect163k1 | sect163r1 | sect163r2 | secp160k1 | secp160r1 |
secp160r2
psk_identity() = string()
srp_identity() = {Username :: string(), Password :: string()}
srp_param_type() =
srp_1024 | srp_1536 | srp_2048 | srp_3072 | srp_4096 |
srp_6144 | srp_8192
app_level_protocol() = binary()
protocol_extensions() =
#{renegotiation_info => binary(),
signature_algs => signature_algs(),
alpn => app_level_protocol(),
srp => binary(),
next_protocol => app_level_protocol(),
max_frag_enum => 1..4,
ec_point_formats => [0..2],
elliptic_curves => [public_key:oid()],
sni => hostname()}
error_alert() =
{tls_alert, {tls_alert(), Description :: string()}}
tls_alert() =
close_notify | unexpected_message | bad_record_mac |
record_overflow | handshake_failure | bad_certificate |
unsupported_certificate | certificate_revoked |
certificate_expired | certificate_unknown |
illegal_parameter | unknown_ca | access_denied |
decode_error | decrypt_error | export_restriction |
protocol_version | insufficient_security | internal_error |
inappropriate_fallback | user_canceled | no_renegotiation |
unsupported_extension | certificate_unobtainable |
unrecognized_name | bad_certificate_status_response |
bad_certificate_hash_value | unknown_psk_identity |
no_application_protocol
reason() = any()
bloom_filter_window_size() = integer()
bloom_filter_hash_functions() = integer()
bloom_filter_bits() = integer()
client_session_tickets() = disabled | manual | auto
server_session_tickets() = disabled | stateful | stateless
TLS/DTLS OPTION DESCRIPTIONS - COMMON for SERVER and CLIENT
common_option() =
{protocol, protocol()} |
{handshake, handshake_completion()} |
{cert, cert()} |
{certfile, cert_pem()} |
{key, key()} |
{keyfile, key_pem()} |
{password, key_password()} |
{ciphers, cipher_suites()} |
{eccs, [named_curve()]} |
{signature_algs_cert, signature_schemes()} |
{supported_groups, supported_groups()} |
{secure_renegotiate, secure_renegotiation()} |
{depth, allowed_cert_chain_length()} |
{verify_fun, custom_verify()} |
{crl_check, crl_check()} |
{crl_cache, crl_cache_opts()} |
{max_handshake_size, handshake_size()} |
{partial_chain, root_fun()} |
{versions, protocol_versions()} |
{user_lookup_fun, custom_user_lookup()} |
{log_level, logging_level()} |
{log_alert, log_alert()} |
{hibernate_after, hibernate_after()} |
{padding_check, padding_check()} |
{beast_mitigation, beast_mitigation()} |
{ssl_imp, ssl_imp()} |
{session_tickets, session_tickets()} |
{key_update_at, key_update_at()} |
{middlebox_comp_mode, middlebox_comp_mode()}
protocol() = tls | dtls
Choose TLS or DTLS protocol for the transport layer security.
Defaults to tls. For DTLS other transports than UDP are not yet
supported.
handshake_completion() = hello | full
Defaults to full. If hello is specified the handshake will pause
after the hello message and give the user a possibility make de-
cisions based on hello extensions before continuing or aborting
the handshake by calling handshake_continue/3 or hand-
shake_cancel/1
cert() = public_key:der_encoded()
The DER-encoded users certificate. If this option is supplied,
it overrides option certfile.
cert_pem() = file:filename()
Path to a file containing the user certificate on PEM format.
key() =
{'RSAPrivateKey' | 'DSAPrivateKey' | 'ECPrivateKey' |
'PrivateKeyInfo',
public_key:der_encoded()} |
#{algorithm := rsa | dss | ecdsa,
engine := crypto:engine_ref(),
key_id := crypto:key_id(),
password => crypto:password()}
The DER-encoded user's private key or a map refering to a crypto
engine and its key reference that optionally can be password
protected, seealso crypto:engine_load/4 and Crypto's Users
Guide. If this option is supplied, it overrides option keyfile.
key_pem() = file:filename()
Path to the file containing the user's private PEM-encoded key.
As PEM-files can contain several entries, this option defaults
to the same file as given by option certfile.
key_password() = string()
String containing the user's password. Only used if the private
keyfile is password-protected.
cipher_suites() = ciphers()
A list of cipher suites that should be supported
The function ssl:cipher_suites/2 can be used to find all ci-
pher suites that are supported by default and all cipher suites
that may be configured.
If you compose your own cipher_suites() make sure they are fil-
tered for cryptolib support ssl:filter_cipher_suites/2 Addi-
tionaly the functions ssl:append_cipher_suites/2 ,
ssl:prepend_cipher_suites/2, ssl:suite_to_str/1,
ssl:str_to_suite/1, and ssl:suite_to_openssl_str/1 also exist to
help creating customized cipher suite lists.
Note:
Note that TLS-1.3 and TLS-1.2 cipher suites are not overlapping
sets of cipher suites so to support both these versions cipher
suites from both versions need to be included. If supporting
TLS-1.3 versions prior to TLS-1.2 can not be supported.
Non-default cipher suites including anonymous cipher suites (PRE
TLS-1.3) are supported for interop/testing purposes and may be
used by adding them to your cipher suite list. Note that they
must also be supported/enabled by the peer to actually be used.
signature_schemes() = [sign_scheme()]
In addition to the signature_algorithms extension from TLS 1.2,
TLS 1.3 (RFC 5246 Section 4.2.3)adds the signature_algo-
rithms_cert extension which enables having special requirements
on the signatures used in the certificates that differs from the
requirements on digital signatures as a whole. If this is not
required this extension is not needed.
The client will send a signature_algorithms_cert extension
(ClientHello), if TLS version 1.3 or later is used, and the sig-
nature_algs_cert option is explicitly specified. By default,
only the signature_algs extension is sent.
The signature schemes shall be ordered according to the client's
preference (favorite choice first).
supported_groups() = [group()]
TLS 1.3 introduces the "supported_groups" extension that is used
for negotiating the Diffie-Hellman parameters in a TLS 1.3 hand-
shake. Both client and server can specify a list of parameters
that they are willing to use.
