5 files changed, 50 insertions, 4 deletions
diff --git a/src/ts/0x.js.ts b/src/ts/0x.js.ts
index 89d049bec..d189b48b1 100644
--- a/src/ts/0x.js.ts
+++ b/src/ts/0x.js.ts
@@ -1,6 +1,7 @@
 import * as BigNumber from 'bignumber.js';
 import * as ethUtil from 'ethereumjs-util';
 import {assert} from './utils/assert';
+import {ECSignatureSchema} from './schemas/ec_signature_schema';
 
 /**
  * Elliptic Curve signature
@@ -21,7 +22,7 @@ export class ZeroEx {
      */
     public static isValidSignature(dataHex: string, signature: ECSignature, signer: ETHAddressHex): boolean {
         assert.isHexString('dataHex', dataHex);
-        assert.isObject('signature', signature);
+        assert.doesConformToSchema('signature', signature, ECSignatureSchema);
         assert.isETHAddressHex('signer', signer);
 
         const dataBuff = ethUtil.toBuffer(dataHex);
diff --git a/src/ts/globals.d.ts b/src/ts/globals.d.ts
index c9cc0d481..58efe136a 100644
--- a/src/ts/globals.d.ts
+++ b/src/ts/globals.d.ts
@@ -2,6 +2,10 @@ declare type ETHPublicKey = string;
 declare type ETHAddressHex = string;
 declare type ETHAddressBuff = Buffer;
 
+declare interface Schema {
+    id: string;
+}
+
 declare module 'ethereumjs-util' {
     const toBuffer: (dataHex: string) => Buffer;
     const hashPersonalMessage: (msg: Buffer) => Buffer;
diff --git a/src/ts/schemas/ec_signature_schema.ts b/src/ts/schemas/ec_signature_schema.ts
new file mode 100644
index 000000000..94e58e53c
--- /dev/null
+++ b/src/ts/schemas/ec_signature_schema.ts
@@ -0,0 +1,20 @@
+export const ECSignatureParameter = {
+    id: '/ECSignatureParameter',
+    type: 'string',
+    pattern: '^0[xX][0-9A-Fa-f]{64}$',
+};
+
+export const ECSignatureSchema = {
+    id: '/ECSignature',
+    properties: {
+        v: {
+            type: 'number',
+            minimum: 27,
+            maximum: 28,
+        },
+        r: {$ref: '/ECSignatureParameter'},
+        s: {$ref: '/ECSignatureParameter'},
+    },
+    required: ['v', 'r', 's'],
+    type: 'object',
+};
diff --git a/src/ts/utils/assert.ts b/src/ts/utils/assert.ts
index 602361233..58182dac0 100644
--- a/src/ts/utils/assert.ts
+++ b/src/ts/utils/assert.ts
@@ -1,6 +1,7 @@
 import * as _ from 'lodash';
 import * as BigNumber from 'bignumber.js';
 import Web3 = require('web3');
+import {SchemaValidator} from './schema_validator';
 
 const HEX_REGEX = /^0x([0-9A-F]{2})*$/i;
 
@@ -20,12 +21,18 @@ export const assert = {
         const web3 = new Web3();
         this.assert(web3.isAddress(value), this.typeAssertionMessage(variableName, 'ETHAddressHex', value));
     },
-    isObject(variableName: string, value: object) {
-        this.assert(_.isObject(value), this.typeAssertionMessage(variableName, 'object', value));
-    },
     isNumber(variableName: string, value: number) {
         this.assert(_.isFinite(value), this.typeAssertionMessage(variableName, 'number', value));
     },
+    doesConformToSchema(variableName: string, value: object, schema: Schema) {
+        const schemaValidator = new SchemaValidator();
+        const validationResult = schemaValidator.validate(value, schema);
+        const hasValidationErrors = validationResult.errors.length > 0;
+        const msg = `Expected ${variableName} to conform to schema ${schema.id}
+Encountered: ${JSON.stringify(value, null, '\t')}
+Validation errors: ${validationResult.errors.join(', ')}`;
+        this.assert(!hasValidationErrors, msg);
+    },
     assert(condition: boolean, message: string) {
         if (!condition) {
             throw new Error(message);
diff --git a/src/ts/utils/schema_validator.ts b/src/ts/utils/schema_validator.ts
new file mode 100644
index 000000000..bd2f97d2b
--- /dev/null
+++ b/src/ts/utils/schema_validator.ts
@@ -0,0 +1,14 @@
+import {Validator, ValidatorResult} from 'jsonschema';
+import {ECSignatureSchema, ECSignatureParameter} from '../schemas/ec_signature_schema';
+
+export class SchemaValidator {
+    private validator: Validator;
+    constructor() {
+        this.validator = new Validator();
+        this.validator.addSchema(ECSignatureParameter, ECSignatureParameter.id);
+        this.validator.addSchema(ECSignatureSchema, ECSignatureSchema.id);
+    }
+    public validate(instance: object, schema: Schema): ValidatorResult {
+        return this.validator.validate(instance, schema);
+    }
+}