C#中利用DPAPI加密解密数据

加密解密的一个函数

 

using  System; using  System.Runtime.InteropServices; using  System.Text; using  System.Security; namespace  CryptProtection ... {    [Serializable()]    public sealed class DataProtection    ...{        [Flags()]        public enum CryptProtectPromptFlags        ...{            CRYPTPROTECT_PROMPT_ON_UNPROTECT = 0x01,            CRYPTPROTECT_PROMPT_ON_PROTECT = 0x02,            CRYPTPROTECT_PROMPT_RESERVED = 0x04,            CRYPTPROTECT_PROMPT_STRONG = 0x08,            CRYPTPROTECT_PROMPT_REQUIRE_STRONG = 0x10        }        [Flags()]        public enum CryptProtectDataFlags        ...{            CRYPTPROTECT_UI_FORBIDDEN = 0x01,            CRYPTPROTECT_LOCAL_MACHINE = 0x04,            CRYPTPROTECT_CRED_SYNC = 0x08,            CRYPTPROTECT_AUDIT = 0x10,            CRYPTPROTECT_NO_RECOVERY = 0x20,            CRYPTPROTECT_VERIFY_PROTECTION = 0x40,            CRYPTPROTECT_CRED_REGENERATE = 0x80        }        加密数据#region 加密数据        public static string ProtectData(string data, string name)        ...{            return ProtectData(data, name,                 CryptProtectDataFlags.CRYPTPROTECT_UI_FORBIDDEN | CryptProtectDataFlags.CRYPTPROTECT_LOCAL_MACHINE);        }        public static byte[] ProtectData(byte[] data, string name)        ...{            return ProtectData(data, name,                 CryptProtectDataFlags.CRYPTPROTECT_UI_FORBIDDEN | CryptProtectDataFlags.CRYPTPROTECT_LOCAL_MACHINE);        }        public static string ProtectData(string data, string name, CryptProtectDataFlags flags)        ...{            byte[] dataIn = Encoding.Unicode.GetBytes(data);            byte[] dataOut = ProtectData(dataIn, name, flags);            if (dataOut != null)                return (Convert.ToBase64String(dataOut));            else                return null;        }        /**//// <summary>        /// 加密数据        /// </summary>        /// <param name="data">要加密的明文数据</param>        /// <param name="name">有意义的描述，此描述会加到加密后的数据中</param>        /// <param name="dwFlags">flags的位标志</param>        /// <returns></returns>        private static byte[] ProtectData(byte[] data, string name, CryptProtectDataFlags dwFlags)        ...{            byte[] cipherText = null;            // copy data into unmanaged memory            //DATA_BLOB结构，用于CryptProtectData参数            DPAPI.DATA_BLOB din = new DPAPI.DATA_BLOB();            din.cbData = data.Length;            //Marshal类的作用：提供了一个方法集，这些方法用于分配非托管内存、复制非托管内存块、将托管类型转换为非托管类型，            //此外还提供了在与非托管代码交互时使用的其他杂项方法。             //为din.pbData分配内存            din.pbData = Marshal.AllocHGlobal(din.cbData);            //InPtr结构:用于表示指针或句柄的平台特定类型            //分配内存错误，抛出内存不足异常            //IntPtr.Zero:一个只读字段，代表已初始化为零的指针或句柄            if (din.pbData.Equals(IntPtr.Zero))                throw new OutOfMemoryException("Unable to allocate memory for buffer.");            //将data数组中的数据复制到pbData内存指针中            Marshal.Copy(data, 0, din.pbData, din.cbData);            //声明DPAPI类的DATA_BLOB公共结构类型            DPAPI.DATA_BLOB dout = new DPAPI.DATA_BLOB();            try            ...{                //加密数据                bool cryptoRetval = DPAPI.CryptProtectData(ref din, name, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, dwFlags, ref dout);                //判断加密是否成功                if (cryptoRetval) // 成功                ...{                    int startIndex = 0;                    //分配cipherText数据元素大小为dout.cbData                    cipherText = new byte[dout.cbData];                    //从dout.pbData内存指针指向的内容拷贝到byte数组cipherText中                    Marshal.Copy(dout.pbData, cipherText, startIndex, dout.cbData);                    //从内存中释放指针指向的数据I                    DPAPI.LocalFree(dout.pbData);                }                else                ...{                    //加密失败，获得错误信息                    int errCode = Marshal.GetLastWin32Error();                    StringBuilder buffer = new StringBuilder(256);                    //显示错误信息                    Win32Error.FormatMessage(Win32Error.FormatMessageFlags.FORMAT_MESSAGE_FROM_SYSTEM, IntPtr.Zero, errCode, 0, buffer, buffer.Capacity, IntPtr.Zero);                }            }            finally            ...{                // 如果din.pbData非空，则释放din.pbData使用的内存                if (!din.pbData.Equals(IntPtr.Zero))                    Marshal.FreeHGlobal(din.pbData);            }            //返回加密后的数据            return cipherText;        }        #endregion        解密数据#region 解密数据        public static byte[] UnprotectData(byte[] data)        ...