From cae35522ce1a546d3eb95628a29ded98619160c3 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Thu, 23 Jan 2020 17:20:34 +0100
Subject: [PATCH] Add decodeCosmosPubkey

---
 src/address.spec.ts | 13 ++++++++++++-
 src/address.ts      | 30 +++++++++++++++++++++++++++++-
 types/address.d.ts  |  6 ++++++
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/address.spec.ts b/src/address.spec.ts
index f0a97792..1d138206 100644
--- a/src/address.spec.ts
+++ b/src/address.spec.ts
@@ -1,7 +1,7 @@
 import { Address, Algorithm, PubkeyBytes } from "@iov/bcp";
 import { Encoding } from "@iov/encoding";
 
-import { decodeCosmosAddress, isValidAddress, pubkeyToAddress } from "./address";
+import { decodeCosmosAddress, decodeCosmosPubkey, isValidAddress, pubkeyToAddress } from "./address";
 
 const { fromBase64, fromHex } = Encoding;
 
@@ -28,6 +28,17 @@ describe("address", () => {
     });
   });
 
+  describe("decodeCosmosPubkey", () => {
+    it("works", () => {
+      expect(
+        decodeCosmosPubkey("cosmospub1addwnpepqd8sgxq7aw348ydctp3n5ajufgxp395hksxjzc6565yfp56scupfqhlgyg5"),
+      ).toEqual({
+        prefix: "cosmospub",
+        data: fromBase64("A08EGB7ro1ORuFhjOnZcSgwYlpe0DSFjVNUIkNNQxwKQ"),
+      });
+    });
+  });
+
   describe("isValidAddress", () => {
     it("accepts valid addresses", () => {
       expect(isValidAddress("cosmos1pkptre7fdkl6gfrzlesjjvhxhlc3r4gmmk8rs6")).toEqual(true);
diff --git a/src/address.ts b/src/address.ts
index 853e24af..d36a50d4 100644
--- a/src/address.ts
+++ b/src/address.ts
@@ -1,15 +1,23 @@
 import { Address, Algorithm, PubkeyBundle } from "@iov/bcp";
 import { Ripemd160, Secp256k1, Sha256 } from "@iov/crypto";
-import { Bech32 } from "@iov/encoding";
+import { Bech32, Encoding } from "@iov/encoding";
+import equal from "fast-deep-equal";
 
 export type CosmosAddressBech32Prefix = "cosmos" | "cosmosvalcons" | "cosmosvaloper";
 export type CosmosPubkeyBech32Prefix = "cosmospub" | "cosmosvalconspub" | "cosmosvaloperpub";
 export type CosmosBech32Prefix = CosmosAddressBech32Prefix | CosmosPubkeyBech32Prefix;
 
+// As discussed in https://github.com/binance-chain/javascript-sdk/issues/163
+const pubkeyAminoPrefix = Encoding.fromHex("eb5ae98721");
+
 function isCosmosAddressBech32Prefix(prefix: string): prefix is CosmosAddressBech32Prefix {
   return ["cosmos", "cosmosvalcons", "cosmosvaloper"].includes(prefix);
 }
 
+function isCosmosPubkeyBech32Prefix(prefix: string): prefix is CosmosPubkeyBech32Prefix {
+  return ["cosmospub", "cosmosvalconspub", "cosmosvaloperpub"].includes(prefix);
+}
+
 export function decodeCosmosAddress(
   address: Address,
 ): { readonly prefix: CosmosAddressBech32Prefix; readonly data: Uint8Array } {
@@ -23,6 +31,26 @@ export function decodeCosmosAddress(
   return { prefix: prefix, data: data };
 }
 
+export function decodeCosmosPubkey(
+  encodedPubkey: string,
+): { readonly prefix: CosmosPubkeyBech32Prefix; readonly data: Uint8Array } {
+  const { prefix, data } = Bech32.decode(encodedPubkey);
+  if (!isCosmosPubkeyBech32Prefix(prefix)) {
+    throw new Error(`Invalid bech32 prefix. Must be one of cosmos, cosmosvalcons, or cosmosvaloper.`);
+  }
+
+  if (!equal(data.slice(0, pubkeyAminoPrefix.length), pubkeyAminoPrefix)) {
+    throw new Error("Pubkey does not have the expected amino prefix " + Encoding.toHex(pubkeyAminoPrefix));
+  }
+
+  const rest = data.slice(pubkeyAminoPrefix.length);
+  if (rest.length !== 33) {
+    throw new Error("Invalid rest data length. Expected 33 bytes (compressed secp256k1 pubkey).");
+  }
+
+  return { prefix: prefix, data: rest };
+}
+
 export function isValidAddress(address: string): boolean {
   try {
     decodeCosmosAddress(address as Address);
diff --git a/types/address.d.ts b/types/address.d.ts
index 776cb61d..252add6e 100644
--- a/types/address.d.ts
+++ b/types/address.d.ts
@@ -8,5 +8,11 @@ export declare function decodeCosmosAddress(
   readonly prefix: CosmosAddressBech32Prefix;
   readonly data: Uint8Array;
 };
+export declare function decodeCosmosPubkey(
+  encodedPubkey: string,
+): {
+  readonly prefix: CosmosPubkeyBech32Prefix;
+  readonly data: Uint8Array;
+};
 export declare function isValidAddress(address: string): boolean;
 export declare function pubkeyToAddress(pubkey: PubkeyBundle, prefix: CosmosBech32Prefix): Address;