There is no specific law governing NDAs. When signing NDA, you promise not to disclose information explicitly listed in the NDA you are signing. Anything not explicitly listed in the NDA you can disclose, including the fact of signing the NDA or your relationship with the company.

PS: In fact, NDAs are usually mutual, so the company can't disclose your sensitive information too. This includes the amount of your pay, the cost of goods you intend to sell to the company, your API specifics, etc.