最近作了一個移動項目,是有服務器和客戶端類型的項目,客戶端是要登陸才行的,登陸的密碼要用DES加密,服務器是用Java開發的,客戶端要同時支持多 平臺(Android、iOS),在處理iOS的DES加密的時候遇到了一些問題,起初怎麼調都調不成和Android端生成的密文相同。最終一個突然的想法讓我找到了問題的所在,如今將代碼總結一下,以備本身之後查閱。java
首先,Java端的DES加密的實現方式,代碼以下:算法
public class DES { private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 }; public static String encryptDES(String encryptString, String encryptKey) throws Exception { IvParameterSpec zeroIv = new IvParameterSpec(iv); SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES"); Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv); byte[] encryptedData = cipher.doFinal(encryptString.getBytes()); return Base64.encode(encryptedData); } }
上述代碼用到了一個Base64的編碼類,其代碼的實現方式以下:數組
public class Base64 { private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray(); public static String encode(byte[] data) { int start = 0; int len = data.length; StringBuffer buf = new StringBuffer(data.length * 3 / 2); int end = len - 3; int i = start; int n = 0; while (i <= end) { int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff); buf.append(legalChars[(d >> 18) & 63]); buf.append(legalChars[(d >> 12) & 63]); buf.append(legalChars[(d >> 6) & 63]); buf.append(legalChars[d & 63]); i += 3; if (n++ >= 14) { n = 0; buf.append(" "); } } if (i == start + len - 2) { int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8); buf.append(legalChars[(d >> 18) & 63]); buf.append(legalChars[(d >> 12) & 63]); buf.append(legalChars[(d >> 6) & 63]); buf.append("="); } else if (i == start + len - 1) { int d = (((int) data[i]) & 0x0ff) << 16; buf.append(legalChars[(d >> 18) & 63]); buf.append(legalChars[(d >> 12) & 63]); buf.append("=="); } return buf.toString(); } }
以上即是Java端的DES加密方法的所有實現過程。服務器
我還編寫了一個將byte的二進制轉換成16進制的方法,以便調試的時候使用打印輸出加密後的byte數組的內容,這個方法不是加密的部分,只是爲調試而使用的:app
public static String parseByte2HexStr(byte buf[]) { StringBuffer sb = new StringBuffer(); for (int i = 0; i < buf.length; i++) { String hex = Integer.toHexString(buf[i] & 0xFF); if (hex.length() == 1) { hex = '0' + hex; } sb.append(hex.toUpperCase()); } return sb.toString(); }
下面是Objective-c在iOS上實現的DES加密算法:測試
static Byte iv[] = {1,2,3,4,5,6,7,8}; +(NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key{ NSString *ciphertext = nil; const char *textBytes = [plainText UTF8String]; NSUInteger dataLength = [plainText length]; unsigned char buffer[1024]; memset(buffer, 0, sizeof(char)); size_t numBytesEncrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding, [key UTF8String], kCCKeySizeDES, iv, textBytes, dataLength, buffer, 1024, &numBytesEncrypted); if (cryptStatus == kCCSuccess) { NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted]; ciphertext = [data base64Encoding]; } return ciphertext; }
下面是一個關鍵的類:NSData的Category實現,關於Category的實現網上不少說明再也不講述。
編碼
static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; - (NSString *)base64Encoding; { if (self.length == 0) return @""; char *characters = malloc(self.length*3/2); if (characters == NULL) return @""; int end = self.length - 3; int index = 0; int charCount = 0; int n = 0; while (index <= end) { int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) | (((int)(((char *)[self bytes])[index + 1]) & 0x0ff) << 8) | ((int)(((char *)[self bytes])[index + 2]) & 0x0ff); characters[charCount++] = encodingTable[(d >> 18) & 63]; characters[charCount++] = encodingTable[(d >> 12) & 63]; characters[charCount++] = encodingTable[(d >> 6) & 63]; characters[charCount++] = encodingTable[d & 63]; index += 3; if(n++ >= 14){ n = 0; characters[charCount++] = ' '; } } if(index == self.length - 2) { int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) | (((int)(((char *)[self bytes])[index + 1]) & 255) << 8); characters[charCount++] = encodingTable[(d >> 18) & 63]; characters[charCount++] = encodingTable[(d >> 12) & 63]; characters[charCount++] = encodingTable[(d >> 6) & 63]; characters[charCount++] = '='; }else if(index == self.length - 1){ int d = ((int)(((char *)[self bytes])[index]) & 0x0ff) << 16; characters[charCount++] = encodingTable[(d >> 18) & 63]; characters[charCount++] = encodingTable[(d >> 12) & 63]; characters[charCount++] = '='; characters[charCount++] = '='; } NSString * rtnStr = [[NSString alloc] initWithBytesNoCopy:characters length:charCount encoding:NSUTF8StringEncoding freeWhenDone:YES]; return rtnStr; }
