- Qt 6.8
- Qt Network
- Network Programming API
- QSsl Namespace
- Qt 6.8.3 Reference Documentation

# QSsl Namespace

The QSsl namespace declares enums common to all SSL classes in Qt Network. More...

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

- QSsl is part of Network Programming API.

## Types

`(since 6.0)` enum class | AlertLevel { Warning, Fatal, Unknown }
`(since 6.0)` enum class | AlertType { CloseNotify, UnexpectedMessage, BadRecordMac, RecordOverflow, DecompressionFailure, …, UnknownAlertMessage }
enum | AlternativeNameEntryType { EmailEntry, DnsEntry, IpAddressEntry }
enum | EncodingFormat { Pem, Der }
`(since 6.1)` enum class | ImplementedClass { Key, Certificate, Socket, DiffieHellman, EllipticCurve, …, DtlsCookie }
enum | KeyAlgorithm { Rsa, Dsa, Ec, Dh, Opaque }
enum | KeyType { PrivateKey, PublicKey }
enum | SslOption { SslOptionDisableEmptyFragments, SslOptionDisableSessionTickets, SslOptionDisableCompression, SslOptionDisableServerNameIndication, SslOptionDisableLegacyRenegotiation, …, SslOptionDisableServerCipherPreference }
flags | SslOptions
enum | SslProtocol { TlsV1_0, TlsV1_0OrLater, TlsV1_1, TlsV1_1OrLater, TlsV1_2, …, SecureProtocols }
`(since 6.1)` enum class | SupportedFeature { CertificateVerification, ClientSideAlpn, ServerSideAlpn, Ocsp, Psk, …, Alerts }

## Detailed Description

## Type Documentation

### `[since 6.0]` enum class AlertLevel

Describes the level of an alert message

This enum describes the level of an alert message that was sent or received.

Constant | Value | Description
--- | --- | ---
`QSslSocket::AlertLevel::Warning` | `0` | Non-fatal alert message
`QSslSocket::AlertLevel::Fatal` | `1` | Fatal alert message, the underlying backend will handle such an alert properly and close the connection.
`QSslSocket::AlertLevel::Unknown` | `2` | An alert of unknown level of severity.

This enum was introduced in Qt 6.0.

### `[since 6.0]` enum class AlertType

Enumerates possible codes that an alert message can have

See RFC 8446, section 6 for the possible values and their meaning.

Constant | Value | Description
--- | --- | ---
`QSslSocket::AlertType::CloseNotify` | `0` | ,
`QSslSocket::AlertType::UnexpectedMessage` | `10` |
`QSslSocket::AlertType::BadRecordMac` | `20` |
`QSslSocket::AlertType::RecordOverflow` | `22` |
`QSslSocket::AlertType::DecompressionFailure` | `30` |
`QSslSocket::AlertType::HandshakeFailure` | `40` |
`QSslSocket::AlertType::NoCertificate` | `41` |
`QSslSocket::AlertType::BadCertificate` | `42` |
`QSslSocket::AlertType::UnsupportedCertificate` | `43` |
`QSslSocket::AlertType::CertificateRevoked` | `44` |
`QSslSocket::AlertType::CertificateExpired` | `45` |
`QSslSocket::AlertType::CertificateUnknown` | `46` |
`QSslSocket::AlertType::IllegalParameter` | `47` |
`QSslSocket::AlertType::UnknownCa` | `48` |
`QSslSocket::AlertType::AccessDenied` | `49` |
`QSslSocket::AlertType::DecodeError` | `50` |
`QSslSocket::AlertType::DecryptError` | `51` |
`QSslSocket::AlertType::ExportRestriction` | `60` |
`QSslSocket::AlertType::ProtocolVersion` | `70` |
`QSslSocket::AlertType::InsufficientSecurity` | `71` |
`QSslSocket::AlertType::InternalError` | `80` |
`QSslSocket::AlertType::InappropriateFallback` | `86` |
`QSslSocket::AlertType::UserCancelled` | `90` |
`QSslSocket::AlertType::NoRenegotiation` | `100` |
`QSslSocket::AlertType::MissingExtension` | `109` |
`QSslSocket::AlertType::UnsupportedExtension` | `110` |
`QSslSocket::AlertType::CertificateUnobtainable` | `111` |
`QSslSocket::AlertType::UnrecognizedName` | `112` |
`QSslSocket::AlertType::BadCertificateStatusResponse` | `113` |
`QSslSocket::AlertType::BadCertificateHashValue` | `114` |
`QSslSocket::AlertType::UnknownPskIdentity` | `115` |
`QSslSocket::AlertType::CertificateRequired` | `116` |
`QSslSocket::AlertType::NoApplicationProtocol` | `120` |
`QSslSocket::AlertType::UnknownAlertMessage` | `255` |

This enum was introduced in Qt 6.0.

