PasswordDeriveBytes 类

定义

命名空间:

System.Security.Cryptography

程序集:

System.Security.Cryptography.dll

Source:

PasswordDeriveBytes.cs

使用 PBKDF1 算法的扩展从密码派生密钥。

public ref class PasswordDeriveBytes : System::Security::Cryptography::DeriveBytes

public class PasswordDeriveBytes : System.Security.Cryptography.DeriveBytes

type PasswordDeriveBytes = class
    inherit DeriveBytes

Public Class PasswordDeriveBytes
Inherits DeriveBytes

继承

Object

DeriveBytes

PasswordDeriveBytes

示例

下面的代码示例使用 PasswordDeriveBytes 类从密码创建密钥。

using namespace System;
using namespace System::Security::Cryptography;
using namespace System::Text;

// Generates a random salt value of the specified length.
array<Byte>^ CreateRandomSalt(int length)
{
    // Create a buffer
    array<Byte>^ randomBytes;

    if (length >= 1)
    {
        randomBytes = gcnew array <Byte>(length);
    }
    else
    {
        randomBytes = gcnew array <Byte>(1);
    }

    // Create a new RNGCryptoServiceProvider.
    RNGCryptoServiceProvider^ cryptoRNGProvider =
        gcnew RNGCryptoServiceProvider();

    // Fill the buffer with random bytes.
    cryptoRNGProvider->GetBytes(randomBytes);

    // return the bytes.
    return randomBytes;
}

// Clears the bytes in a buffer so they can't later be read from memory.
void ClearBytes(array<Byte>^ buffer)
{
    // Check arguments.
    if (buffer == nullptr)
    {
        throw gcnew ArgumentNullException("buffer");
    }

    // Set each byte in the buffer to 0.
    for (int x = 0; x <= buffer->Length - 1; x++)
    {
        buffer[x] = 0;
    }
}

int main(array<String^>^ args)
{

    // Get a password from the user.
    Console::WriteLine("Enter a password to produce a key:");

    // Security Note: Never hard-code a password within your
    // source code.  Hard-coded passwords can be retrieved
    // from a compiled assembly.
    array<Byte>^ password = Encoding::Unicode->GetBytes(Console::ReadLine());

    array<Byte>^ randomSalt = CreateRandomSalt(7);

    // Create a TripleDESCryptoServiceProvider object.
    TripleDESCryptoServiceProvider^ cryptoDESProvider =
        gcnew TripleDESCryptoServiceProvider();

    try
    {
        Console::WriteLine("Creating a key with PasswordDeriveBytes...");

        // Create a PasswordDeriveBytes object and then create
        // a TripleDES key from the password and salt.
        PasswordDeriveBytes^ passwordDeriveBytes = gcnew PasswordDeriveBytes
            (password->ToString(), randomSalt);

       // Create the key and set it to the Key property
       // of the TripleDESCryptoServiceProvider object.
       // This example uses the SHA1 algorithm.
       // Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
        cryptoDESProvider->Key = passwordDeriveBytes->CryptDeriveKey
            ("TripleDES", "SHA1", 192, cryptoDESProvider->IV);
        Console::WriteLine("Operation complete.");
    }
    catch (Exception^ ex)
    {
        Console::WriteLine(ex->Message);
    }
    finally
    {
        // Clear the buffers
        ClearBytes(password);
        ClearBytes(randomSalt);

        // Clear the key.
        cryptoDESProvider->Clear();
    }

    Console::ReadLine();
}

using System;
using System.Security.Cryptography;
using System.Text;

public class PasswordDerivedBytesExample
{

    public static void Main(String[] args)
    {

        // Get a password from the user.
        Console.WriteLine("Enter a password to produce a key:");

        byte[] pwd = Encoding.Unicode.GetBytes(Console.ReadLine());

        byte[] salt = CreateRandomSalt(7);

        // Create a TripleDESCryptoServiceProvider object.
        TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();

        try
        {
            Console.WriteLine("Creating a key with PasswordDeriveBytes...");

            // Create a PasswordDeriveBytes object and then create
            // a TripleDES key from the password and salt.
            PasswordDeriveBytes pdb = new PasswordDeriveBytes(pwd, salt);


            // Create the key and set it to the Key property
            // of the TripleDESCryptoServiceProvider object.
            // This example uses the SHA1 algorithm.
            // Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
            tdes.Key = pdb.CryptDeriveKey("TripleDES", "SHA1", 192, tdes.IV);


            Console.WriteLine("Operation complete.");
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
        finally
        {
            // Clear the buffers
            ClearBytes(pwd);
            ClearBytes(salt);

            // Clear the key.
            tdes.Clear();
        }

        Console.ReadLine();
    }

    //////////////////////////////////////////////////////////
    // Helper methods:
    // CreateRandomSalt: Generates a random salt value of the
    //                   specified length.
    //
    // ClearBytes: Clear the bytes in a buffer so they can't
    //             later be read from memory.
    //////////////////////////////////////////////////////////

    public static byte[] CreateRandomSalt(int length)
    {
        // Create a buffer
        byte[] randBytes;

        if (length >= 1)
        {
            randBytes = new byte[length];
        }
        else
        {
            randBytes = new byte[1];
        }

        // Create a new RNGCryptoServiceProvider.
        RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();

