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In this answer, the answerer suggested that CREATE_CONTRACT could be used to generate a contract address which could then be used as a seed for a pseudorandom number in a contract.
What would a simple example of this look like when using Smartpy?
For context, my end goal would be to provide an endpoint that receives payment, generates a pseudo-random number (via the above method) and then mints an NFT with attributes based partially on the random result.
For the example provided by Rafael, you can do the following in SmartPy.
import smartpy as sp
class Creator(sp.Contract):
def __init__(self):
self.init(address = sp.none)
@sp.entry_point
def generate_address(self):
# Generate the address but don't append the operation
contract = sp.create_contract_operation(sp.Contract(), sp.unit, sp.tez(0), None);
self.data.address = sp.some(sp.pack(contract.address))
@sp.add_test(name = "generate_address")
def test():
scenario = sp.test_scenario()
c1 = Creator()
scenario += c1
c1.generate_address()
this.storage.address will contain the "random" value.
Something similar to: 0x050a0000001601294ce4766fe8c9a9aa375b5413de86998127ffd100
Heres how I ended up doing it. NOTE: this is not at all truly random do not use this for any purposes other than a very very weak random number generator with no funds associated with the output
def get_random(self):
ha = sp.bytes("0x")
bytes_to_nat = sp.local('bytes_to_nat',{})
bytes_to_nat.value = {
sp.bytes('0x00'): 0, sp.bytes('0x01'): 1,
sp.bytes('0x02'): 2, sp.bytes('0x03'): 3,
sp.bytes('0x04'): 4, sp.bytes('0x05'): 5,
sp.bytes('0x06'): 6, sp.bytes('0x07'): 7,
sp.bytes('0x08'): 8, sp.bytes('0x09'): 9,
sp.bytes('0x0a'): 10, sp.bytes('0x0b'): 11,
sp.bytes('0x0c'): 12, sp.bytes('0x0d'): 13,
sp.bytes('0x0e'): 14, sp.bytes('0x0f'): 15,
sp.bytes('0x10'): 16, sp.bytes('0x11'): 17,
sp.bytes('0x12'): 18, sp.bytes('0x13'): 19,
sp.bytes('0x14'): 20, sp.bytes('0x15'): 21,
sp.bytes('0x16'): 22, sp.bytes('0x17'): 23,
sp.bytes('0x18'): 24, sp.bytes('0x19'): 25,
sp.bytes('0x1a'): 26, sp.bytes('0x1b'): 27,
sp.bytes('0x1c'): 28, sp.bytes('0x1d'): 29,
sp.bytes('0x1e'): 30, sp.bytes('0x1f'): 31,
sp.bytes('0x20'): 32, sp.bytes('0x21'): 33,
sp.bytes('0x22'): 34, sp.bytes('0x23'): 35,
sp.bytes('0x24'): 36, sp.bytes('0x25'): 37,
sp.bytes('0x26'): 38, sp.bytes('0x27'): 39,
sp.bytes('0x28'): 40, sp.bytes('0x29'): 41,
sp.bytes('0x2a'): 42, sp.bytes('0x2b'): 43,
sp.bytes('0x2c'): 44, sp.bytes('0x2d'): 45,
sp.bytes('0x2e'): 46, sp.bytes('0x2f'): 47,
sp.bytes('0x30'): 48, sp.bytes('0x31'): 49,
sp.bytes('0x32'): 50, sp.bytes('0x33'): 51,
sp.bytes('0x34'): 52, sp.bytes('0x35'): 53,
