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System::Security::Cryptography::RSACryptoServiceProvider Class Referencefinal

RSA algorithm in CSP form. Objects of this class should only be allocated using System::MakeObject() function. Never create instance of this type on stack or using operator new, as it will result in runtime errors and/or assertion faults. Always wrap this class into System::SmartPtr pointer and use this pointer to pass it to functions as argument. More...

Inherits System::Security::Cryptography::RSA, and System::Security::Cryptography::ICspAsymmetricAlgorithm.

Public Member Functions

 RSACryptoServiceProvider ()
 Constructor. Uses default parameters. More...
 
 RSACryptoServiceProvider (const SharedPtr< CspParameters > &parameters)
 Constructor. Not implemented. More...
 
 RSACryptoServiceProvider (const RSAParameters &parameters)
 Constructor. More...
 
 RSACryptoServiceProvider (int32_t key_size)
 Constructor. More...
 
 RSACryptoServiceProvider (int32_t key_size, const SharedPtr< CspParameters > &parameters)
 Constructor. Not implemented. More...
 
SharedPtr< CspKeyContainerInfoget_CspKeyContainerInfo () override
 Gets a CspKeyContainerInfo object. More...
 
String get_KeyExchangeAlgorithm () override
 Checks key exchange algorithm associated with object. More...
 
int32_t get_KeySize () override
 Gets key size used by algorithm. More...
 
bool get_PersistKeyInCsp () const
 Checks whether key is persisted in CSP object. More...
 
void set_PersistKeyInCsp (bool value)
 Defines whether key is persisted in CSP object. More...
 
bool get_PublicOnly () const
 Checks if public key only is present in CSP object. More...
 
String get_SignatureAlgorithm () override
 Gets signature algorithm associated with CSP object. More...
 
ByteArrayPtr Decrypt (const ByteArrayPtr &rgb, bool use_oaep)
 Decrypts message. Not implemented. More...
 
ByteArrayPtr Decrypt (ByteArrayPtr data, SharedPtr< RSAEncryptionPadding > padding) override
 Decrypts input data using the specified padding mode. More...
 
ByteArrayPtr Encrypt (const ByteArrayPtr &rgb, bool use_oaep)
 Encrypts message. Not implemented. More...
 
ByteArrayPtr Encrypt (ByteArrayPtr data, SharedPtr< RSAEncryptionPadding > padding) override
 Encrypts input data using the specified padding mode. More...
 
ByteArrayPtr ExportCspBlob (bool include_private_parameters) override
 Exports blob with information on key. Not implemented. More...
 
RSAParameters ExportParameters (bool include_private_parameters) override
 Exports CSP parameters. More...
 
void ImportCspBlob (ByteArrayPtr key_blob) override
 Imports blob with information on key. Not implemented. More...
 
void ImportParameters (RSAParameters parameters) override
 Imports CSP parameters. More...
 
ByteArrayPtr SignData (const ByteArrayPtr &buffer, const SharedPtr< Object > &halg)
 Computes the signature of specified input value. More...
 
ByteArrayPtr SignData (const SharedPtr< IO::Stream > &input_stream, const SharedPtr< Object > &halg)
 Computes the signature of specified input value. More...
 
ByteArrayPtr SignData (const ByteArrayPtr &buffer, int32_t offset, int32_t count, const SharedPtr< Object > &halg)
 Computes the signature of specified input value. More...
 
ByteArrayPtr SignHash (ByteArrayPtr hash, HashAlgorithmName hash_algorithm, SharedPtr< RSASignaturePadding > padding) override
 Computes the signature for the specified hash value. More...
 
ByteArrayPtr SignHash (const ByteArrayPtr &rgb_hash, const String &str)
 Computes the signature of specified input value. Not implemented. More...
 
bool VerifyData (const ByteArrayPtr &buffer, const SharedPtr< Object > &halg, const ByteArrayPtr &signature)
 Checks data signature. More...
 
bool VerifyHash (const ByteArrayPtr &rgb_hash, const String &str, const ByteArrayPtr &rgb_signature)
 Checks data signature. More...
 
bool VerifyHash (ByteArrayPtr hash, ByteArrayPtr signature, const HashAlgorithmName &hash_algorithm, SharedPtr< RSASignaturePadding > padding) override
 Verifies that the signature of the specified hash is valid. More...
 
void Dispose () override
 Frees data associated with object. More...
 
