- Qt 6.4
- Qt Network
- C++ Classes
- QSslConfiguration
- Qt 6.4.2 Reference Documentation

# QSslConfiguration Class

The QSslConfiguration class holds the configuration and state of an SSL connection. More...

Header: | #include <QSslConfiguration>
CMake: | find_package(Qt6 REQUIRED COMPONENTS Network) target_link_libraries(mytarget PRIVATE Qt6::Network)
qmake: | QT += network

- List of all members, including inherited members

Note: All functions in this class are reentrant.

## Public Types

enum | NextProtocolNegotiationStatus { NextProtocolNegotiationNone, NextProtocolNegotiationNegotiated, NextProtocolNegotiationUnsupported }

## Public Functions

| QSslConfiguration(const QSslConfiguration &other)
| QSslConfiguration()
QSslConfiguration & | operator=(const QSslConfiguration &other)
| ~QSslConfiguration()
void | addCaCertificate(const QSslCertificate &certificate)
bool | addCaCertificates(const QString &path, QSsl::EncodingFormat format = QSsl::Pem, QSslCertificate::PatternSyntax syntax = QSslCertificate::PatternSyntax::FixedString)
void | addCaCertificates(const QList<QSslCertificate> &certificates)
QList<QByteArray> | allowedNextProtocols() const
QMap<QByteArray, QVariant> | backendConfiguration() const
QList<QSslCertificate> | caCertificates() const
QList<QSslCipher> | ciphers() const
QSslDiffieHellmanParameters | diffieHellmanParameters() const
bool | dtlsCookieVerificationEnabled() const
QList<QSslEllipticCurve> | ellipticCurves() const
QSslKey | ephemeralServerKey() const
bool | handshakeMustInterruptOnError() const
bool | isNull() const
QSslCertificate | localCertificate() const
QList<QSslCertificate> | localCertificateChain() const
bool | missingCertificateIsFatal() const
QByteArray | nextNegotiatedProtocol() const
QSslConfiguration::NextProtocolNegotiationStatus | nextProtocolNegotiationStatus() const
bool | ocspStaplingEnabled() const
QSslCertificate | peerCertificate() const
QList<QSslCertificate> | peerCertificateChain() const
int | peerVerifyDepth() const
QSslSocket::PeerVerifyMode | peerVerifyMode() const
QByteArray | preSharedKeyIdentityHint() const
QSslKey | privateKey() const
QSsl::SslProtocol | protocol() const
QSslCipher | sessionCipher() const
QSsl::SslProtocol | sessionProtocol() const
QByteArray | sessionTicket() const
int | sessionTicketLifeTimeHint() const
void | setAllowedNextProtocols(const QList<QByteArray> &protocols)
void | setBackendConfiguration(const QMap<QByteArray, QVariant> &backendConfiguration = QMap<QByteArray, QVariant>())
void | setBackendConfigurationOption(const QByteArray &name, const QVariant &value)
void | setCaCertificates(const QList<QSslCertificate> &certificates)
void | setCiphers(const QList<QSslCipher> &ciphers)
void | setCiphers(const QString &ciphers)
void | setDiffieHellmanParameters(const QSslDiffieHellmanParameters &dhparams)
void | setDtlsCookieVerificationEnabled(bool enable)
void | setEllipticCurves(const QList<QSslEllipticCurve> &curves)
void | setHandshakeMustInterruptOnError(bool interrupt)
void | setLocalCertificate(const QSslCertificate &certificate)
void | setLocalCertificateChain(const QList<QSslCertificate> &localChain)
void | setMissingCertificateIsFatal(bool cannotRecover)
void | setOcspStaplingEnabled(bool enabled)
void | setPeerVerifyDepth(int depth)
void | setPeerVerifyMode(QSslSocket::PeerVerifyMode mode)
void | setPreSharedKeyIdentityHint(const QByteArray &hint)
void | setPrivateKey(const QSslKey &key)
void | setProtocol(QSsl::SslProtocol protocol)
void | setSessionTicket(const QByteArray &sessionTicket)
void | setSslOption(QSsl::SslOption option, bool on)
void | swap(QSslConfiguration &other)
bool | testSslOption(QSsl::SslOption option) const
bool | operator!=(const QSslConfiguration &other) const
bool | operator==(const QSslConfiguration &other) const

## Static Public Members

const char[] | NextProtocolHttp1_1
QSslConfiguration | defaultConfiguration()
QSslConfiguration | defaultDtlsConfiguration()
void | setDefaultConfiguration(const QSslConfiguration &configuration)
void | setDefaultDtlsConfiguration(const QSslConfiguration &configuration)
QList<QSslCipher> | supportedCiphers()
QList<QSslEllipticCurve> | supportedEllipticCurves()
QList<QSslCertificate> | systemCaCertificates()

## Detailed Description

QSslConfiguration is used by Qt networking classes to relay information about an open SSL connection and to allow the application to control certain features of that connection.

