Welcome!

Industrial IoT Authors: Jason Bloomberg, Scott Allen, Tim Hinds, SmartBear Blog, Elizabeth White

Related Topics: Java IoT, Industrial IoT, Microservices Expo, IoT User Interface, Apache, Cloud Security

Java IoT: Article

Designing a Java Cryptography Header

Encrypt personal files, exchange confidential messages and authenticate the sender

Designing and implementing a hybrid encryption application is a big challenge but without a supporting infrastructure it's almost impossible. There are open source libraries that allow you to encrypt a file but only provide the translation technique. After the information has been encrypted, how do you know what algorithm was used, who you encrypted it, what version did you used, etc. In order to decrypt the protected message or file, a well-defined cryptographic header provides all the information required. This also applies if the encrypted data is digitally signed and the recipient wants to validate the signature.

This article will address one of the critical components of a support infrastructure by providing a design of a cryptographic header used to precede encrypted and/or digitally signed messages and files. The header is used within an application known as DocuArmor that was written using Java and the Cryptography library from the BouncyCastle organization and designed by Logical Answers Inc. The header will store information used when encrypting and/or digitally signing a message or file and allow the recipient to decrypt the information and/or verify the digital signature. With a properly designed header, a person can encrypt their personal files as well as exchange confidential messages and authenticate the sender.

Hybrid Encryption
In order to encrypt personal files and exchange protected data, we use a hybrid technique with two types of encryption, symmetric and asymmetric.

Symmetric encryption uses a single key to hide the message and reveal the message. There are several symmetric algorithms available such as AES (the Advanced Encryption Standard) but the important thing to remember is that the file can be encrypted and decrypted using the same key. An example is the Caesar cipher that shifts the letters of the alphabet by a specific number. If the shift is 2 (single key) then we get the following translation; a=c, b=d, c=e, ..., z=b.

Asymmetric encryption uses a pair of keys (public, private) to hide and reveal the message and the RSA algorithm is most commonly used. The RSA algorithm was credited in 1977 to Ronald Rivest, Adi Shamir, and Leonard Adleman. Sometimes referred to as Public Key Infrastructure (PKI), the pubic key is used to encrypt data and the private key is used to decrypt data.

Figure 1: Public and Private Key Functions

The hybrid technique uses the symmetric key to encrypt a file. The asymmetric public key is used to encrypt the symmetric key and is placed in the header. When the recipient receives an encrypted file, the encrypted symmetric key is extracted from the header. The encrypted symmetric key is decrypted using the private key. The file is decrypted using the symmetric key.

The same pair of keys can be used with digital signatures. The private key is used to generate a digital signature from a file and inserted into the header. The public key is used to verify the authenticity of the signature.

When two people want to exchange encrypted files, they each generate a pair of asymmetric keys and exchange a copy of their public keys. By using the other person's public key, they can encrypt a file, storing the cryptographic information in the header and then e-mail it to the recipient. The recipient will use the header to extract a symmetric key with their private key and decrypt the accompanying file. If a digital signature is included, the recipient can authenticate the sender.

Figure 2: Exchange of Encrypted Files

Cryptographic Header
When a file is encrypted, digitally signed or both, a Cryptographic header is placed in front of the resulting file and has the following structure. The structure consists of two sections, the header and the encrypted/plain file contents.

Figure 3: Encrypted File Structure

The header structure contains information required to reverse the encryption process and decrypt the contents of the file or verify the digital signature. The header contains the total length, an ID, version, and two sections containing encryption and digital signature information. Using Java, you can write out the contents of header within a byte stream as well as read it back in.

Figure 4: Cryptographic Header Structure

  • Total Len: Contains the total length of the header (stored as a 4 byte integer)
  • Header ID: Contains the string "LAHEADER" to identify the file (16 bytes)
  • Header Version: Structural version of the header (stored as a 4 byte integer)
  • Encryption Information: Holds the algorithm, mode, encrypted symmetric key, etc.
  • Digital Signature Information: Holds digital signature

Encryption Information
The Encryption Information structure contains information that was used to encrypt the contents of the file and later decrypt the file. The symmetric key and initialization vector is encrypted with the recipient's asymmetric public key. The recipient could be the owner if you are encrypting a file for yourself or another user you want to send confidential information to.