If it is not specified it will use a default list ([x25519,
x448, secp256r1, secp384r1]) that is filtered based on the in-
stalled crypto library version.
secure_renegotiation() = boolean()
Specifies if to reject renegotiation attempt that does not live
up to RFC 5746. By default secure_renegotiate is set to true,
that is, secure renegotiation is enforced. If set to false se-
cure renegotiation will still be used if possible, but it falls
back to insecure renegotiation if the peer does not support RFC
5746.
allowed_cert_chain_length() = integer()
Maximum number of non-self-issued intermediate certificates that
can follow the peer certificate in a valid certification path.
So, if depth is 0 the PEER must be signed by the trusted ROOT-CA
directly; if 1 the path can be PEER, CA, ROOT-CA; if 2 the path
can be PEER, CA, CA, ROOT-CA, and so on. The default value is 1.
custom_verify() =
{Verifyfun :: function(), InitialUserState :: any()}
The verification fun is to be defined as follows:
fun(OtpCert :: #'OTPCertificate'{}, Event :: {bad_cert, Reason :: atom() |
{revoked, atom()}} |
{extension, #'Extension'{}} | valid | valid_peer, InitialUserState :: term()) ->
{valid, UserState :: term()} |
{fail, Reason :: term()} | {unknown, UserState :: term()}.
The verification fun is called during the X509-path validation
when an error or an extension unknown to the SSL application is
encountered. It is also called when a certificate is considered
valid by the path validation to allow access to each certificate
in the path to the user application. It differentiates between
the peer certificate and the CA certificates by using valid_peer
or valid as second argument to the verification fun. See the
public_key User's Guide for definition of #'OTPCertificate'{}
and #'Extension'{}.
* If the verify callback fun returns {fail, Reason}, the veri-
fication process is immediately stopped, an alert is sent to
the peer, and the TLS/DTLS handshake terminates.
* If the verify callback fun returns {valid, UserState}, the
verification process continues.
* If the verify callback fun always returns {valid, User-
State}, the TLS/DTLS handshake does not terminate regarding
verification failures and the connection is established.
* If called with an extension unknown to the user application,
return value {unknown, UserState} is to be used.
Note that if the fun returns unknown for an extension marked
as critical, validation will fail.
Default option verify_fun in verify_peer mode:
{fun(_,{bad_cert, _} = Reason, _) ->
{fail, Reason};
(_,{extension, _}, UserState) ->
{unknown, UserState};
(_, valid, UserState) ->
{valid, UserState};
(_, valid_peer, UserState) ->
{valid, UserState}
end, []}
Default option verify_fun in mode verify_none:
{fun(_,{bad_cert, _}, UserState) ->
{valid, UserState};
(_,{extension, #'Extension'{critical = true}}, UserState) ->
{valid, UserState};
(_,{extension, _}, UserState) ->
{unknown, UserState};
(_, valid, UserState) ->
{valid, UserState};
(_, valid_peer, UserState) ->
{valid, UserState}
end, []}
The possible path validation errors are given on form {bad_cert,
Reason} where Reason is:
unknown_ca:
No trusted CA was found in the trusted store. The trusted CA
is normally a so called ROOT CA, which is a self-signed cer-
tificate. Trust can be claimed for an intermediate CA
(trusted anchor does not have to be self-signed according to
X-509) by using option partial_chain.
selfsigned_peer:
The chain consisted only of one self-signed certificate.
PKIX X-509-path validation error:
For possible reasons, see public_key:pkix_path_validation/3
crl_check() = boolean() | peer | best_effort
Perform CRL (Certificate Revocation List) verification (pub-
lic_key:pkix_crls_validate/3) on all the certificates during the
path validation (public_key:pkix_path_validation/3) of the cer-
tificate chain. Defaults to false.
peer:
check is only performed on the peer certificate.
best_effort:
if certificate revocation status cannot be determined it
will be accepted as valid.
The CA certificates specified for the connection will be used to
construct the certificate chain validating the CRLs.
The CRLs will be fetched from a local or external cache. See
ssl_crl_cache_api(3erl).
crl_cache_opts() =
{Module :: atom(),
{DbHandle :: internal | term(), Args :: list()}}
Specify how to perform lookup and caching of certificate revoca-
tion lists. Module defaults to ssl_crl_cache with DbHandle be-
ing internal and an empty argument list.
There are two implementations available:
ssl_crl_cache:
This module maintains a cache of CRLs. CRLs can be added to
the cache using the function ssl_crl_cache:insert/1, and op-
tionally automatically fetched through HTTP if the following
argument is specified:
{http, timeout()}:
Enables fetching of CRLs specified as http URIs inX509
certificate extensions. Requires the OTP inets applica-
tion.
ssl_crl_hash_dir:
This module makes use of a directory where CRLs are stored
in files named by the hash of the issuer name.
The file names consist of eight hexadecimal digits followed
by .rN, where N is an integer, e.g. 1a2b3c4d.r0. For the
first version of the CRL, N starts at zero, and for each new
version, N is incremented by one. The OpenSSL utility c_re-
hash creates symlinks according to this pattern.
For a given hash value, this module finds all consecutive
.r* files starting from zero, and those files taken together
make up the revocation list. CRL files whose nextUpdate
fields are in the past, or that are issued by a different CA
that happens to have the same name hash, are excluded.
The following argument is required:
{dir, string()}:
Specifies the directory in which the CRLs can be found.
root_fun() = function()
fun(Chain::[public_key:der_encoded()]) ->
{trusted_ca, DerCert::public_key:der_encoded()} | unknown_ca}
Claim an intermediate CA in the chain as trusted. TLS then per-
forms public_key:pkix_path_validation/3 with the selected CA as
trusted anchor and the rest of the chain.
protocol_versions() = [protocol_version()]
TLS protocol versions supported by started clients and servers.
This option overrides the application environment option proto-
col_version and dtls_protocol_version. If the environment option
is not set, it defaults to all versions, supported by the SSL
application. See also ssl(7).
custom_user_lookup() =
{Lookupfun :: function(), UserState :: any()}
The lookup fun is to defined as follows:
fun(psk, PSKIdentity :: binary(), UserState :: term()) ->
{ok, SharedSecret :: binary()} | error;
fun(srp, Username :: binary(), UserState :: term()) ->
{ok, {SRPParams :: srp_param_type(), Salt :: binary(),
DerivedKey :: binary()}} | error.
