Harvest now, decrypt later

Harvest now, decrypt later^[a] is a surveillance strategy that relies on the acquisition and long-term storage of currently unreadable encrypted data awaiting possible breakthroughs in decryption technology that would render it readable in the future – a hypothetical date referred to as Y2Q (a reference to Y2K) or Q-Day.^[1][2]

The most common concern is the prospect of developments in quantum computing which would allow current strong encryption algorithms to be broken at some time in the future, making it possible to decrypt any stored material that had been encrypted using those algorithms.^[3] However, the improvement in decryption technology need not be due to a quantum-cryptographic advance; any other form of attack capable of enabling decryption would be sufficient.

The existence of this strategy has led to concerns about the need to urgently deploy post-quantum cryptography, even though no practical quantum attacks yet exist, as some data stored now may still remain sensitive even decades into the future.^[1][4][5] As of 2022^[update], the U.S. federal government has proposed a roadmap for organizations to start migrating toward quantum-cryptography-resistant algorithms to mitigate these threats.^[5][6]On January 16, 2025, before the end of his term, Joe Biden issued Executive Order 14144, formally ordering governmental departments to start post-quantum cryptography transitions within a specified timeframe (ranging from 60 to 270 days). Some National Defense departments must complete this transition by January 2, 2030.^[7]

See also

• Communications interception (disambiguation)
• Indiscriminate monitoring
• Mass surveillance
• Perfect forward secrecy

Notes

1. also known as store now, decrypt later, steal now decrypt later or retrospective decryption