Deduped random value generation from salt generation

packages/utils/src/address_utils.ts

@@ -1,7 +1,9 @@
-import { addHexPrefix, stripHexPrefix } from 'ethereumjs-util';
+import { addHexPrefix, sha3, stripHexPrefix } from 'ethereumjs-util';
 import * as jsSHA3 from 'js-sha3';
 import * as _ from 'lodash';
 
+import { generatePseudoRandom256BitNumber } from './random';
+
 const BASIC_ADDRESS_REGEX = /^(0x)?[0-9a-f]{40}$/i;
 const SAME_CASE_ADDRESS_REGEX = /^(0x)?([0-9a-f]{40}|[0-9A-F]{40})$/;
 const ADDRESS_LENGTH = 40;
@@ -43,4 +45,11 @@ export const addressUtils = {
     padZeros(address: string): string {
         return addHexPrefix(_.padStart(stripHexPrefix(address), ADDRESS_LENGTH, '0'));
     },
+    generatePseudoRandomAddress(): string {
+        const randomBigNum = generatePseudoRandom256BitNumber();
+        const randomBuff = sha3(randomBigNum.toString());
+        const addressLengthInBytes = 20;
+        const randomAddress = `0x${randomBuff.slice(0, addressLengthInBytes).toString('hex')}`;
+        return randomAddress;
+    },
 };

packages/utils/src/index.ts

@@ -12,3 +12,4 @@ export { fetchAsync } from './fetch_async';
 export { signTypedDataUtils } from './sign_typed_data_utils';
 export import AbiEncoder = require('./abi_encoder');
 export * from './types';
+export { generatePseudoRandom256BitNumber } from './random';

packages/utils/src/random.ts

@@ -0,0 +1,16 @@
+import { BigNumber } from './configured_bignumber';
+
+const MAX_DIGITS_IN_UNSIGNED_256_INT = 78;
+
+/**
+ * Generates a pseudo-random 256-bit number.
+ * @return  A pseudo-random 256-bit number.
+ */
+export function generatePseudoRandom256BitNumber(): BigNumber {
+    // BigNumber.random returns a pseudo-random number between 0 & 1 with a passed in number of decimal places.
+    // Source: https://mikemcl.github.io/bignumber.js/#random
+    const randomNumber = BigNumber.random(MAX_DIGITS_IN_UNSIGNED_256_INT);
+    const factor = new BigNumber(10).pow(MAX_DIGITS_IN_UNSIGNED_256_INT - 1);
+    const randomNumberScaledTo256Bits = randomNumber.times(factor).integerValue();
+    return randomNumberScaledTo256Bits;
+}