The settings that QSslConfiguration currently supports are:

- The SSL/TLS protocol to be used
- The certificate to be presented to the peer during connection and its associated private key
- The ciphers allowed to be used for encrypting the connection
- The list of Certificate Authorities certificates that are used to validate the peer's certificate

These settings are applied only during the connection handshake. Setting them after the connection has been established has no effect.

The state that QSslConfiguration supports are:

- The certificate the peer presented during handshake, along with the chain leading to a CA certificate
- The cipher used to encrypt this session

The state can only be obtained once the SSL connection starts, but not necessarily before it's done. Some settings may change during the course of the SSL connection without need to restart it (for instance, the cipher can be changed over time).

State in QSslConfiguration objects cannot be changed.

QSslConfiguration can be used with QSslSocket and the Network Access API.

Note that changing settings in QSslConfiguration is not enough to change the settings in the related SSL connection. You must call setSslConfiguration on a modified QSslConfiguration object to achieve that. The following example illustrates how to change the protocol to TLSv1_2 in a QSslSocket object:

     QSslConfiguration config = sslSocket.sslConfiguration();
     config.setProtocol(QSsl::TlsV1_2);
     sslSocket.setSslConfiguration(config);

See also QSsl::SslProtocol, QSslCertificate, QSslCipher, QSslKey, QSslSocket, QNetworkAccessManager, QSslSocket::sslConfiguration(), and QSslSocket::setSslConfiguration().

## Member Type Documentation

### enum QSslConfiguration::NextProtocolNegotiationStatus

Describes the status of the Next Protocol Negotiation (NPN) or Application-Layer Protocol Negotiation (ALPN).

Constant | Value | Description
--- | --- | ---
`QSslConfiguration::NextProtocolNegotiationNone` | `0` | No application protocol has been negotiated (yet).
`QSslConfiguration::NextProtocolNegotiationNegotiated` | `1` | A next protocol has been negotiated (see nextNegotiatedProtocol()).
`QSslConfiguration::NextProtocolNegotiationUnsupported` | `2` | The client and server could not agree on a common next application protocol.

## Member Function Documentation

### QSslConfiguration::QSslConfiguration(const QSslConfiguration &other)

Copies the configuration and state of other. If other is null, this object will be null too.

### QSslConfiguration::QSslConfiguration()

Constructs an empty SSL configuration. This configuration contains no valid settings and the state will be empty. isNull() will return true after this constructor is called.

Once any setter methods are called, isNull() will return false.

### QSslConfiguration &QSslConfiguration::operator=(const QSslConfiguration &other)

Copies the configuration and state of other. If other is null, this object will be null too.

### QSslConfiguration::~QSslConfiguration()

Releases any resources held by QSslConfiguration.

### `[since 5.15]` void QSslConfiguration::addCaCertificate(const QSslCertificate &certificate)

Adds certificate to this configuration's CA certificate database. The certificate database must be set prior to the SSL handshake. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

Note: The default configuration uses the system CA certificate database. If that is not available (as is commonly the case on iOS), the default database is empty.

This function was introduced in Qt 5.15.

See also caCertificates(), setCaCertificates(), and addCaCertificates().

### `[since 5.15]` bool QSslConfiguration::addCaCertificates(const QString &path, QSsl::EncodingFormat format = QSsl::Pem, QSslCertificate::PatternSyntax syntax = QSslCertificate::PatternSyntax::FixedString)

Searches all files in the path for certificates encoded in the specified format and adds them to this socket's CA certificate database. path must be a file or a pattern matching one or more files, as specified by syntax. Returns `true` if one or more certificates are added to the socket's CA certificate database; otherwise returns `false`.

The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

For more precise control, use addCaCertificate().

This function was introduced in Qt 5.15.

See also addCaCertificate() and QSslCertificate::fromPath().

