VB.NET中的安全加密算法

这几天需要对系统中的一些关键数据进行加密。用VB.NET编写CLR函数，然后在存储过程中略加修改即完成任务。

在测试过程中遇到不少问题，比如说不熟悉流对象（初学VB.NET），不熟悉编码转换，最重要的是加密的密钥长度限制，可能很多人会遇到。

下面的代码中实现了散列加密算法和对称加密算法，用的都是.NET安全算法的工厂类，并实现常用的Base64编码和解码。

常用的散列加密算法有：MD5，SHA（SHA1），RIPEMD160，SHA256，SHA384，SHA512，MACTripleDES

常用的对称加密算法有：DES，RC2，Rijndael,TripleDES。对称加密算法有一个key和一个IV，不同的算法要求的key和IV长度不一样，而且同一个字符串在不同的编码下长度也不一样，这一点要特别注意。

经测试，不同编码对应的key和IV长度对应关系如下：

贴代码：

Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports Microsoft.SqlServer.Server
Imports System.Runtime.InteropServices
Imports System.Security
Imports System.Data.SqlTypes
Imports System.Security.Cryptography
Namespace SOP.Security
    Public Class Security
        '散列加密算法
        <Microsoft.SqlServer.Server.SqlFunction()> _
        Public Shared Function HashAlgorithm(ByVal Input As SqlString, ByVal Algorithm As SqlString, ByVal Charset As SqlString) As SqlString
            Dim _md5 As System.Security.Cryptography.HashAlgorithm = System.Security.Cryptography.HashAlgorithm.Create(Algorithm.Value)
            Dim fs() As Byte, sb As New System.Text.StringBuilder
            fs = _md5.ComputeHash(getBytes(Input.Value, Charset.Value))
            For i As Integer = 0 To fs.Length - 1
                sb.Append(fs(i).ToString("x2"))
            Next
            Return sb.ToString()
        End Function
        '对称加密算法
        <Microsoft.SqlServer.Server.SqlFunction()> _
        Public Shared Function SymmetricEncrypt(ByVal Input As SqlString, ByVal Key As SqlString, ByVal IV As SqlString, ByVal Algorithm As SqlString, ByVal Charset As SqlString) As SqlString
            Dim sa As System.Security.Cryptography.SymmetricAlgorithm = System.Security.Cryptography.SymmetricAlgorithm.Create(Algorithm.Value) ' New System.Security.Cryptography.DESCryptoServiceProvider
            Dim data() As Byte
            sa.Key = getBytes(Key.Value, Charset.Value)
            sa.IV = getBytes(IV.Value, Charset.Value)
            '将数据转换成字节
            data = getBytes(Input.Value, Charset.Value)
            Using ms As New System.IO.MemoryStream
                '将数据加密,并准备写入ms内存流中
                Dim cs As New System.Security.Cryptography.CryptoStream(ms, sa.CreateEncryptor, CryptoStreamMode.Write)
                '写入加密数据至缓存区
                cs.Write(data, 0, data.Length)
                '将数据更新到流对象
                cs.FlushFinalBlock()
                '关闭
                cs.Close()
                '用base64编码一次
                Return Convert.ToBase64String(ms.ToArray)
            End Using
        End Function
        '对称解密算法
        <Microsoft.SqlServer.Server.SqlFunction()> _
        Public Shared Function SymmetricDecrypt(ByVal Input As SqlString, ByVal Key As SqlString, ByVal IV As SqlString, ByVal Algorithm As SqlString, ByVal Charset As SqlString) As SqlString
            Dim sa As System.Security.Cryptography.SymmetricAlgorithm = System.Security.Cryptography.SymmetricAlgorithm.Create(Algorithm.Value) '  System.Security.Cryptography.DESCryptoServiceProvider
            Dim data() As Byte
            sa.Key = getBytes(Key.Value, Charset.Value)
            sa.IV = getBytes(IV.Value, Charset.Value)
            '将数据用base64解码一次
            data = Convert.FromBase64String(Input.Value)
            Using ms As New System.IO.MemoryStream()
                '将数据加密,并准备写入ms内存流中
                Dim cs As New System.Security.Cryptography.CryptoStream(ms, sa.CreateDecryptor, CryptoStreamMode.Write)
                '写入加密数据至缓存区
                cs.Write(data, 0, data.Length)
                '将数据更新到流对象
                cs.FlushFinalBlock()
                '关闭
                cs.Close()
                '再转换回字符串
                Return getString(ms.ToArray, Charset.Value)
            End Using
        End Function
        'Base64
        <Microsoft.SqlServer.Server.SqlFunction()> _
        Public Shared Function Base64Encode(ByVal Input As SqlString, ByVal Charset As SqlString) As SqlString
            Return Convert.ToBase64String(getBytes(Input.Value, Charset.Value))
        End Function
        <Microsoft.SqlServer.Server.SqlFunction()> _
        Public Shared Function Base64Decode(ByVal Input As SqlString, ByVal Charset As SqlString) As SqlString
            Return getString(Convert.FromBase64String(Input.Value), Charset.Value)
        End Function
        '转换字符串至指定编码的字节
        Private Shared Function getBytes(ByVal Input As String, ByVal Charset As String) As Byte()
            Select Case Charset
                Case "UTF-16", "Unicode", "UTF16"
                    Return System.Text.Encoding.Unicode.GetBytes(Input)
                Case "UTF-7", "UTF7"
                    Return System.Text.Encoding.UTF7.GetBytes(Input)
                Case "UTF-8", "UTF8"
                    Return System.Text.Encoding.UTF8.GetBytes(Input)
                Case "UTF-32", "UTF32"
                    Return System.Text.Encoding.UTF32.GetBytes(Input)
                Case "ASCII"
                    Return System.Text.Encoding.ASCII.GetBytes(Input)
                Case "", "Default"
                    Return System.Text.Encoding.Default.GetBytes(Input)
                Case Else
                    Return System.Text.Encoding.Default.GetBytes(Input)
            End Select
        End Function
        '字节转换至指定编码的字符串
        Private Shared Function getString(ByVal Input() As Byte, ByVal Charset As String) As String
            Select Case Charset
                Case "UTF-16", "Unicode", "UTF16"
                    Return System.Text.Encoding.Unicode.GetString(Input)
                Case "UTF-7", "UTF7"
                    Return System.Text.Encoding.UTF7.GetString(Input)
                Case "UTF-8", "UTF8"
                    Return System.Text.Encoding.UTF8.GetString(Input)
                Case "UTF-32", "UTF32"
                    Return System.Text.Encoding.UTF32.GetString(Input)
                Case "ASCII"
                    Return System.Text.Encoding.ASCII.GetString(Input)
                Case "", "Default"
                    Return System.Text.Encoding.Default.GetString(Input)
                Case Else
                    Return System.Text.Encoding.Default.GetString(Input)
            End Select
        End Function
    End Class


