HarmonyOS 本地图片资源加密？

Question

有一些放在项目resources中的图片资源（用于在Image组件中展示），但是不想被别人反编译轻松的获取到。有什么办法可以实现？

Answer 1

可以将图片转二进制数组转base64进行传输到客服端/服务端再进行base64转图片，也可以将二进制进行加解密的业务操作。在服务器加密，客户端解密再将base64转成图片。

图片转PixelMap示例：

import photoAccessHelper from '@ohos.file.photoAccessHelper';
import image from '@ohos.multimedia.image';
import fs from '@ohos.file.fs';
import { buffer } from '@kit.ArkTS';

@Entry
@Component
struct Page2 {
  @State resultBase64Str: string = '';
  @State getAlbum: string = '显示相册中的图片';
  @State pixel: image.PixelMap | undefined = undefined;
  @State albumPath: string = '';
  @State photoSize: number = 0;

  async getPictureFromAlbum() {
    // 拉起相册，选择图片
    let PhotoSelectOptions = new photoAccessHelper.PhotoSelectOptions();
    PhotoSelectOptions.MIMEType = photoAccessHelper.PhotoViewMIMETypes.IMAGE_TYPE;
    PhotoSelectOptions.maxSelectNumber = 1;
    let photoPicker = new photoAccessHelper.PhotoViewPicker();
    let photoSelectResult: photoAccessHelper.PhotoSelectResult = await photoPicker.select(PhotoSelectOptions);
    this.albumPath = photoSelectResult.photoUris[0];
    console.info('albumPath: ' + this.albumPath)
    // 读取图片为buffer
    const file = fs.openSync(this.albumPath, fs.OpenMode.READ_WRITE);
    this.photoSize = fs.statSync(file.fd).size;
    console.info('Photo Size: ' + this.photoSize);
    let buffer1 = new ArrayBuffer(this.photoSize);
    fs.readSync(file.fd, buffer1);
    let base64Str: string = buffer.from(buffer1).toString('base64')
    let resultBase64Str = "data:image/png;base64," + base64Str
    this.resultBase64Str = resultBase64Str
    fs.closeSync(file);
    // 解码成PixelMap
    const imageSource = image.createImageSource(buffer1);
    console.log('imageSource: ' + JSON.stringify(imageSource));
    this.pixel = await imageSource.createPixelMap({});
  }

  build() {
    Scroll() {
      Column() {
        Text('获取图片')
          .onClick(async () => {
            await this.getPictureFromAlbum()
          })
        // Image(this.pixel)
        Image(this.resultBase64Str).width(40).height(40)
        Text(this.resultBase64Str)
      }
    }
  }
}

base64转图片的demo：

import { util } from '@kit.ArkTS';
import fs from '@ohos.file.fs';
import { BusinessError } from '@kit.BasicServicesKit';

const base64String =
  'xxxx';

@Entry
@Component
struct Index {
  @State imagestr: string = ''

  base64Image() {
    let begin = 'data:image/jpeg;base64,'
    return begin + base64String
  }

  aboutToAppear(): void {
    this.imagestr = this.base64Image()
  }

  build() {
    Row() {
      Column() {
        Image(this.imagestr)
          .width(300)
          .height(100)
          .backgroundColor(Color.Green)

        Button("保存图片")
          .onClick(() => {
            this.picture()
          })
      }
      .width('100%')
    }
    .height('100%')
  }

  picture() {
    let that = new util.Base64Helper();
    let result: Uint8Array = that.decodeSync(base64String, util.Type.MIME);
    let buf: ArrayBuffer = result.buffer as ArrayBuffer
    const context: Context = getContext(this);
    const path1: string = context.cacheDir + "/pixel_map1169.jpg";
    let file = fs.openSync(path1, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
    fs.write(file.fd, buf).then(async (writeLen) => {
      console.info("write data to file succeed and size is:" + writeLen);
      fs.closeSync(file);
    }).catch((err: BusinessError) => {
      console.info("write data to file failed with error message: " + err.message + ", error code: " + err.code);
    });
  }
}

base64转码参考：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-util-V5\#base64helper9

加解密参考：https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/crypto-encryption-decryption-overview-V5

图片api指南：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-image-V5