The NSA likes to read other people’s mail. It’s a bad habit that would be frowned upon if it weren’t for the fact that the NSA is reading other people’s mail to try to thwart any national security threats. The problem is, the people who send this mail don’t just type their letters in Word and email them. They use cryptographic systems to scramble the mail so that people like the cryptanalysts at the NSA can’t read it. This doesn’t stop the NSA. In fact, it seems they relish the thought of figuring out how to break the code used to encrypt the mail they want to read.
During WWII, the warring factions routinely intercepted encrypted radio transmissions sent by the opposing side and tried to decrypt them. This was often done by hand, with computers — including Colossus — used to decrypt messages that were already from broken cypher systems. However, as the digital age dawned, the NSA knew that it would be impossible to decrypt by hand the number of messages being sent through etherspace.
In 1962, a heavily modified IBM 7030 Stretch computer was delivered to NSA Headquarters. Attached to it was a one-of-a-kind system called Harvest (officially given the designator IBM 7950). The Harvest system increased the performance of the 7030 as well as its storage capabilities. It included a stream coprocessor and a system called Tractor that could retrieve proprietary data tapes from a library, mount the tape in a drive, and return it to the library. The system was coordinated such that Harvest could read data streams from two tapes while simultaneously writing to a third.
The main purposes of Harvest were to break cryptology systems, perform mass decryptions, and search either encrypted or deciphered text for repeating patterns or key words. These functions basically performed the grunt work of the NSA. Rather than having rooms full of codebreakers, they had a big room full of a computer. It could scan over 7,000,000 scanned messages in four hours searching for 7,000 key words. It could also decrypt a stream of messages in minutes. Breaking codes depended on the system and its strength.
As a testament to its power, it remained in use at the NSA until 1976. The only reason why it was decommissioned is because some of the parts in the Tractor system had become worn beyond repair and IBM declined to bring the system up to modern standards.
[Image Credit: NSA]