private PartETag uploadChunk( ByteBuffer bytes, InitiateMultipartUploadResult initResponse, int index) throws Exception { byte[] md5 = S3Utils.md5(bytes); UploadPartRequest request = new UploadPartRequest(); request.setBucketName(initResponse.getBucketName()); request.setKey(initResponse.getKey()); request.setUploadId(initResponse.getUploadId()); request.setPartNumber(index); request.setPartSize(bytes.limit()); request.setMd5Digest(S3Utils.toBase64(md5)); request.setInputStream(new ByteBufferInputStream(bytes)); UploadPartResult response = s3Client.uploadPart(request); PartETag partETag = response.getPartETag(); if (!response.getPartETag().getETag().equals(S3Utils.toHex(md5))) { throw new Exception("Unable to match MD5 for part " + index); } return partETag; }