C # encryption or decryption algorithm cryptography CRC32 MD5 base64

Encryption or decryption algorithms and operations of cryptography, CRC32, MD5, and base64

Using system; <br/> using system. collections. generic; <br/> using system. text; <br/> using system. security; <br/> using system. security. cryptography; <br/> using system. data; <br/> using system. io; </P> <p> namespace sercuritylib <br/>{</P> <p>/** /// <summary> <br/> // For Cryptography summary. <Br/> // </Summary> <br/> public class cryptography <br/> {<br/> // encryption key <br/> Private Static encryption ricalgorithm key; </P> <p> static Cryptography () <br/>{< br/> key = new descryptoserviceprovider (); <br/>}< br/> Public Cryptography (symmetricalgorithm inkey) <br/>{< br/> key = inkey; <br/>}< br/>/** // <summary> <br/> // hash string <br/> /// </Summary> <br/> // <Param name = "PWD"> </param> <br/> /// <Returns> </returns> <br/> Public static string getpwdhash (string PWD) <br/>{< br/> string ret = ""; <br/> byte [] bpwd = encoding. ASCII. getbytes (PWD. trim (); <br/> byte [] edata; <br/> sha256 Sha = new sha256managed (); <br/> edata = Sha. computehash (bpwd); <br/> ret = convert. tobase64string (edata); <br/> return ret. trim (); <br/>}< br/>/** // <summary> <br/> // symmetric encryption of strings to return encrypted data <br/> /// </sum Mary> <br/> /// <Param name = "original"> </param> <br/> /// <returns> </returns> <br/> Public static string getencrypt (string original) <br/>{< br/> return convert. tobase64string (encrypt (original, key )); <br/>}</P> <p>/** // <summary> <br/> // perform symmetric decryption on the string to return the decrypted data <br/> // </Summary> <br/> // <Param name = "encrypt"> </param> <br/> // <returns> </returns> <br/> Public static string getdecrypt (string Encrypt) <br/>{< br/> return decrypt (convert. frombase64string (encrypt), key); <br/>}</P> <p> Public String bytestostring (byte [] BS) <br/>{< br/> stringbuilder sb = new stringbuilder (); <br/> foreach (byte B in BS) <br/>{< br/> Sb. append (B. tostring ("000"); <br/>}< br/> return sb. tostring (); <br/>}< br/> Public static byte [] stringtobytes (string s) <br/>{< br/> int BL = S. length/3; <br/> Te [] BS = new byte [BL]; <br/> for (INT I = 0; I <BL; I ++) <br/> {<br/> BS [I] = byte. parse (S. substring (3 * I, 3); <br/>}< br/> return BS; <br/>}</P> <p> Private Static byte [] encrypt (string plaintext, symmetricalgorithm key) <br/>{< br/> memorystream MS = new memorystream (); <br/> cryptostream encstream = new cryptostream (MS, key. createencryptor (), cryptostreammode. write); <br/> streamwriter s W = new streamwriter (encstream); <br/> SW. writeline (plaintext); <br/> SW. close (); <br/> encstream. close (); <br/> byte [] buffer = Ms. toarray (); <br/> MS. close (); <br/> return buffer; <br/>}</P> <p> Private Static string decrypt (byte [] cyphertext, symmetricalgorithm key) <br/>{< br/> memorystream MS = new memorystream (cyphertext); <br/> cryptostream encstream = new cryptostream (MS, key. createdecryp Tor (), cryptostreammode. read); <br/> streamreader sr = new streamreader (encstream); <br/> string val = sr. readline (); <br/> Sr. close (); <br/> encstream. close (); <br/> MS. close (); <br/> return val; <br/>}< br/>/** // <summary> <br/> // CRC verification <br/> /// quick Detection Algorithm <br/> /// </Summary> <br/> public class CRC32 <br/> {</P> <p> /**//// <summary> <br/> /// </Summary> <br/> protected UlO NG [] crc32table; </P> <p>/** // <summary> <br/> // structure: initialize the validation table <br/> /// </Summary> <br/> Public CRC32 () <br/>{< br/> const ulong ulpolynomial = 0xedb88320; <br/> ulong dwcrc; <br/> crc32table = new ulong [256]; <br/> int I, j; <br/> for (I = 0; I <256; I ++) <br/>{< br/> dwcrc = (ulong) I; <br/> for (j = 8; j> 0; J --) <br/>{< br/> If (dwcrc & 1) = 1) <br/> dwcrc = (dwcrc> 1) ^ ulpolynomial; <Br/> else <br/> dwcrc >>= 1; <br/>}< br/> crc32table [I] = dwcrc; <br/>}</P> <p>/** // <summary> <br/> // verify