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Are one time pads still secure when using randomly generated words as the pad?

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1

$begingroup$

I was researching the US military's DIANA one-time-pad system and came across the following quote purportedly from a former US Special Forces soldier:

Special Forces were one of (if not the only) units in Vietnam to
utilize Morse code on a regular basis. We used a method of encryption
called the Diana Cryptosystem.

The basis of these one-time pads, is that there were only two matching
pads in existence, and they would only be used one time. They were
booklets that contained randomly generated groups of 5-letter words,
30 words to a page. The person sending a message would first write the
letters to the message, over these random groups of words. Included in
the front of each one-time pad was a one-page encryption table. If I
wanted to send the letter P, and the letter under the P was an A, then
I would send a K. The person listening on the frequency at the other
end, would have the other matching pad. They would write the letter
they received (a K) over the letter in their one-time pad (an A), and
decipher it based on the table, yielding the original letter P.

(source: https://dodona.ugent.be/en/exercises/2088793301/)

Wouldn't the use of random words as reported by the soldier rather than groups of random letters diminish the security of the system, as the letters in 5 letter English words are not randomly positioned?

I am aware that "secure" in this context--messages between Special Forces camps during wartime--may just mean keeping messages secure long enough that they are no longer useful even if broken.

one-time-pad

share|improve this question

asked 8 hours ago

jsfierrojsfierro

68129

$endgroup$

add a comment | 

1

$begingroup$

I was researching the US military's DIANA one-time-pad system and came across the following quote purportedly from a former US Special Forces soldier:

Special Forces were one of (if not the only) units in Vietnam to
utilize Morse code on a regular basis. We used a method of encryption
called the Diana Cryptosystem.

The basis of these one-time pads, is that there were only two matching
pads in existence, and they would only be used one time. They were
booklets that contained randomly generated groups of 5-letter words,
30 words to a page. The person sending a message would first write the
letters to the message, over these random groups of words. Included in
the front of each one-time pad was a one-page encryption table. If I
wanted to send the letter P, and the letter under the P was an A, then
I would send a K. The person listening on the frequency at the other
end, would have the other matching pad. They would write the letter
they received (a K) over the letter in their one-time pad (an A), and
decipher it based on the table, yielding the original letter P.

(source: https://dodona.ugent.be/en/exercises/2088793301/)

Wouldn't the use of random words as reported by the soldier rather than groups of random letters diminish the security of the system, as the letters in 5 letter English words are not randomly positioned?

I am aware that "secure" in this context--messages between Special Forces camps during wartime--may just mean keeping messages secure long enough that they are no longer useful even if broken.

one-time-pad

share|improve this question

asked 8 hours ago

jsfierrojsfierro

68129

$endgroup$

add a comment | 

$begingroup$

I was researching the US military's DIANA one-time-pad system and came across the following quote purportedly from a former US Special Forces soldier:

Special Forces were one of (if not the only) units in Vietnam to
utilize Morse code on a regular basis. We used a method of encryption
called the Diana Cryptosystem.

The basis of these one-time pads, is that there were only two matching
pads in existence, and they would only be used one time. They were
booklets that contained randomly generated groups of 5-letter words,
30 words to a page. The person sending a message would first write the
letters to the message, over these random groups of words. Included in
the front of each one-time pad was a one-page encryption table. If I
wanted to send the letter P, and the letter under the P was an A, then
I would send a K. The person listening on the frequency at the other
end, would have the other matching pad. They would write the letter
they received (a K) over the letter in their one-time pad (an A), and
decipher it based on the table, yielding the original letter P.

(source: https://dodona.ugent.be/en/exercises/2088793301/)

Wouldn't the use of random words as reported by the soldier rather than groups of random letters diminish the security of the system, as the letters in 5 letter English words are not randomly positioned?

I am aware that "secure" in this context--messages between Special Forces camps during wartime--may just mean keeping messages secure long enough that they are no longer useful even if broken.

one-time-pad

share|improve this question

asked 8 hours ago

jsfierrojsfierro

68129

$endgroup$

share|improve this question

asked 8 hours ago

jsfierrojsfierro

68129

share|improve this question

asked 8 hours ago

jsfierrojsfierro

68129

asked 8 hours ago

jsfierrojsfierro

68129

asked 8 hours ago

jsfierrojsfierro

68129

1 Answer
1

active

oldest

votes

2

$begingroup$

Do those look like English words to you?

WHTVI AUCFU RETFK OMSAL
MYMNE ZIEGP UKVTF WZHOK

(Quoted from the page.)

