From that point on, either Huang Yiyi didn’t come to work at all, or she would head straight for her cryptography room and lock herself in. Comrade Zha brought both lunch and dinner to her office. When she was at home, the light in her room was often burning until three or four in the morning, and sometimes it was on all night. I understood that she was using her exceptional courage, resourcefulness and intelligence to pit her wits against the dangerous and tricky Sivincy; that they were locked in hand-to-hand combat. In this duel to the death we would see sabre pitted against sword, and blood would flow like a river. It reminded me of something that Anderov often used to say: ‘Decrypting a cipher is like asking a man to give birth to a baby or a woman to grow a beard; under normal circumstances it is impossible.’ But we had to make the impossible possible, and there is only one way to do that: you have to shut yourself up and burn the midnight oil, racking your brains, busting your gut. If you don’t put yourself through that, if you don’t have that kind of mind, then cracking a cipher is just empty words.

During that time, I often went to stand outside Huang Yiyi’s building when her light was still on, silently praying for her, hoping that one day she really would give us a wonderful surprise, that all her hard work would eventually result in a brilliant success!

One evening she came to find me, looking completely exhausted. I quickly got her to sit down, and asked her what was up.

‘Nothing much. I’ve already checked more than twenty thousand of the seventy-four thousand, two hundred and eleven possibilities, and I haven’t found the slightest problem.’

I thought about that for a bit, and then I asked: ‘Why do you think the problem is at this end, rather than intrinsic to Sivincy’s cipher?’

‘I’m working on the theory that RECOVERY isn’t a particularly abstruse cipher, for all that it’s so difficult; so the error rate ought not to be particularly high. Besides, Sivincy wrote it. The Americans use computers now for this sort of thing, so it’s easy for them to check the capabilities of any given cipher. If they tested it and discovered it was fundamentally flawed, there’s no way they would have sold it to Taiwan.’

I was silent for a bit, then I said, ‘There’s a possibility that I don’t know if you have considered …’

‘What possibility?’

‘RECOVERY was tailored by Sivincy to the specifications of the US army, but now this particular dress is being worn by someone quite different. So the dress doesn’t fit any more and needs altering, right?’

‘It wouldn’t be difficult, and surely Sivincy would be happy to do it?’