- Public Member Functions inherited from System::Security::Cryptography::RSA
virtual ByteArrayPtr DecryptValue (ByteArrayPtr rgb)
 Decrypts value using private key. More...
 
virtual ByteArrayPtr EncryptValue (ByteArrayPtr rgb)
 Encrypts value using private key. More...
 
void FromXmlString (String xml_string) override
 Initializes object using XML-encoded parameters. More...
 
String ToXmlString (bool include_private_parameters) override
 Exports all parameters in XML format. More...
 
ByteArrayPtr SignData (const ByteArrayPtr &data, const HashAlgorithmName &hash_algorithm, const SharedPtr< RSASignaturePadding > &padding)
 Computes the hash value of the specified data array using the specified hash algorithm and padding, and signs the result. More...
 
ByteArrayPtr SignData (const ByteArrayPtr &data, int32_t offset, int32_t count, const HashAlgorithmName &hash_algorithm, const SharedPtr< RSASignaturePadding > &padding)
 Computes the hash value of the specified data array using the specified hash algorithm and padding, and signs the result. More...
 
ByteArrayPtr SignData (const StreamPtr &stream, const HashAlgorithmName &hash_algorithm, const SharedPtr< RSASignaturePadding > &padding)
 Computes the hash value of the specified binary stream using the specified hash algorithm and padding, and signs the result. More...
 
bool VerifyData (const ByteArrayPtr &data, const ByteArrayPtr &signature, const HashAlgorithmName &hash_algorithm, const SharedPtr< RSASignaturePadding > &padding)
 Verifies that the signature of the specified data is valid. More...
 
bool VerifyData (const ByteArrayPtr &data, int32_t offset, int32_t count, const ByteArrayPtr &signature, const HashAlgorithmName &hash_algorithm, const SharedPtr< RSASignaturePadding > &padding)
 Verifies that the signature of the specified data is valid. More...
 
bool VerifyData (const StreamPtr &stream, const ByteArrayPtr &signature, const HashAlgorithmName &hash_algorithm, const SharedPtr< RSASignaturePadding > &padding)
 Verifies that the signature of the specified binary stream is valid. More...
 
- Public Member Functions inherited from System::Security::Cryptography::AsymmetricAlgorithm
virtual void set_KeySize (int32_t value)
 Sets key size. More...
 
virtual ArrayPtr< SharedPtr< KeySizes > > get_LegalKeySizes ()
 Gets array of allowed key sizes. More...
 
void Clear ()
 Releases all resources. More...
 
- Public Member Functions inherited from System::Object
 Object ()
 Creates object. Initializes all internal data structures. More...
 
virtual ~Object ()
 Destroys object. Frees all internal data structures. More...
 
 Object (Object const &x)
 Copy constructor. Doesn't copy anything, really, just initializes new object and enables copy constructing subclasses. More...
 
Objectoperator= (Object const &x)
 Assignment operator. Doesn't copy anything, really, just initializes new object and enables copy constructing subclasses. More...
 
ObjectSharedRefAdded ()
 Increments shared reference count. Shouldn't be called directly; instead, use smart pointers or ThisProtector. More...
 
int SharedRefRemovedSafe ()
 Decrements and returns shared reference count. Shouldn't be called directly; instead, use smart pointers or ThisProtector. More...
 
int RemovedSharedRefs (int count)
 Decreases shared reference count by specified value. More...
 
Detail::SmartPtrCounter * WeakRefAdded ()
 Increments weak reference count. Shouldn't be called directly; instead, use smart pointers or ThisProtector. More...
 
void WeakRefRemoved ()
 Decrements weak reference count. Shouldn't be called directly; instead, use smart pointers or ThisProtector. More...
 
