字符串异或

 - (NSString *)encryptForPlainText:(NSString *)plainText

{

//保存加密后的字符

NSMutableString *encryption=[NSMutableString string];

//编码转换后的字符串 UTF_8->iso-8859-1

NSString *encoding=[[NSString alloc]initWithData:[plainText dataUsingEncoding:NSUTF8StringEncoding] encoding:NSISOLatin1StringEncoding];

for(int i=0;i

//异或后的字符

char cipher=(char)([encoding characterAtIndex:i]^0x99);

//NSLog(@"%c转成16进制的字符串：%@,%@",cipher,[NSString stringWithFormat:@"%hhx",cipher],[NSString stringWithFormat:@"%x",cipher&0xff]);

//转成16进制形式的字符串 \x8b转成8b字符串

NSString *strCipher= [NSString stringWithFormat:@"%hhx",cipher];

if(strCipher.length == 1){

[encryption appendFormat:@"0%@",strCipher];

}else{

[encryption appendString:strCipher];

}

}

NSData *data = [encryption dataUsingEncoding:NSUTF8StringEncoding];

NSData *base64Data = [data base64EncodedDataWithOptions:0];

NSString *base64Str = [[NSString alloc]initWithData:base64Data encoding:NSUTF8StringEncoding];

return base64Str;

}

- (NSString *)decryptForEncryption:(NSString *)encryption {

NSData *data = [[NSData alloc]initWithBase64EncodedString:encryption options:NSDataBase64DecodingIgnoreUnknownCharacters];

NSString *string = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];

//保存解密后的字符

NSMutableString *decryption=[NSMutableString string];

//解码字符

NSString *decoding=nil;

for(int i=0;i

//截取16进制形式的字符串 \x8b中的8b

NSString *tem=[string substringWithRange:NSMakeRange(i*2, 2)];

char *endptr;

//把16进制形式的字符串转为字符

char n=(char)(int)strtoul([tem UTF8String],&endptr,16);

//判断是否为加密字符

if (n=='\0'&&*endptr!='\0') {

[decryption setString:@""];

break;

}

[decryption appendFormat:@"%c",(char)(n^0x99)];

}

if (![decryption isEqualToString:@""]) {

//编码后的字符串 iso-8859-1 -> UTF_8

decoding=[[NSString alloc]initWithData:[[decryption copy] dataUsingEncoding:NSISOLatin1StringEncoding] encoding:NSUTF8StringEncoding];

}

if (decoding==nil) {

decoding=string;

}

return decoding;

}