Field of discrete logarithms of a generator of a finite group

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Suppose that $mathbbG$ is finite group of order $p$ ($p$ can be a prime number if necessary) and that $g$ is a generator of $mathbbG$. What is the field of discrete logarithms of $g$?



I can see that the set $g^mathbbZsimeq 1,ldots p-1$ is finite and contains $p$ elements, it also has a commutative group structure with $0$ as neutral element, so it is (isomorphic to) $(mathbbZ_p-1,+)$. Addition is determined by
$c:=a+b$ with $c$ determined by $g^c:= g^ag^b$. This is the discrete logarithm problem



But how can we deduces that there is also a multiplication? Can we derive it from the group law and the generator?



Because $(g^a)^b neq g^a cdot_mathbbZ_pb$ in general.










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  • $g$ is a generator of $G$. So $G$ is cyclic. Now consider the exponents.
    – Wuestenfux
    Sep 2 at 9:23











  • I see how addition work, because $g^acdot g^b= g^a+b$, but I don't see how multiplication works.
    – Mark Neuhaus
    Sep 4 at 18:41














up vote
0
down vote

favorite












Suppose that $mathbbG$ is finite group of order $p$ ($p$ can be a prime number if necessary) and that $g$ is a generator of $mathbbG$. What is the field of discrete logarithms of $g$?



I can see that the set $g^mathbbZsimeq 1,ldots p-1$ is finite and contains $p$ elements, it also has a commutative group structure with $0$ as neutral element, so it is (isomorphic to) $(mathbbZ_p-1,+)$. Addition is determined by
$c:=a+b$ with $c$ determined by $g^c:= g^ag^b$. This is the discrete logarithm problem



But how can we deduces that there is also a multiplication? Can we derive it from the group law and the generator?



Because $(g^a)^b neq g^a cdot_mathbbZ_pb$ in general.










share|cite|improve this question























  • $g$ is a generator of $G$. So $G$ is cyclic. Now consider the exponents.
    – Wuestenfux
    Sep 2 at 9:23











  • I see how addition work, because $g^acdot g^b= g^a+b$, but I don't see how multiplication works.
    – Mark Neuhaus
    Sep 4 at 18:41












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Suppose that $mathbbG$ is finite group of order $p$ ($p$ can be a prime number if necessary) and that $g$ is a generator of $mathbbG$. What is the field of discrete logarithms of $g$?



I can see that the set $g^mathbbZsimeq 1,ldots p-1$ is finite and contains $p$ elements, it also has a commutative group structure with $0$ as neutral element, so it is (isomorphic to) $(mathbbZ_p-1,+)$. Addition is determined by
$c:=a+b$ with $c$ determined by $g^c:= g^ag^b$. This is the discrete logarithm problem



But how can we deduces that there is also a multiplication? Can we derive it from the group law and the generator?



Because $(g^a)^b neq g^a cdot_mathbbZ_pb$ in general.










share|cite|improve this question















Suppose that $mathbbG$ is finite group of order $p$ ($p$ can be a prime number if necessary) and that $g$ is a generator of $mathbbG$. What is the field of discrete logarithms of $g$?



I can see that the set $g^mathbbZsimeq 1,ldots p-1$ is finite and contains $p$ elements, it also has a commutative group structure with $0$ as neutral element, so it is (isomorphic to) $(mathbbZ_p-1,+)$. Addition is determined by
$c:=a+b$ with $c$ determined by $g^c:= g^ag^b$. This is the discrete logarithm problem



But how can we deduces that there is also a multiplication? Can we derive it from the group law and the generator?



Because $(g^a)^b neq g^a cdot_mathbbZ_pb$ in general.







finite-groups finite-fields elliptic-curves cryptography






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edited Sep 4 at 19:17

























asked Sep 2 at 8:49









Mark Neuhaus

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5671312











  • $g$ is a generator of $G$. So $G$ is cyclic. Now consider the exponents.
    – Wuestenfux
    Sep 2 at 9:23











  • I see how addition work, because $g^acdot g^b= g^a+b$, but I don't see how multiplication works.
    – Mark Neuhaus
    Sep 4 at 18:41
















  • $g$ is a generator of $G$. So $G$ is cyclic. Now consider the exponents.
    – Wuestenfux
    Sep 2 at 9:23











  • I see how addition work, because $g^acdot g^b= g^a+b$, but I don't see how multiplication works.
    – Mark Neuhaus
    Sep 4 at 18:41















$g$ is a generator of $G$. So $G$ is cyclic. Now consider the exponents.
– Wuestenfux
Sep 2 at 9:23





$g$ is a generator of $G$. So $G$ is cyclic. Now consider the exponents.
– Wuestenfux
Sep 2 at 9:23













I see how addition work, because $g^acdot g^b= g^a+b$, but I don't see how multiplication works.
– Mark Neuhaus
Sep 4 at 18:41




I see how addition work, because $g^acdot g^b= g^a+b$, but I don't see how multiplication works.
– Mark Neuhaus
Sep 4 at 18:41















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