Suppose sensitive information is sent over an insecure channel, but it is encrypted with a cipher such as AES. As of this writing AES is not broken and brute-forcing it would take more than millions of years (or at least very long). However, the encrypted data is eavesdropped on and stored.
Sometime in the future there will be computers that can brute-force AES or the AES-algorithm itself gets broken. Then this data of the past, that couldn't be decrypted without the key at the time, is now possible to decrypt.
- In what scenarios/applications is this an actual concern?
- Is it realistic that someone will store the encrypted data that long?
I imagine government communication over internet might be at risk for this kind of attack. Is there any policies regarding this?
I understand that if it takes too long until the data of the past can be decrypted, it might not be interesting anymore, i.e. the government communications. Is this the fact that is relied on regarding this concern?
(Note that AES is only used as an example. This question applies to all ciphers.)