C#加密解密类实例程序

前两年写的东西，现在整理一下发出来！以前公司需要做webservice，并且对webservice的soapheader进行加密，所以就写了这么个东东！使用这个类，需要密钥管理！为了保证数据的安全性往往要对数据进行加密，但是加密的缺点之一，就是影响程序的运行效率，所以，当时我的思路是只对用户的登录信息（用户名，密码）进行加密！数据用明文传输，用户信息验证没有通过的情况下, 不进行数据传输。
实际在网络通讯中，使用密钥匙的方式并非无懈可击，如果黑客可以捕捉到用密钥加密的，用户验证信息，然后，做个模拟请求，向提供webservice的服务器发请求，还是可以获得请求数据！所以，我又使用了ip或者域名绑定的方式！毕竟，webservice不是直接对最终用户提供的！所以，加上以上这些手段后，就算有不良企图者想通过非法方式获得webservice提供的服务，就再费点劲吧！
还有一点安全建议，就是定期的更换密钥，在这个例子中，我用的是对称加密，加密方和解密方的密钥一致！定期的更换密钥可以让安全性提高一大截！

大家要有更好的方法，或者建议，可以留言讨论一下！共同提高！

代码如下：

using system;
using system.security.cryptography;
using system.text;
using system.io;

namespace sedo
{
    /// <summary>
    /// sedo 的摘要说明。
    /// sedo 实现的是用一个封装了4种对称加密方法(des,rc2,rijndael,tripledes)的组件
    ///
    /// 注意事项：
    /// 1:tripledes和rijndael加密/解密对象使用16或者24位byte的key
    /// 2:rijndael只能使用16位的初始化向量iv
    /// 3:des和rc2均使用8位byte的key和iv
    /// 4:对需要加密/解密的数据流采用何种方法进行编码/解码，由调用组件的用户自己决定
    /// 5:密钥和初始化向量iv由使用者自己定义
    /// 程序员： 罗旭成2010-10-30 [e-mail]
    /// </summary>

    //定义加密类型的枚举
    public enum encryptionalgorithm { des = 1, rc2, rijndael, tripledes };

    //定义加密类
    internal class encrypttransformer
    {
        private encryptionalgorithm algorithmid;
        private byte[] initvec;
        private byte[] enckey;

        internal encrypttransformer(encryptionalgorithm algid)
        {
            //save the algorithm being used.
            algorithmid = algid;
        }

        internal icryptotransform getcryptoserviceprovider(byte[] byteskey)
        {
            //当数据密钥key或者初始化向量iv为空的时候，
            //将使用加密对象自动产生的密钥key或者初始化向量iv
            switch (algorithmid)
            {
                case encryptionalgorithm.des:
                    {
                        des des = new descryptoserviceprovider();
                        des.mode = ciphermode.cbc;

                        // see if a key was provided
                        if (null == byteskey)
                        {
                            enckey = des.key;
                        }
                        else
                        {
                            des.key = byteskey;
                            enckey = des.key;
                        }
                        // see if the client provided an initialization vector
                        if (null == initvec)
                        { // have the algorithm create one
                            initvec = des.iv;
                        }
                        else
                        { //no, give it to the algorithm
                            des.iv = initvec;
                        }
                        return des.createencryptor();
                    }
                case encryptionalgorithm.tripledes:
                    {
                        tripledes des3 = new tripledescryptoserviceprovider();
                        des3.mode = ciphermode.cbc;
                        // see if a key was provided
                        if (null == byteskey)
                        {
                            enckey = des3.key;
                        }
                        else
                        {
                            des3.key = byteskey;
                            enckey = des3.key;
                        }
                        // see if the client provided an iv
                        if (null == initvec)
                        { //yes, have the alg create one
                            initvec = des3.iv;
                        }
                        else
                        { //no, give it to the alg.
                            des3.iv = initvec;
                        }
                        return des3.createencryptor();
                    }
                case encryptionalgorithm.rc2:
                    {
                        rc2 rc2 = new rc2cryptoserviceprovider();
                        rc2.mode = ciphermode.cbc;
                        // test to see if a key was provided
                        if (null == byteskey)
                        {
                            enckey = rc2.key;
                        }
                        else
                        {
                            rc2.key = byteskey;
                            enckey = rc2.key;
                        }
                        // see if the client provided an iv
                        if (null == initvec)
                        { //yes, have the alg create one
                            initvec = rc2.iv;
                        }
                        else
                        { //no, give it to the alg.
                            rc2.iv = initvec;
                        }
                        return rc2.createencryptor();
                    }
                case encryptionalgorithm.rijndael:
                    {
                        rijndael rijndael = new rijndaelmanaged();
                        rijndael.mode = ciphermode.cbc;
                        // test to see if a key was provided
                        if (null == byteskey)
                        {
                            enckey = rijndael.key;
                        }
                        else
                        {
                            rijndael.key = byteskey;
                            enckey = rijndael.key;
                        }
                        // see if the client provided an iv
                        if (null == initvec)
                        { //yes, have the alg create one
                            initvec = rijndael.iv;
                        }
                        else
                        { //no, give it to the alg.
                            rijndael.iv = initvec;
                        }
                        return rijndael.createencryptor();
                    }
                default:
                    {
                        throw new cryptographicexception("algorithm id '" +
                        algorithmid +
                        "' not supported.");
                    }
            }
        }

