In the finite field $mathbb{F}_{101}$ ,where discrete logarithms are $L_2(3)=69$ and $L_2(5)=24$. Compute the...











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Now, I have that $L_2(60)=L_2(4*3*5)=L_2(4)+L_2(3)+L_2(5)=2+69+24=95$.
So from my work $L_2(60)$ is $95$, but the answer on some other website gives $14$.
I just don't see where I went wrong.










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  • 1




    This does not look like standard notation. Perhaps some definitions would be a good idea.
    – lulu
    Nov 18 at 19:10






  • 1




    Voting to close the question as it is not clear what you are asking. I am guessing that F101 means $mathbb F_{101}$, the finite field with $101$ elements. But I have no guess as to what $L_2(n)$ might mean. Please edit for clarity.
    – lulu
    Nov 18 at 19:27






  • 1




    Ah, fair enough. So you are saying that $2$ is a primitive root $pmod {101}$ and you are asking to compute the minimal positive $a$ such that $2^aequiv 60pmod {101}$, yes? (Note: please edit your post to reflect this, assuming I have it right. Most people won't read through all the comments to discern your meaning.
    – lulu
    Nov 18 at 19:34






  • 1




    I note, by the way, that $2^{14}equiv 22pmod {101}$. $95$ is absolutely correct and your reasoning is sound.
    – lulu
    Nov 18 at 19:35








  • 1




    I can't imagine where the $14$ comes from. I expect some confusion (or just a good old fashioned error).
    – lulu
    Nov 18 at 19:37















up vote
0
down vote

favorite












Now, I have that $L_2(60)=L_2(4*3*5)=L_2(4)+L_2(3)+L_2(5)=2+69+24=95$.
So from my work $L_2(60)$ is $95$, but the answer on some other website gives $14$.
I just don't see where I went wrong.










share|cite|improve this question




















  • 1




    This does not look like standard notation. Perhaps some definitions would be a good idea.
    – lulu
    Nov 18 at 19:10






  • 1




    Voting to close the question as it is not clear what you are asking. I am guessing that F101 means $mathbb F_{101}$, the finite field with $101$ elements. But I have no guess as to what $L_2(n)$ might mean. Please edit for clarity.
    – lulu
    Nov 18 at 19:27






  • 1




    Ah, fair enough. So you are saying that $2$ is a primitive root $pmod {101}$ and you are asking to compute the minimal positive $a$ such that $2^aequiv 60pmod {101}$, yes? (Note: please edit your post to reflect this, assuming I have it right. Most people won't read through all the comments to discern your meaning.
    – lulu
    Nov 18 at 19:34






  • 1




    I note, by the way, that $2^{14}equiv 22pmod {101}$. $95$ is absolutely correct and your reasoning is sound.
    – lulu
    Nov 18 at 19:35








  • 1




    I can't imagine where the $14$ comes from. I expect some confusion (or just a good old fashioned error).
    – lulu
    Nov 18 at 19:37













up vote
0
down vote

favorite









up vote
0
down vote

favorite











Now, I have that $L_2(60)=L_2(4*3*5)=L_2(4)+L_2(3)+L_2(5)=2+69+24=95$.
So from my work $L_2(60)$ is $95$, but the answer on some other website gives $14$.
I just don't see where I went wrong.










share|cite|improve this question















Now, I have that $L_2(60)=L_2(4*3*5)=L_2(4)+L_2(3)+L_2(5)=2+69+24=95$.
So from my work $L_2(60)$ is $95$, but the answer on some other website gives $14$.
I just don't see where I went wrong.







cryptography discrete-logarithms






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edited Nov 18 at 22:08









Yadati Kiran

1,253417




1,253417










asked Nov 18 at 19:08









George S

13010




13010








  • 1




    This does not look like standard notation. Perhaps some definitions would be a good idea.
    – lulu
    Nov 18 at 19:10






