Data encryption
Encryption is a mathematical method of ensuring confidentiality by preventing information from being read by unauthorised parties.
Encryption is a mathematical method of ensuring confidentiality by preventing information from being read by unauthorised parties.
Information is "locked up" using a key, and cannot be read until it has been unlocked using the correct key. The key used to unlock the information does not have to be the same as the one used to lock it in the first place.
Symmetric encryption means that the same key is used to lock up and unlock the data. The sender and the recipient must send the key between them in a safe manner.
Asymmetric encryption is often also called public key encryption. Here a pair of keys is used, one private and one public key, which are mathematically related to each other. The public key can be made available to anyone, but the private key is known only to its owner. Even though there is a mathematical connection between the two keys, the one cannot be extrapolated from the other. The public key can be freely distributed. The validity and authenticity of the public key must, however, be verified and managed.
These two methods have differing requirements with regard to the length of the key.
The Norwegian Data Protection Authority has no legal competence with regard to encryption, and we can offer no guidance about how data should be encrypted. We refer to the guidelines issued by the National Security Authority (NSM) NSM Cryptographic Requirements 3.0 (pdf), and the recommendations they give in their security blog.
This is a question we are often asked. The most important factor is to employ extensively used and well-reputed algorithms and methods, as well as a sufficiently long key.
Three elements determine whether something is encrypted securely enough:
Cryptographic modules which generate, protect and use private keys or session keys should be evaluated against Common Criteria, FIPS 140-2 or similar standards.
If one of these elements is lacking or weak, the security system is not good enough. An updated overview of methods and key lengths can be found in the guide NSM Cryptographic Requirements 3.1 (pdf).
The undertaking (personal data controller) itself must carry out a risk assessment of the information in need of protection. A payslip is an example of a document which may contain sensitive personal data, and which must therefore be kept confidential.
A risk assessment must be made of the encryption passwords used and how these are managed. Passwords for decrypting a payslip should, for example, not be the date of birth of the recipient or any other easily identifiable characteristic.
The Norwegian Data Protection Authority can order the safeguarding of personal data and determine the criteria for acceptable risk associated with the processing of personal information.
We believe confidentiality is necessary when the information being transferred comprises:
Personal data which are to be transferred between two or more locations by means of digital communication. This may be:
HTTPS is the most common format. The highest version of TLS (Transport Layer Security) should be used, while SSL 3.0 (and lower) should be avoided, since they contain known weaknesses. TLS 1.0 is an improvement on SSL 3.0. TLS 1.2 also has its problems, but this depends on the algorithm and the client. TLS 1.3 exists in draft form, and will soon be released.
If, in connection with the transfer of individual files, it is not possible to encrypt the email or to be certain that the email transfer is encrypted, encryption mechanisms built into software systems may be used as an alternative. Examples include 7zip, PDF or more recent versions of MS Office. These support AES 256.
The encryption key must be secured and sent separately to the recipient. One option is to transmit the key as a text message or orally over the telephone. However, the risk that such an approach entails must be assessed, and we recommend it only be employed in individual cases when it is not possible to encrypt the actual communication. The problem is that it may not be possible to adequately control the destination points or protect against hacking.
Hard disk encryption primarily protects the confidentiality of data when the computer is turned off. Data is thereby secured if the computer is lost or stolen. Hard disk encryption has become a standard function in modern operating systems. Examples include FileVault for MacOS, BitLocker for Windows and hardware-based hard disk encryption from Intel.