I have a simple question about the NTRU original cryptosystem using a digital envelope.

The article can be found here: http://grouper.ieee.org/groups/1363/lattPK/submissions/ntru.pdf

It is said that we need a generating function $G$ and a hash function $H$.

Suppose that Alice wants to send a message to Bob. Then she will use some generating function $G$ and some hash function $H$.

Bob recieves the ciphertext $e$ and at a certain point of decryption it is said that Bob should compare $c''$ and $H(c',b)$.

Suppose that Eve exists.

My question is: Do Bob and Eve know $G$ and $H$? In the way the decryption is described, Bob needs to know $H$, but it's not clear if he knows it.

Thanks in advance.


Yes, these are public parameters of the system.

Note that NTRU is not implemented exactly this way any more. The most up-to-date current spec is EESS#1, which can be obtained from https://github.com/NTRUOpenSourceProject/ntru-crypto/blob/master/doc/EESS1-v3.1.pdf.

  • $\begingroup$ Thanks a lot. I am aware of the more recent implementation of NTRU, I'm just starting from its origins $\endgroup$
    – Leafar
    Jul 23 '16 at 21:20

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