Captcha Implementation

CAPTCHA helps protect you from spam and password decryption by asking you to complete a simple test that proves you are human and not a computer trying to break into a password-protected account.

We can implement a captcha in Spring boot where a user can get an encoded image, and the corresponding readable captcha can be stored in the Database.

We can add simplecaptcha in the pom file to include inside the dependencies.

<dependency>
	<groupId>cn.apiclub.tool</groupId>
	<artifactId>simplecaptcha</artifactId>
	<!-- we have to manage version here -->
	<version>1.2.2</version> 
 </dependency>

We can create the captcha by providing the height and width for the same and inside the create captcha we can add the text, background-color, and gimp as well like FishEyeGimpyRenderer

Captcha captcha = createCaptcha(240, 70);
String readableImage = encodeCaptcha(captcha);

public static Captcha createCaptcha(Integer width, Integer height) {

		return new Captcha.Builder(width, height).addBackground(new GradiatedBackgroundProducer())
				.addText(new DefaultTextProducer(6, DEFAULT_CHARS), new DefaultWordRenderer()).gimp(new FishEyeGimpyRenderer()).addNoise()
				.build();
	}

We can also use encode Captcha method by passing the encoded captcha to Base64, getEncoder method

public static String encodeCaptcha(Captcha captcha) {
		String image = null;
		try {
			ByteArrayOutputStream bos = new ByteArrayOutputStream();
			ImageIO.write(captcha.getImage(), "jpg", bos);
			byte[] byteArray = Base64.getEncoder().encode(bos.toByteArray());
			image = new String(byteArray);
		} catch (Exception e) {
			System.out.println(e.toString());
		}
		return image;
}

 When we have the readable captcha, we can store it in DB or cache to validate whether the user has used the correct captcha or not.

Happy Coding!