Qt Cryptographic Architecture: QCA::PublicKey Class Reference

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QCA::PublicKey Class Reference
QCA user API

`#include <QtCrypto>`

Collaboration diagram for QCA::PublicKey:
[legend]

## Public Member Functions
bool | canDecrypt () const
bool | canEncrypt () const
bool | canVerify () const
bool | decrypt (const SecureArray &in, SecureArray *out, EncryptionAlgorithm alg)
SecureArray | encrypt (const SecureArray &a, EncryptionAlgorithm alg)
int | maximumEncryptSize (EncryptionAlgorithm alg) const
PublicKey & | operator= (const PublicKey &from)
| PublicKey ()
| PublicKey (const PrivateKey &k)
| PublicKey (const QString &fileName)
| PublicKey (const PublicKey &from)
void | startVerify (SignatureAlgorithm alg, SignatureFormat format=DefaultFormat)
QByteArray | toDER () const
DHPublicKey | toDH () const
DSAPublicKey | toDSA () const
QString | toPEM () const
bool | toPEMFile (const QString &fileName) const
RSAPublicKey | toRSA () const
void | update (const MemoryRegion &a)
bool | validSignature (const QByteArray &sig)
bool | verifyMessage (const MemoryRegion &a, const QByteArray &sig, SignatureAlgorithm alg, SignatureFormat format=DefaultFormat)
Public Member Functions inherited from QCA::PKey
int | bitSize () const
bool | canExport () const
bool | canKeyAgree () const
bool | isDH () const
bool | isDSA () const
bool | isNull () const
bool | isPrivate () const
bool | isPublic () const
bool | isRSA () const
bool | operator!= (const PKey &a) const
PKey & | operator= (const PKey &from)
bool | operator== (const PKey &a) const
| PKey ()
| PKey (const PKey &from)
PrivateKey | toPrivateKey () const
PublicKey | toPublicKey () const
Type | type () const
Public Member Functions inherited from QCA::Algorithm
| Algorithm (const Algorithm &from)
void | change (Provider::Context *c)
void | change (const QString &type, const QString &provider)
Provider::Context * | context ()
const Provider::Context * | context () const
Algorithm & | operator= (const Algorithm &from)
Provider * | provider () const
Provider::Context * | takeContext ()
QString | type () const

## Static Public Member Functions
static PublicKey | fromDER (const QByteArray &a, ConvertResult *result=0, const QString &provider=QString())
static PublicKey | fromPEM (const QString &s, ConvertResult *result=0, const QString &provider=QString())
static PublicKey | fromPEMFile (const QString &fileName, ConvertResult *result=0, const QString &provider=QString())
Static Public Member Functions inherited from QCA::PKey
static QList< Type > | supportedIOTypes (const QString &provider=QString())
static QList< Type > | supportedTypes (const QString &provider=QString())

## Protected Member Functions
| PublicKey (const QString &type, const QString &provider)
Protected Member Functions inherited from QCA::PKey
| PKey (const QString &type, const QString &provider)
void | set (const PKey &k)
DHPrivateKey | toDHPrivateKey () const
DHPublicKey | toDHPublicKey () const
DSAPrivateKey | toDSAPrivateKey () const
DSAPublicKey | toDSAPublicKey () const
RSAPrivateKey | toRSAPrivateKey () const
RSAPublicKey | toRSAPublicKey () const
Protected Member Functions inherited from QCA::Algorithm
| Algorithm ()
| Algorithm (const QString &type, const QString &provider)

## Additional Inherited Members
Public Types inherited from QCA::PKey
enum | Type { RSA, DSA, DH }

## Detailed Description

Generic public key.

Examples:
  rsatest.cpp.

## Constructor & Destructor Documentation

QCA::PublicKey::PublicKey | ( |  | ) |

Create an empty (null) public key.

QCA::PublicKey::PublicKey | ( | const PrivateKey & | k | ) |

Create a public key based on a specified private key.

Parameters

  k | the private key to extract the public key parts from

QCA::PublicKey::PublicKey | ( | const QString & | fileName | ) |

Import a public key from a PEM representation in a file.