這個方法和java端的那個Base64的encode方法基本上是一個算法,只是根據語言的特色不一樣有少量的改動。加密
下面也是Objective-c的一個二進制轉換爲16進制的方法,也是爲了測試方便查看寫的:調試
+(NSString *) parseByte2HexString:(Byte *) bytes { NSMutableString *hexStr = [[NSMutableString alloc]init]; int i = 0; if(bytes) { while (bytes[i] != '\0') { NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16進制數 if([hexByte length]==1) [hexStr appendFormat:@"0%@", hexByte]; else [hexStr appendFormat:@"%@", hexByte]; i++; } } NSLog(@"bytes 的16進制數爲:%@",hexStr); return hexStr; } +(NSString *) parseByteArray2HexString:(Byte[]) bytes { NSMutableString *hexStr = [[NSMutableString alloc]init]; int i = 0; if(bytes) { while (bytes[i] != '\0') { NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16進制數 if([hexByte length]==1) [hexStr appendFormat:@"0%@", hexByte]; else [hexStr appendFormat:@"%@", hexByte]; i++; } } NSLog(@"bytes 的16進制數爲:%@",hexStr); return hexStr; }
以上的加密方法所在的包是CommonCrypto/CommonCryptor.h。
以上便實現了Objective-c和Java下在相同的明文和密鑰的狀況下生成相同明文的算法。code
Base64的算法能夠用大家本身寫的那個,不必定必須使用我提供的這個。解密的時候還要用Base64進行密文的轉換。
個人解密算法以下:
private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 }; public static String decryptDES(String decryptString, String decryptKey) throws Exception { byte[] byteMi = Base64.decode(decryptString); IvParameterSpec zeroIv = new IvParameterSpec(iv); SecretKeySpec key = new SecretKeySpec(decryptKey.getBytes(), "DES"); Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); cipher.init(Cipher.DECRYPT_MODE, key, zeroIv); byte decryptedData[] = cipher.doFinal(byteMi); return new String(decryptedData); }
Base64的decode方法以下:
public static byte[] decode(String s) { ByteArrayOutputStream bos = new ByteArrayOutputStream(); try { decode(s, bos); } catch (IOException e) { throw new RuntimeException(); } byte[] decodedBytes = bos.toByteArray(); try { bos.close(); bos = null; } catch (IOException ex) { System.err.println("Error while decoding BASE64: " + ex.toString()); } return decodedBytes; } private static void decode(String s, OutputStream os) throws IOException { int i = 0; int len = s.length(); while (true) { while (i < len && s.charAt(i) <= ' ') i++; if (i == len) break; int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3))); os.write((tri >> 16) & 255); if (s.charAt(i + 2) == '=') break; os.write((tri >> 8) & 255); if (s.charAt(i + 3) == '=') break; os.write(tri & 255); i += 4; } } private static int decode(char c) { if (c >= 'A' && c <= 'Z') return ((int) c) - 65; else if (c >= 'a' && c <= 'z') return ((int) c) - 97 + 26; else if (c >= '0' && c <= '9') return ((int) c) - 48 + 26 + 26; else switch (c) { case '+': return 62; case '/': return 63; case '=': return 0; default: throw new RuntimeException("unexpected code: " + c); } }
以上便實現了DES加密後的密文的解密。
Java端的測試代碼以下:
String plaintext = "abcd"; String ciphertext = DES.encryptDES(plaintext, "20120401"); System.out.println("明文:" + plaintext); System.out.println("密鑰:" + "20120401"); System.out.println("密文:" + ciphertext); System.out.println("解密後:" + DES.decryptDES(ciphertext, "20120401"));
輸出結果:
明文:abcd 密鑰:20120401 密文:W7HR43/usys= 解密後:abcd
Objective-c端的測試代碼以下:
NSString *plaintext = @"abcd"; NSString *ciphertext = [EncryptUtil encryptUseDES:plaintext key:@"20120401"]; NSLog(@"明文:%@",plaintext); NSLog(@"祕鑰:%@",@"20120401"); NSLog(@"密文:%@",ciphertext);
輸出結果:
2012-04-05 12:00:47.348 TestEncrypt[806:f803] 明文:abcd 2012-04-05 12:00:47.350 TestEncrypt[806:f803] 祕鑰:20120401 2012-04-05 12:00:47.350 TestEncrypt[806:f803] 密文:W7HR43/usys=