Henryk Zygalski (; 15 July 1908, Poznań – 30 August 1978, Liss ) was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.

This information was essential for the production of a full set Zygalski sheets which allowed resumption of large-scale decryption in January 1940.

One theory, most likely apocryphal, originated with Polish engineer and army officer Tadeusz Lisicki ( who knew Rejewski and his colleague Henryk Zygalski in wartime Britain but was never associated with the Cipher Bureau ).

The method of Zygalski sheets was a cryptologic technique used by the Polish Cipher Bureau before and during World War II, and during the war also by British cryptologists at Bletchley Park, to decrypt messages enciphered on German Enigma machines.

The Zygalski-sheet apparatus takes its name from Polish Cipher Bureau mathematician – cryptologist Henryk Zygalski, who invented it about October 1938.

In September 1932, Maksymilian Ciężki hired three young graduates of the Poznań course to be Bureau staff members: Marian Rejewski, Jerzy Różycki and Henryk Zygalski.

After Rejewski had reconstructed the German military Enigma machine in December 1932, Różycki and Zygalski likewise worked at ongoing development of methods and equipment to exploit Enigma decryption as a source of intelligence.

The students included future Cipher Bureau civilian employees Marian Rejewski, Jerzy Różycki and Henryk Zygalski.

He worked there together with fellow Poznań University mathematics alumni and Cipher Bureau cryptology-course graduates Marian Rejewski and Henryk Zygalski.

They undertook to give each country a Polish-reconstructed Enigma, along with details of their equipment, including Zygalski sheets and Rejewski's cryptologic bomb.

Marian Rejewski and Henryk Zygalski hiked over the Pyrenees with a guide ( who robbed them at gunpoint ) to the Spanish border, where they were arrested on January 30, 1943.

* Polish cryptologists Marian Rejewski, Henryk Zygalski and Jerzy Różycki broke the Enigma machine code.

* Kozaczuk, Władysław, Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War II, edited and translated by Christopher Kasparek, Frederick, MD, 1984: a history of cryptological efforts against Enigma, concentrating on the contributions of Polish mathematicians Marian Rejewski, Jerzy Różycki and Henryk Zygalski ; of particular interest to specialists will be several technical appendices by Rejewski.

They then managed, by a circuitous land – sea – air route, to join the Polish Armed Forces in Britain, Rejewski and Zygalski were inducted into the Polish Army as privates ( they would eventually be promoted to lieutenant ) and put to work breaking German SS and SD hand ciphers at a Polish signals facility in Boxmoor.

In July 1941, Polish cryptologists Marian Rejewski and Henryk Zygalski were asked to test the security of the Polish Lacida ( or LCD ) rotor cipher machine.

* Zygalski sheets, also known as " perforated sheets " ( invented in 1938 by Henryk Zygalski ), were one of a number of devices created by the Polish Cipher Bureau to facilitate the breaking of German Enigma ciphers.

* Zygalski sheets-a system used to decrypt messages enciphered on German Enigma machines.

In late 1938, in response to growing complexities in German encryption procedures, Zygalski designed the " perforated sheets ," also known as " Zygalski sheets ," a manual device for finding Enigma settings.

Both the Zygalski-sheet method and each bomba worked for only a single scrambler rotor order, so six sets of Zygalski sheets and six bomby were produced.

They did not have the resources to produce 54 more bomby or 54 sets of Zygalski sheets.

In return, the British pledged to prepare two full sets of Zygalski sheets for all 60 possible wheel orders.

He had brought the Poles a full set of Zygalski sheets that had been produced at Bletchley Park by John Jeffreys using Polish-supplied information.

The Germans, just before opening their 10 May 1940 offensive in the west that would trample Belgium, Luxembourg and the Netherlands in order to reach the borders of France, once again changed their procedure for enciphering message keys, rendering the Zygalski sheets " completely useless " and temporarily defeating the joint British-Polish cryptologic attacks on Enigma.

Neither Rejewski nor Zygalski would work again as cryptologists.

Zygalski would remain in England until his death in August 1978.

Despite their travails, Rejewski and Zygalski had fared better than some of their colleagues.

Among the University's most famous graduates are the mathematicians who broke the Enigma machine: Marian Rejewski, Henryk Zygalski, and Jerzy Różycki.

* Zygalski sheets: device, invented about October 1938 by Henryk Zygalski and called " perforated sheets " by the Poles, that made possible the recovery of the Enigma's entire cipher key.

They were dirty, their clothes were torn, and the girl was so exhausted that she fell when she was still twenty feet from the front door.

The silence oppressed him, made him bend low over the horse's neck as if to hide from a wind that had begun to blow far away and was twisting slowly through the darkness in its slow search.

Cabot turned back to the men and he was drunk with the thing they would do, wild to break from the cloying warmth of the saloon into the cold of the ebbing night.

The Gap looming before him -- the place where had confronted Jack English on that day so many years ago -- was his exit from all that had meaning to him.

He was too old -- when he passed up and through the corridor of pines that lined the trail he could see ahead, he was passing from life.

He might tell her how sorry a spectacle she was making of herself, pretending to be blind to the way Julia Fortune had taken Dean's affections from her.

A bullet tore the earth from beneath his foot when he was a stride or two from safety.

It was pitiful to see the thin ranks of warriors, old and young, wheeling and twisting their ponies frantically from side to side only to be tumbled bleeding from their saddles by the relentless slam, slam of the cruelly efficient Hawkinses.

She was carrying a quirt, and she started to raise it, then let it fall again and dangle from her wrist.

It was obvious that he wished himself different from the sort of person he thought he was.

Now, here was something of obvious importance to me, yet when I reached for the tickets he snatched them away from my hand.

It was, I felt, possible that they were men who, having received no tickets for that day, had remained in the hall, to sleep perhaps, in the corners farthest removed from the counter with its overhead light.

Though only a relatively short walk separated it from my own part of town, its character was wholly foreign to me.

The river was only a few blocks away but an unbroken line of piers prevented me from seeing it.

It was to him that Barton had sent Carl Dill on Dill's release from the prison.

Hague, like all who worked near the pits, was partly deafened from the constant assault against his eardrums.

But she was caught in it, and she faced the terrible possibility that, if it were a dream, it was one from which she might never awaken.

He had to depend on himself, since he was invariably miles and hours away from others.

An inquest was held, and after a good deal of testimony about the anonymous notes, the county coroner estimated that the shooting had been done from a distance of 300 yards.