        // Fill the buffer with random bytes.
        rand.GetBytes(randBytes);

        // return the bytes.
        return randBytes;
    }

    public static void ClearBytes(byte[] buffer)
    {
        // Check arguments.
        if (buffer == null)
        {
            throw new ArgumentException("buffer");
        }

        // Set each byte in the buffer to 0.
        for (int x = 0; x < buffer.Length; x++)
        {
            buffer[x] = 0;
        }
    }
}

Imports System.Security.Cryptography
Imports System.Text



Module PasswordDerivedBytesExample


    Sub Main(ByVal args() As String)

        ' Get a password from the user.
        Console.WriteLine("Enter a password to produce a key:")

        Dim pwd As Byte() = Encoding.Unicode.GetBytes(Console.ReadLine())

        Dim salt As Byte() = CreateRandomSalt(7)

        ' Create a TripleDESCryptoServiceProvider object.
        Dim tdes As New TripleDESCryptoServiceProvider()

        Try
            Console.WriteLine("Creating a key with PasswordDeriveBytes...")

            ' Create a PasswordDeriveBytes object and then create 
            ' a TripleDES key from the password and salt.
            Dim pdb As New PasswordDeriveBytes(pwd, salt)


            ' Create the key and set it to the Key property
            ' of the TripleDESCryptoServiceProvider object.
            ' This example uses the SHA1 algorithm.
            ' Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
            tdes.Key = pdb.CryptDeriveKey("TripleDES", "SHA1", 192, tdes.IV)


            Console.WriteLine("Operation complete.")
        Catch e As Exception
            Console.WriteLine(e.Message)
        Finally
            ' Clear the buffers
            ClearBytes(pwd)
            ClearBytes(salt)

            ' Clear the key.
            tdes.Clear()
        End Try

        Console.ReadLine()

    End Sub


    '********************************************************
    '* Helper methods:
    '* createRandomSalt: Generates a random salt value of the 
    '*                   specified length.  
    '*
    '* clearBytes: Clear the bytes in a buffer so they can't 
    '*             later be read from memory.
    '********************************************************
    Function CreateRandomSalt(ByVal length As Integer) As Byte()
        ' Create a buffer
        Dim randBytes() As Byte

        If length >= 1 Then
            randBytes = New Byte(length) {}
        Else
            randBytes = New Byte(0) {}
        End If

        ' Create a new RNGCryptoServiceProvider.
        Dim rand As New RNGCryptoServiceProvider()

        ' Fill the buffer with random bytes.
        rand.GetBytes(randBytes)

        ' return the bytes.
        Return randBytes

    End Function


    Sub ClearBytes(ByVal buffer() As Byte)
        ' Check arguments.
        If buffer Is Nothing Then
            Throw New ArgumentException("buffer")
        End If

        ' Set each byte in the buffer to 0.
        Dim x As Integer
        For x = 0 To buffer.Length - 1
            buffer(x) = 0
        Next x

    End Sub
End Module

注解

此类使用 PKCS#5 v2.0 标准中定义的 PBKDF1 算法的扩展来派生适合用作密码密钥材料的字节。 IETF RRC 2898 中记录了该标准。

重要

切勿在源代码中对密码进行硬编码。 可以使用 Ildasm.exe (IL 反汇编程序) 工具、十六进制编辑器或直接在文本编辑器（如 notepad.exe）中打开程序集来检索硬编码密码。

构造函数

PasswordDeriveBytes(Byte[], Byte[])	通过指定用来派生密钥的密码和密钥 salt 初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(Byte[], Byte[], CspParameters)	通过指定用来派生密钥的密码、密钥 salt 和加密服务提供程序 (CSP) 初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(Byte[], Byte[], String, Int32)	通过指定用来派生密钥的密码、密钥 salt、哈希名和迭代数初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(Byte[], Byte[], String, Int32, CspParameters)	通过指定用来派生密钥的密码、密钥 salt、哈希名、迭代数和加密服务提供程序 (CSP) 初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(String, Byte[])	使用用来导出密钥的密码和密钥 salt 初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(String, Byte[], CspParameters)	使用用来导出密钥的密码、密钥 salt 和加密服务提供程序 (CSP) 参数初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(String, Byte[], String, Int32)	使用用来导出密钥的密码、密钥 salt、哈希名和迭代数初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(String, Byte[], String, Int32, CspParameters)	使用用来导出密钥的密码、密钥 salt、哈希名、迭代数和加密服务提供程序 (CSP) 参数初始化 PasswordDeriveBytes 类的新实例。

属性

HashName	获取或设置操作的哈希算法的名称。
IterationCount	获取或设置操作的迭代数。
Salt	获取或设置操作的密钥 salt 值。

方法

CryptDeriveKey(String, String, Int32, Byte[])	从 PasswordDeriveBytes 对象导出加密密钥。
Dispose()	在派生类中重写时，释放由 DeriveBytes 类的当前实例使用的所有资源。 (继承自 DeriveBytes)
Dispose(Boolean)	释放 PasswordDeriveBytes 类使用的非托管资源，并可以选择释放托管资源。
Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetBytes(Int32)	已过时. 返回伪随机密钥字节。
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
Reset()	重置操作的状态。
ToString()	返回表示当前对象的字符串。 (继承自 Object)

另请参阅

• 加密服务