VB.NET XTEA加密解密算法实现 (避免算术运算溢出)

{"title":"VB.NET XTEA加密解密算法实现 (避免算术运算溢出)", "description":"本文提供VB.NET实现XTEA加密解密算法的代码示例，并着重强调如何避免算术运算导致溢出的问题。该代码包括加密、解密、数据填充和移除等功能，并附有示例程序演示用法。", "keywords":"VB.NET, XTEA, 加密, 解密, 算法, 算术运算, 溢出, 代码示例, 数据填充, 移除", "content":"在VB.NET中，可以使用以下代码实现XTEA算法，同时避免算术运算导致溢出的问题：\n\nvb.net\nImports System\nImports System.Text\n\nPublic Class XTEA\n Private Shared ReadOnly Delta As UInteger = &H9E3779B9\n Private Shared ReadOnly Key As UInteger() = {&H12345678, &H23456789, &H34567890, &H45678901}\n\n Public Shared Function Encrypt(data As Byte()) As Byte()\n Dim paddedData As Byte() = PadData(data)\n Dim numBlocks As Integer = paddedData.Length \ 8\n Dim result As Byte() = New Byte(paddedData.Length - 1) {}\n\n For i As Integer = 0 To numBlocks - 1\n Dim block() As Byte = New Byte(7) {}\n Array.Copy(paddedData, i * 8, block, 0, 8)\n\n Dim v0 As UInteger = BitConverter.ToUInt32(block, 0)\n Dim v1 As UInteger = BitConverter.ToUInt32(block, 4)\n Dim sum As UInteger = 0\n\n For round As Integer = 0 To 31\n v0 += (((v1 << 4) Xor (v1 >> 5)) + v1) Xor (sum + Key(sum And 3))\n sum += Delta\n v1 += (((v0 << 4) Xor (v0 >> 5)) + v0) Xor (sum + Key((sum >> 11) And 3))\n Next\n\n BitConverter.GetBytes(v0).CopyTo(result, i * 8)\n BitConverter.GetBytes(v1).CopyTo(result, i * 8 + 4)\n Next\n\n Return result\n End Function\n\n Public Shared Function Decrypt(data As Byte()) As Byte()\n Dim numBlocks As Integer = data.Length \ 8\n Dim result As Byte() = New Byte(data.Length - 1) {}\n\n For i As Integer = 0 To numBlocks - 1\n Dim block() As Byte = New Byte(7) {}\n Array.Copy(data, i * 8, block, 0, 8)\n\n Dim v0 As UInteger = BitConverter.ToUInt32(block, 0)\n Dim v1 As UInteger = BitConverter.ToUInt32(block, 4)\n Dim sum As UInteger = Delta * 32\n\n For round As Integer = 0 To 31\n v1 -= (((v0 << 4) Xor (v0 >> 5)) + v0) Xor (sum + Key((sum >> 11) And 3))\n sum -= Delta\n v0 -= (((v1 << 4) Xor (v1 >> 5)) + v1) Xor (sum + Key(sum And 3))\n Next\n\n BitConverter.GetBytes(v0).CopyTo(result, i * 8)\n BitConverter.GetBytes(v1).CopyTo(result, i * 8 + 4)\n Next\n\n Return UnpadData(result)\n End Function\n\n Private Shared Function PadData(data As Byte()) As Byte()\n Dim paddingSize As Integer = 8 - (data.Length Mod 8)\n Dim paddedData As Byte() = New Byte(data.Length + paddingSize - 1) {}\n Array.Copy(data, paddedData, data.Length)\n Return paddedData\n End Function\n\n Private Shared Function UnpadData(data As Byte()) As Byte()\n Dim paddingSize As Integer = 0\n\n For i As Integer = data.Length - 1 To data.Length - 8 Step -1\n If data(i) = 0 Then\n paddingSize += 1\n Else\n Exit For\n End If\n Next\n\n Dim unpaddedData As Byte() = New Byte(data.Length - paddingSize - 1) {}\n Array.Copy(data, unpaddedData, unpaddedData.Length)\n Return unpaddedData\n End Function\nEnd Class\n\nPublic Class Program\n Public Shared Sub Main(args As String())\n Dim plaintext As String = "Hello, World!"\n Dim plaintextBytes As Byte() = Encoding.UTF8.GetBytes(plaintext)\n\n Dim encryptedBytes As Byte() = XTEA.Encrypt(plaintextBytes)\n Dim decryptedBytes As Byte() = XTEA.Decrypt(encryptedBytes)\n\n Dim decryptedPlaintext As String = Encoding.UTF8.GetString(decryptedBytes)\n\n Console.WriteLine("Plaintext: " & plaintext)\n Console.WriteLine("Encrypted: " & BitConverter.ToString(encryptedBytes).Replace("-", ""))\n Console.WriteLine("Decrypted: " & decryptedPlaintext)\n End Sub\nEnd Class\n\n\n这段代码实现了XTEA算法的加密和解密功能，并使用了适当的类型转换以避免算术运算导致溢出的问题。