This section only punishes people who actually fight against the government.

It punishes people who merely hide knowledge of a war plan, if their concealment helps that plan, even if they never fight themselves.

You must intend to help the war plan to be guilty.

The law also covers cases where a person merely knows their concealment is 'likely' to help the plan, even without direct intention.

Indian Penal Code, 1860

Section 123

repealed

Concealing with intent to facilitate design to wage war

Whoever, by any act, or by any illegal omission, conceals the existence of a design to wage war against the Government of India, intending by such concealment to facilitate, or knowing it to be likely that such concealment will facilitate, the waging of such war, shall be punished with imprisonment of either description for a term which may extend to ten years, and shall also be liable to fine.§

Why this exists

This section is part of Chapter VI of the IPC dealing with offences against the State, drafted by the British colonial administration partly in response to fears of rebellion and organized uprisings against the Crown's government in India. The idea was to punish not just those who wage war, but also those who know about such a plan and deliberately or knowingly help it succeed by staying silent or covering it up, since silence can be as dangerous as active participation. After independence, 'Government of India' was read to mean the constitutionally established government of the Republic.

Common misconceptions

Myth: This section only punishes people who actually fight against the government.
Fact: It punishes people who merely hide knowledge of a war plan, if their concealment helps that plan, even if they never fight themselves.
Myth: You must intend to help the war plan to be guilty.
Fact: The law also covers cases where a person merely knows their concealment is 'likely' to help the plan, even without direct intention.