Parameters

  fileName | the name of the file containing the public key

See also
  fromPEMFile for an alternative method

QCA::PublicKey::PublicKey | ( | const PublicKey & | from | ) |

Copy constructor.

Parameters

  from | the PublicKey to copy from

QCA::PublicKey::PublicKey | ( | const QString & | type,
|  | const QString & | provider
| ) |  |
| protected

Create a new key of a specified type.

Parameters

  type | the type of key to create
  provider | the provider to use, if required

## Member Function Documentation

PublicKey& QCA::PublicKey::operator= | ( | const PublicKey & | from | ) |

Assignment operator.

Parameters

  from | the PublicKey to copy from

RSAPublicKey QCA::PublicKey::toRSA | ( |  | ) | const

Convenience method to convert this key to an RSAPublicKey.

Note that if the key is not an RSA key (eg it is DSA or DH), then this will produce a null key.

DSAPublicKey QCA::PublicKey::toDSA | ( |  | ) | const

Convenience method to convert this key to a DSAPublicKey.

Note that if the key is not an DSA key (eg it is RSA or DH), then this will produce a null key.

DHPublicKey QCA::PublicKey::toDH | ( |  | ) | const

Convenience method to convert this key to a DHPublicKey.

Note that if the key is not an DH key (eg it is DSA or RSA), then this will produce a null key.

bool QCA::PublicKey::canEncrypt | ( |  | ) | const

Test if this key can be used for encryption.

Returns
  true if the key can be used for encryption

Examples:
  rsatest.cpp.

bool QCA::PublicKey::canDecrypt | ( |  | ) | const

Test if this key can be used for decryption.

Returns
  true if the key can be used for decryption

bool QCA::PublicKey::canVerify | ( |  | ) | const

Test if the key can be used for verifying signatures.

Returns
  true of the key can be used for verification

Examples:
  rsatest.cpp.

int QCA::PublicKey::maximumEncryptSize | ( | EncryptionAlgorithm | alg | ) | const

The maximum message size that can be encrypted with a specified algorithm.

Parameters

  alg | the algorithm to check

SecureArray QCA::PublicKey::encrypt | ( | const SecureArray & | a,
|  | EncryptionAlgorithm | alg
| ) |  |

Encrypt a message using a specified algorithm.

Parameters

  a | the message to encrypt
  alg | the algorithm to use

Examples:
  rsatest.cpp.

bool QCA::PublicKey::decrypt | ( | const SecureArray & | in,
|  | SecureArray * | out,
|  | EncryptionAlgorithm | alg
| ) |  |

Decrypt the message.

Parameters

  in | the cipher (encrypted) data
  out | the plain text data
  alg | the algorithm to use

Note
  This synchronous operation may require event handling, and so it must not be called from the same thread as an EventHandler.

void QCA::PublicKey::startVerify | ( | SignatureAlgorithm | alg,
|  | SignatureFormat | format = `DefaultFormat`
| ) |  |

Initialise the signature verification process.

Parameters

  alg | the algorithm to use for signing
  format | the specific format to use, for DSA

Examples:
  rsatest.cpp.

void QCA::PublicKey::update | ( | const MemoryRegion & | a | ) |

Update the signature verification process with more data.

Parameters

  a | the array containing the data that should be added to the signature

Examples:
  rsatest.cpp.

bool QCA::PublicKey::validSignature | ( | const QByteArray & | sig | ) |

Check the signature is valid for the message.

The process to check that a signature is correct is shown below:

// note that pubkey is a PublicKey
if( pubkey.canVerify() )
{
pubkey.startVerify( QCA::EMSA3_MD5 );
pubkey.update( theMessage ); // might be called multiple times
if ( pubkey.validSignature( theSignature ) )
{
// then signature is valid
}
else
{
// then signature is invalid
}
}

Parameters

  sig | the signature to check

Returns
  true if the signature is correct

Examples:
  rsatest.cpp.

bool QCA::PublicKey::verifyMessage | ( | const MemoryRegion & | a,
|  | const QByteArray & | sig,
|  | SignatureAlgorithm | alg,
|  | SignatureFormat | format = `DefaultFormat`
| ) |  |

Single step message verification.

