Introduce support for checksum addresses

ethereum/EIPs#55

index.js

@@ -325,6 +325,38 @@ exports.privateToAddress = function (privateKey) {
   return exports.publicToAddress(privateToPublic(privateKey))
 }
 
+/**
+ * Returns a checksummed address
+ * @method toChecksumAddress
+ * @param {String} address
+ * @return {String}
+ */
+exports.toChecksumAddress = function (address) {
+  address = exports.stripHexPrefix(address)
+  var hash = exports.sha3(address).toString('hex')
+  var ret = '0x'
+
+  for (var i = 0; i < address.length; i++) {
+    if (parseInt(hash[i], 16) >= 8) {
+      ret += address[i].toUpperCase()
+    } else {
+      ret += address[i]
+    }
+  }
+
+  return ret
+}
+
+/**
+ * Checks if the address is a valid checksummed address
+ * @method isValidChecksumAddress
+ * @param {Buffer} address
+ * @return {Boolean}
+ */
+exports.isValidChecksumAddress = function (address) {
+  return exports.toChecksumAddress(address.toLowerCase()) === address
+}
+
 /**
  * Generates an address of a newly created contract
  * @method generateAddress

test/index.js

@@ -380,3 +380,37 @@ describe('ecrecover', function () {
     })
   })
 })
+
+var checksumAddresses = [
+  // All caps
+  '0x52908400098527886E0F7030069857D2E4169EE7',
+  '0x8617E340B3D01FA5F11F306F4090FD50E238070D',
+  // All Lower
+  '0xde709f2102306220921060314715629080e2fb77',
+  '0x27b1fdb04752bbc536007a920d24acb045561c26',
+  // Normal
+  '0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed',
+  '0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359',
+  '0xdbF03B407c01E7cD3CBea99509d93f8DDDC8C6FB',
+  '0xD1220A0cf47c7B9Be7A2E6BA89F429762e7b9aDb'
+]
+
+describe('.toChecksumAddress()', function () {
+  it('should work', function () {
+    for (var i = 0; i < checksumAddresses.length; i++) {
+      var tmp = checksumAddresses[i]
+      assert.equal(ethUtils.toChecksumAddress(tmp.toLowerCase()), tmp)
+    }
+  })
+})
+
+describe('.isValidChecksumAddress()', function () {
+  it('should return true', function () {
+    for (var i = 0; i < checksumAddresses.length; i++) {
+      assert.equal(ethUtils.isValidChecksumAddress(checksumAddresses[i]), true)
+    }
+  })
+  it('should validate', function () {
+    assert.equal(ethUtils.isValidChecksumAddress('0x2f015c60e0be116b1f0cd534704db9c92118fb6a'), false)
+  })
+})