ISLAMABAD: A US-based news organization reported on Monday that a confidential document produced by Pakistan’s top spy agency in response to a query by the country’s foreign ministry “undermined” a high-profile case against former prime minister Imran Khan in which he is charged with leaking state secrets and tried under the Official Secrets Act.

A special court was set up in August to conduct Khan’s prison trial in what is popularly called the cipher case. The court held in-camera proceedings for several weeks before its hearings were declared illegal by the Islamabad High Court that instructed jail authorities to hold an open trial by providing access to the public and media organizations.

The case against Khan relates to an alleged diplomatic correspondence between Washington and Islamabad that the former prime minister says was proof that his ouster as PM in a parliamentary vote of no-confidence in April 2022 was part of a US conspiracy to remove him.

While Washington has denied Khan’s accusations, a complaint against the ex-premier’s decision to share its contents with the public says his mishandling compromised the integrity of the encrypted communication system used by the state’s security apparatus.

A report published in The Intercept quoted a document prepared by the Inter-Services Intelligence (ISI) as saying there had been no threat to the encryption system used by the Pakistani missions abroad.

“If plain text of an encrypted message (cryptogram) ... is leaked it has no effect on security of encryptor,” the document prepared on Aug. 23 said according to the US-based media organization. “Leakage of a plain text message does not compromise the algorithm.”

The Intercept, which published what it called was the text of the confidential diplomatic dispatch from Washington on Aug. 9, said that Pakistan’s foreign ministry sent a query to the ISI soon after its previous story, asking if the revelation of the plain text of a cipher compromised the integrity of the system’s encryption.

“The encryption algorithm is designed with an assumption that the plain/cipher text pairs and algorithms are known to the adversary, the security lies in the secrecy of the key,” the ISI allegedly wrote in its analysis. “Therefore leakage of a plain text message does not compromise the algorithm.”

The American online publication said the Pakistani intelligence agency’s assessment undermined a central plank in the high-profile prosecution of the former prime minister even as the special court continues its hearing in the cipher case.

The government is yet to respond to the story.

Khan is expected to be indicted in the ongoing prison trial against him as he faces the special court in the high-security Adiala Jail in Rawalpindi today.