An additional field has been allocated to allow the encryption of the symmetric key with another set of asymmetric keys. For example, if owner A is sending an encrypted file to another person B, the symmetric key can be encrypted with B's public key as well as A's public key so that either person can decrypt the file.

Alternatively, an employee can encrypt a file with their public key and a corporation could insert an encrypted symmetric key into the header using their asymmetric keys. The corporation's asymmetric keys can be a Certifying Authority (CA), which can be used to issue employee keys.

Figure 5: Encryption Information Structure

  • Encrypt Flag: (Y/N - 2 bytes) specifies whether the file is encrypted.
  • Decrypt ID Length: (integer - 4 bytes) length in chars(bytes) of the Key ID.
  • Decrypt ID: (size varies) an identifier of the RSA keys used in the encryption/decryption process. It is the alias associated to the asymmetric encryption keys (e.g., JaneDoe_12ff).
  • Other Decrypt ID Length: (integer - 4 bytes) length in chars(bytes) of the Key ID.
  • Other Decrypt ID: (size varies) an identifier of the RSA keys used in the encryption/decryption process. It can be the alias or the common name (e.g., JaneDoe_12ff or Logical Answers CA).
  • Symmetric Key Algorithm: (integer - 4 bytes) specifies the symmetric key algorithm used to encrypt the file. The default value is 1=AES.
  • Symmetric Key Mode: (integer - 4 bytes) specifies the symmetric key block cipher mode used to enhance confidentiality. The default value is 5=Segmented Integer Counter mode (CTR).
  • Symmetric Key Padding: (integer - 4 bytes) specifies the type of padding for block cipher. The default value is 1=No Padding
  • Wrapped Symmetric Key Length: (integer - 4 bytes)
  • Wrapped Symmetric Key: (size varies) symmetric key used to encrypt/decrypt the file and encrypted with the asymmetric key.
  • Initialization Vector Length: (integer - 4 bytes)
  • Initialization Vector: (byte[] - size varies) vector used with the symmetric encryption process.
  • Other Wrapped Symmetric Key Length: (integer - 4 bytes)
  • Other Wrapped Symmetric Key: (size varies) symmetric key used to encrypt/decrypt the file and encrypted with another person's asymmetric key.
  • Other Initialization Vector Length: (integer - 4 bytes)
  • Other Initialization Vector: (byte[] - size varies) vector used with the symmetric encryption process.

Digital Signature Information
The Digital Signature Information structure contains information used to add or verify a digital signature generated from the contents of the file. The digital signature is generated with the owner's private key using a specific algorithm and then inserted into the header. When the recipient receives the signed file, they can use the signer's public key to validate its authenticity. If the signature is authenticated, it implies the file has not been altered and the holder of the private key generated the signature.

Figure 6: Digital Signature Information Structure

  • Signed Flag: (Y/N - 2 bytes) specifies whether the file contains a digital signature
  • Signature Algorithm: (integer - 4 bytes) specifies the algorithm used to generate the digital signature. The default value is 12= SHA512WithRSAEncryption
  • Verify Signature Cert Name Length: (integer - 4 bytes) length in chars(bytes) of the filename of the certificate used to verify a digital signature
  • Verify Signature Cert Name: (size varies) filename of the certificate holding the RSA public key used to verify the digital signature of a file (e.g., JaneDoe_fa39.cer).
  • Signature Date/Time: (long - 8 bytes) date the digital signature was generated.
  • Signature Length: (integer - 4 bytes)
  • Signature: (size varies) holds digital signature generated with RSA private key and signature engine

File Naming Conventions
The Cryptographic header holds information that designates which keys were used to encrypt a file but it's not physically accessible without reading it in first. With proper naming conventions, you can determine who the intended recipient is for encrypted files - whether it is for yourself or a colleague. When you generate your pair of asymmetric encryption keys using Java, store them in a file called a key store. The key store holds a pair of asymmetric keys as an entry with a unique alias. The alias typically consists of the initial of your first name and your last name. To make it more unique, you can extract 4 hex digits from your public key and append an underline and the hex digits to the alias. For example, if the person's name was Jane Smith, then the resulting unique alias would be jsmith_ad5e. A certificate holds a person's public key and the alias would be used in the filename, as jsmith_ad5e.cer. Similarly, the key store holding the pair of asymmetric keys would be saved as, jsmith_ad5e.jks.