{            return UnprotectData(data, CryptProtectDataFlags.CRYPTPROTECT_UI_FORBIDDEN);        }        public static string UnprotectData(string data)        ...{            byte[] dataIn = Convert.FromBase64String(data);            byte[] dataOut = UnprotectData(dataIn);            if (dataOut != null)                return Encoding.Unicode.GetString(dataOut);            else                return null;        }        internal static byte[] UnprotectData(byte[] data, CryptProtectDataFlags dwFlags)        ...{            byte[] clearText = null;            // copy data into unmanaged memory            DPAPI.DATA_BLOB din = new DPAPI.DATA_BLOB();            din.cbData = data.Length;            din.pbData = Marshal.AllocHGlobal(din.cbData);            if (din.pbData.Equals(IntPtr.Zero))                throw new OutOfMemoryException("Unable to allocate memory for buffer.");            Marshal.Copy(data, 0, din.pbData, din.cbData);            DPAPI.DATA_BLOB dout = new DPAPI.DATA_BLOB();            try            ...{                bool cryptoRetval = DPAPI.CryptUnprotectData(ref din, null, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, dwFlags, ref dout);                if (cryptoRetval) // ERROR_SUCCESS?                ...{                    clearText = new byte[dout.cbData];                    Marshal.Copy(dout.pbData, clearText, 0, dout.cbData);                    DPAPI.LocalFree(dout.pbData);                }                else                ...{                    int errCode = Marshal.GetLastWin32Error();                    StringBuilder buffer = new StringBuilder(256);                    Win32Error.FormatMessage(Win32Error.FormatMessageFlags.FORMAT_MESSAGE_FROM_SYSTEM, IntPtr.Zero, errCode, 0, buffer, buffer.Capacity, IntPtr.Zero);                }            }            finally            ...{                // free the allocated memory in use                if (!din.pbData.Equals(IntPtr.Zero))                    Marshal.FreeHGlobal(din.pbData);            }            return clearText;        }        #endregion        internal static void InitPromptstruct(ref DPAPI.CRYPTPROTECT_PROMPTSTRUCT ps)        ...{            ps.cbSize = Marshal.SizeOf(typeof(DPAPI.CRYPTPROTECT_PROMPTSTRUCT));            ps.dwPromptFlags = 0;            ps.hwndApp = IntPtr.Zero;            ps.szPrompt = null;        }    }    //允许托管代码不经过堆栈步即调入非托管代码    [SuppressUnmanagedCodeSecurityAttribute()]    internal class DPAPI    ...{        [DllImport("crypt32")]        public static extern bool CryptProtectData(ref DATA_BLOB dataIn, string szDataDescr, IntPtr optionalEntropy, IntPtr pvReserved,            IntPtr pPromptStruct, DataProtection.CryptProtectDataFlags dwFlags, ref DATA_BLOB pDataOut);        [DllImport("crypt32")]        public static extern bool CryptUnprotectData(ref DATA_BLOB dataIn, StringBuilder ppszDataDescr, IntPtr optionalEntropy,            IntPtr pvReserved, IntPtr pPromptStruct, DataProtection.CryptProtectDataFlags dwFlags, ref DATA_BLOB pDataOut);        [DllImport("Kernel32.dll")]        public static extern IntPtr LocalFree(IntPtr hMem);        [StructLayout(LayoutKind.Sequential)]            public struct DATA_BLOB        ...{            public int cbData;            public IntPtr pbData;        }        [StructLayout(LayoutKind.Sequential)]            public struct CRYPTPROTECT_PROMPTSTRUCT        ...{            public int cbSize; // = Marshal.SizeOf(typeof(CRYPTPROTECT_PROMPTSTRUCT))            public int dwPromptFlags; // = 0            public IntPtr hwndApp; // = IntPtr.Zero            public string szPrompt; // = null        }    }    internal class Win32Error    ...{        [Flags()]            public enum FormatMessageFlags : int        ...{            FORMAT_MESSAGE_ALLOCATE_BUFFER = 0x0100,            FORMAT_MESSAGE_IGNORE_INSERTS = 0x0200,            FORMAT_MESSAGE_FROM_STRING = 0x0400,            FORMAT_MESSAGE_FROM_HMODULE = 0x0800,            FORMAT_MESSAGE_FROM_SYSTEM = 0x1000,            FORMAT_MESSAGE_ARGUMENT_ARRAY = 0x2000,            FORMAT_MESSAGE_MAX_WIDTH_MASK = 0xFF,        }        [DllImport("Kernel32.dll")]        public static extern int FormatMessage(FormatMessageFlags flags, IntPtr source, int messageId, int languageId ,             StringBuilder buffer, int size, IntPtr arguments);    }}