Come calcolare un seme casuale?

Question

Come calcolare un seme casuale?

- 6
- 81 2019-05-08
Adesempio,abbiamo 126/128nonce,rivelatenel ciclo 99. /chains/main/blocks/409599/context/raw/json/cycle/98/nonces? depth=1

Se ho capitobene,usando questenoncepossiamo calcolareil seme casuale.Qualcunopuò spiegare comefarlo?

For example, we have 126/128 nonces, revealed in cycle 99. /chains/main/blocks/409599/context/raw/json/cycle/98/nonces?depth=1

If I understand correctly, using these nonces we can calculate the random seed. Can anybody explain how to do this?

protocol consensus cryptography
- fonte
- Groxan

1 risposta

voti

Tom · Accepted Answer · 2019-05-16

7

2019-05-16

Avremobisogno di queste operazioni:

blake2b :taglia 32
concat : concatenazione di array dibyte

Inoltre,lascia che zero_bytes sia 32 zerobyte.

Lamia risposta sibasa su seed_storage.ml e seed_repr.ml ,con qualche sperimentazione.

Semiiniziali

Cominciamo dall'inizio.

I semi conservati_cicli + 2=7iniziali sono stati determinatiin anticipo,come segue. Ilprimo seme è l'hash delmessaggio vuoto:

  seed [0]=blake2b ([])=0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8

I rimanenti 6 seediniziali vengono calcolati ciascuno dalprecedente:

  seed [n]=blake2b (concat (seed [n-1],zero_bytes))

Questo dài seguenti semiiniziali:

 | ciclo| seme|
| ------- + ----------------------------------------- -------------------------|
| 0| 0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8|
| 1| c8db55740733852aa18aa82e108e4475b1abcf3f1f077ac966e9cecca86612ec|
| 2| 270da140de63850f631d09a95eab26dc39cc92f8feae73875c7cf9aaa3bf4cac|
| 3| 97d50852c159ada8e9f107e98f693b059ba28336c723e6cd0f6353eb3c0cb415|
| 4| 0c7ea5ee0b25b7105f934c6511756ec20abcf5c6eea4d45721c138c3e751469b|
| 5| beb4d79b65faa3e902e73d031ad6466299f01aab517d303151a99605a259a11e|
| 6| 5e695ae038c2bdc54706547fc743eb3564ca5a0b4b5d8e9de2ca4780157ca61e|

Il seme del ciclo successivo

Da qui,usiamo lenonce rivelateper calcolareil seme successivo dal semeprecedente:

  seed [n]=seed [n-1]
#inizia con uno 'zerononce':
seed [n]=blake2b (concat (seed [n],zero_bytes))
# quindi usa lenonce rivelate:
pernoncein nonces_for [n]:
  seed [n]=blake2b (concat (seed [n],nonce))

Lenonce sonopresein decrescente ordine di livello.

Adesempio,per calcolareil seme casualeperil ciclo 7,possiamoprenderei nonci rivelatinel corso del ciclo 0:

  # Ilmiglior livello sembraessere ((n-5) * 4096) -1?
# Attenzione,questonon è completo,vedi sotto.
# 8191=((7-5) * 4096) -1
# 0=7-7
curl -s http://localhost: 18732/chains/main/blocks/8191/context/raw/json/cycle/0/nonces? depth=1 \
 | jq -r '. []| "\ (. [0]) \t \ (. [1])" '| sort -rnk1| cut -f2

Ilprimononce (in ordine decrescente di livello) è "1ee95fe66b ..."e l'ultimo è "d1012e79ab ...",quindi calcoliamo:

  # seed=="5e695ae038c2bdc54706547fc743eb3564ca5a0b4b5d8e9de2ca4780157ca61e"

# zerononce
seed=blake2b (concat (seed,"00000000000000000000000000000000000000000000000000000000000000"))
# seed=="9b7328e5393a466fc47ef16eb74121939b06e6ec4c17295eb25611f1b76d6a33"

#primononce
seed=blake2b (concat (seed,"1ee95fe66bb3dc2a62195dd41a07a30835e63b91db395aa64150da3decc3be1c"))
# seed=="f9b94526a502a1d8e4042eba2deb682dd752627ea6e4472187ad1c1e465be0f4")

# ...gli altrinonci ...
# seed=="469a48304fc415870289ac8bd875b04107381a2471a878a2a8da16e43dfc5880"

# ultimononce
seed=blake2b (concat (seed,"d1012e79abc75ffc4228f69ace060e1003c8fff0aa9d58a2d78816713b72c278"))
# seed=="1bcd1d832aff2d72a8d16a9f9e5f994e177e29eac789138b019f0c4a30c4e5ec"

Fin quituttobene:

  $ curl http://localhost: 18732/chains/main/blocks/24575/context/raw/json/cycle/7/random_seed
"1bcd1d832aff2d72a8d16a9f9e5f994e177e29eac789138b019f0c4a30c4e5ec"

Come ottenerei nonce?

Tuttavia,se continui,incontrerai unproblema.

Non credo siapossibile utilizzare context/raw/json/cycle/& lt; cycle >/nonces per ottenere tutte lenonce rivelate. Se unnonce viene rivelato solo all'alba del ciclo,credo che verràeliminato dalprotocolloimmediatamente dopo l'uso,prima che venga reso disponibiletramiteil contesto RPCgrezzo.

Ilprimoproblema sembraessere la rivelazionenelblocco al livello 200704.

Ovviamente,se stai costruendo una shell alternativa,acquisirainaturalmente lenocee se,comeme,sei solo curioso,nonimporta.

We will need these operations:

blake2b: size 32
concat: concatenation of byte arrays

Also, let zero_bytes be 32 zero bytes.

