Mixing
Consuming of entropy
Clash Royale CLAN TAG#URR8PPP
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3
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When I put:
sudo watch tail /proc/sys/kernel/random/entropy_avail && dd if=/dev/random of=/dev/zero
It shows that available entropy is "consumed".
What I can't understand is:
Why does generating random consume entropy? Why does generating random bits cause that entropy to become useless?
entropy
edited 1 hour ago
hunter
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asked 2 hours ago
Carol
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up vote
3
down vote
favorite
When I put:
sudo watch tail /proc/sys/kernel/random/entropy_avail && dd if=/dev/random of=/dev/zero
It shows that available entropy is "consumed".
What I can't understand is:
Why does generating random consume entropy? Why does generating random bits cause that entropy to become useless?
entropy
edited 1 hour ago
hunter
2,45531428
asked 2 hours ago
Carol
161
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
3
down vote
favorite
up vote
3
down vote
favorite
When I put:
sudo watch tail /proc/sys/kernel/random/entropy_avail && dd if=/dev/random of=/dev/zero
It shows that available entropy is "consumed".
What I can't understand is:
Why does generating random consume entropy? Why does generating random bits cause that entropy to become useless?
entropy
edited 1 hour ago
hunter
2,45531428
asked 2 hours ago
Carol
161
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
When I put:
sudo watch tail /proc/sys/kernel/random/entropy_avail && dd if=/dev/random of=/dev/zero
It shows that available entropy is "consumed".
What I can't understand is:
Why does generating random consume entropy? Why does generating random bits cause that entropy to become useless?
entropy
entropy
edited 1 hour ago
hunter
2,45531428
asked 2 hours ago
Carol
161
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 1 hour ago
hunter
2,45531428
asked 2 hours ago
Carol
161
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 1 hour ago
hunter
2,45531428
edited 1 hour ago
hunter
2,45531428
edited 1 hour ago
hunter
2,45531428
2,45531428
asked 2 hours ago
Carol
161
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Carol
161
asked 2 hours ago
Carol
161
161
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Carol is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
add a comment |Â
2 Answers
2
active
oldest
votes
up vote
4
down vote
Why generating random consumes an entropy?
For the same reason that to generate true random bits using coin throws, one needs to throw a coin for each bit generated. Any attempt to use less throws is doomed (against a computationally unbounded adversary, or if the technique relies on few simple bit combinations).
Why generating a random bit causes that entropy to become useless?
Revealing a generated random bit is what makes it useless towards generating further secure random bits.
There's a solution: generate a sufficient number of random bits (like 256 or more) and use these, exclusively, to seed a Cryptographically Secure Pseudo Random Number Generator which will supply an endless stream of bits that have all testable properties of truly random bits. That's part of the strategy of Unix's /dev/urandom
answered 1 hour ago
fgrieu
73.2k6149310
add a comment |Â
up vote
0
down vote
It doesn't. You're not really generating entropy. The operating system does that for you, admittedly with your help as you interact with the machine. You're actively throwing it into the bin with:-
dd if=/dev/random of=/dev/zero
That bit reads any entropy available from /dev/random, and throws it away by trying to overwrite 0. Although it's more common to throw stuff into /dev/null. So it's the same as tossing coins and then forgetting which way they landed.
Try just:-
watch cat /proc/sys/kernel/random/entropy_avail
only, and see it grow as you update your email and send out Facebooks. The more you interact, the more entropy is accumulated, mainly from your keystrokes. You might see it go down sometimes though as the OS uses entropy for it's normal operations.
If you do this in a seperate terminal:-
dd if=/dev/random bs=1 iflag=fullblock | xxd
you'll see the entropy scroll down your screen...
answered 55 mins ago
Paul Uszak
6,00511332
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
Why generating random consumes an entropy?
For the same reason that to generate true random bits using coin throws, one needs to throw a coin for each bit generated. Any attempt to use less throws is doomed (against a computationally unbounded adversary, or if the technique relies on few simple bit combinations).
Why generating a random bit causes that entropy to become useless?
Revealing a generated random bit is what makes it useless towards generating further secure random bits.
There's a solution: generate a sufficient number of random bits (like 256 or more) and use these, exclusively, to seed a Cryptographically Secure Pseudo Random Number Generator which will supply an endless stream of bits that have all testable properties of truly random bits. That's part of the strategy of Unix's /dev/urandom
answered 1 hour ago
fgrieu
73.2k6149310
add a comment |Â
up vote
4
down vote
Why generating random consumes an entropy?
For the same reason that to generate true random bits using coin throws, one needs to throw a coin for each bit generated. Any attempt to use less throws is doomed (against a computationally unbounded adversary, or if the technique relies on few simple bit combinations).
Why generating a random bit causes that entropy to become useless?
Revealing a generated random bit is what makes it useless towards generating further secure random bits.
There's a solution: generate a sufficient number of random bits (like 256 or more) and use these, exclusively, to seed a Cryptographically Secure Pseudo Random Number Generator which will supply an endless stream of bits that have all testable properties of truly random bits. That's part of the strategy of Unix's /dev/urandom
answered 1 hour ago
fgrieu
73.2k6149310
add a comment |Â
up vote
4
down vote
up vote
4
down vote
Why generating random consumes an entropy?
For the same reason that to generate true random bits using coin throws, one needs to throw a coin for each bit generated. Any attempt to use less throws is doomed (against a computationally unbounded adversary, or if the technique relies on few simple bit combinations).
