全栈工程师开发手册 （作者：栾鹏）
c#教程全解
c#使用SHA256算法实现对文件的加密和解密
将当期目录的test.txt加密成文件test1.txt，再将加密后的test1.txt文件解密成test2.txt。
测试代码
static void Main()
{
MyEncrypt.SHA_Encrypt("test.txt", "test1.txt", "123456"); //文件加密
MyEncrypt.SHA_Dencrypt("test1.txt", "test2.txt", "123456"); //文件解密
}
加密解密工具类的实现
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace util
{
public class MyEncrypt
{
private const ulong FC_TAG = 0xFC010203040506CF;
private const int BUFFER_SIZE = 128 * 1024;
//检验两个Byte数组是否相同
private static bool CheckByteArrays(byte[] b1, byte[] b2)
{
if (b1.Length == b2.Length)
{
for (int i = 0; i < b1.Length; ++i)
{
if (b1[i] != b2[i])
return false;
}
return true;
}
return false;
}
/// <param name="password">密码</param>
/// <param name="salt"></param>
/// <returns>加密对象</returns>
private static SymmetricAlgorithm CreateRijndael(string password, byte[] salt)
{
PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, salt, "SHA256", 1000);
SymmetricAlgorithm sma = Rijndael.Create();
sma.KeySize = 256;
sma.Key = pdb.GetBytes(32);
sma.Padding = PaddingMode.PKCS7;
return sma;
}
// 加密文件随机数生成
private static RandomNumberGenerator rand = new RNGCryptoServiceProvider();
// 生成指定长度的随机Byte数组
private static byte[] GenerateRandomBytes(int count)
{
byte[] bytes = new byte[count];
rand.GetBytes(bytes);
return bytes;
}
// 加密文件
public static void SHA_Encrypt(string inFile, string outFile, string password)
{
using (FileStream fin = File.OpenRead(inFile),
fout = File.OpenWrite(outFile))
{
long lSize = fin.Length; // 输入文件长度
int size = (int)lSize;
byte[] bytes = new byte[BUFFER_SIZE]; // 缓存
int read = -1; // 输入文件读取数量
int value = 0;
// 获取IV和salt
byte[] IV = GenerateRandomBytes(16);
byte[] salt = GenerateRandomBytes(16);
// 创建加密对象
SymmetricAlgorithm sma = CreateRijndael(password, salt);
sma.IV = IV;
// 在输出文件开始部分写入IV和salt
fout.Write(IV, 0, IV.Length);
fout.Write(salt, 0, salt.Length);
// 创建散列加密
HashAlgorithm hasher = SHA256.Create();
using (CryptoStream cout = new CryptoStream(fout, sma.CreateEncryptor(), CryptoStreamMode.Write),
chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
{
BinaryWriter bw = new BinaryWriter(cout);
bw.Write(lSize);
bw.Write(FC_TAG);
// 读写字节块到加密流缓冲区
while ((read = fin.Read(bytes, 0, bytes.Length)) != 0)
{
cout.Write(bytes, 0, read);
chash.Write(bytes, 0, read);
value += read;
}
// 关闭加密流
chash.Flush();
chash.Close();
// 读取散列
byte[] hash = hasher.Hash;
// 输入文件写入散列
cout.Write(hash, 0, hash.Length);
// 关闭文件流
cout.Flush();
cout.Close();
}
}
}
// 解密文件
public static void SHA_Dencrypt(string inFile, string outFile, string password)
{
// 创建打开文件流
using (FileStream fin = File.OpenRead(inFile),
fout = File.OpenWrite(outFile))
{
int size = (int)fin.Length;
byte[] bytes = new byte[BUFFER_SIZE];
int read = -1;
int value = 0;
int outValue = 0;
byte[] IV = new byte[16];
fin.Read(IV, 0, 16);
byte[] salt = new byte[16];
fin.Read(salt, 0, 16);
SymmetricAlgorithm sma = CreateRijndael(password, salt);
sma.IV = IV;
value = 32;
long lSize = -1;
// 创建散列对象, 校验文件
HashAlgorithm hasher = SHA256.Create();
using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read),
chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
{
// 读取文件长度
BinaryReader br = new BinaryReader(cin);
lSize = br.ReadInt64();
ulong tag = br.ReadUInt64();
if (FC_TAG != tag)
throw new Exception("文件被破坏");
long numReads = lSize / BUFFER_SIZE;
long slack = (long)lSize % BUFFER_SIZE;
for (int i = 0; i < numReads; ++i)
{
read = cin.Read(bytes, 0, bytes.Length);
fout.Write(bytes, 0, read);
chash.Write(bytes, 0, read);
value += read;
outValue += read;
}
if (slack > 0)
{
read = cin.Read(bytes, 0, (int)slack);
fout.Write(bytes, 0, read);
chash.Write(bytes, 0, read);
value += read;
outValue += read;
}
chash.Flush();
chash.Close();
fout.Flush();
fout.Close();
byte[] curHash = hasher.Hash;
// 获取比较和旧的散列对象
byte[] oldHash = new byte[hasher.HashSize / 8];
read = cin.Read(oldHash, 0, oldHash.Length);
if ((oldHash.Length != read) || (!CheckByteArrays(oldHash, curHash)))
throw new Exception("文件被破坏");
}
if (outValue != lSize)
throw new Exception("文件大小不匹配");
}
}
}
}