My answer is based on seed_storage.ml and seed_repr.ml, with some experimentation.

Initial seeds

Let's start at the beginning.

The initial preserved_cycles+2 = 7 seeds were determined ahead of time, as follows. The first seed is the hash of the empty message:

seed[0] = blake2b([]) = 0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8

The remaining 6 initial seeds are each computed from the previous:

seed[n] = blake2b(concat(seed[n-1], zero_bytes))

This gives the following initial seeds:

| cycle | seed                                                             |
|-------+------------------------------------------------------------------|
|     0 | 0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8 |
|     1 | c8db55740733852aa18aa82e108e4475b1abcf3f1f077ac966e9cecca86612ec |
|     2 | 270da140de63850f631d09a95eab26dc39cc92f8feae73875c7cf9aaa3bf4cac |
|     3 | 97d50852c159ada8e9f107e98f693b059ba28336c723e6cd0f6353eb3c0cb415 |
|     4 | 0c7ea5ee0b25b7105f934c6511756ec20abcf5c6eea4d45721c138c3e751469b |
|     5 | beb4d79b65faa3e902e73d031ad6466299f01aab517d303151a99605a259a11e |
|     6 | 5e695ae038c2bdc54706547fc743eb3564ca5a0b4b5d8e9de2ca4780157ca61e |

The next cycle's seed

From here, we use the revealed nonces to compute the next seed from the previous seed:

seed[n] = seed[n-1]
# start with a 'zero nonce':
seed[n] = blake2b(concat(seed[n], zero_bytes))
# then use the revealed nonces:
for nonce in nonces_for[n]:
  seed[n] = blake2b(concat(seed[n], nonce))

The nonces are taken in decreasing level order.

For example, to calculate the random seed for cycle 7, we can grab the nonces revealed over the course of cycle 0:

# The best level seems to be ((n-5)*4096)-1?
# Warning, this is not complete, see below.
# 8191 = ((7-5)*4096)-1
# 0 = 7-7
curl -s http://localhost:18732/chains/main/blocks/8191/context/raw/json/cycle/0/nonces?depth=1 \
   | jq -r '.[] | "\(.[0])\t\(.[1])"' | sort -rnk1 | cut -f2

The first nonce (in decreasing level order) is "1ee95fe66b...", and the last is "d1012e79ab...", so we compute:

# seed == "5e695ae038c2bdc54706547fc743eb3564ca5a0b4b5d8e9de2ca4780157ca61e"

# zero nonce
seed = blake2b(concat(seed, "0000000000000000000000000000000000000000000000000000000000000000"))
# seed == "9b7328e5393a466fc47ef16eb74121939b06e6ec4c17295eb25611f1b76d6a33"

# first nonce
seed = blake2b(concat(seed, "1ee95fe66bb3dc2a62195dd41a07a30835e63b91db395aa64150da3decc3be1c"))
# seed == "f9b94526a502a1d8e4042eba2deb682dd752627ea6e4472187ad1c1e465be0f4")

# ... the other nonces ...
# seed == "469a48304fc415870289ac8bd875b04107381a2471a878a2a8da16e43dfc5880"

# last nonce
seed = blake2b(concat(seed, "d1012e79abc75ffc4228f69ace060e1003c8fff0aa9d58a2d78816713b72c278"))
# seed == "1bcd1d832aff2d72a8d16a9f9e5f994e177e29eac789138b019f0c4a30c4e5ec"

So far so good:

$ curl http://localhost:18732/chains/main/blocks/24575/context/raw/json/cycle/7/random_seed
"1bcd1d832aff2d72a8d16a9f9e5f994e177e29eac789138b019f0c4a30c4e5ec"

How to get the nonces?

However, if you keep going, you will run into a problem.

I don't believe it is possible to use context/raw/json/cycle/<cycle>/nonces to get all the revealed nonces. If a nonce is revealed just at cycle dawn, I believe it will be deleted by the protocol immediately upon use, before it is made available via the raw context RPC.

The first problem seems to be the revelation in the block at level 200704.

Of course, if you are building an alt-shell, you will naturally acquire the nonces, and if, like me, you are just curious, this doesn't matter.

fonte
Tom

Bella spiegazione,grazie!Haifatto unerrore dibattitura qui `seed [n]=blake2b (concat (seed [n-1],nonce))` - dovrebbeessere `concat (seed [n],nonce)`;) Btw,ho creato una sintesi suC # con lagenerazione di un seme casuale,forse qualcuno lotroverebbe utile.https://gist.github.com/Groxan/c0f11a896bcf9a43e0fff9ba2e46223b

Neat explanation, thanks! You made a typo here `seed[n] = blake2b(concat(seed[n-1], nonce))` - it should be `concat(seed[n], nonce)` ;) Btw, I created a gist on C# with generation of a random seed, maybe someone would find it useful. https://gist.github.com/Groxan/c0f11a896bcf9a43e0fff9ba2e46223b
- 1
- 2019-05-16
- Groxan
Per quanto riguarda la rivelazionenelblocco al livello 200704 - è stata una sorpresaperme=) Hoprovato a ottenereil semee nonera correttofinchénon ho aggiunto l'ultimononce.Purtroppo,ci sono cosìtanteinsidie chenon sono descrittenei documenti.

As for the revelation in the block at level 200704 - it was a surprise for me =) I tried to get the seed an it was incorrect until I appended the last nonce. Sadly, there are so many pitfalls that are not described in the docs.
- 1
- 2019-05-16
- Groxan
Ops,grazie,è quello che ottengoper averprovato a scrivere unopseudocodiceimperativo.;)

Whoops, thanks, that is what I get for trying to write imperative pseudocode. ;)
- 1
- 2019-05-16
- Tom