For Pre-Shared Key (PSK) cipher suites, the lookup fun is called
by the client and server to determine the shared secret. When
called by the client, PSKIdentity is set to the hint presented
by the server or to undefined. When called by the server, PSKI-
dentity is the identity presented by the client.
For Secure Remote Password (SRP), the fun is only used by the
server to obtain parameters that it uses to generate its session
keys. DerivedKey is to be derived according to RFC 2945 and
RFC 5054: crypto:sha([Salt, crypto:sha([Username, <<$:>>, Pass-
word])])
session_id() = binary()
Identifies a TLS session.
log_alert() = boolean()
If set to false, TLS/DTLS Alert reports are not displayed. Dep-
recated in OTP 22, use {log_level, logging_level()} instead.
logging_level() = logger:level()
Specifies the log level for a TLS/DTLS connection. Alerts are
logged on notice level, which is the default level. The level
debug triggers verbose logging of TLS/DTLS protocol messages.
See also ssl(7)
hibernate_after() = timeout()
When an integer-value is specified, TLS/DTLS-connection goes
into hibernation after the specified number of milliseconds of
inactivity, thus reducing its memory footprint. When undefined
is specified (this is the default), the process never goes into
hibernation.
handshake_size() = integer()
Integer (24 bits unsigned). Used to limit the size of valid TLS
handshake packets to avoid DoS attacks. Defaults to 256*1024.
padding_check() = boolean()
Affects TLS-1.0 connections only. If set to false, it disables
the block cipher padding check to be able to interoperate with
legacy software.
Warning:
Using {padding_check, boolean()} makes TLS vulnerable to the
Poodle attack.
beast_mitigation() = one_n_minus_one | zero_n | disabled
Affects TLS-1.0 connections only. Used to change the BEAST miti-
gation strategy to interoperate with legacy software. Defaults
to one_n_minus_one.
one_n_minus_one - Perform 1/n-1 BEAST mitigation.
zero_n - Perform 0/n BEAST mitigation.
disabled - Disable BEAST mitigation.
Warning:
Using {beast_mitigation, disabled} makes TLS-1.0 vulnerable to
the BEAST attack.
ssl_imp() = new | old
Deprecated since OTP-17, has no affect.
session_tickets() =
client_session_tickets() | server_session_tickets()
Configures the session ticket functionalty in TLS 1.3 client and
server.
key_update_at() = integer() >= 1
Configures the maximum amount of bytes that can be sent on a TLS
1.3 connection before an automatic key update is performed.
There are cryptographic limits on the amount of plaintext which
can be safely encrypted under a given set of keys. The current
default ensures that data integrity will not be breached with
probability greater than 1/2^57. For more information see Limits
on Authenticated Encryption Use in TLS.
Warning:
The default value of this option shall provide the above men-
tioned security guarantees and it shall be reasonable for most
applications (~353 TB).
middlebox_comp_mode() = boolean()
Configures the middlebox compatibility mode on a TLS 1.3 connec-
tion.
A significant number of middleboxes misbehave when a TLS 1.3
connection is negotiated. Implementations can increase the
chance of making connections through those middleboxes by making
the TLS 1.3 handshake more like a TLS 1.2 handshake.
The middlebox compatibility mode is enabled (true) by default.
TLS/DTLS OPTION DESCRIPTIONS - CLIENT
client_option() =
{verify, client_verify_type()} |
{reuse_session, client_reuse_session()} |
{reuse_sessions, client_reuse_sessions()} |
{cacerts, client_cacerts()} |
{cacertfile, client_cafile()} |
{alpn_advertised_protocols, client_alpn()} |
{client_preferred_next_protocols,
client_preferred_next_protocols()} |
{psk_identity, client_psk_identity()} |
{srp_identity, client_srp_identity()} |
{server_name_indication, sni()} |
{max_fragment_length, max_fragment_length()} |
{customize_hostname_check, customize_hostname_check()} |
{signature_algs, client_signature_algs()} |
{fallback, fallback()} |
{session_tickets, client_session_tickets()} |
{use_ticket, use_ticket()}
client_verify_type() = verify_type()
In mode verify_none the default behavior is to allow all
x509-path validation errors. See also option verify_fun.
client_reuse_session() = session_id()
Reuses a specific session earlier saved with the option {re-
use_sessions, save} since OTP-21.3
client_reuse_sessions() = boolean() | save
When save is specified a new connection will be negotiated and
saved for later reuse. The session ID can be fetched with con-
nection_information/2 and used with the client option reuse_ses-
sion The boolean value true specifies that if possible, automa-
tized session reuse will be performed. If a new session is cre-
ated, and is unique in regard to previous stored sessions, it
will be saved for possible later reuse. Since OTP-21.3
client_cacerts() = [public_key:der_encoded()]
The DER-encoded trusted certificates. If this option is supplied
it overrides option cacertfile.
client_cafile() = file:filename()
Path to a file containing PEM-encoded CA certificates. The CA
certificates are used during server authentication and when
building the client certificate chain.
client_alpn() = [app_level_protocol()]
The list of protocols supported by the client to be sent to the
server to be used for an Application-Layer Protocol Negotiation
(ALPN). If the server supports ALPN then it will choose a proto-
col from this list; otherwise it will fail the connection with a
"no_application_protocol" alert. A server that does not support
ALPN will ignore this value.
The list of protocols must not contain an empty binary.
The negotiated protocol can be retrieved using the negoti-
ated_protocol/1 function.
client_preferred_next_protocols() =
{Precedence :: server | client,
ClientPrefs :: [app_level_protocol()]} |
{Precedence :: server | client,
ClientPrefs :: [app_level_protocol()],
Default :: app_level_protocol()}
Indicates that the client is to try to perform Next Protocol Ne-
gotiation.
If precedence is server, the negotiated protocol is the first
protocol to be shown on the server advertised list, which is
also on the client preference list.
If precedence is client, the negotiated protocol is the first
protocol to be shown on the client preference list, which is
also on the server advertised list.
If the client does not support any of the server advertised pro-
tocols or the server does not advertise any protocols, the
client falls back to the first protocol in its list or to the
default protocol (if a default is supplied). If the server does
not support Next Protocol Negotiation, the connection terminates
if no default protocol is supplied.
max_fragment_length() = undefined | 512 | 1024 | 2048 | 4096
Specifies the maximum fragment length the client is prepared to
accept from the server. See RFC 6066
client_psk_identity() = psk_identity()
Specifies the identity the client presents to the server. The
matching secret is found by calling user_lookup_fun
client_srp_identity() = srp_identity()
Specifies the username and password to use to authenticate to
the server.
sni() = hostname() | disable
Specify the hostname to be used in TLS Server Name Indication
extension. If not specified it will default to the Host argument
of connect/[3,4] unless it is of type inet:ipaddress().