sp.bytes('0x36'): 54, sp.bytes('0x37'): 55,
sp.bytes('0x38'): 56, sp.bytes('0x39'): 57,
sp.bytes('0x3a'): 58, sp.bytes('0x3b'): 59,
sp.bytes('0x3c'): 60, sp.bytes('0x3d'): 61,
sp.bytes('0x3e'): 62, sp.bytes('0x3f'): 63,
sp.bytes('0x40'): 64, sp.bytes('0x41'): 65,
sp.bytes('0x42'): 66, sp.bytes('0x43'): 67,
sp.bytes('0x44'): 68, sp.bytes('0x45'): 69,
sp.bytes('0x46'): 70, sp.bytes('0x47'): 71,
sp.bytes('0x48'): 72, sp.bytes('0x49'): 73,
sp.bytes('0x4a'): 74, sp.bytes('0x4b'): 75,
sp.bytes('0x4c'): 76, sp.bytes('0x4d'): 77,
sp.bytes('0x4e'): 78, sp.bytes('0x4f'): 79,
sp.bytes('0x50'): 80, sp.bytes('0x51'): 81,
sp.bytes('0x52'): 82, sp.bytes('0x53'): 83,
sp.bytes('0x54'): 84, sp.bytes('0x55'): 85,
sp.bytes('0x56'): 86, sp.bytes('0x57'): 87,
sp.bytes('0x58'): 88, sp.bytes('0x59'): 89,
sp.bytes('0x5a'): 90, sp.bytes('0x5b'): 91,
sp.bytes('0x5c'): 92, sp.bytes('0x5d'): 93,
sp.bytes('0x5e'): 94, sp.bytes('0x5f'): 95,
sp.bytes('0x60'): 96, sp.bytes('0x61'): 97,
sp.bytes('0x62'): 98, sp.bytes('0x63'): 99,
sp.bytes('0x64'): 100, sp.bytes('0x65'): 101,
sp.bytes('0x66'): 102, sp.bytes('0x67'): 103,
sp.bytes('0x68'): 104, sp.bytes('0x69'): 105,
sp.bytes('0x6a'): 106, sp.bytes('0x6b'): 107,
sp.bytes('0x6c'): 108, sp.bytes('0x6d'): 109,
sp.bytes('0x6e'): 110, sp.bytes('0x6f'): 111,
sp.bytes('0x70'): 112, sp.bytes('0x71'): 113,
sp.bytes('0x72'): 114, sp.bytes('0x73'): 115,
sp.bytes('0x74'): 116, sp.bytes('0x75'): 117,
sp.bytes('0x76'): 118, sp.bytes('0x77'): 119,
sp.bytes('0x78'): 120, sp.bytes('0x79'): 121,
sp.bytes('0x7a'): 122, sp.bytes('0x7b'): 123,
sp.bytes('0x7c'): 124, sp.bytes('0x7d'): 125,
sp.bytes('0x7e'): 126, sp.bytes('0x7f'): 127,
sp.bytes('0x80'): 128, sp.bytes('0x81'): 129,
sp.bytes('0x82'): 130, sp.bytes('0x83'): 131,
sp.bytes('0x84'): 132, sp.bytes('0x85'): 133,
sp.bytes('0x86'): 134, sp.bytes('0x87'): 135,
sp.bytes('0x88'): 136, sp.bytes('0x89'): 137,
sp.bytes('0x8a'): 138, sp.bytes('0x8b'): 139,
sp.bytes('0x8c'): 140, sp.bytes('0x8d'): 141,
sp.bytes('0x8e'): 142, sp.bytes('0x8f'): 143,
sp.bytes('0x90'): 144, sp.bytes('0x91'): 145,
sp.bytes('0x92'): 146, sp.bytes('0x93'): 147,
sp.bytes('0x94'): 148, sp.bytes('0x95'): 149,
sp.bytes('0x96'): 150, sp.bytes('0x97'): 151,
sp.bytes('0x98'): 152, sp.bytes('0x99'): 153,
sp.bytes('0x9a'): 154, sp.bytes('0x9b'): 155,
sp.bytes('0x9c'): 156, sp.bytes('0x9d'): 157,
sp.bytes('0x9e'): 158, sp.bytes('0x9f'): 159,
sp.bytes('0xa0'): 160, sp.bytes('0xa1'): 161,
sp.bytes('0xa2'): 162, sp.bytes('0xa3'): 163,
sp.bytes('0xa4'): 164, sp.bytes('0xa5'): 165,
sp.bytes('0xa6'): 166, sp.bytes('0xa7'): 167,
sp.bytes('0xa8'): 168, sp.bytes('0xa9'): 169,
sp.bytes('0xaa'): 170, sp.bytes('0xab'): 171,