### `[since 5.15]` void QSslConfiguration::addCaCertificates(const QList<QSslCertificate> &certificates)

Adds certificates to this configuration's CA certificate database. The certificate database must be set prior to the SSL handshake. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

Note: The default configuration uses the system CA certificate database. If that is not available (as is commonly the case on iOS), the default database is empty.

This function was introduced in Qt 5.15.

See also caCertificates(), setCaCertificates(), and addCaCertificate().

### `[since 5.3]` QList<QByteArray> QSslConfiguration::allowedNextProtocols() const

This function returns the allowed protocols to be negotiated with the server through the Next Protocol Negotiation (NPN) or Application-Layer Protocol Negotiation (ALPN) TLS extension, as set by setAllowedNextProtocols().

This function was introduced in Qt 5.3.

See also nextNegotiatedProtocol(), nextProtocolNegotiationStatus(), setAllowedNextProtocols(), and QSslConfiguration::NextProtocolHttp1_1.

### `[since 5.11]` QMap<QByteArray, QVariant> QSslConfiguration::backendConfiguration() const

Returns the backend-specific configuration.

Only options set by setBackendConfigurationOption() or setBackendConfiguration() will be returned. The internal standard configuration of the backend is not reported.

This function was introduced in Qt 5.11.

See also setBackendConfigurationOption() and setBackendConfiguration().

### QList<QSslCertificate> QSslConfiguration::caCertificates() const

Returns this connection's CA certificate database. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate. It can be modified prior to the handshake with setCaCertificates(), or with addCaCertificate() and addCaCertificates().

See also setCaCertificates(), addCaCertificate(), and addCaCertificates().

### QList<QSslCipher> QSslConfiguration::ciphers() const

Returns this connection's current cryptographic cipher suite. This list is used during the handshake phase for choosing a session cipher. The returned list of ciphers is ordered by descending preference. (i.e., the first cipher in the list is the most preferred cipher). The session cipher will be the first one in the list that is also supported by the peer.

By default, the handshake phase can choose any of the ciphers supported by this system's SSL libraries, which may vary from system to system. The list of ciphers supported by this system's SSL libraries is returned by supportedCiphers(). You can restrict the list of ciphers used for choosing the session cipher for this socket by calling setCiphers() with a subset of the supported ciphers. You can revert to using the entire set by calling setCiphers() with the list returned by supportedCiphers().

Note: This is not currently supported in the Schannel backend.

See also setCiphers() and supportedCiphers().

### `[static]` QSslConfiguration QSslConfiguration::defaultConfiguration()

Returns the default SSL configuration to be used in new SSL connections.

The default SSL configuration consists of:

- no local certificate and no private key
- protocol SecureProtocols
- the system's default CA certificate list
- the cipher list equal to the list of the SSL libraries' supported SSL ciphers that are 128 bits or more

See also supportedCiphers() and setDefaultConfiguration().

### `[static]` QSslConfiguration QSslConfiguration::defaultDtlsConfiguration()

Returns the default DTLS configuration to be used in new DTLS connections.

The default DTLS configuration consists of:

- no local certificate and no private key
- protocol DtlsV1_2OrLater
- the system's default CA certificate list
- the cipher list equal to the list of the SSL libraries' supported TLS 1.2 ciphers that use 128 or more secret bits for the cipher.

See also setDefaultDtlsConfiguration().

### `[since 5.8]` QSslDiffieHellmanParameters QSslConfiguration::diffieHellmanParameters() const

Retrieves the current set of Diffie-Hellman parameters.

If no Diffie-Hellman parameters have been set, the QSslConfiguration object defaults to using the 1024-bit MODP group from RFC 2409.

This function was introduced in Qt 5.8.

See also setDiffieHellmanParameters().

### bool QSslConfiguration::dtlsCookieVerificationEnabled() const

This function returns true if DTLS cookie verification was enabled on a server-side socket.

See also setDtlsCookieVerificationEnabled().

### `[since 5.5]` QList<QSslEllipticCurve> QSslConfiguration::ellipticCurves() const

Returns this connection's current list of elliptic curves. This list is used during the handshake phase for choosing an elliptic curve (when using an elliptic curve cipher). The returned list of curves is ordered by descending preference (i.e., the first curve in the list is the most preferred one).

By default, the handshake phase can choose any of the curves supported by this system's SSL libraries, which may vary from system to system. The list of curves supported by this system's SSL libraries is returned by QSslSocket::supportedEllipticCurves().

