Encryption
Encryption is the process of converting readable data (plaintext) into an unreadable form (ciphertext) using a cryptographic algorithm and a key, so that only those holding the corresponding key can recover the original. Symmetric encryption (for example AES-256) uses one key for both operations and is efficient for bulk data; asymmetric or public-key encryption (RSA, elliptic-curve cryptography) uses a key pair and underpins secure key exchange, digital signatures and protocols such as TLS. Encryption is applied at rest (disks, databases, backups), in transit (TLS for web and API traffic, VPNs, secure file transfer) and increasingly in use, through confidential computing and homomorphic encryption.
The GDPR names encryption expressly among the measures that may be appropriate to ensure security of processing (Art. 32(1)(a)) and as an example of data protection by design. Its legal effects are significant: a personal data breach involving properly encrypted data whose key was not compromised may be exempt from communication to data subjects under Art. 34(3)(a), and encryption with keys held exclusively in the EEA is one of the supplementary measures the EDPB accepts (Recommendations 01/2020) to make transfers to third countries lawful where the importer only stores or transports data. Encrypted data remains personal data, however, since decryption is possible; it is not anonymised.
For life sciences organisations, encryption is a baseline expectation of supervisory authorities, HDS-type health hosting certifications, NIS2, ISO 27001 and the cybersecurity requirements of the MDR. The decisive questions in DPIAs and vendor assessments are less whether encryption is used than how: which algorithms and key lengths, whether the cloud provider or the customer controls the keys (customer-managed or hold-your-own-key models), how keys are stored, rotated and revoked, whether end-to-end encryption protects data from the vendor itself, and whether laptops and removable media used by monitors and site staff are encrypted. Encryption of pseudonymisation key tables and of unblinding information deserves particular attention in clinical trials.