sp.bytes('0xac'): 172, sp.bytes('0xad'): 173,
sp.bytes('0xae'): 174, sp.bytes('0xaf'): 175,
sp.bytes('0xb0'): 176, sp.bytes('0xb1'): 177,
sp.bytes('0xb2'): 178, sp.bytes('0xb3'): 179,
sp.bytes('0xb4'): 180, sp.bytes('0xb5'): 181,
sp.bytes('0xb6'): 182, sp.bytes('0xb7'): 183,
sp.bytes('0xb8'): 184, sp.bytes('0xb9'): 185,
sp.bytes('0xba'): 186, sp.bytes('0xbb'): 187,
sp.bytes('0xbc'): 188, sp.bytes('0xbd'): 189,
sp.bytes('0xbe'): 190, sp.bytes('0xbf'): 191,
sp.bytes('0xc0'): 192, sp.bytes('0xc1'): 193,
sp.bytes('0xc2'): 194, sp.bytes('0xc3'): 195,
sp.bytes('0xc4'): 196, sp.bytes('0xc5'): 197,
sp.bytes('0xc6'): 198, sp.bytes('0xc7'): 199,
sp.bytes('0xc8'): 200, sp.bytes('0xc9'): 201,
sp.bytes('0xca'): 202, sp.bytes('0xcb'): 203,
sp.bytes('0xcc'): 204, sp.bytes('0xcd'): 205,
sp.bytes('0xce'): 206, sp.bytes('0xcf'): 207,
sp.bytes('0xd0'): 208, sp.bytes('0xd1'): 209,
sp.bytes('0xd2'): 210, sp.bytes('0xd3'): 211,
sp.bytes('0xd4'): 212, sp.bytes('0xd5'): 213,
sp.bytes('0xd6'): 214, sp.bytes('0xd7'): 215,
sp.bytes('0xd8'): 216, sp.bytes('0xd9'): 217,
sp.bytes('0xda'): 218, sp.bytes('0xdb'): 219,
sp.bytes('0xdc'): 220, sp.bytes('0xdd'): 221,
sp.bytes('0xde'): 222, sp.bytes('0xdf'): 223,
sp.bytes('0xe0'): 224, sp.bytes('0xe1'): 225,
sp.bytes('0xe2'): 226, sp.bytes('0xe3'): 227,
sp.bytes('0xe4'): 228, sp.bytes('0xe5'): 229,
sp.bytes('0xe6'): 230, sp.bytes('0xe7'): 231,
sp.bytes('0xe8'): 232, sp.bytes('0xe9'): 233,
sp.bytes('0xea'): 234, sp.bytes('0xeb'): 235,
sp.bytes('0xec'): 236, sp.bytes('0xed'): 237,
sp.bytes('0xee'): 238, sp.bytes('0xef'): 239,
sp.bytes('0xf0'): 240, sp.bytes('0xf1'): 241,
sp.bytes('0xf2'): 242, sp.bytes('0xf3'): 243,
sp.bytes('0xf4'): 244, sp.bytes('0xf5'): 245,
sp.bytes('0xf6'): 246, sp.bytes('0xf7'): 247,
sp.bytes('0xf8'): 248, sp.bytes('0xf9'): 249,
sp.bytes('0xfa'): 250, sp.bytes('0xfb'): 251,
sp.bytes('0xfc'): 252, sp.bytes('0xfd'): 253,
sp.bytes('0xfe'): 254, sp.bytes('0xff'): 255
}
nat_value = 0
contract = sp.create_contract_operation(sp.Contract(), sp.unit, sp.tez(0), None);
# Convert given string (as bytes) to sha256 hash
b = sp.pack(contract.address)
ha = sp.sha256(b)
# Iterate over each byte of the hash and look up the corresponding int value from our big table above
x = sp.local('x', 0)
# Store the 'total' Nat value of the bytes
total = sp.local('total', 0)
hash_len = sp.local("hash_len", sp.len(ha))
sp.while x.value < hash_len.value:
# Add to previous total and then multiple the new value by 256
total.value = (total.value + bytes_to_nat.value.get(sp.slice(ha, x.value, 1).open_some())) * 256
sp.if total.value >= 1000000000000000:
x.value = 1000000000000000
sp.else:
x.value = x.value + 1
num = (total.value // 10)
return num