You can restrict the list of curves used for choosing the session cipher for this socket by calling setEllipticCurves() with a subset of the supported ciphers. You can revert to using the entire set by calling setEllipticCurves() with the list returned by QSslSocket::supportedEllipticCurves().

This function was introduced in Qt 5.5.

See also setEllipticCurves.

### `[since 5.7]` QSslKey QSslConfiguration::ephemeralServerKey() const

Returns the ephemeral server key used for cipher algorithms with forward secrecy, e.g. DHE-RSA-AES128-SHA.

The ephemeral key is only available when running in client mode, i.e. QSslSocket::SslClientMode. When running in server mode or using a cipher algorithm without forward secrecy a null key is returned. The ephemeral server key will be set before emitting the encrypted() signal.

This function was introduced in Qt 5.7.

### `[since 6.0]` bool QSslConfiguration::handshakeMustInterruptOnError() const

Returns true if a verification callback will emit QSslSocket::handshakeInterruptedOnError() early, before concluding the handshake.

Note: This function always returns false for all backends but OpenSSL.

This function was introduced in Qt 6.0.

See also setHandshakeMustInterruptOnError(), QSslSocket::handshakeInterruptedOnError(), and QSslSocket::continueInterruptedHandshake().

### bool QSslConfiguration::isNull() const

Returns `true` if this is a null QSslConfiguration object.

A QSslConfiguration object is null if it has been default-constructed and no setter methods have been called.

See also setProtocol(), setLocalCertificate(), setPrivateKey(), setCiphers(), and setCaCertificates().

### QSslCertificate QSslConfiguration::localCertificate() const

Returns the certificate to be presented to the peer during the SSL handshake process.

See also setLocalCertificate().

### `[since 5.1]` QList<QSslCertificate> QSslConfiguration::localCertificateChain() const

Returns the certificate chain to be presented to the peer during the SSL handshake process.

This function was introduced in Qt 5.1.

See also setLocalCertificateChain() and localCertificate().

### `[since 6.0]` bool QSslConfiguration::missingCertificateIsFatal() const

Returns true if errors with code QSslError::NoPeerCertificate cannot be ignored.

Note: Always returns false for all TLS backends but OpenSSL.

This function was introduced in Qt 6.0.

See also QSslSocket::ignoreSslErrors() and setMissingCertificateIsFatal().

### `[since 5.3]` QByteArray QSslConfiguration::nextNegotiatedProtocol() const

This function returns the protocol negotiated with the server if the Next Protocol Negotiation (NPN) or Application-Layer Protocol Negotiation (ALPN) TLS extension was enabled. In order for the NPN/ALPN extension to be enabled, setAllowedNextProtocols() needs to be called explicitly before connecting to the server.

If no protocol could be negotiated or the extension was not enabled, this function returns a QByteArray which is null.

This function was introduced in Qt 5.3.

See also setAllowedNextProtocols() and nextProtocolNegotiationStatus().

### `[since 5.3]` QSslConfiguration::NextProtocolNegotiationStatus QSslConfiguration::nextProtocolNegotiationStatus() const

This function returns the status of the Next Protocol Negotiation (NPN) or Application-Layer Protocol Negotiation (ALPN). If the feature has not been enabled through setAllowedNextProtocols(), this function returns NextProtocolNegotiationNone. The status will be set before emitting the encrypted() signal.

This function was introduced in Qt 5.3.

See also setAllowedNextProtocols(), allowedNextProtocols(), nextNegotiatedProtocol(), and QSslConfiguration::NextProtocolNegotiationStatus.

### `[since 5.13]` bool QSslConfiguration::ocspStaplingEnabled() const

Returns true if OCSP stapling was enabled by setOCSPStaplingEnabled(), otherwise false (which is the default value).

This function was introduced in Qt 5.13.

See also setOcspStaplingEnabled().

### QSslCertificate QSslConfiguration::peerCertificate() const

Returns the peer's digital certificate (i.e., the immediate certificate of the host you are connected to), or a null certificate, if the peer has not assigned a certificate.

The peer certificate is checked automatically during the handshake phase, so this function is normally used to fetch the certificate for display or for connection diagnostic purposes. It contains information about the peer, including its host name, the certificate issuer, and the peer's public key.

Because the peer certificate is set during the handshake phase, it is safe to access the peer certificate from a slot connected to the QSslSocket::sslErrors() signal, QNetworkReply::sslErrors() signal, or the QSslSocket::encrypted() signal.

If a null certificate is returned, it can mean the SSL handshake failed, or it can mean the host you are connected to doesn't have a certificate, or it can mean there is no connection.

