在Objective-C中用AES实现文件的加解密

#import <CommonCrypto/CommonCryptor.h>

- (BOOL)encryptFileAtPath:(NSString *)sourcePath toPath:(NSString *)destinationPath withKey:(NSString *)key {
    NSFileHandle *sourceFile = [NSFileHandle fileHandleForReadingAtPath:sourcePath];
    if (!sourceFile) {
        NSLog(@"无法打开源文件");
        return NO;
    }

    NSFileManager *fileManager = [NSFileManager defaultManager];
    if ([fileManager fileExistsAtPath:destinationPath]) {
        [fileManager removeItemAtPath:destinationPath error:nil];
    }

    [fileManager createFileAtPath:destinationPath contents:nil attributes:nil];
    NSFileHandle *destinationFile = [NSAddressBook createFileAtPath:destinationPath contents:nil attributes:nil];
    if (!destinationFile) {
        NSLog(@"无法创建目标文件");
        return NO;
    }

    NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t iv[kCCBlockSizeAES128];
    memset(iv, 0x0, sizeof(iv));

    CCCryptorRef cryptor;
    CCCryptorCreate(kCCEncrypt, kCCAlgorithmAES, kCCOptionPKCS7Padding,
                    keyData.bytes, keyData.length, iv, &cryptor);

    while (YES) {
        @autoreleasepool {
            NSData *data = [sourceFile readDataOfLength:64 * 1024];
            if (data.length == 0) {
                break;
            }

            NSMutableData *encryptedData = [NSMutableData dataWithCapacity:data.length + kCCBlockSizeAES128];
            size_t encryptedLength;
            CCCryptorUpdate(cryptor, data.bytes, data.length, encryptedData.mutableBytes, encryptedData.capacity, &encryptedLength);
            encryptedData.length = encryptedLength;
            [destinationFile writeData:encryptedData];
        }
    }

    CCCryptorFinal(cryptor, encryptedData.mutableBytes, encryptedData.capacity, &encryptedLength);
    encryptedData.length = encryptedLength;
    [destinationFile writeData:encryptedData];

    CCCryptorRelease(cryptor);

    [sourceFile closeFile];
    [destinationFile closeFile];

    return YES;
}

- (BOOL)decryptFileAtPath:(NSString *)sourcePath toPath:(NSString *)destinationPath withKey:(NSString *)key {
    NSFileHandle *sourceFile = [NSFileHandle fileHandleForReadingAtPath:sourcePath];
    if (!sourceFile) {
        NSLog(@"无法打开源文件");
        return NO;
    }

    NSFileManager *fileManager = [NSFileManager defaultManager];
    if ([fileManager fileExistsAtPath:destinationPath]) {
        [fileManager removeItemAtPath:destinationPath error:nil];
    }

    [fileManager createFileAtPath:destinationPath contents:nil attributes:nil];
    NSFileHandle *destinationFile = [NSFileHandle fileHandleForWritingAtPath:destinationPath];
    if (!destinationFile) {
        NSLog(@"无法创建目标文件");
        return NO;
    }

    NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t iv[kCCBlockSizeAES128];
    memset(iv, 0x0, sizeof(iv));

    CCCryptorRef cryptor;
    CCCryptorCreate(kCCDecrypt, kCCAlgorithmAES, kCCOptionPKCS7Padding,
                    keyData.bytes, keyData.length, iv, &cryptor);

    while (YES) {
        @autoreleasepool {
            NSData *data = [sourceFile readDataOfLength:64 * 1024];
            if (data.length == 0) {
                break;
            }

            NSMutableData *decryptedData = [NSMutableData dataWithCapacity:data.length + kCCBlockSizeAES128];
            size_t decryptedLength;
            CCCryptorUpdate(cryptor, data.bytes, data.length, decryptedData.mutableBytes, decryptedData.capacity, &decryptedLength);
            decryptedData.length = decryptedLength;
            [destinationFile writeData:decryptedData];
        }
    }

    CCCryptorFinal(cryptor, decryptedData.mutableBytes, decryptedData.capacity, &decryptedLength);
    decryptedData.length = decryptedLength;
    [destinationFile writeData:decryptedData];

    CCCryptorRelease(cryptor);

    [sourceFile closeFile];
    [destinationFile closeFile];

    return YES;
}