首先是一段对MD5的简介
＊出自一位大牛之手＊
Message Digest Algorithm MD5（中文名为消息摘要算法第五版）为计算机安全领域广泛使用的一种散列函数，用以提供消息的完整性保护
是计算机广泛使用的杂凑算法之一（又译摘要算法、哈希算法），主流编程语言普遍已有MD5实现。
MD5算法具有以下特点：
1、压缩性：任意长度的数据，算出的MD5值长度都是固定的。
2、容易计算：从原数据计算出MD5值很容易。
3、抗修改性：对原数据进行任何改动，哪怕只修改1个字节，所得到的MD5值都有很大区别。
4、强抗碰撞：已知原数据和其MD5值，想找到一个具有相同MD5值的数据（即伪造数据）是非常困难的。
MD5的作用是让大容量信息在用数字签名软件签署私人密钥前被"压缩"成一种保密的格式（就是把一个任意长度的字节串变换成一定长的十六进制数字串）。除了MD5以外，其中比较有名的还有sha-1、RIPEMD以及Haval等。
//
// ViewController.m
// CX－MD5加密
//
// Created by xubaoaichiyu on 16/3/22.
// Copyright © 2016年 大xubaoaichiyu. All rights reserved.
// #import "ViewController.h"
#import "NSString+Hash.h" @interface ViewController () @end @implementation ViewController - (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib. NSString * password = @"xubaoaichiyu"; NSLog(@"%@",password.md5String); //md5加盐
NSString * repassword = [password stringByAppendingString:@"love"]; NSLog(@"%@",repassword.md5String);
} @end
MD5 可以说是用c语言编程，但是对于喜欢面向对象的我们当然会有三方实现。通过这个三方我门可以很方便的解决繁重的c语言代码上。下面是三方的.h.m文件。
//
// NSString+Hash.h
//
// Created by Tom Corwine on 5/30/12..
// #import <Foundation/Foundation.h> @interface NSString (Hash) @property (readonly) NSString *md5String;
@property (readonly) NSString *sha1String;
@property (readonly) NSString *sha256String;
@property (readonly) NSString *sha512String; - (NSString *)hmacSHA1StringWithKey:(NSString *)key;
- (NSString *)hmacSHA256StringWithKey:(NSString *)key;
- (NSString *)hmacSHA512StringWithKey:(NSString *)key; @end
//
// NSString+Hash.m
//
// Created by Tom Corwine on 5/30/12.
// #import "NSString+hash.h" #import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonHMAC.h> @implementation NSString (Hash) - (NSString *)md5String
{
const char *string = self.UTF8String;
int length = (int)strlen(string);
unsigned char bytes[CC_MD5_DIGEST_LENGTH];
CC_MD5(string, length, bytes);
return [self stringFromBytes:bytes length:CC_MD5_DIGEST_LENGTH];
} - (NSString *)sha1String
{
const char *string = self.UTF8String;
int length = (int)strlen(string);
unsigned char bytes[CC_SHA1_DIGEST_LENGTH];
CC_SHA1(string, length, bytes);
return [self stringFromBytes:bytes length:CC_SHA1_DIGEST_LENGTH];
} - (NSString *)sha256String
{
const char *string = self.UTF8String;
int length = (int)strlen(string);
unsigned char bytes[CC_SHA256_DIGEST_LENGTH];
CC_SHA256(string, length, bytes);
return [self stringFromBytes:bytes length:CC_SHA256_DIGEST_LENGTH];
} - (NSString *)sha512String
{
const char *string = self.UTF8String;
int length = (int)strlen(string);
unsigned char bytes[CC_SHA512_DIGEST_LENGTH];
CC_SHA512(string, length, bytes);
return [self stringFromBytes:bytes length:CC_SHA512_DIGEST_LENGTH];
} - (NSString *)hmacSHA1StringWithKey:(NSString *)key
{
NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
NSData *messageData = [self dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData *mutableData = [NSMutableData dataWithLength:CC_SHA1_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA1, keyData.bytes, keyData.length, messageData.bytes, messageData.length, mutableData.mutableBytes);
return [self stringFromBytes:(unsigned char *)mutableData.bytes length:mutableData.length];
} - (NSString *)hmacSHA256StringWithKey:(NSString *)key
{
NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
NSData *messageData = [self dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData *mutableData = [NSMutableData dataWithLength:CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, keyData.bytes, keyData.length, messageData.bytes, messageData.length, mutableData.mutableBytes);
return [self stringFromBytes:(unsigned char *)mutableData.bytes length:mutableData.length];
} - (NSString *)hmacSHA512StringWithKey:(NSString *)key
{
NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
NSData *messageData = [self dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData *mutableData = [NSMutableData dataWithLength:CC_SHA512_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA512, keyData.bytes, keyData.length, messageData.bytes, messageData.length, mutableData.mutableBytes);
return [self stringFromBytes:(unsigned char *)mutableData.bytes length:mutableData.length];
} #pragma mark - Helpers - (NSString *)stringFromBytes:(unsigned char *)bytes length:(int)length
{
NSMutableString *mutableString = @"".mutableCopy;
for (int i = ; i < length; i++)
[mutableString appendFormat:@"%02x", bytes[i]];
return [NSString stringWithString:mutableString];
} @end