If you want to check the peer's complete chain of certificates, use peerCertificateChain() to get them all at once.

See also peerCertificateChain(), QSslSocket::sslErrors(), QSslSocket::ignoreSslErrors(), QNetworkReply::sslErrors(), and QNetworkReply::ignoreSslErrors().

### QList<QSslCertificate> QSslConfiguration::peerCertificateChain() const

Returns the peer's chain of digital certificates, starting with the peer's immediate certificate and ending with the CA's certificate.

Peer certificates are checked automatically during the handshake phase. This function is normally used to fetch certificates for display, or for performing connection diagnostics. Certificates contain information about the peer and the certificate issuers, including host name, issuer names, and issuer public keys.

Because the peer certificate is set during the handshake phase, it is safe to access the peer certificate from a slot connected to the QSslSocket::sslErrors() signal, QNetworkReply::sslErrors() signal, or the QSslSocket::encrypted() signal.

If an empty list is returned, it can mean the SSL handshake failed, or it can mean the host you are connected to doesn't have a certificate, or it can mean there is no connection.

If you want to get only the peer's immediate certificate, use peerCertificate().

See also peerCertificate(), QSslSocket::sslErrors(), QSslSocket::ignoreSslErrors(), QNetworkReply::sslErrors(), and QNetworkReply::ignoreSslErrors().

### int QSslConfiguration::peerVerifyDepth() const

Returns the maximum number of certificates in the peer's certificate chain to be checked during the SSL handshake phase, or 0 (the default) if no maximum depth has been set, indicating that the whole certificate chain should be checked.

The certificates are checked in issuing order, starting with the peer's own certificate, then its issuer's certificate, and so on.

See also setPeerVerifyDepth() and peerVerifyMode().

### QSslSocket::PeerVerifyMode QSslConfiguration::peerVerifyMode() const

Returns the verify mode. This mode decides whether QSslSocket should request a certificate from the peer (i.e., the client requests a certificate from the server, or a server requesting a certificate from the client), and whether it should require that this certificate is valid.

The default mode is AutoVerifyPeer, which tells QSslSocket to use VerifyPeer for clients, QueryPeer for servers.

See also setPeerVerifyMode().

### `[since 5.8]` QByteArray QSslConfiguration::preSharedKeyIdentityHint() const

Returns the identity hint.

This function was introduced in Qt 5.8.

See also setPreSharedKeyIdentityHint().

### QSslKey QSslConfiguration::privateKey() const

Returns the SSL key assigned to this connection or a null key if none has been assigned yet.

See also setPrivateKey() and localCertificate().

### QSsl::SslProtocol QSslConfiguration::protocol() const

Returns the protocol setting for this SSL configuration.

See also setProtocol().

### QSslCipher QSslConfiguration::sessionCipher() const

Returns the socket's cryptographic cipher, or a null cipher if the connection isn't encrypted. The socket's cipher for the session is set during the handshake phase. The cipher is used to encrypt and decrypt data transmitted through the socket.

The SSL infrastructure also provides functions for setting the ordered list of ciphers from which the handshake phase will eventually select the session cipher. This ordered list must be in place before the handshake phase begins.

See also ciphers(), setCiphers(), and supportedCiphers().

### `[since 5.4]` QSsl::SslProtocol QSslConfiguration::sessionProtocol() const

Returns the socket's SSL/TLS protocol or UnknownProtocol if the connection isn't encrypted. The socket's protocol for the session is set during the handshake phase.

This function was introduced in Qt 5.4.

See also protocol() and setProtocol().

### `[since 5.2]` QByteArray QSslConfiguration::sessionTicket() const

If QSsl::SslOptionDisableSessionPersistence was turned off, this function returns the session ticket used in the SSL handshake in ASN.1 format, suitable to e.g. be persisted to disk. If no session ticket was used or QSsl::SslOptionDisableSessionPersistence was not turned off, this function returns an empty QByteArray.

Note: When persisting the session ticket to disk or similar, be careful not to expose the session to a potential attacker, as knowledge of the session allows for eavesdropping on data encrypted with the session parameters.

This function was introduced in Qt 5.2.

See also setSessionTicket(), QSsl::SslOptionDisableSessionPersistence, setSslOption(), and QSslSocket::newSessionTicketReceived().

