Reusable hash objects (XAML)
The CryptographicHash object can be used to repeatedly hash different data without having to re-create the object for each use. The Append method adds new data to a buffer to be hashed. The GetValueAndReset method hashes the data and resets the object for another use. This is shown by the following example.
public void SampleReusableHash()
{
// Create a string that contains the name of the hashing algorithm to use.
String strAlgName = HashAlgorithmNames.Sha512;
// Create a HashAlgorithmProvider object.
HashAlgorithmProvider objAlgProv = HashAlgorithmProvider.OpenAlgorithm(strAlgName);
// Create a CryptographicHash object. This object can be reused to continually
// hash new messages.
CryptographicHash objHash = objAlgProv.CreateHash();
// Hash message 1.
String strMsg1 = "This is message 1.";
IBuffer buffMsg1 = CryptographicBuffer.ConvertStringToBinary(strMsg1, BinaryStringEncoding.Utf16BE);
objHash.Append(buffMsg1);
IBuffer buffHash1 = objHash.GetValueAndReset();
// Hash message 2.
String strMsg2 = "This is message 2.";
IBuffer buffMsg2 = CryptographicBuffer.ConvertStringToBinary(strMsg2, BinaryStringEncoding.Utf16BE);
objHash.Append(buffMsg2);
IBuffer buffHash2 = objHash.GetValueAndReset();
// Hash message 3.
String strMsg3 = "This is message 3.";
IBuffer buffMsg3 = CryptographicBuffer.ConvertStringToBinary(strMsg3, BinaryStringEncoding.Utf16BE);
objHash.Append(buffMsg3);
IBuffer buffHash3 = objHash.GetValueAndReset();
// Convert the hashes to string values (for display);
String strHash1 = CryptographicBuffer.EncodeToBase64String(buffHash1);
String strHash2 = CryptographicBuffer.EncodeToBase64String(buffHash2);
String strHash3 = CryptographicBuffer.EncodeToBase64String(buffHash3);
}