Qt 5.11 | Qt Network | QSsl Namespace

Qt 5.11.3 Reference Documentation

# QSsl Namespace

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

Header: | #include <QSsl>
qmake: | QT += network
Since: | Qt 4.3

- Obsolete members

## Types

enum | AlternativeNameEntryType { EmailEntry, DnsEntry }
enum | EncodingFormat { Pem, Der }
enum | KeyAlgorithm { Rsa, Dsa, Ec, Opaque }
enum | KeyType { PrivateKey, PublicKey }
enum | SslOption { SslOptionDisableEmptyFragments, SslOptionDisableSessionTickets, SslOptionDisableCompression, SslOptionDisableServerNameIndication, ..., SslOptionDisableServerCipherPreference }
flags | SslOptions
enum | SslProtocol { SslV3, SslV2, TlsV1_0, TlsV1_0OrLater, ..., SecureProtocols }

## Detailed Description

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

## Type Documentation

### 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.

Note: In Qt 4, this enum was called `AlternateNameEntryType`. That name is deprecated in Qt 5.

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.

### 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::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::SslV3` | `0` | SSLv3. When using the WinRT backend this option will also enable TLSv1.0
`QSsl::SslV2` | `1` | SSLv2. Note, SSLv2 support was removed in OpenSSL 1.1.
`QSsl::TlsV1_0` | `2` | TLSv1.0
`QSsl::TlsV1_0OrLater` | `8` | TLSv1.0 and later versions. This option is not available when using the WinRT backend due to platform limitations.
`QSsl::TlsV1` | `TlsV1_0` | Obsolete, means the same as TlsV1_0
`QSsl::TlsV1_1` | `3` | TLSv1.1. When using the WinRT backend this option will also enable TLSv1.0.
`QSsl::TlsV1_1OrLater` | `9` | TLSv1.1 and later versions. This option is not available when using the WinRT backend due to platform limitations.
`QSsl::TlsV1_2` | `4` | TLSv1.2. When using the WinRT backend this option will also enable TLSv1.0 and TLSv1.1.
`QSsl::TlsV1_2OrLater` | `10` | TLSv1.2 and later versions. This option is not available when using the WinRT backend due to platform limitations.
`QSsl::UnknownProtocol` | `-1` | The cipher's protocol cannot be determined.
`QSsl::AnyProtocol` | `5` | The socket understands SSLv2, SSLv3, TLSv1.0 and all supported later versions of TLS. This value is used by QSslSocket only.
`QSsl::TlsV1SslV3` | `6` | On the client side, this will send a TLS 1.0 Client Hello, enabling TLSv1_0 and SSLv3 connections. On the server side, this will enable both SSLv3 and TLSv1_0 connections.
`QSsl::SecureProtocols` | `7` | The default option, using protocols known to be secure; currently behaves similar to TlsV1Ssl3 except denying SSLv3 connections that does not upgrade to TLS.

Note: most servers understand both SSL and TLS, but it is recommended to use TLS only for security reasons. However, SSL and TLS are not compatible with each other: if you get unexpected handshake failures, verify that you chose the correct setting for your protocol.