Detail::SmartPtrCounter * GetCounter ()
 Gets reference counter data structure associated with the object. More...
 
int SharedCount () const
 Gets current value of shared reference counter. More...
 
void Lock ()
 Implements C# lock() statement locking. Call directly or use LockContext sentry object. More...
 
void Unlock ()
 Implements C# lock() statement unlocking. Call directly or use LockContext sentry object. More...
 
virtual bool Equals (ptr obj)
 Compares objects using C# Object.Equals semantics. More...
 
virtual int32_t GetHashCode () const
 Analog of C# Object.GetHashCode() method. Enables hashing of custom objects. More...
 
virtual String ToString () const
 Analog of C# Object.ToString() method. Enables converting custom objects to string. More...
 
virtual ptr MemberwiseClone () const
 Analog of C# Object.MemberwiseClone() method. Enables cloning custom types. More...
 
virtual const TypeInfoGetType () const
 Gets actual type of object. Analog of C# System.Object.GetType() call. More...
 
virtual bool Is (const TypeInfo &targetType) const
 Check if object represents an instance of type described by targetType. Analog of C# 'is' operator. More...
 
virtual void SetTemplateWeakPtr (uint32_t argument)
 Set n'th template argument a weak pointer (rather than shared). Allows switching pointers in containers to weak mode. More...
 
virtual bool FastCast (const Details::FastRttiBase &helper, void **out_ptr) const
 For internal purposes only. More...
 
template<>
bool ReferenceEquals (String const &str, std::nullptr_t)
 Specialization of Object::ReferenceEquals for case of string and nullptr. More...
 
template<>
bool ReferenceEquals (String const &str1, String const &str2)
 Specialization of Object::ReferenceEquals for case of strings. More...
 

Static Public Member Functions

static bool get_UseMachineKeyStore ()
 Checks whether the key persists in machine store instead of user store. More...
 
static void set_UseMachineKeyStore (bool value)
 Defines whether the key persists in machine store instead of user store. More...
 
- Static Public Member Functions inherited from System::Security::Cryptography::RSA
static SharedPtr< RSACreate ()
 Creates default RSA aglorithm implementation. More...
 
static SharedPtr< RSACreate (const String &alg_name)
 Creates default RSA algorithm implementation. More...
 
static SharedPtr< RSACreate (int32_t key_size_in_bits)
 Creates default RSA algorithm implementation with specifed key size. More...
 
static SharedPtr< RSACreate (const RSAParameters &parameters)
 Creates default RSA algorithm implementation with specifed parameters. More...
 
static SharedPtr< RSACreateFromXmlString (const String &xml_string)
 Creates default RSA algorithm implementation with specifed XML-encoded parameters. More...
 
- Static Public Member Functions inherited from System::Security::Cryptography::AsymmetricAlgorithm
static SharedPtr< AsymmetricAlgorithmCreate ()
 Creates a default algorithm. Not implemented. More...
 
static SharedPtr< AsymmetricAlgorithmCreate (const String &alg_name)
 Creates algorithm by name. Not implemented. More...
 
- Static Public Member Functions inherited from System::Object
static bool ReferenceEquals (ptr const &objA, ptr const &objB)
 Compares objects by reference. More...
 
template<typename T >
static std::enable_if<!IsSmartPtr< T >::value, bool >::type ReferenceEquals (T const &objA, T const &objB)
 Compares objects by reference. More...
 
template<typename T >
static std::enable_if<!IsSmartPtr< T >::value, bool >::type ReferenceEquals (T const &objA, std::nullptr_t)
 Reference-compares value type object with nullptr. More...
 
template<typename T1 , typename T2 >
static std::enable_if< IsSmartPtr< T1 >::value &&IsSmartPtr< T2 >::value, bool >::type Equals (T1 const &objA, T2 const &objB)
 Compares reference type objects in C# style. More...
 
template<typename T1 , typename T2 >
static std::enable_if<!IsSmartPtr< T1 >::value &&!IsSmartPtr< T2 >::value, bool >::type Equals (T1 const &objA, T2 const &objB)
 Compares value type objects in C# style. More...
 
static const TypeInfoType ()
 Implements C# typeof(System.Object) construct. More...
 
template<>
bool Equals (float const &objA, float const &objB)
 Emulates C#-style floating point comparison where two NaNs are considered equal even though according to IEC 60559:1989 NaN is not equal to any value, including NaN. More...
 
template<>
bool Equals (double const &objA, double const &objB)
 Emulates C#-style floating point comparison where two NaNs are considered equal even though according to IEC 60559:1989 NaN is not equal to any value, including NaN. More...
 