### enum QSsl::AlternativeNameEntryType

Describes the key types for alternative name entries in QSslCertificate.

Constant | Value | Description
--- | --- | ---
`QSsl::EmailEntry` | `0` | An email entry; the entry contains an email address that the certificate is valid for.
`QSsl::DnsEntry` | `1` | A DNS host name entry; the entry contains a host name entry that the certificate is valid for. The entry may contain wildcards.
`QSsl::IpAddressEntry` | `2` | An IP address entry; the entry contains an IP address entry that the certificate is valid for, introduced in Qt 5.13.

See also QSslCertificate::subjectAlternativeNames().

### enum QSsl::EncodingFormat

Describes supported encoding formats for certificates and keys.

Constant | Value | Description
--- | --- | ---
`QSsl::Pem` | `0` | The PEM format.
`QSsl::Der` | `1` | The DER format.

### `[since 6.1]` enum class ImplementedClass

Enumerates classes that a TLS backend implements

In QtNetwork, some classes have backend-specific implementation and thus can be left unimplemented. Enumerators in this enum indicate, which class has a working implementation in the backend.

Constant | Value | Description
--- | --- | ---
`QSslSocket::ImplementedClass::Key` | `0` | Class QSslKey.
`QSslSocket::ImplementedClass::Certificate` | `1` | Class QSslCertificate.
`QSslSocket::ImplementedClass::Socket` | `2` | Class QSslSocket.
`QSslSocket::ImplementedClass::DiffieHellman` | `3` | Class QSslDiffieHellmanParameters.
`QSslSocket::ImplementedClass::EllipticCurve` | `4` | Class QSslEllipticCurve.
`QSslSocket::ImplementedClass::Dtls` | `5` | Class QDtls.
`QSslSocket::ImplementedClass::DtlsCookie` | `6` | Class QDtlsClientVerifier.

This enum was introduced in Qt 6.1.

### enum QSsl::KeyAlgorithm

Describes the different key algorithms supported by QSslKey.

Constant | Value | Description
--- | --- | ---
`QSsl::Rsa` | `1` | The RSA algorithm.
`QSsl::Dsa` | `2` | The DSA algorithm.
`QSsl::Ec` | `3` | The Elliptic Curve algorithm.
`QSsl::Dh` | `4` | The Diffie-Hellman algorithm.
`QSsl::Opaque` | `0` | A key that should be treated as a 'black box' by QSslKey.

The opaque key facility allows applications to add support for facilities such as PKCS#11 that Qt does not currently offer natively.

### enum QSsl::KeyType

Describes the two types of keys QSslKey supports.

Constant | Value | Description
--- | --- | ---
`QSsl::PrivateKey` | `0` | A private key.
`QSsl::PublicKey` | `1` | A public key.

### enum QSsl::SslOption
flags QSsl::SslOptions

Describes the options that can be used to control the details of SSL behaviour. These options are generally used to turn features off to work around buggy servers.