the byte array <br/> /// </Summary> <br/> /// <Param name = "buffer"> ref byte array </param> <br/> // <returns> </returns> <br/> Public ulong bytecrc (ref byte [] buffer) <br/> {<br/> ulong ulcrc = 0 xffffffff; <br/> ulong Len; <br/> Len = (ulong) buffer. length; <br/> for (ulong buffptr = 0; buffptr <Len; buffptr ++) <br/>{< br/> ulong tabptr = ulcrc & 0xff; <br/> tabptr = tabptr ^ buffer [buffptr]; <br/> ulcrc = ulcrc> 8; <br/> ulcrc = ulcrc ^ crc32table [tabptr]; <br/>}< br/> return ulcrc ^ 0 xffffffff; <br/>}</P> <p>/** // <summary> <br/> // string verification <br/> // </ summary> <br/> /// <Param name = "sinputstring"> string </param> <br/> /// <returns> </returns> <br/> public ulong stringcrc (string sinpu Tstring) <br/>{< br/> byte [] buffer = encoding. default. getbytes (sinputstring); <br/> return bytecrc (ref buffer ); <br/>}</P> <p>/** // <summary> <br/> // file verification <br/> // </ summary> <br/> /// <Param name = "sinputfilename"> input file </param> <br/> /// <returns> </returns> <br/> Public ulong filecrc (string sinputfilename) <br/>{< br/> filestream infile = new system. io. filestream (sinputfilename, system. io. Filemode. open, system. io. fileaccess. read); <br/> byte [] binput = new byte [infile. length]; <br/> infile. read (binput, 0, binput. length); <br/> infile. close (); </P> <p> return bytecrc (ref binput ); <br/>}</P> <p>/** // <summary> <br/> // MD5 is not reversed. encoding <br/> // obtain the unique feature string, password Encryption <br/> // (cannot be restored) <br/> // </Summary> <br/> public class MD5 <br/> {</P> <p>/** // <summary> <br/> /// </summ Ary> <br/> Public MD5 () <br/>{< br/>}</P> <p>/** // <summary> <br/> /// obtain the character string. <br/> // </Summary> <br/> // <Param name = "sinputstring"> input text </param> <br/> // <returns> </returns> <br/> Public static string hashstring (string sinputstring) <br/>{< br/> system. security. cryptography. MD5 MD5 = system. security. cryptography. md5.create (); <br/> string encoded = bitconverter. tostring (md5.computehas H (encoding. default. getbytes (sinputstring ))). replace ("-", ""); <br/> return encoded; <br/>}</P> <p>/** // <summary> <br/> // obtain the feature string of the file. <br/> // /</Summary> <br/> // <Param name = "sinputfilename"> input file </param> <br/> // <returns> </returns> <br/> Public String hashfile (string sinputfilename) <br/>{< br/> system. security. cryptography. MD5 MD5 = system. security. cryptography. md5.create (); <br/> filestr EAM infile = new system. io. filestream (sinputfilename, system. io. filemode. open, system. io. fileaccess. read); <br/> byte [] binput = new byte [infile. length]; <br/> infile. read (binput, 0, binput. length); <br/> infile. close (); </P> <p> string encoded = bitconverter. tostring (md5.computehash (binput )). replace ("-", ""); <br/> return encoded; <br/>}</P> <p>/** // <summary> <br/> // base64 uuencoded Encoding <br/> // encodes the binary into ASCII text for network transmission <br/> // (recoverable) <br/> // </Summary> <br/> public class base64 <br/> {</P> <p>/** // <summary> <br/> /// </Summary> <br/> Public base64 () <br/>{< br/>}</P> <p>/** // <summary> <br/> // decodes the string. <br/> /// </Summary> <br/> /// <Param name = "sinputstring"> input text </param> <br/> // <returns> </ returns> <br/> Public String decryptstring (string sinputstring) <br />{< Br/> char [] sinput = sinputstring. tochararray (); <br/> try <br/> {<br/> byte [] boutput = system. convert. frombase64string (sinputstring); <br/> return encoding. default. getstring (boutput); <br/>}< br/> catch (system. argumentnullexception) <br/>{< br/> // The 64-character array of base is null <br/> return "; <br/>}< br/> catch (system. formatexception) <br/>{< br/> // The length is incorrect. 