Brief Explanation

How do you speak to the youths about smoking when they don't listen to good advice? The youths don't like to be told what to do. But they do listen to each other. And one the most popular way they communicate with each other is over WhatsApp - the No.1 texting platform in Singapore. Youths like it because it's free to send and receive messages. So we decided to spread awareness about the effects of smoking through texts. We discovered a little secret about WhatsApp. With some simple tech wizardry it's possible conceal an image within an image. We used this simple visual trickery to create several thumbnails that teased youths with glamourous photos – the kind they like sharing with each other. At first, the messages seemed innocuous, but when the thumbnails were opened, they revealed the harmful effects of smoking. How it works: 1. When a sender forwards an image, Whatsapp uploads thumbnails and actual images separately. The Thumbnail needs to be in a string format (base64 encoded). 2. The message recived in the conversation dialog downloads the thumbnail first and then downloads the actual image (if they set to auto download). 3. The trick lies in how we generate the thumbnail. We use different images for the thumbnail before we upload the actual image to the Whatsapp server, so the receiver sees different image as a thumbnail and a different image after enlarging it. In other words, the thumbnail and the actual image use different data. So we used a different data while generating the thumbnail and uploaded different data while creating the actual image on the server. In Whatsapp, image data of thumbnails and actual images were stored and called separately. So when a receiver views an image in the conversation box, the actual image is only called when enlarged. The texts instantly struck a chord with the youths and the message spread from phone to phone. Because these messages reached 18-year olds via their friends, they listened. Most importantly, they shared a public service message they would normally ignore. And since we used Whatsapp, the no.1 free texting platform, it cost us nothing in media. The Singapore Cancer Society and The Health Promotion Board of Singapore have many youth ambassadors and volunteers. We tapped into this pool and gave them the unbranded MMS texts to send to their friends. The initial texts were seeded to about 300 volunteers and from there on it was exponentially shared to thousands.