        //加密的偏移向量
        internal byte[] iv
        {
            get { return initvec; }
            set { initvec = value; }
        }
        //加密的密钥
        internal byte[] key
        {
            get { return enckey; }
            set { enckey = value; }
        }

    }

    //定义解密类
    internal class decrypttransformer
    {
        private encryptionalgorithm algorithmid;
        private byte[] initvec;
        private byte[] enckey;

        internal decrypttransformer(encryptionalgorithm decryptid)
        {
            algorithmid = decryptid;
        }

        //加密的偏移向量
        internal byte[] iv
        {
            get { return initvec; }
            set { initvec = value; }
        }

        //加密的密钥
        internal byte[] key
        {
            get { return enckey; }
            set { enckey = value; }
        }

        internal icryptotransform getcryptoserviceprovider(byte[] byteskey)
        {
            //当数据密钥key或者初始化向量iv为空的时候，
            //将使用加密对象自动产生的密钥key或者初始化向量iv
            switch (algorithmid)
            {
                case encryptionalgorithm.des:
                    {
                        des des = new descryptoserviceprovider();
                        des.mode = ciphermode.cbc;
                        des.key = byteskey;
                        des.iv = initvec;
                        return des.createdecryptor();
                    }
                case encryptionalgorithm.tripledes:
                    {
                        tripledes des3 = new tripledescryptoserviceprovider();
                        des3.mode = ciphermode.cbc;
                        return des3.createdecryptor(byteskey, initvec);
                    }
                case encryptionalgorithm.rc2:
                    {
                        rc2 rc2 = new rc2cryptoserviceprovider();
                        rc2.mode = ciphermode.cbc;
                        return rc2.createdecryptor(byteskey, initvec);
                    }
                case encryptionalgorithm.rijndael:
                    {
                        rijndael rijndael = new rijndaelmanaged();
                        rijndael.mode = ciphermode.cbc;
                        return rijndael.createdecryptor(byteskey, initvec);
                    }
                default:
                    {
                        throw new cryptographicexception("algorithm id '" +
                        algorithmid +
                        "' not supported.");
                    }
            }
        } //end getcryptoserviceprovider

    }

    //定义加密者类
    public class encryptor
    {
        private encrypttransformer transformer;
        private byte[] initvec;
        private byte[] enckey;

        public encryptor(encryptionalgorithm algid)
        {
            transformer = new encrypttransformer(algid);
        }

        public byte[] encrypt(byte[] bytesdata, byte[] byteskey, byte[] bytesiv)
        {
            //设置流对象用来保存加密数据字节流.
            memorystream memstreamencrypteddata = new memorystream();

            transformer.iv = bytesiv;
            transformer.key = byteskey;

            icryptotransform transform =
                transformer.getcryptoserviceprovider(byteskey);
            cryptostream encstream =
                new cryptostream(memstreamencrypteddata,
                    transform, cryptostreammode.write);

            try
            {
                //将加密数据写进流对象
                encstream.write(bytesdata, 0, bytesdata.length);
            }
            catch (exception ex)
            {
                throw new exception("在数据加密的时候出现错误！"+
                    "错误提示： \n" + ex.message);
            }

            //设置加密的key和初始向量iv属性
            enckey = transformer.key;
            initvec = transformer.iv;

            encstream.flushfinalblock();
            encstream.close();

            //send the data back.
            return memstreamencrypteddata.toarray();
        }

        public byte[] iv
        {
            get { return initvec; }
            set { initvec = value; }
        }

        public byte[] key
        {
            get { return enckey; }
            set { enckey = value; }
        }

