The phrase "a covert message" is correct and usable in written English.
It can be used when referring to a message that is intended to be secret or hidden from others.
Example: "The spy sent a covert message to his handler, ensuring that no one else could decipher its meaning."
Alternatives: "a hidden message" or "a secret message."
Perhaps there was a covert message in all this that Washington was sending to Moscow.
The design of this project is to enable the sending of a covert message between 2 communication devices utilizing steganographic techniques.
Residents/fellows are also often exposed to a covert message that an academic career is "the best use of your talent" — an attitude that fails to recognize the optimal career path differs for each individual based on their talents, goals, and what activities they find most personally meaningful.
"Yeah, we got a little crazy," he might say, "Sorry if we kept you up". This way a clear, if covert, message has been transmitted.
A woman in entrepreneurship who steps out onto the world stage and has a social media presence is sending an overt and covert message (depending on style, content, and platform), maybe several, to all children and all women around the globe looking for guidance in thought, deed, conduct, and the current economic, social, and political climate they find themselves in.
I sent him a covert text message that went unanswered.
There is a covert feminist message, of sorts, in Lang's coded but perfectly discernible disgust for rape as an untold part of the old pioneer story.
What Ms. Jerrell may call a lack of political unity at Bonnaroo, I construe as a covert political message, one in which my generation aspires to bring peace and understanding through shared interests and goals.
Asked to comment on Mr. Kavanagh's column, Roy Greenslade, a Guardian media blogger who worked at The Sun when Mr. Murdoch prowled its newsroom during the Falklands war, endorsing sensational headlines, told BBC Radio 4: "it's an overt attack on the police, but the covert message is the most interesting one.
In order to build CTCs in such scenario, we propose a robust and undetectable CTC by packet rearrangement which can modulate covert message into number of packets between RTCP packets of VoLTE traffic.
To improve the robustness, we employ Gray code to encode the covert message for mitigating the packet loss and reordering.