### `[since 5.2]` int QSslConfiguration::sessionTicketLifeTimeHint() const

If QSsl::SslOptionDisableSessionPersistence was turned off, this function returns the session ticket life time hint sent by the server (which might be 0). If the server did not send a session ticket (e.g. when resuming a session or when the server does not support it) or QSsl::SslOptionDisableSessionPersistence was not turned off, this function returns -1.

This function was introduced in Qt 5.2.

See also sessionTicket(), QSsl::SslOptionDisableSessionPersistence, setSslOption(), and QSslSocket::newSessionTicketReceived().

### `[since 5.3]` void QSslConfiguration::setAllowedNextProtocols(const QList<QByteArray> &protocols)

This function sets the allowed protocols to be negotiated with the server through the Next Protocol Negotiation (NPN) or Application-Layer Protocol Negotiation (ALPN) TLS extension; each element in protocols must define one allowed protocol. The function must be called explicitly before connecting to send the NPN/ALPN extension in the SSL handshake. Whether or not the negotiation succeeded can be queried through nextProtocolNegotiationStatus().

This function was introduced in Qt 5.3.

See also nextNegotiatedProtocol(), nextProtocolNegotiationStatus(), allowedNextProtocols(), and QSslConfiguration::NextProtocolHttp1_1.

### `[since 5.11]` void QSslConfiguration::setBackendConfiguration(const QMap<QByteArray, QVariant> &backendConfiguration = QMap<QByteArray, QVariant>())

Sets or clears the backend-specific configuration.

Without a backendConfiguration parameter this function will clear the backend-specific configuration. More information about the supported options is available in the documentation of setBackendConfigurationOption().

This function was introduced in Qt 5.11.

See also backendConfiguration() and setBackendConfigurationOption().

### `[since 5.11]` void QSslConfiguration::setBackendConfigurationOption(const QByteArray &name, const QVariant &value)

Sets the option name in the backend-specific configuration to value.

Options supported by the OpenSSL (>= 1.0.2) backend are available in the supported configuration file commands documentation. The expected type for the value parameter is a QByteArray for all options. The examples show how to use some of the options.

Note: The backend-specific configuration will be applied after the general configuration. Using the backend-specific configuration to set a general configuration option again will overwrite the general configuration option.

This function was introduced in Qt 5.11.

See also backendConfiguration() and setBackendConfiguration().

### void QSslConfiguration::setCaCertificates(const QList<QSslCertificate> &certificates)

Sets this socket's CA certificate database to be certificates. The certificate database must be set prior to the SSL handshake. The CA certificate database is used by the socket during the handshake phase to validate the peer's certificate.

Note: The default configuration uses the system CA certificate database. If that is not available (as is commonly the case on iOS), the default database is empty.

See also caCertificates(), addCaCertificates(), and addCaCertificate().

### void QSslConfiguration::setCiphers(const QList<QSslCipher> &ciphers)

Sets the cryptographic cipher suite for this socket to ciphers, which must contain a subset of the ciphers in the list returned by supportedCiphers().

Restricting the cipher suite must be done before the handshake phase, where the session cipher is chosen.

Note: This is not currently supported in the Schannel backend.

See also ciphers() and supportedCiphers().

### `[since 6.0]` void QSslConfiguration::setCiphers(const QString &ciphers)

Sets the cryptographic cipher suite for this configuration to ciphers, which is a colon-separated list of cipher suite names. The ciphers are listed in order of preference, starting with the most preferred cipher. For example:

     QSslConfiguration tlsConfig = QSslConfiguration::defaultConfiguration();
     tlsConfig.setCiphers(QStringLiteral("DHE-RSA-AES256-SHA:DHE-DSS-AES256-SHA:AES256-SHA"));

Each cipher name in ciphers must be the name of a cipher in the list returned by supportedCiphers(). Restricting the cipher suite must be done before the handshake phase, where the session cipher is chosen.

Note: This is not currently supported in the Schannel backend.

This function was introduced in Qt 6.0.

See also ciphers().

### `[static]` void QSslConfiguration::setDefaultConfiguration(const QSslConfiguration &configuration)

Sets the default SSL configuration to be used in new SSL connections to be configuration. Existing connections are not affected by this call.

See also supportedCiphers() and defaultConfiguration().

### `[static]` void QSslConfiguration::setDefaultDtlsConfiguration(const QSslConfiguration &configuration)

Sets the default DTLS configuration to be used in new DTLS connections to be configuration. Existing connections are not affected by this call.

See also defaultDtlsConfiguration().

