Decoding the IRA (9 page)

The IRA is known to have had experience with cipher and code before 1925. This originated with its forerunner, the Irish Republican Brotherhood (IRB), which together with its sister organisation in America, Clan na Gael, revelled in cloak and dagger work. In 1893 when Joseph McGarrity was inducted into Clan na Gael in Philadelphia he swore that he would ‘defend a Republican form of government in Jsfmboe'.
‘Jsfmboe'
is a simple form of substitution cipher, which can be deciphered by replacing each letter with the letter that comes before it in the alphabet – giving the word ‘Ireland'.
⁹
During the Anglo-Irish War the IRA in Cork and Kerry was familiar with the use of cipher by the police.
¹⁰
And in 1920, after the IRA in Cork city obtained the keywords for the police's ciphers, it decrypted a police despatch, leading to the capture of a British spy by the name of Quinlisk, who was shot and his body dumped in a ditch.

By 1926, the IRA had trained officers throughout Ireland and Britain, as well as key agents abroad in the use of cipher. IRA units were assigned a secret keyword which they used to both encrypt messages they sent and to decrypt those they received. So as to maintain security, the director of intelligence in Dublin could change the keyword as needed. Examples of keywords include: ‘teapot' for GHQ, ‘dry-the-teapot' for the IRA unit in Manchester, and the unfortunate ‘insignificant' for the Armagh battalion.
¹¹
On the other hand, the IRA's agents in America used keywords selected from a copy of the novel
The Scarlet Letter
they carried with them, while another copy was kept back at GHQ (see
Chapter 1
).

Considering that most of the IRA's officers lacked formal military training and hadn't gone beyond a secondary education, their ability to
develop a communications system based on cipher was quite an achievement. However, by conventional military standards of the time these ciphers were relatively unsophisticated, and the British government's cipher division undoubtedly would have been able to break them. In Ireland the intelligence section of the Free State army had some experience of cryptanalysis, though I'm uncertain as to whether it had the capability to decrypt these messages without having the keywords.
¹²
On several occasions the Free State authorities allowed the Irish newspapers to print the contents of seized despatches to discredit the IRA. But I've no evidence to suggest that the Free State government ever learned the contents of these encrypted documents; if they had, there would have been a major propaganda value in publicising them. Alternatively, it may be argued, that if the gardaí were intercepting and decrypting IRA communications, it was in their interest to hide this from the IRA.

The use of cipher alone did not make IRA despatches secure, and the sender was expected to adhere to a whole set of precautions. Twomey reminded Connie Neenan in New York to ‘be very careful even in sending cipher messages, things which you may assume I will know, can be referred to in an obscure way'.
¹³
There are very few direct references to Moscow in cipher; rather it was referred to as
‘Stephen's headquarters'
, etc., ‘Stephen' being a Soviet intelligence officer.
¹⁴

However, there are many instances in these papers where the IRA operatives made serious security blunders. The OC in Britain wrote to Twomey that he was concerned that the IRA's agents in America were careless with their communications regarding the Soviet connection:
‘Is there [too] much writing regarding this affair? I am sure you have no idea, what kind of precautions, are being taken by your people at the US end'
.
¹⁵
Twomey replied:
‘In my last communication to America, I strongly urged the necessity for secrecy and caution, and to avoid any unnecessary reference to the matter on paper'
.
¹⁶

In January 1925 the then director of intelligence, Michael Carolan, made a major mistake when he issued a memo listing the keywords for several units in plain text rather than in cipher.
¹⁷
Had the Special Branch seized this document they could have gone on to decrypt subsequent despatches they intercepted from these units.

In particular the IRA encrypted the names and addresses of members and supporters. And Moss Twomey wrote: ‘never mention an address, even when coming by hand [i.e. carried by a courier] except in cipher'.
¹⁸
In October 1926 Twomey sent a message in cipher to the OC of the Scotland battalion ordering him to send
‘gelignite and detonators … to Mrs Coady, 5 Glegg Street, off Great Howard Street, Liverpool'
.
¹⁹
However, two weeks later the adjutant of the Liverpool unit tripped up by listing her name and address in plain text in a despatch sent to GHQ.
²⁰

Another security feature was that all documents had a unique identifier. For instance, letters from the OC in Britain carried the letters ‘HS' followed by the number of the despatch in sequence. Thus, if Twomey received HS 10 and the next letter from Britain was HS 12, he'd know that a despatch was either delayed or possibly captured. This would allow the IRA to consider that the contents and the method of transport may have been compromised. Frank Kerlin explained this in a letter, ‘Dw 99 – Despatch 1', which he had smuggled into Mountjoy prison for Donal O'Donoghue:
‘The despatch number on this despatch will be used in sequence in all despatches sent to you, to enable you to know if all despatches sent are received.'
Kerlin told him to acknowledge this despatch by way of a cryptic question to one of his visitors:
‘When you receive this despatch, ask Mary Mc or Kathleen how their sister Madge is.'
²¹
More commonly the recipient was expected to acknowledge each letter in writing. And O'Donoghue wrote to Kerlin:
‘[I] wrote last week [and] received no reply. Always acknowledge [my letters] otherwise [I'm] uneasy.'
²²

Like any other organisation, the IRA needed ready access to its files to effectively manage and administer its affairs. This posed a problem when documents were encrypted. The letters to America often contained long policy discussions and for these documents a short summary of the document in plain text or précis was kept. The précis was usually cryptic and omitted sensitive information such as names and addresses, but at the same time enabled officers at GHQ to refresh their memory of a despatch without having to decode the original again.