The HostName will also be used in the hostname verification of
the peer certificate using public_key:pkix_verify_hostname/2.
The special value disable prevents the Server Name Indication
extension from being sent and disables the hostname verification
check public_key:pkix_verify_hostname/2
customize_hostname_check() = list()
Customizes the hostname verification of the peer certificate, as
different protocols that use TLS such as HTTP or LDAP may want
to do it differently, for possible options see pub-
lic_key:pkix_verify_hostname/3
fallback() = boolean()
Send special cipher suite TLS_FALLBACK_SCSV to avoid undesired
TLS version downgrade. Defaults to false
Warning:
Note this option is not needed in normal TLS usage and should
not be used to implement new clients. But legacy clients that
retries connections in the following manner
ssl:connect(Host, Port, [...{versions, ['tlsv2', 'tlsv1.1',
'tlsv1']}])
ssl:connect(Host, Port, [...{versions, [tlsv1.1', 'tlsv1']},
{fallback, true}])
ssl:connect(Host, Port, [...{versions, ['tlsv1']}, {fallback,
true}])
may use it to avoid undesired TLS version downgrade. Note that
TLS_FALLBACK_SCSV must also be supported by the server for the
prevention to work.
client_signature_algs() = signature_algs()
In addition to the algorithms negotiated by the cipher suite
used for key exchange, payload encryption, message authentica-
tion and pseudo random calculation, the TLS signature algorithm
extension Section 7.4.1.4.1 in RFC 5246 may be used, from TLS
1.2, to negotiate which signature algorithm to use during the
TLS handshake. If no lower TLS versions than 1.2 are supported,
the client will send a TLS signature algorithm extension with
the algorithms specified by this option. Defaults to
[
%% SHA2
{sha512, ecdsa},
{sha512, rsa},
{sha384, ecdsa},
{sha384, rsa},
{sha256, ecdsa},
{sha256, rsa},
{sha224, ecdsa},
{sha224, rsa},
%% SHA
{sha, ecdsa},
{sha, rsa},
{sha, dsa},
]
The algorithms should be in the preferred order. Selected signa-
ture algorithm can restrict which hash functions that may be se-
lected. Default support for {md5, rsa} removed in ssl-8.0
client_session_tickets() = disabled | manual | auto
Configures the session ticket functionality. Allowed values are
disabled, manual and auto. If it is set to manual the client
will send the ticket information to user process in a 3-tuple:
{ssl, session_ticket, {SNI, TicketData}}
where SNI is the ServerNameIndication and TicketData is the ex-
tended ticket data that can be used in subsequent session re-
sumptions.
If it is set to auto, the client automatically handles received
tickets and tries to use them when making new TLS connections
(session resumption with pre-shared keys).
Note:
This option is supported by TLS 1.3 and above. See also SSL's
Users Guide, Session Tickets and Session Resumption in TLS 1.3
use_ticket() = [binary()]
Configures the session tickets to be used for session resump-
tion. It is a mandatory option in manual mode (session_tickets =
manual).
Note:
Session tickets are only sent to user if option session_tickets
is set to manual
This option is supported by TLS 1.3 and above. See also SSL's
Users Guide, Session Tickets and Session Resumption in TLS 1.3
TLS/DTLS OPTION DESCRIPTIONS - SERVER
server_option() =
{cacerts, server_cacerts()} |
{cacertfile, server_cafile()} |
{dh, dh_der()} |
{dhfile, dh_file()} |
{verify, server_verify_type()} |
{fail_if_no_peer_cert, fail_if_no_peer_cert()} |
{reuse_sessions, server_reuse_sessions()} |
{reuse_session, server_reuse_session()} |
{alpn_preferred_protocols, server_alpn()} |
{next_protocols_advertised, server_next_protocol()} |
{psk_identity, server_psk_identity()} |
{honor_cipher_order, boolean()} |
{sni_hosts, sni_hosts()} |
{sni_fun, sni_fun()} |
{honor_cipher_order, honor_cipher_order()} |
{honor_ecc_order, honor_ecc_order()} |
{client_renegotiation, client_renegotiation()} |
{signature_algs, server_signature_algs()} |
{session_tickets, server_session_tickets()} |
{anti_replay, anti_replay()}
server_cacerts() = [public_key:der_encoded()]
The DER-encoded trusted certificates. If this option is supplied
it overrides option cacertfile.
server_cafile() = file:filename()
Path to a file containing PEM-encoded CA certificates. The CA
certificates are used to build the server certificate chain and
for client authentication. The CAs are also used in the list of
acceptable client CAs passed to the client when a certificate is
requested. Can be omitted if there is no need to verify the
client and if there are no intermediate CAs for the server cer-
tificate.
dh_der() = binary()
The DER-encoded Diffie-Hellman parameters. If specified, it
overrides option dhfile.
Warning:
The dh_der option is not supported by TLS 1.3. Use the sup-
ported_groups option instead.
dh_file() = file:filename()
Path to a file containing PEM-encoded Diffie Hellman parameters
to be used by the server if a cipher suite using Diffie Hellman
key exchange is negotiated. If not specified, default parameters
are used.
Warning:
The dh_file option is not supported by TLS 1.3. Use the sup-
ported_groups option instead.
server_verify_type() = verify_type()
A server only does x509-path validation in mode verify_peer, as
it then sends a certificate request to the client (this message
is not sent if the verify option is verify_none). You can then
also want to specify option fail_if_no_peer_cert.
fail_if_no_peer_cert() = boolean()
Used together with {verify, verify_peer} by an TLS/DTLS server.
