HashAlgorithm.ComputeHash Method
Definition
Important
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Computes the hash value for the input data.
Overloads
ComputeHash(Byte[]) |
Computes the hash value for the specified byte array. |
ComputeHash(Stream) |
Computes the hash value for the specified Stream object. |
ComputeHash(Byte[], Int32, Int32) |
Computes the hash value for the specified region of the specified byte array. |
ComputeHash(Byte[])
- Source:
- HashAlgorithm.cs
- Source:
- HashAlgorithm.cs
- Source:
- HashAlgorithm.cs
Computes the hash value for the specified byte array.
public:
cli::array <System::Byte> ^ ComputeHash(cli::array <System::Byte> ^ buffer);
public byte[] ComputeHash (byte[] buffer);
member this.ComputeHash : byte[] -> byte[]
Public Function ComputeHash (buffer As Byte()) As Byte()
Parameters
- buffer
- Byte[]
The input to compute the hash code for.
Returns
The computed hash code.
Exceptions
buffer
is null
.
The object has already been disposed.
Examples
The following example computes the SHA256 hash value of a string and returns the hash as a 64-character, hexadecimal-formatted string. The hash string created by this code example is compatible with any SHA256 hash function (on any platform) that creates a 64-character, hexadecimal-formatted hash string.
using System;
using System.Security.Cryptography;
using System.Text;
public class Program
{
public static void Main()
{
string source = "Hello World!";
using (SHA256 sha256Hash = SHA256.Create())
{
string hash = GetHash(sha256Hash, source);
Console.WriteLine($"The SHA256 hash of {source} is: {hash}.");
Console.WriteLine("Verifying the hash...");
if (VerifyHash(sha256Hash, source, hash))
{
Console.WriteLine("The hashes are the same.");
}
else
{
Console.WriteLine("The hashes are not same.");
}
}
}
private static string GetHash(HashAlgorithm hashAlgorithm, string input)
{
// Convert the input string to a byte array and compute the hash.
byte[] data = hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(input));
// Create a new Stringbuilder to collect the bytes
// and create a string.
var sBuilder = new StringBuilder();
// Loop through each byte of the hashed data
// and format each one as a hexadecimal string.
for (int i = 0; i < data.Length; i++)
{
sBuilder.Append(data[i].ToString("x2"));
}
// Return the hexadecimal string.
return sBuilder.ToString();
}
// Verify a hash against a string.
private static bool VerifyHash(HashAlgorithm hashAlgorithm, string input, string hash)
{
// Hash the input.
var hashOfInput = GetHash(hashAlgorithm, input);
// Create a StringComparer an compare the hashes.
StringComparer comparer = StringComparer.OrdinalIgnoreCase;
return comparer.Compare(hashOfInput, hash) == 0;
}
}
// The example displays the following output:
// The SHA256 hash of Hello World! is: 7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069.
// Verifying the hash...
// The hashes are the same.
Imports System.Security.Cryptography
Imports System.Text
Public Module Program
Public Sub Main()
Dim source As String = "Hello World!"
Using sha256Hash As SHA256 = SHA256.Create()
Dim hash As String = GetHash(sha256Hash, source)
Console.WriteLine($"The SHA256 hash of {source} is: {hash}.")
Console.WriteLine("Verifying the hash...")
If VerifyHash(sha256Hash, source, hash) Then
Console.WriteLine("The hashes are the same.")
Else
Console.WriteLine("The hashes are not same.")
End If
End Using
End Sub
Private Function GetHash(ByVal hashAlgorithm As HashAlgorithm, ByVal input As String) As String
' Convert the input string to a byte array and compute the hash.
Dim data As Byte() = hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(input))
' Create a new Stringbuilder to collect the bytes
' and create a string.
Dim sBuilder As New StringBuilder()
' Loop through each byte of the hashed data
' and format each one as a hexadecimal string.
For i As Integer = 0 To data.Length - 1
sBuilder.Append(data(i).ToString("x2"))
Next
' Return the hexadecimal string.
Return sBuilder.ToString()
End Function
' Verify a hash against a string.
Private Function VerifyHash(hashAlgorithm As HashAlgorithm, input As String, hash As String) As Boolean
' Hash the input.
Dim hashOfInput As String = GetHash(hashAlgorithm, input)
' Create a StringComparer an compare the hashes.
Dim comparer As StringComparer = StringComparer.OrdinalIgnoreCase
Return comparer.Compare(hashOfInput, hash) = 0
End Function
End Module
' The example displays the following output:
' The SHA256 hash of Hello World! is: 7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069.
' Verifying the hash...
' The hashes are the same.