Protected Member Functions

ByteArrayPtr HashData (ByteArrayPtr data, int32_t offset, int32_t count, HashAlgorithmName hash_algorithm) override
 Computes the hash value of the specified data array using the specified hash algorithm. More...
 
ByteArrayPtr HashData (StreamPtr stream, HashAlgorithmName hash_algorithm) override
 Computes the hash value of the specified binary stream using the specified hash algorithm. More...
 
- Protected Member Functions inherited from System::Security::Cryptography::RSA
 RSA ()
 Constructor. More...
 
- Protected Member Functions inherited from System::Security::Cryptography::AsymmetricAlgorithm
 AsymmetricAlgorithm ()
 Constructor. More...
 

Additional Inherited Members

- Public Types inherited from System::Object
typedef SmartPtr< Objectptr
 Alias for smart pointer type. More...
 
- Protected Attributes inherited from System::Security::Cryptography::AsymmetricAlgorithm
int32_t KeySizeValue
 Key size associated with algorithm. More...
 
ArrayPtr< SharedPtr< KeySizes > > LegalKeySizesValue
 Enabled key sizes. More...
 

Detailed Description

RSA algorithm in CSP form. Objects of this class should only be allocated using System::MakeObject() function. Never create instance of this type on stack or using operator new, as it will result in runtime errors and/or assertion faults. Always wrap this class into System::SmartPtr pointer and use this pointer to pass it to functions as argument.

Constructor & Destructor Documentation

◆ RSACryptoServiceProvider() [1/5]

System::Security::Cryptography::RSACryptoServiceProvider::RSACryptoServiceProvider ( )

Constructor. Uses default parameters.

◆ RSACryptoServiceProvider() [2/5]

System::Security::Cryptography::RSACryptoServiceProvider::RSACryptoServiceProvider ( const SharedPtr< CspParameters > &  parameters)

Constructor. Not implemented.

Parameters
parametersAlgorithm parameters.

◆ RSACryptoServiceProvider() [3/5]

System::Security::Cryptography::RSACryptoServiceProvider::RSACryptoServiceProvider ( const RSAParameters parameters)

Constructor.

Parameters
parametersAlgorithm parameters.

◆ RSACryptoServiceProvider() [4/5]

System::Security::Cryptography::RSACryptoServiceProvider::RSACryptoServiceProvider ( int32_t  key_size)

Constructor.

Parameters
key_sizeKey size in bits.

◆ RSACryptoServiceProvider() [5/5]

System::Security::Cryptography::RSACryptoServiceProvider::RSACryptoServiceProvider ( int32_t  key_size,
const SharedPtr< CspParameters > &  parameters 
)

Constructor. Not implemented.

Parameters
key_sizeKey size in bits.
parametersAlgorithm parameters.

Member Function Documentation

◆ Decrypt() [1/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::Decrypt ( ByteArrayPtr  data,
SharedPtr< RSAEncryptionPadding padding 
)
overridevirtual

Decrypts input data using the specified padding mode.

Parameters
dataByte array to decrypt.
paddingPadding mode.
Returns
Decrypted data in byte array format.

Reimplemented from System::Security::Cryptography::RSA.

◆ Decrypt() [2/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::Decrypt ( const ByteArrayPtr rgb,
bool  use_oaep 
)

Decrypts message. Not implemented.

Parameters
rgbData to decrypt.
use_oaepTrue to use OAEP padding, false to use PKCS#1 v1.5 padding.
Returns
Decrypted data array.

◆ Dispose()

void System::Security::Cryptography::RSACryptoServiceProvider::Dispose ( )
overridevirtual

Frees data associated with object.

Reimplemented from System::Security::Cryptography::AsymmetricAlgorithm.

◆ Encrypt() [1/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::Encrypt ( ByteArrayPtr  data,
SharedPtr< RSAEncryptionPadding padding 
)
overridevirtual

Encrypts input data using the specified padding mode.

