Generating Amazon S3 Pre-signed URLs with Server Side Encryption - KMS

PresignedURLGenerator.java

public class PresignedLinkGenerator {
    private static final int EXPIRATION_TIME_IN_MILLISECONDS = 1000 * 60 * 60; // 1 hour
    private static final String SIGNER_TYPE = "AWSS3V4SignerType";
    private String KmsKeyARN = "<EncryptionKeyARN>";

    public URL generatePresignedLink(final String bucketName, final String objectKey, final HttpMethod httpMethod) throws Exception {
        final Region currentRegion = Regions.getCurrentRegion() == null ? Region.getRegion(Regions.US_WEST_2) : Regions.getCurrentRegion();
        final AmazonS3 s3client = AmazonS3ClientBuilder.standard()
                .withClientConfiguration(new ClientConfiguration().withSignerOverride(SIGNER_TYPE))
                .withRegion(currentRegion.getName())
                .build();
        URL url;

        try {
            final Date expiration = new Date();
            long milliSeconds = expiration.getTime();
            milliSeconds += EXPIRATION_TIME_IN_MILLISECONDS;

            expiration.setTime(milliSeconds);

            final GeneratePresignedUrlRequest generatePresignedUrlRequest = new GeneratePresignedUrlRequest(bucketName, 
                                                                                                            objectKey);

            generatePresignedUrlRequest.setMethod(httpMethod);
            generatePresignedUrlRequest.setExpiration(expiration);

            if (httpMethod != HttpMethod.GET) {
                generatePresignedUrlRequest.setSSEAlgorithm(SSEAlgorithm.KMS.getAlgorithm());
                generatePresignedUrlRequest.setKmsCmkId(KmsKeyARN);
                generatePresignedUrlRequest.setContentType("application/octet-stream");
            }

            url = s3client.generatePresignedUrl(generatePresignedUrlRequest);
        } catch (AmazonClientException e) {
            throw e;
        }

        return url;
    }