When they say ‘5-letter words’, they don't mean words chosen from an English dictionary. They mean that they rolled a d26 five times independently and strung the resulting letters together, with spaces between every five letters and line breaks between every four ‘words’ for legibility. This method is just as secure as using a d2 (i.e., flipping a coin) to choose the bits of a binary one-time pad; it just uses a different alphabet.

share|improve this answer

edited 6 hours ago

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  That's an example from the page author, not an actual Vietnam-era pad which may be different.
  $endgroup$
  – jsfierro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  OK, but why do you suspect that the system being described was not actually…the system being described? Is your question ‘Does this source accurately describe the history?’, or is your question ‘Is the system described in this source secure?’?
  $endgroup$
  – Squeamish Ossifrage
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I want to know whether the system described by the quoted soldier (using randomly generated groups of words as pad material) is secure.
  $endgroup$
  – jsfierro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @ jsfierro Yes, the system used by the SF soldier is secure if the key is at least as long as the message, the key is not compromised, and the key is used once. Squeamish answered your question perfectly: "word" means a group of five letters generated in a truly random manner. I have actually used that system in Special Forces--many moons ago--and yes, it provides confidentiality.
  $endgroup$
  – Patriot
  5 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  The National Security Agency has an extremely interesting history of VC SIGINT on their website. You might like that. VC Special Forces cryptographic teams were small and used Vernam Cipher and HF too, sometimes in Near Vertical Incidence Skywave.
  $endgroup$
  – Patriot
  5 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

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2

$begingroup$

Do those look like English words to you?

WHTVI AUCFU RETFK OMSAL
MYMNE ZIEGP UKVTF WZHOK

(Quoted from the page.)

When they say ‘5-letter words’, they don't mean words chosen from an English dictionary. They mean that they rolled a d26 five times independently and strung the resulting letters together, with spaces between every five letters and line breaks between every four ‘words’ for legibility. This method is just as secure as using a d2 (i.e., flipping a coin) to choose the bits of a binary one-time pad; it just uses a different alphabet.

share|improve this answer

edited 6 hours ago

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  That's an example from the page author, not an actual Vietnam-era pad which may be different.
  $endgroup$
  – jsfierro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  OK, but why do you suspect that the system being described was not actually…the system being described? Is your question ‘Does this source accurately describe the history?’, or is your question ‘Is the system described in this source secure?’?
  $endgroup$
  – Squeamish Ossifrage
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I want to know whether the system described by the quoted soldier (using randomly generated groups of words as pad material) is secure.
  $endgroup$
  – jsfierro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @ jsfierro Yes, the system used by the SF soldier is secure if the key is at least as long as the message, the key is not compromised, and the key is used once. Squeamish answered your question perfectly: "word" means a group of five letters generated in a truly random manner. I have actually used that system in Special Forces--many moons ago--and yes, it provides confidentiality.
  $endgroup$
  – Patriot
  5 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  The National Security Agency has an extremely interesting history of VC SIGINT on their website. You might like that. VC Special Forces cryptographic teams were small and used Vernam Cipher and HF too, sometimes in Near Vertical Incidence Skywave.
  $endgroup$
  – Patriot
  5 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

2

$begingroup$

Do those look like English words to you?

WHTVI AUCFU RETFK OMSAL
MYMNE ZIEGP UKVTF WZHOK

(Quoted from the page.)

When they say ‘5-letter words’, they don't mean words chosen from an English dictionary. They mean that they rolled a d26 five times independently and strung the resulting letters together, with spaces between every five letters and line breaks between every four ‘words’ for legibility. This method is just as secure as using a d2 (i.e., flipping a coin) to choose the bits of a binary one-time pad; it just uses a different alphabet.

share|improve this answer

edited 6 hours ago

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  That's an example from the page author, not an actual Vietnam-era pad which may be different.
  $endgroup$
  – jsfierro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  OK, but why do you suspect that the system being described was not actually…the system being described? Is your question ‘Does this source accurately describe the history?’, or is your question ‘Is the system described in this source secure?’?
  $endgroup$
  – Squeamish Ossifrage
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I want to know whether the system described by the quoted soldier (using randomly generated groups of words as pad material) is secure.
  $endgroup$
  – jsfierro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @ jsfierro Yes, the system used by the SF soldier is secure if the key is at least as long as the message, the key is not compromised, and the key is used once. Squeamish answered your question perfectly: "word" means a group of five letters generated in a truly random manner. I have actually used that system in Special Forces--many moons ago--and yes, it provides confidentiality.
  $endgroup$
  – Patriot
  5 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  The National Security Agency has an extremely interesting history of VC SIGINT on their website. You might like that. VC Special Forces cryptographic teams were small and used Vernam Cipher and HF too, sometimes in Near Vertical Incidence Skywave.
  $endgroup$
  – Patriot
  5 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

$begingroup$

Do those look like English words to you?

WHTVI AUCFU RETFK OMSAL
MYMNE ZIEGP UKVTF WZHOK

(Quoted from the page.)

When they say ‘5-letter words’, they don't mean words chosen from an English dictionary. They mean that they rolled a d26 five times independently and strung the resulting letters together, with spaces between every five letters and line breaks between every four ‘words’ for legibility. This method is just as secure as using a d2 (i.e., flipping a coin) to choose the bits of a binary one-time pad; it just uses a different alphabet.

share|improve this answer

edited 6 hours ago

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121

$endgroup$

WHTVI AUCFU RETFK OMSAL
MYMNE ZIEGP UKVTF WZHOK

share|improve this answer

edited 6 hours ago

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121

answered 6 hours ago

Squeamish OssifrageSqueamish Ossifrage

28.5k144121