iOS开发（93）之常用加密方法（aes、md5、base64）

ios常用方法（aes、md5、base64）

1、aes加密
nsdata+aes.h文件

[plain]  // 
//  nsdata-aes.h 
//  smile 
// 
//  created by 周 敏 on 12-11-24. 
//  copyright (c) 2012年 box. all rights reserved. 
// 
 
#import <foundation/foundation.h> 
 
@class nsstring; 
 
@interface nsdata (encryption) 
 
- (nsdata *)aes256encryptwithkey:(nsstring *)key;   //加密 
- (nsdata *)aes256decryptwithkey:(nsstring *)key;   //解密 
 
@end 

nsdata+aes.m文件
[plain]  // 
//  nsdata-aes.h 
//  smile 
// 
//  created by 周 敏 on 12-11-24. 
//  copyright (c) 2012年 box. all rights reserved. 
// 
 
#import "nsdata+aes.h" 
#import <commoncrypto/commoncryptor.h> 
 
@implementation nsdata (encryption) 
 
- (nsdata *)aes256encryptwithkey:(nsstring *)key {//加密 
    char keyptr[kcckeysizeaes256+1]; 
    bzero(keyptr, sizeof(keyptr)); 
    [key getcstring:keyptr maxlength:sizeof(keyptr) encoding:nsutf8stringencoding]; 
    nsuinteger datalength = [self length]; 
    size_t buffersize = datalength + kccblocksizeaes128; 
    void *buffer = malloc(buffersize); 
    size_t numbytesencrypted = 0; 
    cccryptorstatus cryptstatus = cccrypt(kccencrypt, kccalgorithmaes128, 
                                          kccoptionpkcs7padding | kccoptionecbmode, 
                                          keyptr, kccblocksizeaes128, 
                                          null, 
                                          [self bytes], datalength, 
                                          buffer, buffersize, 
                                          &numbytesencrypted); 
    if (cryptstatus == kccsuccess) { 
        return [nsdata datawithbytesnocopy:buffer length:numbytesencrypted]; 
    } 
    free(buffer); 
    return nil; 
} 
 
 
- (nsdata *)aes256decryptwithkey:(nsstring *)key {//解密 
    char keyptr[kcckeysizeaes256+1]; 
    bzero(keyptr, sizeof(keyptr)); 
    [key getcstring:keyptr maxlength:sizeof(keyptr) encoding:nsutf8stringencoding]; 
    nsuinteger datalength = [self length]; 
    size_t buffersize = datalength + kccblocksizeaes128; 
    void *buffer = malloc(buffersize); 
    size_t numbytesdecrypted = 0; 
    cccryptorstatus cryptstatus = cccrypt(kccdecrypt, kccalgorithmaes128, 
                                          kccoptionpkcs7padding | kccoptionecbmode, 
                                          keyptr, kccblocksizeaes128, 
                                          null, 
                                          [self bytes], datalength, 
                                          buffer, buffersize, 
                                          &numbytesdecrypted); 
    if (cryptstatus == kccsuccess) { 
        return [nsdata datawithbytesnocopy:buffer length:numbytesdecrypted]; 
    } 
    free(buffer); 
    return nil; 
} 
 
@end 
这里aes在ios加过密以后以nsdata的形式存下来，如果想以nsstring形式存储，那么对nsdata进行base64位编码。
2、base64编码
首先下载gtmbase64文件，在工程中加入三个文件
gtmdefines.h
gtmbase64.h
gtmbase64.m
你可以在这里找到这三个文件
https://code.google.com/p/google-toolbox-for-mac/source/browse/trunk/foundation/?r=87
你也可以在下面的demo里面找到这3个文件，demo会完整实现文章里面常用的3种编码方法。
我在此稍微封装一下：

.h文件
[plain]   #pragma mark - base64 
+ (nsstring*)encodebase64string:(nsstring *)input; 
+ (nsstring*)decodebase64string:(nsstring *)input; 
+ (nsstring*)encodebase64data:(nsdata *)data; 
+ (nsstring*)decodebase64data:(nsdata *)data; 

.m文件
[plain]  #pragma mark - base64 
+ (nsstring*)encodebase64string:(nsstring * )input {  
    nsdata *data = [input datausingencoding:nsutf8stringencoding allowlossyconversion:yes];  
    data = [gtmbase64 encodedata:data];  
    nsstring *base64string = [[[nsstring alloc] initwithdata:data encoding:nsutf8stringencoding] autorelease];  
    return base64string; 
} 
 
+ (nsstring*)decodebase64string:(nsstring * )input {  
    nsdata *data = [input datausingencoding:nsutf8stringencoding allowlossyconversion:yes];  
    data = [gtmbase64 decodedata:data];  
    nsstring *base64string = [[[nsstring alloc] initwithdata:data encoding:nsutf8stringencoding] autorelease];  
    return base64string; 
}  
 
+ (nsstring*)encodebase64data:(nsdata *)data { 
    data = [gtmbase64 encodedata:data];  
    nsstring *base64string = [[[nsstring alloc] initwithdata:data encoding:nsutf8stringencoding] autorelease]; 
    return base64string; 
} 
 
+ (nsstring*)decodebase64data:(nsdata *)data { 
    data = [gtmbase64 decodedata:data];  
    nsstring *base64string = [[[nsstring alloc] initwithdata:data encoding:nsutf8stringencoding] autorelease]; 
    return base64string; 
} 

3、md5加密
nsstring+md5.h文件
[plain]  // 
//  nsstring+md5encrypt.h 
//  smile 
// 
//  created by 周 敏 on 12-11-24. 
//  copyright (c) 2012年 box. all rights reserved. 
// 
 
#import <commoncrypto/commondigest.h> 
 
@interface nsstring (md5) 
 
- (nsstring *)md5encrypt; 
 
@end 

 

nsstring+md5.m文件
[plain]  // 
//  nsstring+md5encrypt.h 
//  smile 
// 
//  created by 周 敏 on 12-11-24. 
//  copyright (c) 2012年 box. all rights reserved. 
// 
 
#import "nsstring+md5.h" 
 
@implementation nsstring (md5) 
 
- (nsstring *)md5encrypt { 
    const char *original_str = [self utf8string]; 
    unsigned char result[cc_md5_digest_length]; 
    cc_md5(original_str, strlen(original_str), result); 
    nsmutablestring *hash = [nsmutablestring string]; 
    for (int i = 0; i < 16; i++) 
        [hash appendformat:@"%02x", result[i]]; 
    return [hash lowercasestring]; 
} 
 
@end