If you have the whole message to be verified, then this offers a more convenient approach to verification.

Parameters

  a | the message to check the signature on
  sig | the signature to be checked
  alg | the algorithm to use
  format | the signature format to use, for DSA

Returns
  true if the signature is valid for the message

Examples:
  rsatest.cpp.

QByteArray QCA::PublicKey::toDER | ( |  | ) | const

Export the key in Distinguished Encoding Rules (DER) format.

QString QCA::PublicKey::toPEM | ( |  | ) | const

Export the key in Privacy Enhanced Mail (PEM) format.

See also
  toPEMFile provides a convenient way to save the PEM encoded key to a file
  fromPEM provides an inverse of toPEM, converting the PEM encoded key back to a PublicKey

bool QCA::PublicKey::toPEMFile | ( | const QString & | fileName | ) | const

Export the key in Privacy Enhanced Mail (PEM) to a file.

Parameters

  fileName | the name (and path, if necessary) of the file to save the PEM encoded key to.

See also
  toPEM for a version that exports to a QString, which may be useful if you need to do more sophisticated handling
  fromPEMFile provides an inverse of toPEMFile, reading a PEM encoded key from a file

static PublicKey QCA::PublicKey::fromDER | ( | const QByteArray & | a,
|  | ConvertResult * | result = `0`,
|  | const QString & | provider = `QString()`
| ) |  |
| static

Import a key in Distinguished Encoding Rules (DER) format.

This function takes a binary array, which is assumed to contain a public key in DER encoding, and returns the key. Unless you don't care whether the import succeeded, you should test the result, as shown below.

QCA::ConvertResult conversionResult;
QCA::PublicKey publicKey = QCA::PublicKey::fromDER(keyArray, &conversionResult);
if (! QCA::ConvertGood == conversionResult)
{
std::cout << "Public key read failed" << std::endl;
}

Parameters

  a | the array containing a DER encoded key
  result | pointer to a variable, which returns whether the conversion succeeded (ConvertGood) or not
  provider | the name of the provider to use for the import.

static PublicKey QCA::PublicKey::fromPEM | ( | const QString & | s,
|  | ConvertResult * | result = `0`,
|  | const QString & | provider = `QString()`
| ) |  |
| static

Import a key in Privacy Enhanced Mail (PEM) format.

This function takes a string, which is assumed to contain a public key in PEM encoding, and returns that key. Unless you don't care whether the import succeeded, you should test the result, as shown below.

QCA::ConvertResult conversionResult;
QCA::PublicKey publicKey = QCA::PublicKey::fromPEM(keyAsString, &conversionResult);
if (! QCA::ConvertGood == conversionResult)
{
std::cout << "Public key read failed" << std::endl;
}

Parameters

  s | the string containing a PEM encoded key
  result | pointer to a variable, which returns whether the conversion succeeded (ConvertGood) or not
  provider | the name of the provider to use for the import.

See also
  toPEM, which provides an inverse of fromPEM()
  fromPEMFile, which provides an import direct from a file.

static PublicKey QCA::PublicKey::fromPEMFile | ( | const QString & | fileName,
|  | ConvertResult * | result = `0`,
|  | const QString & | provider = `QString()`
| ) |  |
| static

Import a key in Privacy Enhanced Mail (PEM) format from a file.

This function takes the name of a file, which is assumed to contain a public key in PEM encoding, and returns that key. Unless you don't care whether the import succeeded, you should test the result, as shown below.

QCA::ConvertResult conversionResult;
QCA::PublicKey publicKey = QCA::PublicKey::fromPEMFile(fileName, &conversionResult);
if (! QCA::ConvertGood == conversionResult)
{
std::cout << "Public key read failed" << std::endl;
}

Parameters

  fileName | a string containing the name of the file
  result | pointer to a variable, which returns whether the conversion succeeded (ConvertGood) or not
  provider | the name of the provider to use for the import.

See also
  toPEMFile, which provides an inverse of fromPEMFile()
  fromPEM, which provides an import from a string

Note
  there is also a constructor form that can import from a file

The documentation for this class was generated from the following file:

- qca_publickey.h