4 cannot be divisible. <br/> return ""; <br/>}< br/>} </P> <p>/** // <summary> <br/> // encode the string <br/> /// </Summary> <br/> /// <Param name = "sinputstring"> input text </param> <br/> /// <returns> </returns> <br/> Public String encryptstring (string sinputstring) <br/> {<br/> byte [] binput = encoding. default. getbytes (sinputstring); <br/> try <br/>{< br/> return system. convert. tobase64string (binput, 0, binput. length); <br/>}< br/> catch (system. argumentnullexc Eption) <br/>{< br/> // The binary array is null. <br/> return ""; <br/>}< br/> catch (system. argumentoutofrangeexception) <br/>{< br/> // insufficient length <br/> return ""; <br/>}</P> <p>/** // <summary> <br/> // decode the file. <br/> /// </Summary> <br/> /// <Param name = "sinputfilename"> input file </param> <br/> /// <Param name =" soutputfilename "> output file </param> <br/> Public void decryptfile (string sinputfilename, string soutputfil Ename) <br/>{< br/> system. io. streamreader infile; <br/> char [] base64chararray; </P> <p> try <br/>{< br/> infile = new system. io. streamreader (sinputfilename, <br/> system. text. encoding. ASCII); <br/> base64chararray = new char [infile. basestream. length]; <br/> infile. read (base64chararray, 0, (INT) infile. basestream. length); <br/> infile. close (); <br/>}< br/> catch <br/> {// (system. exception exp) {< Br/> return; <br/>}</P> <p> // convert base64 uuencoded to binary output. <br/> byte [] binarydata; <br/> try <br/> {<br/> binarydata = <br/> system. convert. frombase64chararray (base64chararray, <br/> 0, <br/> base64chararray. length); <br/>}< br/> catch (system. argumentnullexception) <br/>{< br/> // The 64-character array of base is null <br/> return; <br/>}< br/> catch (system. formatexception) <br/>{< br/> // The length is incorrect and cannot be divisible by 4 <br/> return; <Br/>}</P> <p> // write output data <br/> system. io. filestream OUTFILE; <br/> try <br/>{< br/> OUTFILE = new system. io. filestream (soutputfilename, <br/> system. io. filemode. create, <br/> system. io. fileaccess. write); <br/> OUTFILE. write (binarydata, 0, binarydata. length); <br/> OUTFILE. close (); <br/>}< br/> catch <br/> {// (system. exception exp) {<br/> // stream error <br/>}</P> <p>/** // <summary> <br/>/ // Encode the file <br/> /// </Summary> <br/> /// <Param name = "sinputfilename"> input file </param> <br/> /// <Param name = "soutputfilename"> output file </param> <br/> Public void encryptfile (string sinputfilename, string soutputfilename) <br/>{</P> <p> system. io. filestream infile; <br/> byte [] binarydata; </P> <p> try <br/>{< br/> infile = new system. io. filestream (sinputfilename, <br/> system. io. filemode. open, <br/> system. I O. fileaccess. read); <br/> binarydata = new byte [infile. length]; <br/> long bytesread = infile. read (binarydata, 0, <br/> (INT) infile. length); <br/> infile. close (); <br/>}< br/> catch <br/> {// (system. exception exp) {<br/> return; <br/>}</P> <p> // convert the binary input to base64 uuencoded output. <br/> // each 3 bytes is used as 4 bytes in the source data. <br /> long arraylength = (long) (4.0d/3.0d) * binarydata. length); </P> <p> // if it cannot be divisible by 4 <br/> if (Rraylength % 4! = 0) <br/>{< br/> arraylength + = 4-arraylength % 4; <br/>}</P> <p> char [] base64chararray = new char [arraylength]; <br/> try <br/>{< br/> system. convert. tobase64chararray (binarydata, <br/> 0, <br/> binarydata. length, <br/> base64chararray, <br/> 0); <br/>}< br/> catch (system. argumentnullexception) <br/>{< br/> // The binary array is null. <br/> return; <br/>}< br/> catch (system. argumentoutofrangeexception) <br/>{< br/> // insufficient length <br/> return; <br/>}</P> <p> // write uencoded data to the file. <br/> system. io. streamwriter OUTFILE; <br/> try <br/>{< br/> OUTFILE = new system. io. streamwriter (soutputfilename, <br/> false, <br/> system. text. encoding. ASCII); <br/> OUTFILE. write (base64chararray); <br/> OUTFILE. close (); <br/>}< br/> catch <br/> {// (system. exception exp) {<br/> // file stream error <br/>}</P> <p >}< br/>}</P> <p>}

Source: http://blog.csdn.net/beasyer/archive/2007/06/20/1660103.aspx