feat: break out address checksum encoding to erc55EncodeAddress function

src/hex.test.ts

@@ -8,6 +8,7 @@ import {
   isStrictHexString,
   isValidHexAddress,
   remove0x,
+  getChecksumAddress,
 } from './hex';
 
 describe('isHexString', () => {
@@ -192,6 +193,30 @@ describe('isValidHexAddress', () => {
   });
 });
 
+describe('getChecksumAddress', () => {
+  it('returns the checksum address for a valid hex address', () => {
+    expect(
+      getChecksumAddress('0x5aaeb6053f3e94c9b9a09f33669435e7ef1beaed'),
+    ).toBe('0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed');
+
+    expect(
+      getChecksumAddress('0xfb6916095ca1df60bb79ce92ce3ea74c37c5d359'),
+    ).toBe('0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359');
+
+    expect(
+      getChecksumAddress('0x52908400098527886e0f7030069857d2e4169ee7'),
+    ).toBe('0x52908400098527886E0F7030069857D2E4169EE7');
+
+    expect(
+      getChecksumAddress('0xde709f2102306220921060314715629080e2fb77'),
+    ).toBe('0xde709f2102306220921060314715629080e2fb77');
+
+    expect(
+      getChecksumAddress('0x0000000000000000000000000000000000000000'),
+    ).toBe('0x0000000000000000000000000000000000000000');
+  });
+});
+
 describe('isValidChecksumAddress', () => {
   it.each([
     '0x0000000000000000000000000000000000000000' as Hex,

src/hex.ts

@@ -79,6 +79,26 @@ export function isValidHexAddress(possibleAddress: Hex) {
   );
 }
 
+/**
+ * Encode a passed hex string as an ERC-55 mixed-case checksum address.
+ *
+ * @param address - The hex address to encode.
+ * @returns The address encoded according to ERC-55.
+ * @see https://eips.ethereum.org/EIPS/eip-55
+ */
+export function getChecksumAddress(address: Hex) {
+  const unPrefixed = remove0x(address.toLowerCase());
+  const unPrefixedHash = remove0x(bytesToHex(keccak256(unPrefixed)));
+  return `0x${unPrefixed
+    .split('')
+    .map((character, nibbleIndex) =>
+      parseInt(unPrefixedHash[nibbleIndex] as string, 16) > 7
+        ? character.toUpperCase()
+        : character,
+    )
+    .join('')}`;
+}
+
 /**
  * Validate that the passed hex string is a valid ERC-55 mixed-case
  * checksum address.
@@ -91,22 +111,7 @@ export function isValidChecksumAddress(possibleChecksum: Hex) {
     return false;
   }
 
-  const unPrefixed = remove0x(possibleChecksum);
-  const unPrefixedHash = remove0x(
-    bytesToHex(keccak256(unPrefixed.toLowerCase())),
-  );
-
-  for (let i = 0; i < unPrefixedHash.length; i++) {
-    const value = parseInt(unPrefixedHash[i] as string, 16);
-    if (
-      (value > 7 && unPrefixed[i]?.toUpperCase() !== unPrefixed[i]) ||
-      (value <= 7 && unPrefixed[i]?.toLowerCase() !== unPrefixed[i])
-    ) {
-      return false;
-    }
-  }
-
-  return true;
+  return getChecksumAddress(possibleChecksum) === possibleChecksum;
 }
 
 /**

yarn.lock

@@ -1100,23 +1100,16 @@ __metadata:
   languageName: unknown
   linkType: soft
 
-"@noble/curves@npm:1.0.0, @noble/curves@npm:~1.0.0":
-  version: 1.0.0
-  resolution: "@noble/curves@npm:1.0.0"
+"@noble/curves@npm:1.1.0, @noble/curves@npm:~1.1.0":
+  version: 1.1.0
+  resolution: "@noble/curves@npm:1.1.0"
   dependencies:
-    "@noble/hashes": 1.3.0
-  checksum: 6bcef44d626c640dc8961819d68dd67dffb907e3b973b7c27efe0ecdd9a5c6ce62c7b9e3dfc930c66605dced7f1ec0514d191c09a2ce98d6d52b66e3315ffa79
+    "@noble/hashes": 1.3.1
+  checksum: 2658cdd3f84f71079b4e3516c47559d22cf4b55c23ac8ee9d2b1f8e5b72916d9689e59820e0f9d9cb4a46a8423af5b56dc6bb7782405c88be06a015180508db5
   languageName: node
   linkType: hard
 
