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random Standard Library ​

random is a pseudorandom number generator that derives a deterministic seed state from the current block number and block hash. In Contracting, these environment variables are not automatically supplied. The ContractingClient also does not current have support for this feature, so you will have to automatically update your environment with a block height and hash that you would like to use.

Simply do the following:

python
def random_contract():
	@export
	def uses_random_function():
		...

client = ContractingClient()
client.submit(random_contract)

rc = client.get_contract('random_contract')
rc.uses_random_function(environment={
	'block_height': 0,
	'block_hash': 'any_string'
	})

random.seed() ​

This function is required to be run once per transaction. If it is not called, the contract will fail. You must seed every contract like so:

python
random.seed()

@export
def random_one():
    ...

@export
def random_two():
    ...

Available functions ​

Besides seeding, the rest of the module follows Python random 1:1. Here are the functions you can use and reference the Python manual to read more about how each one behaves.

python
random.shuffle(l: list)
random.getrandbits(k: int)
random.randrange(k: int)
random.randint(a: int, b: int)
random.choice(l: list)
random.choices(l: list, k: int)

Limitations and Security Considerations ​

Deterministic Randomness ​

Random outputs are seeded from publicly available data (block_num, block_hash).
This means that while outputs appear random, they could theoretically be predicted if an attacker knows the block information — however, in normal operation, block hashes are unknown until after block production.

Front-Running Risk ​

Since randomness depends on the current block's hash, a malicious actor would need to predict or control the future block hash to front-run a transaction.
On a DPoS chain like Xian, this is virtually impossible unless validators themselves act maliciously and collude.

Not Cryptographically Secure ​

Do not use random for generating secrets, encryption keys, or in scenarios where truly unpredictable randomness is required.

Best Use Cases ​

Randomization for gaming, raffles, randomized shuffles, or non-critical randomized operations where full cryptographic unpredictability is not necessary.