### `[since 5.8]` void QSslConfiguration::setDiffieHellmanParameters(const QSslDiffieHellmanParameters &dhparams)

Sets a custom set of Diffie-Hellman parameters to be used by this socket when functioning as a server to dhparams.

If no Diffie-Hellman parameters have been set, the QSslConfiguration object defaults to using the 1024-bit MODP group from RFC 2409.

This function was introduced in Qt 5.8.

See also diffieHellmanParameters().

### void QSslConfiguration::setDtlsCookieVerificationEnabled(bool enable)

This function enables DTLS cookie verification when enable is true.

See also dtlsCookieVerificationEnabled().

### `[since 5.5]` void QSslConfiguration::setEllipticCurves(const QList<QSslEllipticCurve> &curves)

Sets the list of elliptic curves to be used by this socket to curves, which must contain a subset of the curves in the list returned by supportedEllipticCurves().

Restricting the elliptic curves must be done before the handshake phase, where the session cipher is chosen.

This function was introduced in Qt 5.5.

See also ellipticCurves.

### `[since 6.0]` void QSslConfiguration::setHandshakeMustInterruptOnError(bool interrupt)

If interrupt is true and the underlying backend supports this option, errors found during certificate verification are reported immediately by emitting QSslSocket::handshakeInterruptedOnError(). This allows to stop the unfinished handshake and send a proper alert message to a peer. No special action is required from the application in this case. QSslSocket will close the connection after sending the alert message. If the application after inspecting the error wants to continue the handshake, it must call QSslSocket::continueInterruptedHandshake() from its slot function. The signal-slot connection must be direct.

Note: When interrupting handshake is enabled, errors that would otherwise be reported by QSslSocket::peerVerifyError() are instead only reported by QSslSocket::handshakeInterruptedOnError().

Note: Even if the handshake was continued, these errors will be reported when emitting QSslSocket::sslErrors() signal (and thus must be ignored in the corresponding function slot).

This function was introduced in Qt 6.0.

See also handshakeMustInterruptOnError(), QSslSocket::handshakeInterruptedOnError(), and QSslSocket::continueInterruptedHandshake().

### void QSslConfiguration::setLocalCertificate(const QSslCertificate &certificate)

Sets the certificate to be presented to the peer during SSL handshake to be certificate.

Setting the certificate once the connection has been established has no effect.

A certificate is the means of identification used in the SSL process. The local certificate is used by the remote end to verify the local user's identity against its list of Certification Authorities. In most cases, such as in HTTP web browsing, only servers identify to the clients, so the client does not send a certificate.

See also localCertificate().

### `[since 5.1]` void QSslConfiguration::setLocalCertificateChain(const QList<QSslCertificate> &localChain)

Sets the certificate chain to be presented to the peer during the SSL handshake to be localChain.

Setting the certificate chain once the connection has been established has no effect.

A certificate is the means of identification used in the SSL process. The local certificate is used by the remote end to verify the local user's identity against its list of Certification Authorities. In most cases, such as in HTTP web browsing, only servers identify to the clients, so the client does not send a certificate.

Unlike QSslConfiguration::setLocalCertificate() this method allows you to specify any intermediate certificates required in order to validate your certificate. The first item in the list must be the leaf certificate.

This function was introduced in Qt 5.1.

See also localCertificateChain().

### `[since 6.0]` void QSslConfiguration::setMissingCertificateIsFatal(bool cannotRecover)

If cannotRecover is true, and verification mode in use is QSslSocket::VerifyPeer or QSslSocket::AutoVerifyPeer (for a client-side socket), the missing peer's certificate would be treated as an unrecoverable error that cannot be ignored. A proper alert message will be sent to the peer before closing the connection.

Note: Only available if Qt was configured and built with OpenSSL backend.

This function was introduced in Qt 6.0.

See also QSslSocket::ignoreSslErrors(), QSslSocket::PeerVerifyMode, and missingCertificateIsFatal().

### `[since 5.13]` void QSslConfiguration::setOcspStaplingEnabled(bool enabled)

If enabled is true, client QSslSocket will send a certificate status request to its peer when initiating a handshake. During the handshake QSslSocket will verify the server's response. This value must be set before the handshake starts.

This function was introduced in Qt 5.13.

See also ocspStaplingEnabled().

### void QSslConfiguration::setPeerVerifyDepth(int depth)

Sets the maximum number of certificates in the peer's certificate chain to be checked during the SSL handshake phase, to depth. Setting a depth of 0 means that no maximum depth is set, indicating that the whole certificate chain should be checked.

