RSACryptoServiceProvider::SignData Method (array<Byte>^, Int32, Int32, Object^)
Computes the hash value of a subset of the specified byte array using the specified hash algorithm, and signs the resulting hash value.
Assembly: mscorlib (in mscorlib.dll)
public: array<unsigned char>^ SignData( array<unsigned char>^ buffer, int offset, int count, Object^ halg )
Parameters
- buffer
-
Type:
array<System::Byte>^
The input data for which to compute the hash.
- offset
-
Type:
System::Int32
The offset into the array from which to begin using data.
- count
-
Type:
System::Int32
The number of bytes in the array to use as data.
- halg
-
Type:
System::Object^
The hash algorithm to use to create the hash value.
| Exception | Condition |
|---|---|
| ArgumentNullException | The halg parameter is null. |
| ArgumentException | The halg parameter is not a valid type. |
This method creates a digital signature that is verified using the VerifyData method.
The halg parameter can accept a String, a HashAlgorithm, or a Type. The string value can be one of the following:
The object identifier (OID) friendly name of the hash algorithm to use, either a name registered in the crypto config file or one in the Crypto API OID table.
The OID value. The OID must be one recognized by the Crypto API.
For example, you could use SignData(new byte[5], "1.3.14.3.2.26") or SignData(new byte[5], "sha1"), or SignData(new byte[5], "SHA1").
The following code example signs and verifies data.
using namespace System; using namespace System::Security::Cryptography; using namespace System::Text; array<Byte>^ HashAndSignBytes( array<Byte>^DataToSign, RSAParameters Key, int Index, int Length ) { try { // Create a new instance of RSACryptoServiceProvider using the // key from RSAParameters. RSACryptoServiceProvider^ RSAalg = gcnew RSACryptoServiceProvider; RSAalg->ImportParameters( Key ); // Hash and sign the data. Pass a new instance of SHA1CryptoServiceProvider // to specify the use of SHA1 for hashing. return RSAalg->SignData( DataToSign, Index, Length, gcnew SHA1CryptoServiceProvider ); } catch ( CryptographicException^ e ) { Console::WriteLine( e->Message ); return nullptr; } } bool VerifySignedHash( array<Byte>^DataToVerify, array<Byte>^SignedData, RSAParameters Key ) { try { // Create a new instance of RSACryptoServiceProvider using the // key from RSAParameters. RSACryptoServiceProvider^ RSAalg = gcnew RSACryptoServiceProvider; RSAalg->ImportParameters( Key ); // Verify the data using the signature. Pass a new instance of SHA1CryptoServiceProvider // to specify the use of SHA1 for hashing. return RSAalg->VerifyData( DataToVerify, gcnew SHA1CryptoServiceProvider, SignedData ); } catch ( CryptographicException^ e ) { Console::WriteLine( e->Message ); return false; } } int main() { try { // Create a UnicodeEncoder to convert between byte array and string. ASCIIEncoding^ ByteConverter = gcnew ASCIIEncoding; String^ dataString = "Data to Sign"; // Create byte arrays to hold original, encrypted, and decrypted data. array<Byte>^originalData = ByteConverter->GetBytes( dataString ); array<Byte>^signedData; array<Byte>^smallArray; // Create a new instance of the RSACryptoServiceProvider class // and automatically create a new key-pair. RSACryptoServiceProvider^ RSAalg = gcnew RSACryptoServiceProvider; // Export the key information to an RSAParameters object. // You must pass true to export the private key for signing. // However, you do not need to export the private key // for verification. RSAParameters Key = RSAalg->ExportParameters( true ); // Hash and sign the data. Start at the fifth offset // only use data from the next 7 bytes. signedData = HashAndSignBytes( originalData, Key, 5, 7 ); // The previous method only signed one segment // of the array. Create a new array for verification // that only holds the data that was actually signed. // // Initialize the array. smallArray = gcnew array<Byte>(7); // Copy 7 bytes starting at the 5th index to // the new array. Array::Copy( originalData, 5, smallArray, 0, 7 ); // Verify the data and display the result to the // console. if ( VerifySignedHash( smallArray, signedData, Key ) ) { Console::WriteLine( "The data was verified." ); } else { Console::WriteLine( "The data does not match the signature." ); } } catch ( ArgumentNullException^ ) { Console::WriteLine( "The data was not signed or verified" ); } }
Available since 1.1
Windows Phone Silverlight
Available since 7.1