Merge pull request #9 from 0xProject/generateSalt

Add generateSalt and tests for it

1 files changed, 15 insertions, 0 deletions

diff --git a/src/ts/0x.js.ts b/src/ts/0x.js.ts
index acbdd01e2..4b9680a18 100644
--- a/src/ts/0x.js.ts
+++ b/src/ts/0x.js.ts
@@ -11,6 +11,8 @@ export interface ECSignature {
     s: string;
 }
 
+const MAX_DIGITS_IN_UNSIGNED_256_INT = 78;
+
 export class ZeroEx {
     /**
      * Verifies that the elliptic curve signature `signature` was generated
@@ -34,4 +36,17 @@ export class ZeroEx {
             return false;
         }
     }
+    /**
+     * Generates pseudo-random 256 bit salt.
+     * The salt is used to ensure that the 0x order generated has a unique orderHash that does
+     * not collide with any other outstanding orders.
+     */
+    public static generatePseudoRandomSalt(): BigNumber.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 salt = randomNumber.times(factor).round();
+        return salt;
+    }
 }