  • 1




    Voting to close the question as it is not clear what you are asking. I am guessing that F101 means $mathbb F_{101}$, the finite field with $101$ elements. But I have no guess as to what $L_2(n)$ might mean. Please edit for clarity.
    – lulu
    Nov 18 at 19:27






  • 1




    Ah, fair enough. So you are saying that $2$ is a primitive root $pmod {101}$ and you are asking to compute the minimal positive $a$ such that $2^aequiv 60pmod {101}$, yes? (Note: please edit your post to reflect this, assuming I have it right. Most people won't read through all the comments to discern your meaning.
    – lulu
    Nov 18 at 19:34






  • 1




    I note, by the way, that $2^{14}equiv 22pmod {101}$. $95$ is absolutely correct and your reasoning is sound.
    – lulu
    Nov 18 at 19:35








  • 1




    I can't imagine where the $14$ comes from. I expect some confusion (or just a good old fashioned error).
    – lulu
    Nov 18 at 19:37














  • 1




    This does not look like standard notation. Perhaps some definitions would be a good idea.
    – lulu
    Nov 18 at 19:10






  • 1




    Voting to close the question as it is not clear what you are asking. I am guessing that F101 means $mathbb F_{101}$, the finite field with $101$ elements. But I have no guess as to what $L_2(n)$ might mean. Please edit for clarity.
    – lulu
    Nov 18 at 19:27






  • 1




    Ah, fair enough. So you are saying that $2$ is a primitive root $pmod {101}$ and you are asking to compute the minimal positive $a$ such that $2^aequiv 60pmod {101}$, yes? (Note: please edit your post to reflect this, assuming I have it right. Most people won't read through all the comments to discern your meaning.
    – lulu
    Nov 18 at 19:34






  • 1




    I note, by the way, that $2^{14}equiv 22pmod {101}$. $95$ is absolutely correct and your reasoning is sound.
    – lulu
    Nov 18 at 19:35








  • 1




    I can't imagine where the $14$ comes from. I expect some confusion (or just a good old fashioned error).
    – lulu
    Nov 18 at 19:37








1




1




This does not look like standard notation. Perhaps some definitions would be a good idea.
– lulu
Nov 18 at 19:10




This does not look like standard notation. Perhaps some definitions would be a good idea.
– lulu
Nov 18 at 19:10




1




1




Voting to close the question as it is not clear what you are asking. I am guessing that F101 means $mathbb F_{101}$, the finite field with $101$ elements. But I have no guess as to what $L_2(n)$ might mean. Please edit for clarity.
– lulu
Nov 18 at 19:27




Voting to close the question as it is not clear what you are asking. I am guessing that F101 means $mathbb F_{101}$, the finite field with $101$ elements. But I have no guess as to what $L_2(n)$ might mean. Please edit for clarity.
– lulu
Nov 18 at 19:27




1




1




Ah, fair enough. So you are saying that $2$ is a primitive root $pmod {101}$ and you are asking to compute the minimal positive $a$ such that $2^aequiv 60pmod {101}$, yes? (Note: please edit your post to reflect this, assuming I have it right. Most people won't read through all the comments to discern your meaning.
– lulu
Nov 18 at 19:34




Ah, fair enough. So you are saying that $2$ is a primitive root $pmod {101}$ and you are asking to compute the minimal positive $a$ such that $2^aequiv 60pmod {101}$, yes? (Note: please edit your post to reflect this, assuming I have it right. Most people won't read through all the comments to discern your meaning.
– lulu
Nov 18 at 19:34




1




1




I note, by the way, that $2^{14}equiv 22pmod {101}$. $95$ is absolutely correct and your reasoning is sound.
– lulu
Nov 18 at 19:35






I note, by the way, that $2^{14}equiv 22pmod {101}$. $95$ is absolutely correct and your reasoning is sound.
– lulu
Nov 18 at 19:35