Following the unique alias analogy, Jane Smith could encrypt files for herself and the file name would be appended with her alias and an appropriate file extension. For example, if Jane encrypted a personal file, myTaxes.txt, then the result would be myTaxes.txt.jsmith_ad5e.aes. If Jane wanted to send her colleague Dick an encrypted document, she would use Dick's certificate to encrypt it. If Dick's certificate is djones_9fa2, Jane could encrypt the file, comments.doc, for Dick and the resulting file would be comments.doc.djones_9fa2.aes. When Dick receives the file, he knows it is for him by recognizing his alias on the file name.

The unique alias is stored within the header. This reinforces the importance of having a well-defined Cryptographic header for implementing encryption within your applications.

Benefits
A well-defined cryptographic header stores the information required to encrypt, decrypt and digitally sign a file. Along with facilitating the implementation of standard cryptographic functions, the header also provides the following benefits:

  • The header allows for the protection of personal files as well as the exchange of confidential data.
  • Using the stored digital signature, the recipient can determine if the sender is valid and whether file has been altered.
  • The header allows either the sender or recipient to decrypt the encrypted file since both would encrypt the symmetric key with their public key.
  • Using the concept of a Certifying Authority pair of asymmetric keys, a corporation, group, or family could issue pairs of asymmetric keys to their employees or members and decipher files encrypted by them in case of emergencies.
  • The header allows for using different combinations of symmetric algorithms, modes, padding and key sizes to be used to encrypt information.
  • The header version allows for enhancements to be added to the structure for implementing new functions and still support older versions.

References and Other Technical Notes
Software requirements:

Recommended Reading:

  • "Beginning Cryptography with Java" by David Hook.
  • "The Code Book" by Simon Singh