If set to true, the server fails if the client does not have a
certificate to send, that is, sends an empty certificate. If set
to false, it fails only if the client sends an invalid certifi-
cate (an empty certificate is considered valid). Defaults to
false.
server_reuse_sessions() = boolean()
The boolean value true specifies that the server will agree to
reuse sessions. Setting it to false will result in an empty ses-
sion table, that is no sessions will be reused. See also option
reuse_session
server_reuse_session() = function()
Enables the TLS/DTLS server to have a local policy for deciding
if a session is to be reused or not. Meaningful only if re-
use_sessions is set to true. SuggestedSessionId is a binary(),
PeerCert is a DER-encoded certificate, Compression is an enumer-
ation integer, and CipherSuite is of type ciphersuite().
server_alpn() = [app_level_protocol()]
Indicates the server will try to perform Application-Layer Pro-
tocol Negotiation (ALPN).
The list of protocols is in order of preference. The protocol
negotiated will be the first in the list that matches one of the
protocols advertised by the client. If no protocol matches, the
server will fail the connection with a "no_application_protocol"
alert.
The negotiated protocol can be retrieved using the negoti-
ated_protocol/1 function.
server_next_protocol() = [app_level_protocol()]
List of protocols to send to the client if the client indicates
that it supports the Next Protocol extension. The client can se-
lect a protocol that is not on this list. The list of protocols
must not contain an empty binary. If the server negotiates a
Next Protocol, it can be accessed using the negotiated_next_pro-
tocol/1 method.
server_psk_identity() = psk_identity()
Specifies the server identity hint, which the server presents to
the client.
honor_cipher_order() = boolean()
If set to true, use the server preference for cipher selection.
If set to false (the default), use the client preference.
sni_hosts() =
[{hostname(), [server_option() | common_option()]}]
If the server receives a SNI (Server Name Indication) from the
client matching a host listed in the sni_hosts option, the spe-
cific options for that host will override previously specified
options. The option sni_fun, and sni_hosts are mutually exclu-
sive.
sni_fun() = function()
If the server receives a SNI (Server Name Indication) from the
client, the given function will be called to retrieve
[server_option()] for the indicated server. These options will
be merged into predefined [server_option()] list. The function
should be defined as: fun(ServerName :: string()) -> [server_op-
tion()] and can be specified as a fun or as named fun mod-
ule:function/1 The option sni_fun, and sni_hosts are mutually
exclusive.
client_renegotiation() = boolean()
In protocols that support client-initiated renegotiation, the
cost of resources of such an operation is higher for the server
than the client. This can act as a vector for denial of service
attacks. The SSL application already takes measures to counter-
act such attempts, but client-initiated renegotiation can be
strictly disabled by setting this option to false. The default
value is true. Note that disabling renegotiation can result in
long-lived connections becoming unusable due to limits on the
number of messages the underlying cipher suite can encipher.
honor_cipher_order() = boolean()
If true, use the server's preference for cipher selection. If
false (the default), use the client's preference.
honor_ecc_order() = boolean()
If true, use the server's preference for ECC curve selection. If
false (the default), use the client's preference.
server_signature_algs() = signature_algs()
The algorithms specified by this option will be the ones ac-
cepted by the server in a signature algorithm negotiation, in-
troduced in TLS-1.2. The algorithms will also be offered to the
client if a client certificate is requested. For more details
see the corresponding client option.
server_session_tickets() = disabled | stateful | stateless
Configures the session ticket functionality. Allowed values are
disabled, stateful and stateless.
If it is set to stateful or stateless, session resumption with
pre-shared keys is enabled and the server will send stateful or
stateless session tickets to the client after successful connec-
tions.
A stateful session ticket is a database reference to internal
state information. A stateless session ticket is a self-en-
crypted binary that contains both cryptographic keying material
and state data.
Note:
This option is supported by TLS 1.3 and above. See also SSL's
Users Guide, Session Tickets and Session Resumption in TLS 1.3
anti_replay() =
'10k' | '100k' |
{bloom_filter_window_size(),
bloom_filter_hash_functions(),
bloom_filter_bits()}
Configures the server's built-in anti replay feature based on
Bloom filters.
Allowed values are the pre-defined '10k', '100k' or a custom
3-tuple that defines the properties of the bloom filters: {Win-
dowSize, HashFunctions, Bits}. WindowSize is the number of sec-
onds after the current Bloom filter is rotated and also the win-
dow size used for freshness checks. HashFunctions is the number
hash functions and Bits is the number of bits in the bit vector.
'10k' and '100k' are simple defaults with the following proper-
ties:
* '10k': Bloom filters can hold 10000 elements with 3% proba-
bility of false positives. WindowSize: 10, HashFunctions: 5,
Bits: 72985 (8.91 KiB).
* '100k': Bloom filters can hold 100000 elements with 3% prob-
ability of false positives. WindowSize: 10, HashFunctions:
5, Bits: 729845 (89.09 KiB).
Note:
This option is supported by TLS 1.3 and above and only with
stateless session tickets. Ticket lifetime, the number of tick-
ets sent by the server and the maximum number of tickets stored
by the server in stateful mode are configured by application
variables. See also SSL's Users Guide, Anti-Replay Protection
in TLS 1.3
connection_info() =
[common_info() |
curve_info() |
ssl_options_info() |
security_info()]
common_info() =
{protocol, protocol_version()} |
{session_id, session_id()} |
{session_resumption, boolean()} |
{selected_cipher_suite, erl_cipher_suite()} |
{sni_hostname, term()} |
{srp_username, term()}
curve_info() = {ecc, {named_curve, term()}}
ssl_options_info() = tls_option()
security_info() =
{client_random, binary()} |
{server_random, binary()} |
{master_secret, binary()}
connection_info_items() = [connection_info_item()]
connection_info_item() =
protocol | session_id | session_resumption |
selected_cipher_suite | sni_hostname | srp_username | ecc |
client_random | server_random | master_secret |
tls_options_name()
tls_options_name() = atom()
EXPORTS
append_cipher_suites(Deferred, Suites) -> ciphers()
Types:
Deferred = ciphers() | cipher_filters()
Suites = ciphers()
Make Deferred suites become the least preferred suites, that is
put them at the end of the cipher suite list Suites after remov-
ing them from Suites if present. Deferred may be a list of ci-
pher suits or a list of filters in which case the filters are
use on Suites to extract the Deferred cipher list.
cipher_suites() -> [old_cipher_suite()] | [string()]
cipher_suites(Type) -> [old_cipher_suite() | string()]
Types:
Type = erlang | openssl | all
Deprecated in OTP 21, use cipher_suites/2 instead.
cipher_suites(Description, Version) -> ciphers()
Types:
Description = default | all | exclusive | anonymous
Version = protocol_version()
Lists all possible cipher suites corresponding to Description
that are available. The exclusive option will exclusively list
cipher suites introduced in Version whereas the the other op-
tions are inclusive from the lowest possible version to Version.
