Encryption
Encryption is the process of converting readable information into an unreadable format so that only authorized parties can recover the original data.
“The process of encoding information so that only authorized parties can retrieve the original information, usually by means of a specific decryption key or process.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Encryption?
Encryption protects data confidentiality during storage and transmission using cryptographic algorithms and secure keys.
Data protection: Prevents unauthorized access to sensitive information.
Key management: Encryption strength depends on protecting cryptographic keys.
Testing focus: Verify encrypted data remains secure while authorized users retain access.
Real World Example
A healthcare app encrypts patient data in transit with TLS and at rest in its production database with AES.
A tester confirms the padlock icon and a valid HTTPS certificate and is ready to sign off, until someone opens a routine database backup file and finds patient names and diagnoses sitting in plain text.
The tester broadens the check beyond the browser connection: examining backup exports, log files, and error messages for unmasked personal data, confirming the storage layer uses a current algorithm rather than a deprecated cipher, and verifying that a user with the correct key can retrieve the original data while anyone without it cannot.
The gap is closed before the next backup cycle runs. Encryption that only protects data in transit while leaving backups and logs untouched gives a false sense of security — the full data lifecycle has to be in scope.
Practice Questions
Question 1
A tester opens a routine database backup file and can read customer social security numbers directly in plain text, even though all traffic to the application is sent over HTTPS. What gap has the tester found?
Question 2
Which test BEST verifies that an encryption implementation is working correctly, beyond simply confirming that stored data looks unreadable?
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