PURPLE

PURPLE is the cipher created by Liseiwicz and deciphered by Rong Jinzhen, a breakthrough that makes it both a strategic weapon and a defining test of Jinzhen’s mind. Its history connects a commission for the state of Israel to a dream-born solution, a personal rivalry, and the later effort to make BLACK resist the very talent that had defeated PURPLE.

Creation and Intended Use

In the spring of 1946, a former fellow student from Cambridge University approached Liseiwicz, who was then living in China, on behalf of a man preparing to take an important government post for Israel. The visitor took him to a church on Gulou Street and asked him, in the name of Jewish compatriots, to devise a cipher for the state. Liseiwicz spent more than a year constructing the first version. Though its sponsors were pleased, he came to believe that it was flawed and had been made too hastily.

Rather than accept that first design, Liseiwicz undertook a replacement. The work drew him further into cryptography, and after nearly three years he completed the cipher he considered satisfactory: PURPLE. The Israeli authorities tested it, but found it too difficult to use. Its complexity therefore had a double edge: the property that made it formidable against a cryptanalyst also made it impractical for its intended users.

The account conveys that difficulty through the reaction of the famous cryptanalyst Klaus Johannes. On seeing a telegram encrypted with PURPLE, he reportedly estimated that even the remaining years of his life would not give him enough examples to decipher it. The comment presents PURPLE not merely as a complicated system but as a cipher whose challenge seemed to exceed a single expert’s working lifetime.

The Breakthrough and Its Dream Frame

Rong Jinzhen’s solution arrives in a dream of Dmitri Ivanovich Mendeleev, who is himself associated in the account with receiving the idea for the periodic table in a dream. The narrative says that the secret to cracking PURPLE came to Jinzhen in this dream, ten years before the moment being recounted. The parallel gives the discovery an almost uncanny form without removing it from the history of cryptographic work: a solution to a designed system appears in sleep, as a sudden arrival of knowledge.

The narration emphasizes the tension between the unbelievable and the real. It says that events can seem unreal precisely because they are too real, then places Jinzhen’s dream-born breakthrough within that paradox. PURPLE’s decipherment becomes an extraordinary event that, in the telling, is surpassed by what follows. The dream is therefore both the frame for a decisive intellectual achievement and a warning that the cipher’s story will not end with its solution.

Rivalry, Knowledge, and BLACK

Liseiwicz believed that Jinzhen would sooner or later decipher PURPLE and made efforts to impede his progress. That resistance arose from an unusually precise understanding of Jinzhen: Liseiwicz admired him above all others and regarded him as possessing an extraordinary concentration of Western knowledge and wisdom. Their conflict is not simply between a cipher maker and an unknown opponent. The creator knows the mind that may undo his work, and that knowledge makes the prospect of defeat personal as well as technical.

PURPLE also shapes the account of BLACK. After Liseiwicz reached X Country, he was taken into work on BLACK, but his role was that of an observer rather than a direct researcher. He was meant to explain what distinguished PURPLE and guide the researchers away from making a simple replica. The account compares his contribution to navigation: he could indicate that BLACK should turn in a different direction, while leaving the practical design to the researchers.

BLACK’s underlying structure had already been completed by the time its makers learned that Jinzhen had cracked PURPLE. The two ciphers were then of roughly comparable difficulty. Once Liseiwicz knew of the breakthrough, however, he insisted that BLACK be revised. Because he knew Jinzhen’s appetite for problems that seemed impenetrable, he expected that the same talent might be brought to bear on BLACK. The resulting cipher was made deliberately uneven: some parts were extraordinarily difficult and others very easy. Its strangeness was a countermeasure, an attempt to unsettle Jinzhen’s expectations rather than simply to increase complexity.

Cryptographic Limits and Consequences

The book describes an unwritten, nearly ironclad principle: one person should either create ciphers or crack them. Similar ciphers, it argues, would cancel their distinctiveness and become worthless. Jinzhen’s exceptional ability to both create and destroy ciphers places him in conflict with that boundary. In the narrator’s interpretation, his mind already belonged to PURPLE; taking responsibility for deciphering BLACK risked fragmenting it further. The danger was not presented as a routine consequence of difficult work, but as a threat to the coherence of the very intelligence that made his achievement possible.

Yet Unit 701 entrusted BLACK to Jinzhen because it believed in his capacity to rebuild his mind. Its members regarded ordinary rules as insufficient for him: his talent had repeatedly made what seemed impossible real. The assignment thus followed from the success of PURPLE while also reversing its meaning. Cracking PURPLE had made the organization feel invulnerable and forced its adversary to become more cautious; it also gave Liseiwicz reason to reshape BLACK around the possibility that Jinzhen might crack that, too. PURPLE’s triumph becomes the source of both confidence and danger, binding technical accomplishment to the personal cost of asking the same exceptional mind to cross its limits again.