Parameters
dataByte array to encrypt.
paddingPadding mode.
Returns
Encrypted data in byte array format.

Reimplemented from System::Security::Cryptography::RSA.

◆ Encrypt() [2/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::Encrypt ( const ByteArrayPtr rgb,
bool  use_oaep 
)

Encrypts message. Not implemented.

Parameters
rgbData to encrypt.
use_oaepTrue to use OAEP padding, false to use PKCS#1 v1.5 padding.
Returns
Encrypted data array.

◆ ExportCspBlob()

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::ExportCspBlob ( bool  include_private_parameters)
overridevirtual

Exports blob with information on key. Not implemented.

Parameters
include_private_parametersWhether to include private key parameters in blob.
Returns
Blob with key information.

Implements System::Security::Cryptography::ICspAsymmetricAlgorithm.

◆ ExportParameters()

RSAParameters System::Security::Cryptography::RSACryptoServiceProvider::ExportParameters ( bool  include_private_parameters)
overridevirtual

Exports CSP parameters.

Parameters
include_private_parametersWhether to include private key parameters in blob.
Returns
Data structure with CSP parameters.

Implements System::Security::Cryptography::RSA.

◆ get_CspKeyContainerInfo()

SharedPtr<CspKeyContainerInfo> System::Security::Cryptography::RSACryptoServiceProvider::get_CspKeyContainerInfo ( )
overridevirtual

◆ get_KeyExchangeAlgorithm()

String System::Security::Cryptography::RSACryptoServiceProvider::get_KeyExchangeAlgorithm ( )
overridevirtual

Checks key exchange algorithm associated with object.

Returns
Key exchange algorithm name.

Reimplemented from System::Security::Cryptography::RSA.

◆ get_KeySize()

int32_t System::Security::Cryptography::RSACryptoServiceProvider::get_KeySize ( )
overridevirtual

Gets key size used by algorithm.

Returns
Key size in bits.

Reimplemented from System::Security::Cryptography::AsymmetricAlgorithm.

◆ get_PersistKeyInCsp()

bool System::Security::Cryptography::RSACryptoServiceProvider::get_PersistKeyInCsp ( ) const

Checks whether key is persisted in CSP object.

Returns
True if key is persisted, false otherwise.

◆ get_PublicOnly()

bool System::Security::Cryptography::RSACryptoServiceProvider::get_PublicOnly ( ) const

Checks if public key only is present in CSP object.

Returns
True if public key is present and private one is not, false otherwise.

◆ get_SignatureAlgorithm()

String System::Security::Cryptography::RSACryptoServiceProvider::get_SignatureAlgorithm ( )
overridevirtual

Gets signature algorithm associated with CSP object.

Returns
Signature algorithm name.

Reimplemented from System::Security::Cryptography::RSA.

◆ get_UseMachineKeyStore()

static bool System::Security::Cryptography::RSACryptoServiceProvider::get_UseMachineKeyStore ( )
static

Checks whether the key persists in machine store instead of user store.

Returns
True if the key should be persisted in machine store, false if it should be persisted in user store.

◆ HashData() [1/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::HashData ( ByteArrayPtr  data,
int32_t  offset,
int32_t  count,
HashAlgorithmName  hash_algorithm 
)
overrideprotectedvirtual

Computes the hash value of the specified data array using the specified hash algorithm.

Parameters
dataData to hash.
offsetOffset in data.
countNumber of bytes to hash.
hash_algorithmHash algorithm.
Returns
Hashed data.

Reimplemented from System::Security::Cryptography::RSA.

◆ HashData() [2/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::HashData ( StreamPtr  stream,
HashAlgorithmName  hash_algorithm 
)
overrideprotectedvirtual

Computes the hash value of the specified binary stream using the specified hash algorithm.

Parameters
streamBynary stream to hashed.
hash_algorithmHash algorithm.
Returns
Hashed data.

Reimplemented from System::Security::Cryptography::RSA.

◆ ImportCspBlob()

void System::Security::Cryptography::RSACryptoServiceProvider::ImportCspBlob ( ByteArrayPtr  key_blob)
overridevirtual

Imports blob with information on key. Not implemented.

