feat: encode principal to Eth address as hex

packages/cketh/src/index.ts

@@ -4,3 +4,4 @@ export type {
 } from "../candid/minter";
 export * from "./errors/minter.errors";
 export { CkETHMinterCanister } from "./minter.canister";
+export * from "./utils/minter.utils";

packages/cketh/src/utils/minter.utils.spec.ts

@@ -0,0 +1,36 @@
+import { Principal } from "@dfinity/principal";
+import { encodePrincipalToEthAddress } from "./minter.utils";
+
+describe("minter-utils", () => {
+  const mockPrincipalExample1 = Principal.from(
+    "esd5n-wtdqq-kimdw-qrxjr-7luer-zjhez-hsauj-pu5ox-2y6ov-g53g4-xqe",
+  );
+  const ethExample1 =
+    "0x1d638414860ed08dd31fae848e527264f20512fa75d7d63cea9bbb372f020000";
+
+  const mockPrincipalExample2 = Principal.from(
+    "auycm-ouxjf-el73p-7cfpm-73w3q-fd7xc-ubevq-ea4vt-vpe2n-rs7e5-qqe",
+  );
+  const ethExample2 =
+    "0x1d974948bfedff115ecfeedb8147fb8a8125604072b3abc9a6c65f2761020000";
+
+  const mockPrincipalExample3 = Principal.from(
+    "ouoed-xoejt-4ssko-nf4tu-w3wbu-x2lz7-qfili-67oyv-kz4kf-nmo7q-yqe",
+  );
+  const ethExample3 =
+    "0x1dc44cf92929cd2f274b6ec1a5f4bcfe0542d1efbb155678a2b58efc31020000";
+
+  it("should encode principal into fixed 32-byte representation suitable for calling Ethereum smart contracts", () => {
+    expect(encodePrincipalToEthAddress(mockPrincipalExample1)).toEqual(
+      ethExample1,
+    );
+
+    expect(encodePrincipalToEthAddress(mockPrincipalExample2)).toEqual(
+      ethExample2,
+    );
+
+    expect(encodePrincipalToEthAddress(mockPrincipalExample3)).toEqual(
+      ethExample3,
+    );
+  });
+});

packages/cketh/src/utils/minter.utils.ts

@@ -0,0 +1,45 @@
+import type { Principal } from "@dfinity/principal";
+import { decodeBase32 } from "@dfinity/utils";
+
+/**
+ * Encode a principal to a byte array as Ethereum data hex (staring with 0x).
+ * Such a conversion is required to deposit ETH to the ckETH helper contract.
+ *
+ * Code adapted from the ckETH minter dashboard JS function: https://github.com/dfinity/ic/blob/master/rs/ethereum/cketh/minter/templates/principal_to_bytes.js
+ *
+ * @param principal The principal to encode into a fixed 32-byte representation suitable for calling Ethereum smart contracts.
+ */
+export const encodePrincipalToEthAddress = (principal: Principal): string => {
+  const rawBytes = decodeBase32(principal.toText().replace(/-/g, ""));
+  return bytes32Encode(rawBytes.slice(4));
+};
+
+/**
+ * Appends a hex representation of a number to string.
+ * @param {string} s A string to append the hex to.
+ * @param {number} b A byte.
+ * @return {string} An updated string.
+ */
+const appendHexByte = (s: string, b: number): string => {
+  s += ((b >> 4) & 0x0f).toString(16);
+  s += (b & 0x0f).toString(16);
+  return s;
+};
+
+/**
+ * Encodes a byte array as Ethereum data hex (staring with 0x).
+ * @param {Array<number>} bytes A byte array.
+ * @return {string} A hex string.
+ */
+const bytes32Encode = (bytes: Uint8Array): string => {
+  const n = bytes.length;
+  let s = "0x";
+  s = appendHexByte(s, n);
+  for (let i = 0; i < bytes.length; i++) {
+    s = appendHexByte(s, bytes[i]);
+  }
+  for (let i = 0; i < 31 - bytes.length; i++) {
+    s += "00";
+  }
+  return s;
+};

scripts/docs.js

@@ -40,7 +40,10 @@ const ckBTCInputFiles = [
   "./packages/ckbtc/src/utils/btc.utils.ts",
 ];
 
-const ckETHInputFiles = ["./packages/cketh/src/minter.canister.ts"];
+const ckETHInputFiles = [
+  "./packages/cketh/src/minter.canister.ts",
+  "./packages/ledger-icrc/src/utils/minter.utils.ts",
+];
 
 const icMgmtInputFiles = [
   "./packages/ic-management/src/ic-management.canister.ts",