iOS 常用加密

MD5加密

MD5加密是移动开发的常用加密方法，由于他的随机加密性和不可逆性被广泛应用于用户信息的网络传输。
简单的MD5加密可以参照广大的参考库进行参照对比破解，但是复杂的字符串进行MD5加密是无法用常规方法进行破解的。
传说可以用暴力破解方法，由于笔者黑客技术浅薄这里就不做讲解，感兴趣的小伙伴可以自己查询。
这里主要讲解iOS针对字符串的MD5加密操作，代码块如下：

#import "MD5Util.h"
#import 
@interface MD5Util ()

@end

@implementation MD5Util

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (NSString *)md5:(NSString *)str
{
    const char *cStr = [str UTF8String];
    unsigned char result[16];
    CC_MD5(cStr, strlen(cStr), result); // This is the md5 call
    return [NSString stringWithFormat:
             result[0], result[1], result[2], result[3],
            result[4], result[5], result[6], result[7],
            result[8], result[9], result[10], result[11],
            result[12], result[13], result[14], result[15],
            @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x"           
            ];
}

AES加密

AES加密也是一种常用的加密方法，加密解密需要专属的key值，一般都是与Base64结合起来一起使~代码如下：

    + (NSString *)encrypt:(NSString *)message password:(NSString *)password {
  NSData *encryptedData = [[message dataUsingEncoding:NSUTF8StringEncoding] AES256EncryptedDataUsingKey:[[password dataUsingEncoding:NSUTF8StringEncoding] SHA256Hash] error:nil];
  NSString *base64EncodedString = [NSString base64StringFromData:encryptedData length:[encryptedData length]];
  return base64EncodedString;
}

+ (NSString *)decrypt:(NSString *)base64EncodedString password:(NSString *)password {
  NSData *encryptedData = [NSData base64DataFromString:base64EncodedString];
  NSData *decryptedData = [encryptedData decryptedAES256DataUsingKey:[[password dataUsingEncoding:NSUTF8StringEncoding] SHA256Hash] error:nil];
  return [[NSString alloc] initWithData:decryptedData encoding:NSUTF8StringEncoding];
}

Base64编码

#import "NSString+Base64.h"

static char base64EncodingTable[64] = {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
  'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
  'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};

@implementation NSString (Base64Additions)

+ (NSString *)base64StringFromData: (NSData *)data length: (NSUInteger)length {
  unsigned long ixtext, lentext;
  long ctremaining;
  unsigned char input[3], output[4];
  short i, charsonline = 0, ctcopy;
  const unsigned char *raw;
  NSMutableString *result;
  lentext = [data length];
  if (lentext < 1) {
    return @"";
  }
  result = [NSMutableString stringWithCapacity: lentext];
  raw = [data bytes];
  ixtext = 0; 

  while (true) {
    ctremaining = lentext - ixtext;
    if (ctremaining <= 0) {
      break;
    }
    for (i = 0; i < 3; i++) { 
      unsigned long ix = ixtext + i;
      if (ix < lentext) {
        input[i] = raw[ix];
      }
      else {
        input[i] = 0;
      }
    }
    output[0] = (input[0] & 0xFC) >> 2;
    output[1] = ((input[0] & 0x03) << 4) | ((input[1] & 0xF0) >> 4);
    output[2] = ((input[1] & 0x0F) << 2) | ((input[2] & 0xC0) >> 6);
    output[3] = input[2] & 0x3F;
    ctcopy = 4;
    switch (ctremaining) {
      case 1: 
        ctcopy = 2; 
        break;
      case 2: 
        ctcopy = 3; 
        break;
    }

    for (i = 0; i < ctcopy; i++) {
      [result appendString: [NSString stringWithFormat: @"%c", base64EncodingTable[output[i]]]];
    }

    for (i = ctcopy; i < 4; i++) {
      [result appendString: @"="];
    }

    ixtext += 3;
    charsonline += 4;

    if ((length > 0) && (charsonline >= length)) {
      charsonline = 0;
    }
  }     
  return result;
}

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