ファイルを暗号化する方法(パスワード付き)

ファイルを暗号化する方法(パスワード付き)
VB.NET

Public Shared Sub EncryptFile(ByVal sourceFile As String, _
                              ByVal destFile As String, _
                              ByRef key As Byte(), _
                              ByRef iv As Byte())
    Dim rijndael As New System.Security.Cryptography.RijndaelManaged()

    key = rijndael.Key
    iv = rijndael.IV

    Dim outFs As New System.IO.FileStream( _
        destFile, System.IO.FileMode.Create, System.IO.FileAccess.Write)

    Dim encryptor As System.Security.Cryptography.ICryptoTransform = _
        rijndael.CreateEncryptor()
    Dim cryptStrm As New System.Security.Cryptography.CryptoStream( _
        outFs, encryptor, System.Security.Cryptography.CryptoStreamMode.Write)

    Dim inFs As New System.IO.FileStream( _
        sourceFile, System.IO.FileMode.Open, System.IO.FileAccess.Read)
    Dim bs As Byte() = New Byte(1023) {}
    Dim readLen As Integer
    While True
        readLen = inFs.Read(bs, 0, bs.Length)
        If readLen = 0 Then
            Exit While
        End If
        cryptStrm.Write(bs, 0, readLen)
    End While

    inFs.Close()
    cryptStrm.Close()
    encryptor.Dispose()
    outFs.Close()
End Sub

Public Shared Sub DecryptFile(ByVal sourceFile As String, _
                              ByVal destFile As String, _
                              ByVal key As Byte(), _
                              ByVal iv As Byte())
    Dim rijndael As New System.Security.Cryptography.RijndaelManaged()

    rijndael.Key = key
    rijndael.IV = iv

    Dim inFs As New System.IO.FileStream( _
        sourceFile, System.IO.FileMode.Open, System.IO.FileAccess.Read)
    Dim decryptor As System.Security.Cryptography.ICryptoTransform = _
        rijndael.CreateDecryptor()
    Dim cryptStrm As New System.Security.Cryptography.CryptoStream( _
        inFs, decryptor, System.Security.Cryptography.CryptoStreamMode.Read)

    Dim outFs As New System.IO.FileStream( _
        destFile, System.IO.FileMode.Create, System.IO.FileAccess.Write)
    Dim bs As Byte() = New Byte(1023) {}
    Dim readLen As Integer
    While True
        readLen = cryptStrm.Read(bs, 0, bs.Length)
        If readLen = 0 Then
            Exit While
        End If
        outFs.Write(bs, 0, readLen)
    End While

    outFs.Close()
    cryptStrm.Close()
    decryptor.Dispose()
    inFs.Close()
End Sub

Dim key As Byte(), iv As Byte()

EncryptFile("C:\test.txt", "C:\test.enc", key, iv)
DecryptFile("C:\test.enc", "C:\test2.txt", key, iv)

C#

public static void EncryptFile(
    string sourceFile, string destFile, out byte[] key, out byte[] iv)
{
    System.Security.Cryptography.RijndaelManaged rijndael =
        new System.Security.Cryptography.RijndaelManaged();

    key = rijndael.Key;
    iv = rijndael.IV;

    System.IO.FileStream outFs = new System.IO.FileStream(
        destFile, System.IO.FileMode.Create, System.IO.FileAccess.Write);
    System.Security.Cryptography.ICryptoTransform encryptor =
        rijndael.CreateEncryptor();
    System.Security.Cryptography.CryptoStream cryptStrm =
        new System.Security.Cryptography.CryptoStream(
            outFs, encryptor,
            System.Security.Cryptography.CryptoStreamMode.Write);

    System.IO.FileStream inFs = new System.IO.FileStream(
        sourceFile, System.IO.FileMode.Open, System.IO.FileAccess.Read);
    byte[] bs = new byte[1024];
    int readLen;
    while ((readLen = inFs.Read(bs, 0, bs.Length)) > 0)
    {
        cryptStrm.Write(bs, 0, readLen);
    }
    inFs.Close();
    cryptStrm.Close();
    encryptor.Dispose();
    outFs.Close();
}

public static void DecryptFile(
    string sourceFile, string destFile, byte[] key, byte[] iv)
{
    System.Security.Cryptography.RijndaelManaged rijndael =
        new System.Security.Cryptography.RijndaelManaged();

    rijndael.Key = key;
    rijndael.IV = iv;

    System.IO.FileStream inFs = new System.IO.FileStream(
        sourceFile, System.IO.FileMode.Open, System.IO.FileAccess.Read);
    System.Security.Cryptography.ICryptoTransform decryptor =
        rijndael.CreateDecryptor();
    System.Security.Cryptography.CryptoStream cryptStrm =
        new System.Security.Cryptography.CryptoStream(
            inFs, decryptor,
            System.Security.Cryptography.CryptoStreamMode.Read);

    System.IO.FileStream outFs = new System.IO.FileStream(
        destFile, System.IO.FileMode.Create, System.IO.FileAccess.Write);
    byte[] bs = new byte[1024];
    int readLen;
    while ((readLen = cryptStrm.Read(bs, 0, bs.Length)) > 0)
    {
        outFs.Write(bs, 0, readLen);
    }
    outFs.Close();
    cryptStrm.Close();
    decryptor.Dispose();
    inFs.Close();
}

byte[] key, iv;

EncryptFile(@"C:\test.txt", @"C:\test.enc", out key, out iv);
DecryptFile(@"C:\test.enc", @"C:\test2.txt", key, iv);