AES encryption and decryption for iPhone Development

Reference from: http://zhiwei.li/text/2011/07/iphone%E4%B8%8Aaes%E5%8A%A0%E5%AF%86%E7%9A%84%E5% AE %9E%E7%8E%B0/

Header file NSDataEncryption. h

# Import <UIKit/UIKit. h> @ interface NSData (AES256)-(NSData *) AES256EncryptWithKey :( NSString *) key; // encrypted-(NSData *) AES256DecryptWithKey :( NSString *) key; // decrypt @ end

NSDataEncryption. m

#import "NSDataEncryption.h"#import <CommonCrypto/CommonDigest.h>#import <CommonCrypto/CommonCryptor.h>#import <CommonCrypto/CommonHMAC.h>@implementation NSData (AES256)- (NSData *)AES256EncryptWithKey:(NSString *)key {    // 'key' should be 32 bytes for AES256, will be null-padded otherwise    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)        // fetch key data    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];        NSUInteger dataLength = [self length];        //See the doc: For block ciphers, the output size will always be less than or    //equal to the input size plus the size of one block.    //That's why we need to add the size of one block here    size_t bufferSize = dataLength + kCCBlockSizeAES128;    void *buffer = malloc(bufferSize);        size_t numBytesEncrypted = 0;    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,                                          keyPtr, kCCKeySizeAES256,                                          NULL /* initialization vector (optional) */,                                          [self bytes], dataLength, /* input */                                          buffer, bufferSize, /* output */                                          &numBytesEncrypted);    if (cryptStatus == kCCSuccess) {        //the returned NSData takes ownership of the buffer and will free it on deallocation        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];    }        free(buffer); //free the buffer;    return nil;}- (NSData *)AES256DecryptWithKey:(NSString *)key {    // 'key' should be 32 bytes for AES256, will be null-padded otherwise    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)        // fetch key data    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];        NSUInteger dataLength = [self length];        //See the doc: For block ciphers, the output size will always be less than or    //equal to the input size plus the size of one block.    //That's why we need to add the size of one block here    size_t bufferSize = dataLength + kCCBlockSizeAES128;    void *buffer = malloc(bufferSize);        size_t numBytesDecrypted = 0;    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,                                          keyPtr, kCCKeySizeAES256,                                          NULL /* initialization vector (optional) */,                                          [self bytes], dataLength, /* input */                                          buffer, bufferSize, /* output */                                          &numBytesDecrypted);        if (cryptStatus == kCCSuccess) {        //the returned NSData takes ownership of the buffer and will free it on deallocation        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];    }        free(buffer); //free the buffer;    return nil;}@end

Usage:

NSString * key = @ "my password"; // password NSString * secret = @ "text to encrypt "; // The text to be encrypted // The encryption process NSData * plain = [secret dataUsingEncoding: NSUTF8StringEncoding]; // convert NSString to NSData * cipher = [plain AES256EncryptWithKey: key]; // ASE encrypted password printf ("% s \ n", [[cipher description] UTF8String]); // output the AES encrypted content after secret passes the key // decryption process plain = [cipher AES256DecryptWithKey: key]; // decrypts printf ("% s \ n ", [[plain description] UTF8String]); printf ("% s \ n", [[NSString alloc] initWithData: plain encoding: NSUTF8StringEncoding] UTF8String]);

Open Source Project Reference: https://github.com/AlanQuatermain/aqtoolkit/tree/master/CommonCrypto/