iphone AES加密

1 頭檔案
  2 
  3 #import <Foundation/Foundation.h>
  4 
  5 @interface NSData (AESTest) 
  6 -(NSData*)AES256EncryptWithKey:(NSString*)key;
  7 -(NSData*)AES256DecryptWithKey:(NSString*)key;
  8 
  9 @end
 10 
 11 實作檔案
 12 
 13 #import <CommonCrypto/CommonCryptor.h>
 14 #import "NSData.h"
 15 
 16 
 17 @implementation NSData(AESAdditions)
 18 
 19 -(NSData*)AES256EncryptWithKey:(NSString *)key{
 20 
 21     // 'key' should be 32 bytes for AES256, will be null-padded otherwise
 22     char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
 23     bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
 24 
 25 // fetch key data
 26     [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
 27 
 28     NSUInteger dataLength = [self length];
 29 
 30     //See the doc: For block ciphers, the output size will always be less than or
 31 //equal to the input size plus the size of one block.
 32 //That's why we need to add the size of one block here
 33     size_t bufferSize           = dataLength + kCCBlockSizeAES128;
 34     void* buffer                = malloc(bufferSize);
 35 
 36     size_t numBytesEncrypted    = 0;
 37     CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
 38                                           keyPtr, kCCKeySizeAES256,
 39                                           NULL /* initialization vector (optional) */,
 40                                           [self bytes], dataLength, /* input */
 41                                           buffer, bufferSize, /* output */
 42                                           &numBytesEncrypted);
 43 
 44     if (cryptStatus == kCCSuccess)
 45     {
 46         //the returned NSData takes ownership of the buffer and will free it on deallocation
 47         return [NSMutableData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
 48     }
 49 
 50     free(buffer); //free the buffer;
 51     return nil;
 52 }
 53 
 54 
 55 
 56 
 57 - (NSData*)AES256DecryptWithKey:(NSString*)key {
 58     // 'key' should be 32 bytes for AES256, will be null-padded otherwise
 59     char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
 60     bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
 61 
 62 // fetch key data
 63     [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
 64 
 65     NSUInteger dataLength = [self length];
 66 
 67     //See the doc: For block ciphers, the output size will always be less than or
 68 //equal to the input size plus the size of one block.
 69 //That's why we need to add the size of one block here
 70     size_t bufferSize           = dataLength + kCCBlockSizeAES128;
 71     void* buffer                = malloc(bufferSize);
 72 
 73     size_t numBytesDecrypted    = 0;
 74     CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
 75                                           keyPtr, kCCKeySizeAES256,
 76                                           NULL /* initialization vector (optional) */,
 77                                           [self bytes], dataLength, /* input */
 78                                           buffer, bufferSize, /* output */
 79                                           &numBytesDecrypted);
 80 
 81     if (cryptStatus == kCCSuccess)
 82     {
 83         //the returned NSData takes ownership of the buffer and will free it on deallocation
 84         return [NSMutableData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
 85     }
 86 
 87     free(buffer); //free the buffer;
 88     return nil;
 89 }
 90 @end
 91 
 92 
 93 
 94 調用
 95 - (void)loadView {
 96 
 97 
 98 NSString *key = @"my password";
 99 NSString *secret = @"text to encrypt";
100 
101 NSData *plain = [secret dataUsingEncoding:NSUTF8StringEncoding];
102 NSData *cipher = [plain AES256EncryptWithKey:key];
103 printf("............%s\n", [[cipher description] UTF8String]);
104 
105 plain = [cipher AES256DecryptWithKey:key];
106 printf("............%s\n", [[plain description] UTF8String]);
107 printf("............%s\n", [[[NSString alloc] initWithData:plain encoding:NSUTF8StringEncoding] UTF8String]);
108 
109 ｝