Retired Navy communications expert Jerry Alfred Whitworth had access to information about codes throughout the period he is accused of spying for the Soviet Union, a Navy witness testified today.

As a radioman with an increasingly high rank aboard ships and at naval communications centers on shore, Whitworth "would necessarily have had access" to cryptographic information, Master Chief Petty Officer Thomas F. Bennett told the jury of seven women and five men.

For example, he said, as a chief petty officer aboard the aircraft carrier USS Constellation from 1976 to 1978, Whitworth would have been "responsible for supervising, protecting and destroying cryptographic material."

Bennett said an aircraft carrier normally carries a supply of cryptographic "key cards" and "keylists" -- the daily-changing codes that are used to transmit Navy messages -- to cover at least three months.

Whitworth is alleged to have delivered classified information to admitted spy John Anthony Walker Jr. seven times during the period he served aboard the Constellation. After many of those meetings, Walker has admitted, he then met with his Soviet contact.

As the custodian of communications material security -- the person who controls the vault where the code material is stored -- aboard the supply ship USS Niagara Falls from 1978 to 1979, Whitworth would have had access to even more cryptographic material, Bennett said. He said a supply ship carries codes for other ships as well because it is "a floating grocery store."

During the period Whitworth was allegedly passing the coding information -- from 1974 until his retirement in October 1983 with the rank of senior chief radioman -- his job performance was excellent, Bennett said. Whitworth, he said, was "not quite 4.0, but doggone close to it." A 4.0 sailor, he said, "that's the guy that walks on water without getting his shoes wet."

Earlier today, a former top-ranking official of the National Security Agency testified that the diagrams that would permit an adversary to recreate a coding machine are contained in a Navy repair manual classified "confidential," the lowest category of classified information.

Whitworth is charged with passing the Soviet Union manuals containing the "logic diagrams" for coding machines. "If this logic is the guts of the machine . . . why is a diagram that makes it possible to reproduce that material widely disseminated" and only classified "confidential?" asked defense lawyer James Larson.

Earl D. Clark Jr., who retired last month as NSA deputy chief of communications security, replied that security officials permitted that low level of classification because "it is essential from a practical standpoint to put this out" so that the machine may be repaired.

Clark also acknowledged that the coding machine prosecutors wheeled into court yesterday, the KW-7, probably had been "compromised" when North Korea seized the USS Pueblo in 1968. However, Clark said, the machine, which is still in use, has been modified since then.

Whitworth, 46, is the last of four Navy men charged in the Walker spy ring to face trial. He is charged with receiving $332,000 for secrets he allegedly funneled to the Soviets through John Walker.