I'll have to give a spoken presentation on cryptography and I don't want to make any pronunciation mistakes. Therefore I'm asking how I should pronounce acronyms like RSA, AES, SHA-1, SHA-256, IGE and CBC, Curve25519, ECDH, MAC, HMAC, etc., both in English and in other languages. (The presentation is in Italian, so I'd prefer it.)

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    $\begingroup$ This appears to be a question of personal style and local convention, but here's my two cents: For all the acronyms except SHA, I simply spell out the letters. I pronounce "SHA" as in "shark". When reading the numbers, I often leave out the word "hundred", so "SHA-256" becomes "sha two fifty-six" and "Curve25519" becomes "curve two fifty-five nineteen". (I'm positive "25519" should be read as "255 19" since it refers to Curve25519's field size, $2^{255}-19$.) $\endgroup$ – yyyyyyy Sep 22 '16 at 11:42
  • $\begingroup$ Portuguese speakers (Brazilians) tend to spell character by character (letters, numbers, symbols, punctuation: dash, dot, comma,...). There are exceptions mainly for acronyms composed by pairs of consonant and vowel (CVCVCV...), in this case Portuguese Speakers will have a very strong trend to pronounce it as a single word. If the acronym is a name for an organization or product it increases the tendency to be spelled as a single word. But, In general, in technical and scientific world, acronyms (in capital letters) are spelled "char" by "char". $\endgroup$ – Luciano Nov 30 '16 at 13:54

However you pronounce them, the important thing is to make sure that your listeners understand you. In general, it's never wrong to pronounce acronyms letter by letter (and digit by digit), as in:

  • RSA → "arr ess ay"
  • AES → "ay ee ess"
  • SHA-1 → "ess aitch ay one"
  • SHA-256 → "ess aitch ay two five six" (or "ess aitch ay two fifty six" or even "ess aitch ay two hundred and fifty six")

If the acronym could also be pronounced as a word, and the resulting pronunciation is clear and distinct enough, you can also do that. So "shuh two fifty-six" for SHA-256 is OK, too. Certainly this is true for longer acronyms that "just happen to" spell out an English word; I'd much rather hear e.g. SHAKE256 pronounced "shake two fifty six" than "ess aitch ay kay ee two five six", even if the latter isn't strictly speaking wrong, either.

Curve25519 is a bit of a special case. Obviously the word "curve" should be pronounced as the English word, and I would say that it's perfectly fine to just read out the numbers one by one, as in "curve two five five one nine", although "curve two five five nineteen" or "curve two fifty five nineteen" would also be OK.

As yyyyyyy notes in the comments, though, the number 25519 in the name is really made up of the two numbers 255 and 19, so you should not read it as e.g. "curve twenty-five thousand five hundred and nineteen". You can thank D.J. Bernstein for this naming ambiguity; his Poly1305 MAC is arguably even worse named, since the two numbers concatenated into that name are 130 and 5, but pronouncing it e.g. as "poly one thirty five" would just invite naïve listeners into parsing it as "Poly135". I don't know how DJB himself pronounces that name, but I'd probably just read it digit by digit as "poly one three oh five". Peter Schwabe pronounces it at "poly thirteen oh five".

Of course, where it gets really tricky are names like Rijndael or Grøstl which are not acronyms, and which even (or perhaps especially) native English speakers have trouble pronouncing. In those cases, I'd suggest either looking up an audio sample of the "official" pronunciation and imitating it as well as you can, or just giving up and pronouncing the name according to the standard pronunciation in whatever language you're speaking.

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    $\begingroup$ Personally, I'd pronounce MAC as "mac", and HMAC as "aitch mac" (and e.g. CMAC* as "cee mac star"), but "aitch em ay cee" isn't IMO wrong either, just a bit slower to say. Trying to pronounce HMAC as a single word (i.e. "h'mac" or something like that) sounds weird to my ear, especially given that English doesn't normally have a syllabic "h". $\endgroup$ – Ilmari Karonen Sep 22 '16 at 14:25
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    $\begingroup$ I've always read/been told that Rijndael for English speakers can be most easily pronounced by thinking of the two words "Rain doll". $\endgroup$ – John Wu Sep 22 '16 at 15:50
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    $\begingroup$ It's worth noting that pronouncing 0 as oh is a peculiarity of the English language which applies only when reading a list of digits, not in other circumstances. $\endgroup$ – TRiG Sep 22 '16 at 16:03
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    $\begingroup$ I wouldn't pronounce SHA-256 as "shuh...". It'd be "shah", rhyming with the first syllable of "father". $\endgroup$ – mbomb007 Sep 22 '16 at 18:44
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    $\begingroup$ @JohnWu The sound of the "ij" digraph in "Rijndael" is very similar to the "ei" part of "Einstein", and the "ae" part sounds a bit like the vowel in an Australian "car". $\endgroup$ – Rhymoid Sep 22 '16 at 20:55

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