The all options includes all suites except the anonymous.
Note:
TLS-1.3 has no overlapping cipher suites with previous TLS ver-
sions, that is the result of cipher_suites(all, 'tlsv1.3'). con-
tains a separate set of suites that can be used with TLS-1.3 an
other set that can be used if a lower version is negotiated. No
anonymous suites are supported by TLS-1.3.
Also note that the cipher suites returned by this function are
the cipher suites that the OTP ssl application can support pro-
vided that they are supported by the cryptolib linked with the
OTP crypto application. Use ssl:filter_cipher_suites(Suites,
[]). to filter the list for the current cryptolib. Note that ci-
pher suites may be filtered out because they are too old or too
new depending on the cryptolib
cipher_suites(Description, Version, StringType :: rfc | openssl) ->
[string()]
Types:
Description = default | all | exclusive | anonymous
Version = protocol_version()
Same as cipher_suites/2 but lists RFC or OpenSSL string names
instead of erl_cipher_suite()
eccs() -> NamedCurves
eccs(Version) -> NamedCurves
Types:
Version = protocol_version()
NamedCurves = [named_curve()]
Returns a list of supported ECCs. eccs() is equivalent to call-
ing eccs(Protocol) with all supported protocols and then dedu-
plicating the output.
clear_pem_cache() -> ok
PEM files, used by ssl API-functions, are cached. The cache is
regularly checked to see if any cache entries should be invali-
dated, however this function provides a way to unconditionally
clear the whole cache.
connect(TCPSocket, TLSOptions) ->
{ok, sslsocket()} |
{error, reason()} |
{option_not_a_key_value_tuple, any()}
connect(TCPSocket, TLSOptions, Timeout) ->
{ok, sslsocket()} | {error, reason()}
Types:
TCPSocket = socket()
TLSOptions = [tls_client_option()]
Timeout = timeout()
Upgrades a gen_tcp, or equivalent, connected socket to a TLS
socket, that is, performs the client-side TLS handshake.
Note:
If the option verify is set to verify_peer the option
server_name_indication shall also be specified, if it is not no
Server Name Indication extension will be sent, and pub-
lic_key:pkix_verify_hostname/2 will be called with the IP-ad-
dress of the connection as ReferenceID, which is proably not
what you want.
If the option {handshake, hello} is used the handshake is paused
after receiving the server hello message and the success re-
sponse is {ok, SslSocket, Ext} instead of {ok, SslSocket}.
Thereafter the handshake is continued or canceled by calling
handshake_continue/3 or handshake_cancel/1.
If the option active is set to once, true or an integer value,
the process owning the sslsocket will receive messages of type
active_msgs()
connect(Host, Port, TLSOptions) ->
{ok, sslsocket()} |
{ok, sslsocket(), Ext :: protocol_extensions()} |
{error, reason()} |
{option_not_a_key_value_tuple, any()}
connect(Host, Port, TLSOptions, Timeout) ->
{ok, sslsocket()} |
{ok, sslsocket(), Ext :: protocol_extensions()} |
{error, reason()} |
{option_not_a_key_value_tuple, any()}
Types:
Host = host()
Port = inet:port_number()
TLSOptions = [tls_client_option()]
Timeout = timeout()
Opens a TLS/DTLS connection to Host, Port.
When the option verify is set to verify_peer the check pub-
lic_key:pkix_verify_hostname/2 will be performed in addition to
the usual x509-path validation checks. If the check fails the
error {bad_cert, hostname_check_failed} will be propagated to
the path validation fun verify_fun, where it is possible to do
customized checks by using the full possibilities of the pub-
lic_key:pkix_verify_hostname/3 API. When the option
server_name_indication is provided, its value (the DNS name)
will be used as ReferenceID to public_key:pkix_verify_host-
name/2. When no server_name_indication option is given, the Host
argument will be used as Server Name Indication extension. The
Host argument will also be used for the public_key:pkix_ver-
ify_hostname/2 check and if the Host argument is an inet:ip_ad-
dress() the ReferenceID used for the check will be {ip, Host}
otherwise dns_id will be assumed with a fallback to ip if that
fails.
Note:
According to good practices certificates should not use IP-ad-
dresses as "server names". It would be very surprising if this
happen outside a closed network.
If the option {handshake, hello} is used the handshake is paused
after receiving the server hello message and the success re-
sponse is {ok, SslSocket, Ext} instead of {ok, SslSocket}.
Thereafter the handshake is continued or canceled by calling
handshake_continue/3 or handshake_cancel/1.
If the option active is set to once, true or an integer value,
the process owning the sslsocket will receive messages of type
active_msgs()
close(SslSocket) -> ok | {error, Reason}
Types:
SslSocket = sslsocket()
Reason = any()
Closes a TLS/DTLS connection.
close(SslSocket, How) -> ok | {ok, port()} | {error, Reason}
Types:
SslSocket = sslsocket()
How = timeout() | {NewController :: pid(), timeout()}
Reason = any()
Closes or downgrades a TLS connection. In the latter case the
transport connection will be handed over to the NewController
process after receiving the TLS close alert from the peer. The
returned transport socket will have the following options set:
[{active, false}, {packet, 0}, {mode, binary}]
controlling_process(SslSocket, NewOwner) -> ok | {error, Reason}
Types:
SslSocket = sslsocket()
NewOwner = pid()
Reason = any()
Assigns a new controlling process to the SSL socket. A control-
ling process is the owner of an SSL socket, and receives all
messages from the socket.
connection_information(SslSocket) ->
{ok, Result} | {error, reason()}
Types:
SslSocket = sslsocket()
Result = connection_info()
Returns the most relevant information about the connection, ssl
options that are undefined will be filtered out. Note that val-
ues that affect the security of the connection will only be re-
turned if explicitly requested by connection_information/2.
Note:
The legacy Item = cipher_suite is still supported and returns
the cipher suite on its (undocumented) legacy format. It should
be replaced by selected_cipher_suite.
connection_information(SslSocket, Items) ->
{ok, Result} | {error, reason()}
Types:
SslSocket = sslsocket()
Items = connection_info_items()
Result = connection_info()
Returns the requested information items about the connection, if
they are defined.