Applies to
ComputeHash(Stream)
- Source:
- HashAlgorithm.cs
- Source:
- HashAlgorithm.cs
- Source:
- HashAlgorithm.cs
Computes the hash value for the specified Stream object.
public:
cli::array <System::Byte> ^ ComputeHash(System::IO::Stream ^ inputStream);
public byte[] ComputeHash (System.IO.Stream inputStream);
member this.ComputeHash : System.IO.Stream -> byte[]
Public Function ComputeHash (inputStream As Stream) As Byte()
Parameters
- inputStream
- Stream
The input to compute the hash code for.
Returns
The computed hash code.
Exceptions
The object has already been disposed.
Examples
The following example calculates the SHA256 hash for all files in a directory.
using System;
using System.IO;
using System.Security.Cryptography;
public class HashDirectory
{
public static void Main(string[] args)
{
if (args.Length < 1)
{
Console.WriteLine("No directory selected.");
return;
}
string directory = args[0];
if (Directory.Exists(directory))
{
// Create a DirectoryInfo object representing the specified directory.
var dir = new DirectoryInfo(directory);
// Get the FileInfo objects for every file in the directory.
FileInfo[] files = dir.GetFiles();
// Initialize a SHA256 hash object.
using (SHA256 mySHA256 = SHA256.Create())
{
// Compute and print the hash values for each file in directory.
foreach (FileInfo fInfo in files)
{
using (FileStream fileStream = fInfo.Open(FileMode.Open))
{
try
{
// Create a fileStream for the file.
// Be sure it's positioned to the beginning of the stream.
fileStream.Position = 0;
// Compute the hash of the fileStream.
byte[] hashValue = mySHA256.ComputeHash(fileStream);
// Write the name and hash value of the file to the console.
Console.Write($"{fInfo.Name}: ");
PrintByteArray(hashValue);
}
catch (IOException e)
{
Console.WriteLine($"I/O Exception: {e.Message}");
}
catch (UnauthorizedAccessException e)
{
Console.WriteLine($"Access Exception: {e.Message}");
}
}
}
}
}
else
{
Console.WriteLine("The directory specified could not be found.");
}
}
// Display the byte array in a readable format.
public static void PrintByteArray(byte[] array)
{
for (int i = 0; i < array.Length; i++)
{
Console.Write($"{array[i]:X2}");
if ((i % 4) == 3) Console.Write(" ");
}
Console.WriteLine();
}
}
Imports System.IO
Imports System.Security.Cryptography
Public Module HashDirectory
Public Sub Main(ByVal args() As String)
If args.Length < 1 Then
Console.WriteLine("No directory selected")
Return
End If
Dim targetDirectory As String = args(0)
If Directory.Exists(targetDirectory) Then
' Create a DirectoryInfo object representing the specified directory.
Dim dir As New DirectoryInfo(targetDirectory)
' Get the FileInfo objects for every file in the directory.
Dim files As FileInfo() = dir.GetFiles()
' Initialize a SHA256 hash object.
Using mySHA256 As SHA256 = SHA256.Create()
' Compute and print the hash values for each file in directory.
For Each fInfo As FileInfo In files
Try
' Create a fileStream for the file.
Dim fileStream = fInfo.Open(FileMode.Open)
' Be sure it's positioned to the beginning of the stream.
fileStream.Position = 0
' Compute the hash of the fileStream.
Dim hashValue() As Byte = mySHA256.ComputeHash(fileStream)
' Write the name of the file to the Console.
Console.Write(fInfo.Name + ": ")
' Write the hash value to the Console.
PrintByteArray(hashValue)
' Close the file.
fileStream.Close()
Catch e As IOException
Console.WriteLine($"I/O Exception: {e.Message}")
Catch e As UnauthorizedAccessException
Console.WriteLine($"Access Exception: {e.Message}")
End Try
Next
End Using
Else
Console.WriteLine("The directory specified could not be found.")
End If
End Sub
' Print the byte array in a readable format.
Public Sub PrintByteArray(array() As Byte)
For i As Integer = 0 To array.Length - 1
Console.Write($"{array(i):X2}")
If i Mod 4 = 3 Then
Console.Write(" ")
End If
Next
Console.WriteLine()
End Sub
End Module
Applies to
ComputeHash(Byte[], Int32, Int32)
- Source:
- HashAlgorithm.cs
- Source:
- HashAlgorithm.cs
- Source:
- HashAlgorithm.cs
Computes the hash value for the specified region of the specified byte array.
public:
cli::array <System::Byte> ^ ComputeHash(cli::array <System::Byte> ^ buffer, int offset, int count);
public byte[] ComputeHash (byte[] buffer, int offset, int count);
member this.ComputeHash : byte[] * int * int -> byte[]
Public Function ComputeHash (buffer As Byte(), offset As Integer, count As Integer) As Byte()
Parameters
- buffer
- Byte[]
The input to compute the hash code for.
- offset
- Int32
The offset into the byte array from which to begin using data.
- count
- Int32
The number of bytes in the array to use as data.
Returns
The computed hash code.
Exceptions
buffer
is null
.
offset
is out of range. This parameter requires a non-negative number.
The object has already been disposed.