1 files changed, 38 insertions, 0 deletions
diff --git a/packages/contracts/util/crypto.ts b/packages/contracts/util/crypto.ts
new file mode 100644
index 000000000..e4baee021
--- /dev/null
+++ b/packages/contracts/util/crypto.ts
@@ -0,0 +1,38 @@
+import {BigNumber} from 'bignumber.js';
+import BN = require('bn.js');
+import ABI = require('ethereumjs-abi');
+import ethUtil = require('ethereumjs-util');
+import * as _ from 'lodash';
+
+export const crypto = {
+  /*
+   * We convert types from JS to Solidity as follows:
+   * BigNumber -> uint256
+   * number -> uint8
+   * string -> string
+   * boolean -> bool
+   * valid Ethereum address -> address
+   */
+  solSHA3(args: any[]): Buffer {
+    const argTypes: string[] = [];
+    _.each(args, (arg, i) => {
+      const isNumber = _.isFinite(arg);
+      if (isNumber) {
+        argTypes.push('uint8');
+      } else if ((arg).isBigNumber) {
+        argTypes.push('uint256');
+        args[i] = new BN(arg.toString(10), 10);
+      } else if (ethUtil.isValidAddress(arg)) {
+        argTypes.push('address');
+      } else if (_.isString(arg)) {
+        argTypes.push('string');
+      } else if  (_.isBoolean(arg)) {
+        argTypes.push('bool');
+      } else {
+        throw new Error(`Unable to guess arg type: ${arg}`);
+      }
+    });
+    const hash = ABI.soliditySHA3(argTypes, args);
+    return hash;
+  },
+};