WikiLeaks did not identify the source of the documents, which it called Vault 7, but said they had been “circulated among former U.S. government hackers and contractors in an unauthorized manner, one of whom has provided WikiLeaks with portions of the archive.”

WikiLeaks said the source, in a statement, set out policy questions that “urgently need to be debated in public, including whether the C.I.A.’s hacking capabilities exceed its mandated powers and the problem of public oversight of the agency.” The source, the group said, “wishes to initiate a public debate about the security, creation, use, proliferation and democratic control of cyberweapons.”

But James Lewis, an expert on cybersecurity at the Center for Strategic and International Studies in Washington, raised another possibility: that a foreign state, most likely Russia, stole the documents by hacking or other means and delivered them to WikiLeaks, which may not know how they were obtained. Mr. Lewis noted that, according to American intelligence agencies, Russia hacked Democratic targets during the presidential campaign and gave thousands of emails to WikiLeaks for publication.

“I think a foreign power is much more likely the source of these documents than a conscience-stricken C.I.A. whistle-blower,” Mr. Lewis said.

At a time of increasing concern about the privacy of calls and messages, the revelations did not suggest that the C.I.A. can actually break the encryption used by popular messaging apps. Instead, by penetrating the user’s phone, the agency can make the encryption irrelevant by intercepting messages and calls before their content is encrypted, or, on the other end, after messages are decrypted.

WikiLeaks, which has sometimes been accused of recklessly leaking information that could do harm, said it had redacted names and other identifying information from the collection. It said it was not releasing the computer code for actual, usable weapons “until a consensus emerges on the technical and political nature of the C.I.A.’s program and how such ‘weapons’ should be analyzed, disarmed and published.”

The codes names used for projects revealed in the WikiLeaks documents appear to reflect the likely demographic of the cyberexperts employed by the C.I.A. — that is, young and male. There are numerous references to “Harry Potter,” Pokémon and Adderall, the drug used to treat hyperactivity.