It's usually extremely difficult to understand the meaning of a despatch by reading the précis unless one is already familiar with the full decryption. As an example, in March 1927 Twomey wrote to an IRA agent,
‘Mr Jones', in New York:
‘Try and get formulae for these tear gases and mustard gases and [an] idea of [the] plant [or facility] necessary [for production].'
The précis for this sentence merely states: ‘Try and get formulae. Plant'.
²³
Twomey himself removed the précis on a highly sensitive document that listed American military intelligence provided to the Soviets in America. The document (dated 10 May 1927) is in cipher, and written at the top of the page in handwriting is ‘précis taken by C/S [chief of staff] 6/7/27'.
²⁴
The IRA also frequently backdated letters to potentially mislead an unauthorised reader. Usually only the year was changed, so that 1926 was written as 1923 and 1927 as 1924.
²⁵

Telegrams (or cable) were another useful method of communication. As these messages needed to be brief, they could only contain a limited amount of information. Additionally, since they were sent by the post office they were in a sense always intercepted by the authorities and therefore had to be cryptic. Usually they contained a prearranged sentence that signified the sender's assent or disagreement to a proposal. For instance, Twomey asked the OC in Britain to wire a Mrs Plunkett
‘examination papers correct'
if he had cash for him, and
‘examination papers inaccurate'
if he didn't. The telegram was to be signed
‘Armstrong'
.
²⁶
On another occasion Twomey told ‘Mr Jones' to demand $25,000 from ‘Stephen' (the Soviet intelligence agent) in return for American military secrets which the IRA was obtaining. Twomey added:
‘If ‘Stephen' agrees to conditions cable as follows: ‘quotation accepted', if partially agreed to: ‘can you quote lower', if he rejects and breaks [the connection with us]: ‘quotation unacceptable' … You may add any other message which may be intelligible.'
²⁷
Occasionally telegrams were sent in cipher, though these would have appeared suspicious to any vigilant employee of the post office. In 1926 Seán MacBride complained that he was unable to decipher two telegrams sent to him in Paris and that ‘it appears to me as if they were interfered with in transmission'.
²⁸
Given MacBride's penchant for espionage and his evident abilities, his suspicion was likely warranted.

The IRA used invisible ink, though it's difficult to know how frequently. Naturally one can't keep on file a collection of documents in invisible ink! In April 1927 ‘Mr Jones' obtained secret ink, possibly from ‘Stephen', and passed it on to Moss Twomey by way of Art O'Connor:
‘Gave Art invisible
ink. You can use it to a great extent safely. I also showed him how to send communications on picture postcards.'
²⁹
Twomey replied: ‘I made a few experiments here and they are quite satisfactory'.
³⁰
However, at least for the period 1926/1927, cipher was the primary technique used by the IRA to keep its correspondence secret.

In the latter half of 1926 three senior IRA leaders, Mick Price, Donal O'Donoghue and George Gilmore were imprisoned in Mountjoy prison. Frank Kerlin and GHQ, however, managed to keep in contact with all three by a variety of methods. The driver of a truck who brought coal to the prison delivered encrypted messages
‘bound in silk paper stuck to the outside of [the] despatch and sealed'
to the prisoners by placing them on the ground at a pre-arranged site. The IRA also likely availed of the services of corrupt warders. The prisoners used any paper they had to send messages out, including toilet paper, which was extremely thin and easy to conceal.
³¹
This is reminiscent of the Provisional IRA's use in the 1970s of cigarette paper (along with toilet paper) for messages smuggled out of Long Kesh prison. However, to provide Gilmore and his comrades with more writing paper, Kerlin told him:
‘I am getting white paper sent around parcels in future.'
³²

Gilmore appears to have suggested to Kerlin to send written notes inside ‘sugar sticks' and barm brack. Presumably by ‘sugar sticks' he meant the hard sugar ‘rock', which to this day is sold in souvenir shops and contains little hidden notes with messages such as ‘A greeting from Ireland'. While traditionally messages or predictions are hidden in barm brack at Halloween, Kerlin replied to Gilmore:
‘[I] will try your suggestion re sugar sticks as soon as I can get some made, but I am sending barm brack or cake at once.'
³³

Kerlin also told Gilmore and Price to soak certain letters in water to make a ‘watermark' visible. It's unclear what exactly he meant by ‘watermark'. He doesn't appear to have meant a form of invisible ink, as water usually has to be acidic, alkaline or coloured to reveal an invisible ink. It's also unlikely to be a reference to a true watermark which is produced with a wire during the manufacturing process of the paper itself. However, if one scratches a message onto paper with a sharp instrument and then soaks the paper in water the message becomes visible and this rather
crude method may have been Kerlin's technique.
³⁴
He wrote to Gilmore:
‘Wet in water any letters from your mother, in which there is any reference to your cousin Mary and look for [the] watermark'
and told Price to do the same with
‘any letter from your brother Charlie, in which there is [a] reference to Peg'
.
³⁵

Figure 14. Letter from Frank Kerlin, the director of intelligence, to George Gilmore, in Mountjoy prison. It was smuggled in by a man delivering coal to the prison.

[The] bearer of this despatch is prepared to do anything required. He goes in with coal lorries and says h[e] saw you in [the] hospital grounds. Three or four other lorries go in with him and also some horses and carts. Can you suggest a way by which, this could b[e] availed of? Leave reply to this despatch at the exact place on [the] ground, where [the] bearer is leaving this note for you, and pin it to a piece of the blue hospital cloth to enable [the] bearer to find it easily. When writing [g]ive full details of your location and hours of exercise, also any suggestions re. [an] escape [plan].