End Namespace

以下是在SQL SERVER2005中安装CLR函数的方法：

alter database    sop set TRUSTWORTHY on;
exec sp_changedbowner sa
go
CREATE ASSEMBLY [SOP.Security]
AUTHORIZATION [dbo]
FROM 'E:\hsl\sop\sop.ScriptEngine.dll'
WITH PERMISSION_SET = unsafe
go
 CREATE ASSEMBLY [SOP.Security]
AUTHORIZATION [dbo]
 WITH PERMISSION_SET = UNSAFE
go
Create FUNCTION [dbo].[SymmetricDecrypt](@Input [nvarchar](4000), @Key [nvarchar](4000), @IV [nvarchar](4000), @Algorithm [nvarchar](4000), @Charset [nvarchar](4000))
RETURNS [nvarchar](4000) WITH EXECUTE AS CALLER
AS 
EXTERNAL NAME [SOP.Security].[SOP.Security.Security].[SymmetricDecrypt]
go
Create FUNCTION [dbo].[SymmetricEncrypt](@Input [nvarchar](4000), @Key [nvarchar](4000), @IV [nvarchar](4000), @Algorithm [nvarchar](4000), @Charset [nvarchar](4000))
RETURNS [nvarchar](4000) WITH EXECUTE AS CALLER
AS 
EXTERNAL NAME [SOP.Security].[SOP.Security.Security].[SymmetricEncrypt]
GO
Create FUNCTION [dbo].[HashAlgorithm](@Input [nvarchar](4000), @Algorithm [nvarchar](4000), @Charset [nvarchar](4000))
RETURNS [nvarchar](4000) WITH EXECUTE AS CALLER
AS 
EXTERNAL NAME [SOP.Security].[SOP.Security.Security].[HashAlgorithm]
GO
Create FUNCTION [dbo].[Base64Encode](@Input [nvarchar](4000), @Charset [nvarchar](4000))
RETURNS [nvarchar](4000) WITH EXECUTE AS CALLER
AS 
EXTERNAL NAME [SOP.Security].[SOP.Security.Security].[Base64Encode]
GO
Create FUNCTION [dbo].[Base64Decode](@Input [nvarchar](4000), @Charset [nvarchar](4000))
RETURNS [nvarchar](4000) WITH EXECUTE AS CALLER
AS 
EXTERNAL NAME [SOP.Security].[SOP.Security.Security].[Base64Decode]
go

调用示例：

DECLARE @key VARCHAR(500),@VI VARCHAR(500),@s nVARCHAR(MAX),@d nVARCHAR(MAX),@d1 nVARCHAR(MAX)
SELECT @key='55523423123456785552342312345678',@VI='55523423123456785552342312345678',@s='定义全局变量,并改写afterFinalSubmit方法'
SELECT @d=dbo.SymmetricEncrypt(@s,left(@key,4),left(@VI,2),'TripleDES','UTF32')
PRINT @d
输出：
e2TRpdUG4+bY1Glg0roDFinHcKU+s2aKxNnVSdfSKPt4i8bN8leTWqWelGtMndbv2cDp2vacfMN8WmzwYyr6l1Q2pdO3Xsx6xykVcpfGXk2sjS//jO4/AyrDWT7h+HRECmETmS3M2poZhbEYsrNerA/hny/J1xzO

由于不太了解.net和加密算法，此文只是我简单测试后的结果，如有错误，请及时指出。