    }

 
    //定义解密者类
    public class decryptor
    {
        private decrypttransformer transformer;
        private byte[] initvec;
        private byte[] enckey;

        public decryptor(encryptionalgorithm algid)
        {
            transformer = new decrypttransformer(algid);
        }

        public byte[] decrypt(byte[] bytesdata,
            byte[] byteskey, byte[] bytesiv)
        {
            //设置流对象用来保存解密数据字节流.
            memorystream memstreamdecrypteddata =
                new memorystream();

            //pass in the initialization vector.
            transformer.iv = bytesiv;
            transformer.key = byteskey;

            icryptotransform transform =
                transformer.getcryptoserviceprovider(byteskey);
            cryptostream decstream =
                new cryptostream(memstreamdecrypteddata,
                    transform, cryptostreammode.write);

            try
            {
                decstream.write(bytesdata, 0, bytesdata.length);
            }
            catch (exception ex)
            {
                throw new exception("在数据解密的时候出现错误！"+
                    "错误提示： \n" + ex.message);
            }
            decstream.flushfinalblock();
            decstream.close();
            // 返回解密数据.
            return memstreamdecrypteddata.toarray();
        }

        public byte[] iv
        {
            get { return initvec; }
            set { initvec = value; }
        }

        public byte[] key
        {
            get { return enckey; }
            set { enckey = value; }
        }

    }

    //类描述：文件加密/解密类
    public class securityfile
    {
        private decrypttransformer dec_transformer; //解密转换器
        private encrypttransformer enc_transformer; //加密转换器
        private byte[] initvec;
        private byte[] enckey;

        public securityfile(encryptionalgorithm algid)
        {
            dec_transformer = new decrypttransformer(algid);
            enc_transformer = new encrypttransformer(algid);
        }

        //加密的偏移向量
        internal byte[] iv
        {
            get { return initvec; }
            set { initvec = value; }
        }
        //加密的密钥
        internal byte[] key
        {
            get { return enckey; }
            set { enckey = value; }
        }

        //功能描述：加密文件
        public void encryptfile(string infilename,
            string outfilename, byte[] byteskey, byte[] bytesiv)
        {
            try
            {
                filestream fin =
                    new filestream(infilename, filemode.open,
                        fileaccess.read);
                filestream fout = new filestream(outfilename,
                    filemode.openorcreate, fileaccess.write);
                fout.setlength(0);

                //create variables to help with read and write.
                //this is intermediate storage for the encryption.
                byte[] bin = new byte[100];
                //this is the total number of bytes written.
                long rdlen = 0;
                //this is the total length of the input file.
                long totlen = fin.length;
                //this is the number of bytes to be written at a time.
                int len;

                enc_transformer.iv = bytesiv;
                enc_transformer.key = byteskey;

                icryptotransform transform =
                    enc_transformer.getcryptoserviceprovider(byteskey);
                cryptostream encstream =
                    new cryptostream(fout, transform, cryptostreammode.write);

                //read from the input file, then encrypt and write to the output file.
                while (rdlen < totlen)
                {
                    len = fin.read(bin, 0, 100);
                    encstream.write(bin, 0, len);
                    rdlen = rdlen + len;
                }

                encstream.close();
                fout.close();
                fin.close();
            }
            catch (exception ex)
            {
                throw new exception("在文件加密的时候出现错误！"+
                    "错误提示： \n" + ex.message);
            }
        }

        //功能描述：解密文件
        public void decryptfile(string infilename,
            string outfilename, byte[] byteskey, byte[] bytesiv)
        {
            try
            {
                filestream fin =
                    new filestream(infilename, filemode.open,
                        fileaccess.read);
                filestream fout =
                    new filestream(outfilename,
                        filemode.openorcreate, fileaccess.write);
                fout.setlength(0);

                //create variables to help with read and write.
                //this is intermediate storage for the encryption.
                byte[] bin = new byte[100];
                //this is the total number of bytes written.
                long rdlen = 0;
                //this is the total length of the input file.
                long totlen = fin.length;
                //this is the number of bytes to be written at a time.
                int len;

                dec_transformer.iv = bytesiv;
                dec_transformer.key = byteskey;

                icryptotransform transform =
                    dec_transformer.getcryptoserviceprovider(byteskey);
                cryptostream encstream =
                    new cryptostream(fout, transform, cryptostreammode.write);

                //read from the input file, then encrypt and
                //write to the output file.
                while (rdlen < totlen)
                {
                    len = fin.read(bin, 0, 100);
                    encstream.write(bin, 0, len);
                    rdlen = rdlen + len;
                }
                encstream.close();
                fout.close();
                fin.close();
            }
            catch (exception ex)
            {
                throw new exception("在文件加密的时候出现"+
                    "错误！错误提示： \n" + ex.message);
            }
        }
    }
}