1 files changed, 34 insertions, 0 deletions
diff --git a/packages/assert/src/address_utils.ts b/packages/assert/src/address_utils.ts
new file mode 100644
index 000000000..bdbcd3a89
--- /dev/null
+++ b/packages/assert/src/address_utils.ts
@@ -0,0 +1,34 @@
+import * as jsSHA3 from 'js-sha3';
+
+const BASIC_ADDRESS_REGEX = /^(0x)?[0-9a-f]{40}$/i;
+const SAME_CASE_ADDRESS_REGEX = /^(0x)?([0-9a-f]{40}|[0-9A-F]{40})$/;
+
+export const addressUtils = {
+    isChecksumAddress(address: string): boolean {
+        // Check each case
+        const unprefixedAddress = address.replace('0x', '');
+        const addressHash = jsSHA3.keccak256(unprefixedAddress.toLowerCase());
+
+        for (let i = 0; i < 40; i++) {
+            // The nth letter should be uppercase if the nth digit of casemap is 1
+            if ((parseInt(addressHash[i], 16) > 7 && unprefixedAddress[i].toUpperCase() !== unprefixedAddress[i]) ||
+                (parseInt(addressHash[i], 16) <= 7 && unprefixedAddress[i].toLowerCase() !== unprefixedAddress[i])) {
+                return false;
+            }
+        }
+        return true;
+    },
+    isAddress(address: string): boolean {
+        if (!BASIC_ADDRESS_REGEX.test(address)) {
+            // Check if it has the basic requirements of an address
+            return false;
+        } else if (SAME_CASE_ADDRESS_REGEX.test(address)) {
+            // If it's all small caps or all all caps, return true
+            return true;
+        } else {
+            // Otherwise check each case
+            const isValidChecksummedAddress = addressUtils.isChecksumAddress(address);
+            return isValidChecksummedAddress;
+        }
+    },
+};