1




1




I can't imagine where the $14$ comes from. I expect some confusion (or just a good old fashioned error).
– lulu
Nov 18 at 19:37




I can't imagine where the $14$ comes from. I expect some confusion (or just a good old fashioned error).
– lulu
Nov 18 at 19:37










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Write $equiv$ for "equal modulo $101$". You are told that $2^{69}equiv 3$ and $2^{24}equiv5$. Furthermore $2^2equiv4$ trivially. From $60=3cdot 5cdot 4$ it then follows that
$$60equiv2^{69}cdot2^{24}cdot2^2equiv2^{95} .$$
This shows that in ${mathbb F}_{101}$ one has $L_2(60)=95$, whereby we have not checked that $2$ is actually a generator of the multiplicative group ${mathbb F}_{101}^*$, vulgo: a primitive root.






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  • 1




    I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
    – Henno Brandsma
    Nov 18 at 22:43













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Write $equiv$ for "equal modulo $101$". You are told that $2^{69}equiv 3$ and $2^{24}equiv5$. Furthermore $2^2equiv4$ trivially. From $60=3cdot 5cdot 4$ it then follows that
$$60equiv2^{69}cdot2^{24}cdot2^2equiv2^{95} .$$
This shows that in ${mathbb F}_{101}$ one has $L_2(60)=95$, whereby we have not checked that $2$ is actually a generator of the multiplicative group ${mathbb F}_{101}^*$, vulgo: a primitive root.






share|cite|improve this answer

















  • 1




    I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
    – Henno Brandsma
    Nov 18 at 22:43

















up vote
1
down vote













Write $equiv$ for "equal modulo $101$". You are told that $2^{69}equiv 3$ and $2^{24}equiv5$. Furthermore $2^2equiv4$ trivially. From $60=3cdot 5cdot 4$ it then follows that
$$60equiv2^{69}cdot2^{24}cdot2^2equiv2^{95} .$$
This shows that in ${mathbb F}_{101}$ one has $L_2(60)=95$, whereby we have not checked that $2$ is actually a generator of the multiplicative group ${mathbb F}_{101}^*$, vulgo: a primitive root.






share|cite|improve this answer

















  • 1




    I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
    – Henno Brandsma
    Nov 18 at 22:43















up vote
1
down vote










up vote
1
down vote









Write $equiv$ for "equal modulo $101$". You are told that $2^{69}equiv 3$ and $2^{24}equiv5$. Furthermore $2^2equiv4$ trivially. From $60=3cdot 5cdot 4$ it then follows that
$$60equiv2^{69}cdot2^{24}cdot2^2equiv2^{95} .$$
This shows that in ${mathbb F}_{101}$ one has $L_2(60)=95$, whereby we have not checked that $2$ is actually a generator of the multiplicative group ${mathbb F}_{101}^*$, vulgo: a primitive root.






share|cite|improve this answer












Write $equiv$ for "equal modulo $101$". You are told that $2^{69}equiv 3$ and $2^{24}equiv5$. Furthermore $2^2equiv4$ trivially. From $60=3cdot 5cdot 4$ it then follows that
$$60equiv2^{69}cdot2^{24}cdot2^2equiv2^{95} .$$
This shows that in ${mathbb F}_{101}$ one has $L_2(60)=95$, whereby we have not checked that $2$ is actually a generator of the multiplicative group ${mathbb F}_{101}^*$, vulgo: a primitive root.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Nov 18 at 20:15









Christian Blatter

171k7111325




171k7111325








  • 1




    I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
    – Henno Brandsma
    Nov 18 at 22:43
















  • 1




    I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
    – Henno Brandsma
    Nov 18 at 22:43










1




1




I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
– Henno Brandsma
Nov 18 at 22:43






I did check and it is a primitive root modulo $101$. I also check $2^{95} equiv 60$ and $2^{14} equiv 22$ so the OP's source was wrong.
– Henno Brandsma
Nov 18 at 22:43




















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