The certificates are checked in issuing order, starting with the peer's own certificate, then its issuer's certificate, and so on.

See also peerVerifyDepth() and setPeerVerifyMode().

### void QSslConfiguration::setPeerVerifyMode(QSslSocket::PeerVerifyMode mode)

Sets the verify mode to mode. This mode decides whether QSslSocket should request a certificate from the peer (i.e., the client requests a certificate from the server, or a server requesting a certificate from the client), and whether it should require that this certificate is valid.

The default mode is AutoVerifyPeer, which tells QSslSocket to use VerifyPeer for clients, QueryPeer for servers.

See also peerVerifyMode().

### `[since 5.8]` void QSslConfiguration::setPreSharedKeyIdentityHint(const QByteArray &hint)

Sets the identity hint for a preshared key authentication to hint. This will affect the next initiated handshake; calling this function on an already-encrypted socket will not affect the socket's identity hint.

The identity hint is used in QSslSocket::SslServerMode only!

This function was introduced in Qt 5.8.

See also preSharedKeyIdentityHint().

### void QSslConfiguration::setPrivateKey(const QSslKey &key)

Sets the connection's private key to key. The private key and the local certificate are used by clients and servers that must prove their identity to SSL peers.

Both the key and the local certificate are required if you are creating an SSL server socket. If you are creating an SSL client socket, the key and local certificate are required if your client must identify itself to an SSL server.

See also privateKey() and setLocalCertificate().

### void QSslConfiguration::setProtocol(QSsl::SslProtocol protocol)

Sets the protocol setting for this configuration to be protocol.

Setting the protocol once the connection has already been established has no effect.

See also protocol().

### `[since 5.2]` void QSslConfiguration::setSessionTicket(const QByteArray &sessionTicket)

Sets the session ticket to be used in an SSL handshake. QSsl::SslOptionDisableSessionPersistence must be turned off for this to work, and sessionTicket must be in ASN.1 format as returned by sessionTicket().

This function was introduced in Qt 5.2.

See also sessionTicket(), QSsl::SslOptionDisableSessionPersistence, setSslOption(), and QSslSocket::newSessionTicketReceived().

### void QSslConfiguration::setSslOption(QSsl::SslOption option, bool on)

Enables or disables an SSL compatibility option. If on is true, the option is enabled. If on is false, the option is disabled.

See also testSslOption().

### `[static, since 5.5]` QList<QSslCipher> QSslConfiguration::supportedCiphers()

Returns the list of cryptographic ciphers supported by this system. This list is set by the system's SSL libraries and may vary from system to system.

This function was introduced in Qt 5.5.

See also ciphers() and setCiphers().

### `[static, since 5.5]` QList<QSslEllipticCurve> QSslConfiguration::supportedEllipticCurves()

Returns the list of elliptic curves supported by this system. This list is set by the system's SSL libraries and may vary from system to system.

This function was introduced in Qt 5.5.

See also ellipticCurves() and setEllipticCurves().

### `[since 5.0]` void QSslConfiguration::swap(QSslConfiguration &other)

Swaps this SSL configuration instance with other. This function is very fast and never fails.

This function was introduced in Qt 5.0.

### `[static, since 5.5]` QList<QSslCertificate> QSslConfiguration::systemCaCertificates()

This function provides the CA certificate database provided by the operating system. The CA certificate database returned by this function is used to initialize the database returned by caCertificates() on the default QSslConfiguration.

This function was introduced in Qt 5.5.

See also caCertificates(), setCaCertificates(), defaultConfiguration(), addCaCertificate(), and addCaCertificates().

### bool QSslConfiguration::testSslOption(QSsl::SslOption option) const

Returns `true` if the specified SSL compatibility option is enabled.

See also setSslOption().

### bool QSslConfiguration::operator!=(const QSslConfiguration &other) const

Returns `true` if this QSslConfiguration differs from other. Two QSslConfiguration objects are considered different if any state or setting is different.

See also operator==().

### bool QSslConfiguration::operator==(const QSslConfiguration &other) const

Returns `true` if this QSslConfiguration object is equal to other.

Two QSslConfiguration objects are considered equal if they have the exact same settings and state.

See also operator!=().

## Member Variable Documentation

### const char[] QSslConfiguration::NextProtocolHttp1_1

This variable holds the value used for negotiating HTTP 1.1 during the Next Protocol Negotiation.