Constant | Value | Description
--- | --- | ---
`QSsl::SslOptionDisableEmptyFragments` | `0x01` | Disables the insertion of empty fragments into the data when using block ciphers. When enabled, this prevents some attacks (such as the BEAST attack), however it is incompatible with some servers.
`QSsl::SslOptionDisableSessionTickets` | `0x02` | Disables the SSL session ticket extension. This can cause slower connection setup, however some servers are not compatible with the extension.
`QSsl::SslOptionDisableCompression` | `0x04` | Disables the SSL compression extension. When enabled, this allows the data being passed over SSL to be compressed, however some servers are not compatible with this extension.
`QSsl::SslOptionDisableServerNameIndication` | `0x08` | Disables the SSL server name indication extension. When enabled, this tells the server the virtual host being accessed allowing it to respond with the correct certificate.
`QSsl::SslOptionDisableLegacyRenegotiation` | `0x10` | Disables the older insecure mechanism for renegotiating the connection parameters. When enabled, this option can allow connections for legacy servers, but it introduces the possibility that an attacker could inject plaintext into the SSL session.
`QSsl::SslOptionDisableSessionSharing` | `0x20` | Disables SSL session sharing via the session ID handshake attribute.
`QSsl::SslOptionDisableSessionPersistence` | `0x40` | Disables storing the SSL session in ASN.1 format as returned by QSslConfiguration::sessionTicket(). Enabling this feature adds memory overhead of approximately 1K per used session ticket.
`QSsl::SslOptionDisableServerCipherPreference` | `0x80` | Disables selecting the cipher chosen based on the servers preferences rather than the order ciphers were sent by the client. This option is only relevant to server sockets, and is only honored by the OpenSSL backend.

By default, SslOptionDisableEmptyFragments is turned on since this causes problems with a large number of servers. SslOptionDisableLegacyRenegotiation is also turned on, since it introduces a security risk. SslOptionDisableCompression is turned on to prevent the attack publicised by CRIME. SslOptionDisableSessionPersistence is turned on to optimize memory usage. The other options are turned off.

Note: Availability of above options depends on the version of the SSL backend in use.

The SslOptions type is a typedef for QFlags<SslOption>. It stores an OR combination of SslOption values.

### enum QSsl::SslProtocol

Describes the protocol of the cipher.

Constant | Value | Description
--- | --- | ---
`QSsl::TlsV1_0` | `0` | TLSv1.0
`QSsl::TlsV1_0OrLater` | `5` | TLSv1.0 and later versions.
`QSsl::TlsV1_1` | `1` | TLSv1.1.
`QSsl::TlsV1_1OrLater` | `6` | TLSv1.1 and later versions.
`QSsl::TlsV1_2` | `2` | TLSv1.2.
`QSsl::TlsV1_2OrLater` | `7` | TLSv1.2 and later versions.
`QSsl::DtlsV1_0` | `8` | DTLSv1.0
`QSsl::DtlsV1_0OrLater` | `9` | DTLSv1.0 and later versions.
`QSsl::DtlsV1_2` | `10` | DTLSv1.2
`QSsl::DtlsV1_2OrLater` | `11` | DTLSv1.2 and later versions.
`QSsl::TlsV1_3` | `12` | TLSv1.3. (Since Qt 5.12)
`QSsl::TlsV1_3OrLater` | `13` | TLSv1.3 and later versions. (Since Qt 5.12)
`QSsl::UnknownProtocol` | `-1` | The cipher's protocol cannot be determined.
`QSsl::AnyProtocol` | `3` | Any supported protocol. This value is used by QSslSocket only.
`QSsl::SecureProtocols` | `4` | The default option, using protocols known to be secure.

### `[since 6.1]` enum class SupportedFeature

Enumerates possible features that a TLS backend supports

In QtNetwork TLS-related classes have public API, that may be left unimplemented by some backend, for example, our SecureTransport backend does not support server-side ALPN. Enumerators from SupportedFeature enum indicate that a particular feature is supported.

Constant | Value | Description
--- | --- | ---
`QSslSocket::SupportedFeature::CertificateVerification` | `0` | Indicates that QSslCertificate::verify() is implemented by the backend.
`QSslSocket::SupportedFeature::ClientSideAlpn` | `1` | Client-side ALPN (Application Layer Protocol Negotiation).
`QSslSocket::SupportedFeature::ServerSideAlpn` | `2` | Server-side ALPN.
`QSslSocket::SupportedFeature::Ocsp` | `3` | OCSP stapling (Online Certificate Status Protocol).
`QSslSocket::SupportedFeature::Psk` | `4` | Pre-shared keys.
`QSslSocket::SupportedFeature::SessionTicket` | `5` | Session tickets.
`QSslSocket::SupportedFeature::Alerts` | `6` | Information about alert messages sent and received.

This enum was introduced in Qt 6.1.