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Pseudorandom Number Generator
Feature is currently live on previewnet and testnet.
A transaction that generates a pseudorandom number. When the pseudorandom number generate transaction executes, its transaction record will contain the 384-bit array of pseudorandom bytes. The transaction has an optional range parameter. If the parameter is given and is positive, then the record will contain a 32-bit pseudorandom integer r, where 0 <= r < range instead of containing the 384 pseudorandom bits.
When the nth transaction needs a pseudorandom number, it is given the running hash of all records up to and including the record for transaction n-3. If it needs 384 bits, then it uses the entire hash. If it needs 256 bits, it uses the first 256 bits of the hash. If it needs a random number r that is in the range 0 <= r < range, then it lets x be the first 32 bits of the hash (interpreted as a signed integer).
The choice of using the hash up to transaction n-3 rather than n-1 is to ensure the transactions can be processed quickly. Because the thread calculating the hash will have more time to complete it before it is needed. The use of n-3 rather than n-1000000 is to make it hard to predict the pseudorandom number in advance.
Reference: HIP-351​
Field
Description
Range
The specified range to return the pseudorandom number from.

Methods

V2
Method
Type
Requirement
setRange(<range>)
integer
Optional
getRange(<range>)
integer
Optional
Java
//Create the transaction with range set
TransactionResponse transaction = new PrngTransaction()
//Set the range
.setRange(250)
.execute(client);
​
//Get the record
TransactionRecord transactionRecord = transaction.getRecord(client);
​
//Get the number
int prngNumber = transactionRecord.prngNumber;
​
System.out.println(prngNumber);
​
//SDK version 2.17.0
JavaScript
//Create the transaction with range set
const transaction = await new PrngTransaction()
//Set the range
.setRange(250)
.execute(client);
​
//Get the record
const transactionRecord = await transaction.getRecord(client);
​
//Get the number
const prngNumber = transactionRecord.prngNumber;
​
console.log(prngNumber);
​
//SDK version 2.17.0
Go
transaction, err := hedera.NewPrngTransaction().
// Set the range
SetRange(250).
Execute(client)
if err != nil {
println(err.Error(), ": error executing rng transaction")
return
}
​
transactionRecord, err := createResponse.GetRecord(client)
if err != nil {
println(err.Error(), ": error getting receipt")
return
}
​
if transactionRecord.PrngNumber != nil {
println(err.Error(), ": error, pseudo-random number is nil")
return
}
​
println("The pseudorandom number is:", *transactionRecord.PrngNumber)
​
//Version 2.17.0

​

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