Note that client_random, server_random and master_secret are
values that affect the security of connection. Meaningful atoms,
not specified above, are the ssl option names.
Note:
If only undefined options are requested the resulting list can
be empty.
filter_cipher_suites(Suites, Filters) -> Ciphers
Types:
Suites = ciphers()
Filters = cipher_filters()
Ciphers = ciphers()
Removes cipher suites if any of the filter functions returns
false for any part of the cipher suite. If no filter function is
supplied for some part the default behaviour regards it as if
there was a filter function that returned true. For examples see
Customizing cipher suits Additionaly this function also filters
the cipher suites to exclude cipher suites not supported by the
cryptolib used by the OTP crypto application. That is calling
ssl:filter_cipher_suites(Suites, []) will be equivalent to only
applying the filters for cryptolib support.
format_error(Reason :: {error, Reason}) -> string()
Types:
Reason = any()
Presents the error returned by an SSL function as a printable
string.
getopts(SslSocket, OptionNames) ->
{ok, [gen_tcp:option()]} | {error, reason()}
Types:
SslSocket = sslsocket()
OptionNames = [gen_tcp:option_name()]
Gets the values of the specified socket options.
getstat(SslSocket) -> {ok, OptionValues} | {error, inet:posix()}
getstat(SslSocket, Options) ->
{ok, OptionValues} | {error, inet:posix()}
Types:
SslSocket = sslsocket()
Options = [inet:stat_option()]
OptionValues = [{inet:stat_option(), integer()}]
Gets one or more statistic options for the underlying TCP
socket.
See inet:getstat/2 for statistic options description.
handshake(HsSocket) ->
{ok, SslSocket} |
{ok, SslSocket, Ext} |
{error, Reason}
handshake(HsSocket, Timeout) ->
{ok, SslSocket} |
{ok, SslSocket, Ext} |
{error, Reason}
Types:
HsSocket = sslsocket()
Timeout = timeout()
SslSocket = sslsocket()
Ext = protocol_extensions()
Reason = closed | timeout | error_alert()
Performs the TLS/DTLS server-side handshake.
Returns a new TLS/DTLS socket if the handshake is successful.
If the option active is set to once, true or an integer value,
the process owning the sslsocket will receive messages of type
active_msgs()
handshake(Socket, Options) ->
{ok, SslSocket} |
{ok, SslSocket, Ext} |
{error, Reason}
handshake(Socket, Options, Timeout) ->
{ok, SslSocket} |
{ok, SslSocket, Ext} |
{error, Reason}
Types:
Socket = socket() | sslsocket()
SslSocket = sslsocket()
Options = [server_option()]
Timeout = timeout()
Ext = protocol_extensions()
Reason = closed | timeout | {options, any()} | error_alert()
If Socket is a ordinary socket(): upgrades a gen_tcp, or equiva-
lent, socket to an SSL socket, that is, performs the TLS server-
side handshake and returns a TLS socket.
Warning:
The Socket shall be in passive mode ({active, false}) before
calling this function or else the behavior of this function is
undefined.
If Socket is an sslsocket() : provides extra TLS/DTLS options
to those specified in listen/2 and then performs the TLS/DTLS
handshake. Returns a new TLS/DTLS socket if the handshake is
successful.
If option {handshake, hello} is specified the handshake is
paused after receiving the client hello message and the success
response is {ok, SslSocket, Ext} instead of {ok, SslSocket}.
Thereafter the handshake is continued or canceled by calling
handshake_continue/3 or handshake_cancel/1.
If the option active is set to once, true or an integer value,
the process owning the sslsocket will receive messages of type
active_msgs()
handshake_cancel(Sslsocket :: #sslsocket{}) -> any()
Cancel the handshake with a fatal USER_CANCELED alert.
handshake_continue(HsSocket, Options) ->
{ok, SslSocket} | {error, Reason}
handshake_continue(HsSocket, Options, Timeout) ->
{ok, SslSocket} | {error, Reason}
Types:
HsSocket = sslsocket()
Options = [tls_client_option() | tls_server_option()]
Timeout = timeout()
SslSocket = sslsocket()
Reason = closed | timeout | error_alert()
Continue the TLS handshake possiby with new, additional or
changed options.
listen(Port, Options) -> {ok, ListenSocket} | {error, reason()}
Types:
Port = inet:port_number()
Options = [tls_server_option()]
ListenSocket = sslsocket()
Creates an SSL listen socket.
negotiated_protocol(SslSocket) -> {ok, Protocol} | {error, Reason}
Types:
SslSocket = sslsocket()
Protocol = binary()
Reason = protocol_not_negotiated
Returns the protocol negotiated through ALPN or NPN extensions.
peercert(SslSocket) -> {ok, Cert} | {error, reason()}
Types:
SslSocket = sslsocket()
Cert = binary()
The peer certificate is returned as a DER-encoded binary. The
certificate can be decoded with public_key:pkix_decode_cert/2
peername(SslSocket) -> {ok, {Address, Port}} | {error, reason()}
Types:
SslSocket = sslsocket()
Address = inet:ip_address()
Port = inet:port_number()
Returns the address and port number of the peer.
prepend_cipher_suites(Preferred, Suites) -> ciphers()
Types:
Preferred = ciphers() | cipher_filters()
Suites = ciphers()
Make Preferred suites become the most preferred suites that is
put them at the head of the cipher suite list Suites after re-
moving them from Suites if present. Preferred may be a list of
cipher suits or a list of filters in which case the filters are
use on Suites to extract the preferred cipher list.
prf(SslSocket, Secret, Label, Seed, WantedLength) ->
{ok, binary()} | {error, reason()}
Types:
SslSocket = sslsocket()
Secret = binary() | master_secret
Label = binary()
Seed = [binary() | prf_random()]
WantedLength = integer() >= 0
Uses the Pseudo-Random Function (PRF) of a TLS session to gener-
ate extra key material. It either takes user-generated values
for Secret and Seed or atoms directing it to use a specific
value from the session security parameters.
recv(SslSocket, Length) -> {ok, Data} | {error, reason()}
recv(SslSocket, Length, Timeout) -> {ok, Data} | {error, reason()}
Types:
SslSocket = sslsocket()
Length = integer()
Data = binary() | list() | HttpPacket
Timeout = timeout()
HttpPacket = any()
See the description of HttpPacket in erlang:decode_packet/3
in ERTS.
