Crypto AG was selling knowingly-weak products for decades in conjunction with US and UK agencies. Post-war they commercially sold an Enigma variant, C-52, with

Crypto AG was selling knowingly-weak products for decades in conjunction with US and UK agencies. Post-war they commercially sold an Enigma variant, C-52, with documented vulnerabilities to nations that were considered to be 'of interest'. Cracking their encrypted messages was trivial. Meanwhile, trusted nations were allowed to buy the otherwise secret and secure CX-52. Rumours of this arrangement surfaced in the 1970s and again in the 1990s. Why anyone still bought from them is a mystery.