More Stories By James H. Wong

James H. Wong has been involved in the technology field for over 30 years and has dual MS degrees in mathematics and computer science from the University of Michigan. He worked for IBM for almost 10 years designing and implementing software. Founding Logical Answers Corp in 1992, he has provided technical consulting/programming services to clients, providing their business with a competitive edge. With his partner they offer a Java developed suite of “Secure Applications” that protect client’s data using the standard RSA (asymmetric) and AES (symmetric) encryption algorithms.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
SYS-CON Events announced today that DatacenterDynamics has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY. DatacenterDynamics is a brand of DCD Group, a global B2B media and publishing company that develops products to help senior professionals in the world's most ICT dependent organizations make risk-based infrastructure and capacity decisions.
SYS-CON Events announced today TMCnet has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Technology Marketing Corporation (TMC) is the world's leading business-to-business and integrated marketing media company, servicing niche markets within the com...
The IoT has the potential to create a renaissance of manufacturing in the US and elsewhere. In his session at 18th Cloud Expo, Florent Solt, CTO and chief architect of Netvibes, will discuss how the expected exponential increase in the amount of data that will be processed, transported, stored, and accessed means there will be a huge demand for smart technologies to deliver it. Florent Solt is the CTO and chief architect of Netvibes. Prior to joining Netvibes in 2007, he co-founded Rift Technol...
Join IBM June 8 at 18th Cloud Expo at the Javits Center in New York City, NY, and learn how to innovate like a startup and scale for the enterprise. You need to deliver quality applications faster and cheaper, attract and retain customers with an engaging experience across devices, and seamlessly integrate your enterprise systems. And you can't take 12 months to do it.
This is not a small hotel event. It is also not a big vendor party where politicians and entertainers are more important than real content. This is Cloud Expo, the world's longest-running conference and exhibition focused on Cloud Computing and all that it entails. If you want serious presentations and valuable insight about Cloud Computing for three straight days, then register now for Cloud Expo.
IoT device adoption is growing at staggering rates, and with it comes opportunity for developers to meet consumer demand for an ever more connected world. Wireless communication is the key part of the encompassing components of any IoT device. Wireless connectivity enhances the device utility at the expense of ease of use and deployment challenges. Since connectivity is fundamental for IoT device development, engineers must understand how to overcome the hurdles inherent in incorporating multipl...
Machine Learning helps make complex systems more efficient. By applying advanced Machine Learning techniques such as Cognitive Fingerprinting, wind project operators can utilize these tools to learn from collected data, detect regular patterns, and optimize their own operations. In his session at 18th Cloud Expo, Stuart Gillen, Director of Business Development at SparkCognition, will discuss how research has demonstrated the value of Machine Learning in delivering next generation analytics to im...
Manufacturers are embracing the Industrial Internet the same way consumers are leveraging Fitbits – to improve overall health and wellness. Both can provide consistent measurement, visibility, and suggest performance improvements customized to help reach goals. Fitbit users can view real-time data and make adjustments to increase their activity. In his session at @ThingsExpo, Mark Bernardo Professional Services Leader, Americas, at GE Digital, will discuss how leveraging the Industrial Interne...
The paradigm has shifted. A Gartner survey shows that 43% of organizations are using or plan to implement the Internet of Things in 2016. However, not just a handful of companies are still using the old-style ad-hoc trial-and-error ways, unaware of the critical barriers, paint points, traps, and hidden roadblocks. How can you become a winner? In his session at @ThingsExpo, Tony Shan will present a methodical approach to guide the holistic adoption and enablement of IoT implementations. This ov...
SYS-CON Events announced today that Stratoscale, the software company developing the next generation data center operating system, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Stratoscale is revolutionizing the data center with a zero-to-cloud-in-minutes solution. With Stratoscale’s hardware-agnostic, Software Defined Data Center (SDDC) solution to store everything, run anything and scale everywhere...
Angular 2 is a complete re-write of the popular framework AngularJS. Programming in Angular 2 is greatly simplified – now it's a component-based well-performing framework. This immersive one-day workshop at 18th Cloud Expo, led by Yakov Fain, a Java Champion and a co-founder of the IT consultancy Farata Systems and the product company SuranceBay, will provide you with everything you wanted to know about Angular 2.
Digital payments using wearable devices such as smart watches, fitness trackers, and payment wristbands are an increasing area of focus for industry participants, and consumer acceptance from early trials and deployments has encouraged some of the biggest names in technology and banking to continue their push to drive growth in this nascent market. Wearable payment systems may utilize near field communication (NFC), radio frequency identification (RFID), or quick response (QR) codes and barcodes...
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
You deployed your app with the Bluemix PaaS and it's gaining some serious traction, so it's time to make some tweaks. Did you design your application in a way that it can scale in the cloud? Were you even thinking about the cloud when you built the app? If not, chances are your app is going to break. Check out this webcast to learn various techniques for designing applications that will scale successfully in Bluemix, for the confidence you need to take your apps to the next level and beyond.
The increasing popularity of the Internet of Things necessitates that our physical and cognitive relationship with wearable technology will change rapidly in the near future. This advent means logging has become a thing of the past. Before, it was on us to track our own data, but now that data is automatically available. What does this mean for mHealth and the "connected" body? In her session at @ThingsExpo, Lisa Calkins, CEO and co-founder of Amadeus Consulting, will discuss the impact of wea...
Whether your IoT service is connecting cars, homes, appliances, wearable, cameras or other devices, one question hangs in the balance – how do you actually make money from this service? The ability to turn your IoT service into profit requires the ability to create a monetization strategy that is flexible, scalable and working for you in real-time. It must be a transparent, smoothly implemented strategy that all stakeholders – from customers to the board – will be able to understand and comprehe...
So, you bought into the current machine learning craze and went on to collect millions/billions of records from this promising new data source. Now, what do you do with them? Too often, the abundance of data quickly turns into an abundance of problems. How do you extract that "magic essence" from your data without falling into the common pitfalls? In her session at @ThingsExpo, Natalia Ponomareva, Software Engineer at Google, will provide tips on how to be successful in large scale machine lear...
SYS-CON Events announced today that Ericsson has been named “Gold Sponsor” of SYS-CON's @ThingsExpo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. Ericsson is a world leader in the rapidly changing environment of communications technology – providing equipment, software and services to enable transformation through mobility. Some 40 percent of global mobile traffic runs through networks we have supplied. More than 1 billion subscribers around the world re...
SYS-CON Events announced today that Fusion, a leading provider of cloud services, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Fusion, a leading provider of integrated cloud solutions to small, medium and large businesses, is the industry's single source for the cloud. Fusion's advanced, proprietary cloud service platform enables the integration of leading edge solutions in the cloud, including cloud...
The IETF draft standard for M2M certificates is a security solution specifically designed for the demanding needs of IoT/M2M applications. In his session at @ThingsExpo, Brian Romansky, VP of Strategic Technology at TrustPoint Innovation, will explain how M2M certificates can efficiently enable confidentiality, integrity, and authenticity on highly constrained devices.