Receives a packet from a socket in passive mode. A closed socket
is indicated by return value {error, closed}.
Argument Length is meaningful only when the socket is in mode
raw and denotes the number of bytes to read. If Length = 0, all
available bytes are returned. If Length > 0, exactly Length
bytes are returned, or an error; possibly discarding less than
Length bytes of data when the socket gets closed from the other
side.
Optional argument Timeout specifies a time-out in milliseconds.
The default value is infinity.
renegotiate(SslSocket) -> ok | {error, reason()}
Types:
SslSocket = sslsocket()
Initiates a new handshake. A notable return value is {error,
renegotiation_rejected} indicating that the peer refused to go
through with the renegotiation, but the connection is still ac-
tive using the previously negotiated session.
update_keys(SslSocket, Type) -> ok | {error, reason()}
Types:
SslSocket = sslsocket()
Type = write | read_write
There are cryptographic limits on the amount of plaintext which
can be safely encrypted under a given set of keys. If the amount
of data surpasses those limits, a key update is triggered and a
new set of keys are installed. See also the option key_up-
date_at.
This function can be used to explicitly start a key update on a
TLS 1.3 connection. There are two types of the key update: if
Type is set to write, only the writing key is updated; if Type
is set to read_write, both the reading and writing keys are up-
dated.
send(SslSocket, Data) -> ok | {error, reason()}
Types:
SslSocket = sslsocket()
Data = iodata()
Writes Data to SslSocket.
A notable return value is {error, closed} indicating that the
socket is closed.
setopts(SslSocket, Options) -> ok | {error, reason()}
Types:
SslSocket = sslsocket()
Options = [gen_tcp:option()]
Sets options according to Options for socket SslSocket.
shutdown(SslSocket, How) -> ok | {error, reason()}
Types:
SslSocket = sslsocket()
How = read | write | read_write
Immediately closes a socket in one or two directions.
How == write means closing the socket for writing, reading from
it is still possible.
To be able to handle that the peer has done a shutdown on the
write side, option {exit_on_close, false} is useful.
ssl_accept(SslSocket) -> ok | {error, Reason}
ssl_accept(Socket, TimeoutOrOptions) ->
ok | {ok, sslsocket()} | {error, Reason}
Types:
Socket = sslsocket() | socket()
TimeoutOrOptions = timeout() | [tls_server_option()]
Reason = timeout | closed | {options, any()} | error_alert()
Deprecated in OTP 21, use handshake/[1,2] instead.
Note:
handshake/[1,2] always returns a new socket.
ssl_accept(Socket, Options, Timeout) ->
ok | {ok, sslsocket()} | {error, Reason}
Types:
Socket = sslsocket() | socket()
Options = [tls_server_option()]
Timeout = timeout()
Reason = timeout | closed | {options, any()} | error_alert()
Deprecated in OTP 21, use handshake/[2,3] instead.
Note:
handshake/[2,3] always returns a new socket.
sockname(SslSocket) -> {ok, {Address, Port}} | {error, reason()}
Types:
SslSocket = sslsocket()
Address = inet:ip_address()
Port = inet:port_number()
Returns the local address and port number of socket SslSocket.
start() -> ok | {error, reason()}
start(Type :: permanent | transient | temporary) ->
ok | {error, reason()}
Starts the SSL application. Default type is temporary.
stop() -> ok
Stops the SSL application.
str_to_suite(CipherSuiteName) -> erl_cipher_suite()
Types:
CipherSuiteName =
string() |
{error, {not_recognized, CipherSuiteName :: string()}}
Converts an RFC or OpenSSL name string to an erl_cipher_suite()
Returns an error if the cipher suite is not supported or the
name is not a valid cipher suite name.
suite_to_openssl_str(CipherSuite) -> string()
Types:
CipherSuite = erl_cipher_suite()
Converts erl_cipher_suite() to OpenSSL name string.
PRE TLS-1.3 these names differ for RFC names
suite_to_str(CipherSuite) -> string()
Types:
CipherSuite = erl_cipher_suite()
Converts erl_cipher_suite() to RFC name string.
transport_accept(ListenSocket) ->
{ok, SslSocket} | {error, reason()}
transport_accept(ListenSocket, Timeout) ->
{ok, SslSocket} | {error, reason()}
Types:
ListenSocket = sslsocket()
Timeout = timeout()
SslSocket = sslsocket()
Accepts an incoming connection request on a listen socket. Lis-
tenSocket must be a socket returned from listen/2. The socket
returned is to be passed to handshake/[2,3] to complete hand-
shaking, that is, establishing the TLS/DTLS connection.
Warning:
Most API functions require that the TLS/DTLS connection is es-
tablished to work as expected.
The accepted socket inherits the options set for ListenSocket in
listen/2.
The default value for Timeout is infinity. If Timeout is speci-
fied and no connection is accepted within the given time, {er-
ror, timeout} is returned.
versions() -> [VersionInfo]
Types:
VersionInfo =
{ssl_app, string()} |
{supported | available | implemented, [tls_version()]} |
{supported_dtls | available_dtls | implemented_dtls,
[dtls_version()]}
Lists information, mainly concerning TLS/DTLS versions, in run-
time for debugging and testing purposes.
app_vsn:
The application version of the SSL application.
supported:
TLS versions supported with current application environment
and crypto library configuration. Overridden by a version
option on connect/[2,3,4], listen/2, and ssl_ac-
cept/[1,2,3]. For the negotiated TLS version, see connec-
tion_information/1 .
supported_dtls:
DTLS versions supported with current application environment
and crypto library configuration. Overridden by a version
option on connect/[2,3,4], listen/2, and ssl_ac-
cept/[1,2,3]. For the negotiated DTLS version, see connec-
tion_information/1 .
available:
All TLS versions supported with the linked crypto library.
available_dtls:
All DTLS versions supported with the linked crypto library.
implemented:
All TLS versions supported by the SSL application if linked
with a crypto library with the necessary support.
implemented_dtls:
All DTLS versions supported by the SSL application if linked
with a crypto library with the necessary support.
SEE ALSO
inet(3erl) and gen_tcp(3erl) gen_udp(3erl)
Ericsson AB ssl 10.0 ssl(3erl)