-"@noble/hashes@npm:1.3.0":
-  version: 1.3.0
-  resolution: "@noble/hashes@npm:1.3.0"
-  checksum: d7ddb6d7c60f1ce1f87facbbef5b724cdea536fc9e7f59ae96e0fc9de96c8f1a2ae2bdedbce10f7dcc621338dfef8533daa73c873f2b5c87fa1a4e05a95c2e2e
-  languageName: node
-  linkType: hard
-
-"@noble/hashes@npm:^1.3.0, @noble/hashes@npm:^1.3.1, @noble/hashes@npm:~1.3.0":
+"@noble/hashes@npm:1.3.1, @noble/hashes@npm:^1.3.0, @noble/hashes@npm:^1.3.1, @noble/hashes@npm:~1.3.0, @noble/hashes@npm:~1.3.1":
   version: 1.3.1
   resolution: "@noble/hashes@npm:1.3.1"
   checksum: 7fdefc0f7a0c1ec27acc6ff88841793e3f93ec4ce6b8a6a12bfc0dd70ae6b7c4c82fe305fdfeda1735d5ad4a9eebe761e6693b3d355689c559e91242f4bc95b1
@@ -1219,24 +1212,24 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@scure/bip32@npm:1.3.0":
-  version: 1.3.0
-  resolution: "@scure/bip32@npm:1.3.0"
+"@scure/bip32@npm:1.3.1":
+  version: 1.3.1
+  resolution: "@scure/bip32@npm:1.3.1"
   dependencies:
-    "@noble/curves": ~1.0.0
-    "@noble/hashes": ~1.3.0
+    "@noble/curves": ~1.1.0
+    "@noble/hashes": ~1.3.1
     "@scure/base": ~1.1.0
-  checksum: 6eae997f9bdf41fe848134898960ac48e645fa10e63d579be965ca331afd0b7c1b8ebac170770d237ab4099dafc35e5a82995384510025ccf2abe669f85e8918
+  checksum: 394d65f77a40651eba21a5096da0f4233c3b50d422864751d373fcf142eeedb94a1149f9ab1dbb078086dab2d0bc27e2b1afec8321bf22d4403c7df2fea5bfe2
   languageName: node
   linkType: hard
 
-"@scure/bip39@npm:1.2.0":
-  version: 1.2.0
-  resolution: "@scure/bip39@npm:1.2.0"
+"@scure/bip39@npm:1.2.1":
+  version: 1.2.1
+  resolution: "@scure/bip39@npm:1.2.1"
   dependencies:
     "@noble/hashes": ~1.3.0
     "@scure/base": ~1.1.0
-  checksum: 980d761f53e63de04a9e4db840eb13bfb1bd1b664ecb04a71824c12c190f4972fd84146f3ed89b2a8e4c6bd2c17c15f8b592b7ac029e903323b0f9e2dae6916b
+  checksum: c5bd6f1328fdbeae2dcdd891825b1610225310e5e62a4942714db51066866e4f7bef242c7b06a1b9dcc8043a4a13412cf5c5df76d3b10aa9e36b82e9b6e3eeaa
   languageName: node
   linkType: hard
 
@@ -3231,14 +3224,14 @@ __metadata:
   linkType: hard
 
 "ethereum-cryptography@npm:^2.0.0":
-  version: 2.0.0
-  resolution: "ethereum-cryptography@npm:2.0.0"
+  version: 2.1.0
+  resolution: "ethereum-cryptography@npm:2.1.0"
   dependencies:
-    "@noble/curves": 1.0.0
-    "@noble/hashes": 1.3.0
-    "@scure/bip32": 1.3.0
-    "@scure/bip39": 1.2.0
-  checksum: 958f8aab2d1b32aa759fb27a27877b3647410e8bb9aca7d65d1d477db4864cf7fc46b918eb52a1e246c25e98ee0a35a632c88b496aeaefa13469ee767a76c8db
+    "@noble/curves": 1.1.0
+    "@noble/hashes": 1.3.1
+    "@scure/bip32": 1.3.1
+    "@scure/bip39": 1.2.1
+  checksum: 47bd69103f0553e5c98e0645c295ca74e0da53a92b8d26237287f528521cd2aa13d5cd1e288c36e59ce885451199cef8e4de424a93c45bacf54a06bdd09946a4
   languageName: node
   linkType: hard