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Jul 15 2015   2:18PM GMT

A primer on healthcare encryption

Posted by: adelvecchio
data encryption, Encryption

Dr  Mathews (2)Guest post by Dr. Michael G. Mathews, president, COO, & co-founder, CynergisTek, Inc.

Designed as a piece in a four-part series, this article will provide a brief primer on encryption before the remainder of the series addresses integrity and nonrepudiation, then encryption of data in motion and data at rest.

Historically, information security has addressed the confidentiality, integrity, and availability of data across a relatively broad base of domain expertise from compliance to business continuity, to identity and access management. One domain that is generally feared or lightly understood by many in the information security field — likely in part due to a general aversion to math — is encryption. That a generalization definitely holds true in healthcare. In this first installment of a four-part series, I will provide a basic primer (no pun intended) on cryptography to explain symmetric, public-key (asymmetric), and hybrid approaches to encrypt data.

Symmetric cryptography comes in many different cipher varieties, but they are unified by the fact the keys work like a traditional deadbolt on a home door — the same key is used to both lock and unlock. Key management works similarly as well; if someone else needs access, they would need to share the same key. Sharing of keys, physical or digital, is always a challenge in this mode of operation since losing or disclosing the key compromises that which is being protected.

Public key (asymmetric) cryptography relies on two different keys (a public and private key pair) that are related to each other. One key is used to encrypt data and the other to decipher data. The private key (used to decipher) is intended to be kept strictly private, where the public key (used to encrypt) is designed to be distributed widely among anyone who might need to share encrypted data.

A significant goal of public-key cryptography was to address the biggest issue of symmetric key management by removing the requirement to safeguard the key and its communication to those that need it. Due to the algorithmic design of public-key cryptography, it is more computationally demanding (and as a result, slower) than symmetric cryptography.

Combining the best parts of both types of cryptography to avoid the downfalls of the other creates the hybrid approach. Symmetric excels at speed and public-key excels at key distribution. Using the public-key model, an encrypted connection can be established without ever needing to share a key. Once the session is established, a symmetric key can be securely exchanged between the parties across the already encrypted channel. Typically, the symmetric key exchanged in this manner is deemed a “session key” and is considered a one-time use (disposable) key for protocols such as Secure Sockets Layer (SSL)/ Transport Layer Security (TLS). This method of key exchange can just as easily be applied to non-automated approaches (i.e. public-key encryption of email to share a symmetric key between two parties) to both key distribution and protection.

The cryptographic topics presented in this article are intended to fit a general need of keeping data confidential, but cryptography can be used for more than simply keeping prying eyes on the sidelines. In the next part of this series, I will cover cryptographic methods that help ensure the integrity and authenticate the originator (nonrepudiation) of data.

Part two: Data integrity and nonrepudiation in healthcare
Part three: Data in motion within healthcare
Part four: Data at rest within healthcare

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