我使用的是this code的略微修改版本。创建关键任务应用程序。那些将被加密的文件非常重要。这必须从头开始，因为还有其他一些事情必须与此一起完成。
这有多安全？不可能破解这种加密吗？
很抱歉这里有一个工作链接。 http://www.codeproject.com/Articles/12092/Encrypt-Decrypt-Files-in-VB-NET-Using-Rijndael
Imports System
Imports System.IO
Imports System.Security
Imports System.Security.Cryptography
'*************************
'** Global Variables
'*************************
Dim strFileToEncrypt As String
Dim strFileToDecrypt As String
Dim strOutputEncrypt As String
Dim strOutputDecrypt As String
Dim fsInput As System.IO.FileStream
Dim fsOutput As System.IO.FileStream
'*************************
'** Create A Key
'*************************
Private Function CreateKey(ByVal strPassword As String) As Byte()
'Convert strPassword to an array and store in chrData.
Dim chrData() As Char = strPassword.ToCharArray
'Use intLength to get strPassword size.
Dim intLength As Integer = chrData.GetUpperBound(0)
'Declare bytDataToHash and make it the same size as chrData.
Dim bytDataToHash(intLength) As Byte
'Use For Next to convert and store chrData into bytDataToHash.
For i As Integer = 0 To chrData.GetUpperBound(0)
bytDataToHash(i) = CByte(Asc(chrData(i)))
Next
'Declare what hash to use.
Dim SHA512 As New System.Security.Cryptography.SHA512Managed
'Declare bytResult, Hash bytDataToHash and store it in bytResult.
Dim bytResult As Byte() = SHA512.ComputeHash(bytDataToHash)
'Declare bytKey(31). It will hold 256 bits.
Dim bytKey(31) As Byte
'Use For Next to put a specific size (256 bits) of
'bytResult into bytKey. The 0 To 31 will put the first 256 bits
'of 512 bits into bytKey.
For i As Integer = 0 To 31
bytKey(i) = bytResult(i)
Next
Return bytKey 'Return the key.
End Function
'*************************
'** Create An IV
'*************************
Private Function CreateIV(ByVal strPassword As String) As Byte()
'Convert strPassword to an array and store in chrData.
Dim chrData() As Char = strPassword.ToCharArray
'Use intLength to get strPassword size.
Dim intLength As Integer = chrData.GetUpperBound(0)
'Declare bytDataToHash and make it the same size as chrData.
Dim bytDataToHash(intLength) As Byte
'Use For Next to convert and store chrData into bytDataToHash.
For i As Integer = 0 To chrData.GetUpperBound(0)
bytDataToHash(i) = CByte(Asc(chrData(i)))
Next
'Declare what hash to use.
Dim SHA512 As New System.Security.Cryptography.SHA512Managed
'Declare bytResult, Hash bytDataToHash and store it in bytResult.
Dim bytResult As Byte() = SHA512.ComputeHash(bytDataToHash)
'Declare bytIV(15). It will hold 128 bits.
Dim bytIV(15) As Byte
'Use For Next to put a specific size (128 bits) of bytResult into bytIV.
'The 0 To 30 for bytKey used the first 256 bits of the hashed password.
'The 32 To 47 will put the next 128 bits into bytIV.
For i As Integer = 32 To 47
bytIV(i - 32) = bytResult(i)
Next
Return bytIV 'Return the IV.
End Function
加密和解密
'****************************
'** Encrypt/Decrypt File
'****************************
Private Enum CryptoAction
'Define the enumeration for CryptoAction.
ActionEncrypt = 1
ActionDecrypt = 2
End Enum
Private Sub EncryptOrDecryptFile(ByVal strInputFile As String, _
ByVal strOutputFile As String, _
ByVal bytKey() As Byte, _
ByVal bytIV() As Byte, _
ByVal Direction As CryptoAction)
Try 'In case of errors.
'Setup file streams to handle input and output.
fsInput = New System.IO.FileStream(strInputFile, FileMode.Open, _
FileAccess.Read)
fsOutput = New System.IO.FileStream(strOutputFile, _
FileMode.OpenOrCreate, _
FileAccess.Write)
fsOutput.SetLength(0) 'make sure fsOutput is empty
'Declare variables for encrypt/decrypt process.
Dim bytBuffer(4096) As Byte 'holds a block of bytes for processing
Dim lngBytesProcessed As Long = 0 'running count of bytes processed
Dim lngFileLength As Long = fsInput.Length 'the input file's length
Dim intBytesInCurrentBlock As Integer 'current bytes being processed
Dim csCryptoStream As CryptoStream
'Declare your CryptoServiceProvider.
Dim cspRijndael As New System.Security.Cryptography.RijndaelManaged
'Setup Progress Bar
pbStatus.Value = 0
pbStatus.Maximum = 100
'Determine if ecryption or decryption and setup CryptoStream.
Select Case Direction
Case CryptoAction.ActionEncrypt
csCryptoStream = New CryptoStream(fsOutput, _
cspRijndael.CreateEncryptor(bytKey, bytIV), _
CryptoStreamMode.Write)
Case CryptoAction.ActionDecrypt
csCryptoStream = New CryptoStream(fsOutput, _
cspRijndael.CreateDecryptor(bytKey, bytIV), _
CryptoStreamMode.Write)
End Select
'Use While to loop until all of the file is processed.
While lngBytesProcessed < lngFileLength
'Read file with the input filestream.
intBytesInCurrentBlock = fsInput.Read(bytBuffer, 0, 4096)
'Write output file with the cryptostream.
csCryptoStream.Write(bytBuffer, 0, intBytesInCurrentBlock)
'Update lngBytesProcessed
lngBytesProcessed = lngBytesProcessed + _
CLng(intBytesInCurrentBlock)
'Update Progress Bar
pbStatus.Value = CInt((lngBytesProcessed / lngFileLength) * 100)
End While
'Close FileStreams and CryptoStream.
csCryptoStream.Close()
fsInput.Close()
fsOutput.Close()
我已将主要代码粘贴到此处。
答案 0 :(得分：9)
如上所述，没有什么是不可能破解的，你只能遵循最佳实践，尽可能让任何潜在的攻击者尽可能地努力。
实际上，您链接的代码不再被视为最先进的代码（如果有的话）。它通过散列密码来创建对称加密密钥。这很糟糕，因为密码通常没有足够的熵来阻止基于字典的复杂攻击。此外，它不使用任何salt或等效的，因此使用预先计算的表来攻击它很容易。
无论何时，您都应该使用安全的PRNG（伪随机数生成器）生成对称密钥。如果没有特别需要涉及密码，请不要这样做。如果绝对必须是密码，请使用PKCS5中的PBKDF2或bcrypt或scrypt等替代品。
IV也应始终从安全的PRNG生成，并且如果可能，永远不会重复使用。也没有必要从密码中派生出来，如您链接的示例所示。 IV是公共信息，这意味着您可以安全地发布它 - 但必须保持不可预测和随机 - 否则您会受到某些dedicated attacks的影响，除非您使用经过验证的加密模式（如GCM）。
如果您不熟悉这些主题并且有疑问，我强烈建议咨询专家。如果要保护的数据与您说的一样重要，那么应该花费额外的资金。如果在该地区没有经验，那么在设计您自己的解决方案时，您可能会忽略一些重要的事情。
答案 1 :(得分：3)
没有什么是不可能的，特别是如果你使用弱IV或钥匙。然而，它在统计上是微不足道的，你应该能够在晚上睡得好。如果你问其他人是否使用这种算法进行关键任务加密，答案肯定是肯定的。