Here is an abstract of a report the German newsmagazine Focus published on March 11, 1996 (p. 16) - "Spaete Ermittlungen gegen Techno-Spione" (late/belated investigations against technology spies). I do not include a translation of the whole original text for copyright reasons. "Specialists of the German Federal Police Agency (BKA) have decrypted 44 floppy disks from the former [East German] Ministry for State Security" (MfS). A defector had handed over the floppies to the German Federal Intelligence Agency (BND) in spring 1990. The disks contain information on East German spies in former West Germany. Judicial inquiries against 29 suspects have started now. Apparently, the BKA got the data no sooner than 1994. This is because the BND did not tell law authorities about the floppy disks. German federal DAs learned about the data in late summer 1994 by chance. The article does not say whether the defector came over with the keys. - Probably not, otherwise prosecution should have started much earlier. It is likely that the extremely paranoic MfS used a cipher and a key length it believed to be sufficiently strong. According to Bruce Schneier's Applied Cryptography East Germany was quite aware of DES, it even produced DES chips. Another possibly strong algorithm used in the former Soviet block is GOST (a block cipher derived from the concepts of DES, also described by Schneier). Let us assume BKA specialists have broken the code using a combination of cryptoanalysis, brute force and good luck. They are policemen, not espionage professionals. Further, the BKA is much smaller than the FBI. Imagine what code breaking capabilities a well-funded, big intelligence agency should have then!