Parameters
key_blobPreviously exported blob with key information.

Implements System::Security::Cryptography::ICspAsymmetricAlgorithm.

◆ ImportParameters()

void System::Security::Cryptography::RSACryptoServiceProvider::ImportParameters ( RSAParameters  parameters)
overridevirtual

Imports CSP parameters.

Parameters
parametersData structure with CSP parameters.

Implements System::Security::Cryptography::RSA.

◆ set_PersistKeyInCsp()

void System::Security::Cryptography::RSACryptoServiceProvider::set_PersistKeyInCsp ( bool  value)

Defines whether key is persisted in CSP object.

Parameters
valueTrue to persist the key, false otherwise.

◆ set_UseMachineKeyStore()

static void System::Security::Cryptography::RSACryptoServiceProvider::set_UseMachineKeyStore ( bool  value)
static

Defines whether the key persists in machine store instead of user store.

Parameters
valueTrue if the key should be persisted in machine store, false if it should be persisted in user store.

◆ SignData() [1/3]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::SignData ( const ByteArrayPtr buffer,
const SharedPtr< Object > &  halg 
)

Computes the signature of specified input value.

Parameters
bufferBuffer to read input data from.
halgHash algorithm to use.
Returns
RSA signature for specified data.

◆ SignData() [2/3]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::SignData ( const ByteArrayPtr buffer,
int32_t  offset,
int32_t  count,
const SharedPtr< Object > &  halg 
)

Computes the signature of specified input value.

Parameters
bufferBuffer to read input data from.
offsetInput buffer slice beginning index.
countInput buffer slice size.
halgHash algorithm to use.
Returns
RSA signature for specified data.

◆ SignData() [3/3]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::SignData ( const SharedPtr< IO::Stream > &  input_stream,
const SharedPtr< Object > &  halg 
)

Computes the signature of specified input value.

Parameters
input_streamStream to read data being signed from.
halgHash algorithm to use.
Returns
RSA signature for specified data.

◆ SignHash() [1/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::SignHash ( ByteArrayPtr  hash,
HashAlgorithmName  hash_algorithm,
SharedPtr< RSASignaturePadding padding 
)
overridevirtual

Computes the signature for the specified hash value.

Parameters
hashHash value.
hash_algorithmHash algorithm.
paddingPadding mode. return RSA signature for the specified hash.

Reimplemented from System::Security::Cryptography::RSA.

◆ SignHash() [2/2]

ByteArrayPtr System::Security::Cryptography::RSACryptoServiceProvider::SignHash ( const ByteArrayPtr rgb_hash,
const String str 
)

Computes the signature of specified input value. Not implemented.

Parameters
rgb_hashHash value of data to be signed.
strHash algorithm identifier used to create the hash.
Returns
RSA signature for specified data.

◆ VerifyData()

bool System::Security::Cryptography::RSACryptoServiceProvider::VerifyData ( const ByteArrayPtr buffer,
const SharedPtr< Object > &  halg,
const ByteArrayPtr signature 
)

Checks data signature.

Parameters
bufferData to check signature for.
halgHash algorithm to use.
signatureSignature as received.
Returns
True if signature is valid, false otherwise.

◆ VerifyHash() [1/2]

bool System::Security::Cryptography::RSACryptoServiceProvider::VerifyHash ( ByteArrayPtr  hash,
ByteArrayPtr  signature,
const HashAlgorithmName hash_algorithm,
SharedPtr< RSASignaturePadding padding 
)
overridevirtual

Verifies that the signature of the specified hash is valid.

Parameters
hashHash value of the signed data.
signatureSignature data.
hash_algorithmHash algorithm.
paddingPadding mode. return true if signature is valid, otherwise - false.

Reimplemented from System::Security::Cryptography::RSA.

◆ VerifyHash() [2/2]

bool System::Security::Cryptography::RSACryptoServiceProvider::VerifyHash ( const ByteArrayPtr rgb_hash,
const String str,
const ByteArrayPtr rgb_signature 
)

Checks data signature.

Parameters
rgb_hashHash calculated for received data.
strName of hash algorithm used.
rgb_signatureSignature as received.
Returns
True if signature is valid, false otherwise.