The phrase "a group of keys" is correct and usable in written English.
It can be used when referring to multiple keys that are together, such as on a keyring or in a set.
Example: "I found a group of keys on the kitchen counter that must belong to someone in the house."
Alternatives: "a set of keys" or "a collection of keys."
A popular approach is to carefully distribute a group of keys to several, carefully designed subsets of the receivers beforehand, and later use a precise subset of keys so that only intended users have those keys, thus decrypt the content.
When a group of keys is pressed simultaneously (like a chord on a piano), computer software translates them, and up pops the proper name, word or number — most of the time.
Mohammed's first converts are his family circle and a group of key friends.
The setting points for a group of key variables were considered as reference values.
Many miles south, in the heart of Oxfordshire, a group of key stage 3 pupils have been up all night on rowing machines.
-- Escalating the GOP civil war: A group of key Trump loyalists, led by Steve Bannon, is seeking to build out their own constellation of outside groups for the midterms.
A group of key Linux software developers and major computer manufacturers are planning to announce on Tuesday at a Silicon Valley computer conference the first effort to compete directly with Microsoft's Office suite of applications for the personal computer.
The next round of races in Nevada and South Carolina will matter more than in other years, and the contest may not be settled until after a group of key states including Florida, Missouri and Ohio hold their primaries on 15 March.
When Cannon asked a group of key aides who among them had authority to sign for Reagan, there was a long, uncomfortable silence, after which one answered, "Well everybody, and nobody".
He has a group of key interpreters — Ann Friedman called them his "wise men" — one of whom is Michael Mandelbaum, the foreign-policy expert at Johns Hopkins University, whose name has appeared in fifty columns, and whose guidance is in many others.
This week, a group of key senators wrote to the leaders of the House and Senate armed services committees, urging them to include a repatriation provision in the defense authorization bill that's in conference committee.
