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 RandomNumberGenerator.
    RandomNumberGenerator^ randomNumberGenerator =
        RandomNumberGenerator::Create();

    // Fill the buffer with random bytes.
    randomNumberGenerator->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];
        }

        using (RandomNumberGenerator rng = RandomNumberGenerator.Create())
        {
            // Fill the buffer with random bytes.
            rng.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 RandomNumberGenerator.
        Using rand As RandomNumberGenerator = RandomNumberGenerator.Create()
            ' Fill the buffer with random bytes.
            rand.GetBytes(randBytes)
        End Using

        ' 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中的密钥材料的字节。 该标准记录在 IETF RRC 2898 中。

重要

从不对源代码中的密码进行硬编码。 硬编码的密码可以使用 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的密码。

构造函数

PasswordDeriveBytes(Byte[], Byte[], CspParameters)	初始化 PasswordDeriveBytes 类的新实例，该实例指定用于派生密钥的密码、密钥盐和加密服务提供程序（CSP）。
PasswordDeriveBytes(Byte[], Byte[], String, Int32, CspParameters)	初始化 PasswordDeriveBytes 类的新实例，该类指定用于派生密钥的密码、密钥盐、哈希名称、迭代和加密服务提供程序（CSP）。
PasswordDeriveBytes(Byte[], Byte[], String, Int32)	初始化 PasswordDeriveBytes 类的新实例，指定用于派生密钥的密码、密钥盐、哈希名称和迭代。
PasswordDeriveBytes(Byte[], Byte[])	初始化 PasswordDeriveBytes 类的新实例，该实例指定用于派生密钥的密码和密钥盐。
PasswordDeriveBytes(String, Byte[], CspParameters)	使用密码、密钥盐和加密服务提供商（CSP）参数初始化 PasswordDeriveBytes 类的新实例，以派生密钥。
PasswordDeriveBytes(String, Byte[], String, Int32, CspParameters)	使用密码、密钥盐、哈希名称、迭代次数和加密服务提供程序 （CSP） 参数初始化 PasswordDeriveBytes 类的新实例，以派生密钥。
PasswordDeriveBytes(String, Byte[], String, Int32)	使用密码、密钥盐、哈希名称和用于派生密钥的迭代数初始化 PasswordDeriveBytes 类的新实例。
PasswordDeriveBytes(String, Byte[])	使用密码和密钥 salt 初始化 PasswordDeriveBytes 类的新实例，以用于派生密钥。

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	获取或设置操作的键盐值。

方法

CryptDeriveKey(String, String, Int32, Byte[])	从 PasswordDeriveBytes 对象派生加密密钥。
Dispose()	在派生类中重写时，释放 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，并选择性地释放托管资源。
Equals(Object)	确定指定的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()	用作默认哈希函数。 (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()	返回一个表示当前对象的字符串。 (继承自 Object)

另请参阅

• 加密服务