Why generating a random bit causes that entropy to become useless?
Revealing a generated random bit is what makes it useless towards generating further secure random bits.
There's a solution: generate a sufficient number of random bits (like 256 or more) and use these, exclusively, to seed a Cryptographically Secure Pseudo Random Number Generator which will supply an endless stream of bits that have all testable properties of truly random bits. That's part of the strategy of Unix's /dev/urandom
answered 1 hour ago
fgrieu
73.2k6149310
Why generating random consumes an entropy?
For the same reason that to generate true random bits using coin throws, one needs to throw a coin for each bit generated. Any attempt to use less throws is doomed (against a computationally unbounded adversary, or if the technique relies on few simple bit combinations).
Why generating a random bit causes that entropy to become useless?
Revealing a generated random bit is what makes it useless towards generating further secure random bits.
There's a solution: generate a sufficient number of random bits (like 256 or more) and use these, exclusively, to seed a Cryptographically Secure Pseudo Random Number Generator which will supply an endless stream of bits that have all testable properties of truly random bits. That's part of the strategy of Unix's /dev/urandom
answered 1 hour ago
fgrieu
73.2k6149310
edited 50 mins ago
answered 1 hour ago
fgrieu
73.2k6149310
answered 1 hour ago
fgrieu
73.2k6149310
answered 1 hour ago
fgrieu
73.2k6149310
73.2k6149310
add a comment |Â
add a comment |Â
up vote
0
down vote
It doesn't. You're not really generating entropy. The operating system does that for you, admittedly with your help as you interact with the machine. You're actively throwing it into the bin with:-
dd if=/dev/random of=/dev/zero
That bit reads any entropy available from /dev/random, and throws it away by trying to overwrite 0. Although it's more common to throw stuff into /dev/null. So it's the same as tossing coins and then forgetting which way they landed.
Try just:-
watch cat /proc/sys/kernel/random/entropy_avail
only, and see it grow as you update your email and send out Facebooks. The more you interact, the more entropy is accumulated, mainly from your keystrokes. You might see it go down sometimes though as the OS uses entropy for it's normal operations.
If you do this in a seperate terminal:-
dd if=/dev/random bs=1 iflag=fullblock | xxd
you'll see the entropy scroll down your screen...
answered 55 mins ago
Paul Uszak
6,00511332
add a comment |Â
up vote
0
down vote
It doesn't. You're not really generating entropy. The operating system does that for you, admittedly with your help as you interact with the machine. You're actively throwing it into the bin with:-
dd if=/dev/random of=/dev/zero
That bit reads any entropy available from /dev/random, and throws it away by trying to overwrite 0. Although it's more common to throw stuff into /dev/null. So it's the same as tossing coins and then forgetting which way they landed.
Try just:-
watch cat /proc/sys/kernel/random/entropy_avail
only, and see it grow as you update your email and send out Facebooks. The more you interact, the more entropy is accumulated, mainly from your keystrokes. You might see it go down sometimes though as the OS uses entropy for it's normal operations.
If you do this in a seperate terminal:-
dd if=/dev/random bs=1 iflag=fullblock | xxd
you'll see the entropy scroll down your screen...
answered 55 mins ago
Paul Uszak
6,00511332
add a comment |Â
up vote
0
down vote
up vote
0
down vote
It doesn't. You're not really generating entropy. The operating system does that for you, admittedly with your help as you interact with the machine. You're actively throwing it into the bin with:-
dd if=/dev/random of=/dev/zero
That bit reads any entropy available from /dev/random, and throws it away by trying to overwrite 0. Although it's more common to throw stuff into /dev/null. So it's the same as tossing coins and then forgetting which way they landed.
Try just:-
watch cat /proc/sys/kernel/random/entropy_avail
only, and see it grow as you update your email and send out Facebooks. The more you interact, the more entropy is accumulated, mainly from your keystrokes. You might see it go down sometimes though as the OS uses entropy for it's normal operations.
If you do this in a seperate terminal:-
dd if=/dev/random bs=1 iflag=fullblock | xxd
you'll see the entropy scroll down your screen...
answered 55 mins ago
Paul Uszak
6,00511332
It doesn't. You're not really generating entropy. The operating system does that for you, admittedly with your help as you interact with the machine. You're actively throwing it into the bin with:-
dd if=/dev/random of=/dev/zero
That bit reads any entropy available from /dev/random, and throws it away by trying to overwrite 0. Although it's more common to throw stuff into /dev/null. So it's the same as tossing coins and then forgetting which way they landed.
Try just:-
watch cat /proc/sys/kernel/random/entropy_avail
only, and see it grow as you update your email and send out Facebooks. The more you interact, the more entropy is accumulated, mainly from your keystrokes. You might see it go down sometimes though as the OS uses entropy for it's normal operations.
If you do this in a seperate terminal:-
dd if=/dev/random bs=1 iflag=fullblock | xxd
you'll see the entropy scroll down your screen...
answered 55 mins ago
Paul Uszak
6,00511332
answered 55 mins ago
Paul Uszak
6,00511332
answered 55 mins ago
Paul Uszak
6,00511332
answered 55 mins ago
Paul Uszak
6,00511332
6,00511332
add a comment |Â
add a comment |Â
Carol is a new contributor. Be nice, and check out our Code of Conduct.
Carol is a new contributor. Be nice, and check out our Code of Conduct.
Carol is a new contributor. Be nice, and check out our Code of Conduct.
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