fix(Crypto): Fix keypair verification (#605)

* convert test message to buffer in isValidKeypair 

fixes aeternity/aepp-base#1090

* add test for keypair validity verification

Author: mradkov

es/utils/crypto.js

@@ -498,7 +498,7 @@ export function encodeTx (txData) {
  * @return {Boolean} Valid?
  */
 export function isValidKeypair (privateKey, publicKey) {
-  const message = 'TheMessage'
+  const message = Buffer.from('TheMessage')
   const signature = sign(message, privateKey)
   return verify(message, signature, publicKey)
 }

test/unit/crypto.js

@@ -48,7 +48,16 @@ describe('crypto', () => {
       assert.isAtMost(keyPair.publicKey.length, 53)
     })
   })
-
+  
+  describe('isValidKeypair', () => {
+    it('verify the generated key pair', () => {
+      const keyPair = Crypto.generateKeyPair(true)
+      assert.ok(keyPair)
+      const verifyResult = Crypto.isValidKeypair(keyPair.secretKey, keyPair.publicKey)
+      assert.isTrue(verifyResult)
+    })
+  })
+  
   describe('encryptPassword', () => {
     describe('generate a password encrypted key pair', () => {
       const keyPair = Crypto.generateKeyPair(true)