olemus
ajas muutuva tähendusega suhteline nimetus, väljendab eelkõige (hetkel) turvalist võtme pikkust, kuid arvutite jõudluse kasv nõuab võtmete pidevat pikenemist

PCMag Encyclopedia:
An encryption method that uses a very large number as its cryptographic key. The larger the key, the longer it takes to unlawfully break the code. Today, 256 bits is considered strong encryption. As computers become faster, the length of the key must be increased.

ülevaateid
https://www.lawinsider.com/dictionary/strong-encryption

https://en.wikipedia.org/wiki/Strong_cryptography

https://en.wikipedia.org/wiki/Export_of_cryptography_from_the_United_States