diff --git a/packages/cli/src/cli.ts b/packages/cli/src/cli.ts
index d39287a9..42b4ff56 100644
--- a/packages/cli/src/cli.ts
+++ b/packages/cli/src/cli.ts
@@ -41,6 +41,7 @@ export function main(originalArgs: readonly string[]): void {
     [
       "@cosmwasm/sdk",
       [
+        "encodeSecp256k1Pubkey",
         "encodeSecp256k1Signature",
         "makeSignBytes",
         "marshalTx",
diff --git a/packages/sdk/src/encoding.ts b/packages/sdk/src/encoding.ts
index ad3a4fa1..49a9fde4 100644
--- a/packages/sdk/src/encoding.ts
+++ b/packages/sdk/src/encoding.ts
@@ -1,7 +1,8 @@
 import { Secp256k1 } from "@iov/crypto";
 import { Encoding } from "@iov/encoding";
 
-import { Msg, NonceInfo, pubkeyType, StdFee, StdSignature, StdTx } from "./types";
+import { encodeSecp256k1Pubkey } from "./pubkey";
+import { Msg, NonceInfo, StdFee, StdSignature, StdTx } from "./types";
 
 const { toBase64, toUtf8 } = Encoding;
 
@@ -61,10 +62,7 @@ export function makeSignBytes(
 export function encodeSecp256k1Signature(pubkey: Uint8Array, signature: Uint8Array): StdSignature {
   return {
     // eslint-disable-next-line @typescript-eslint/camelcase
-    pub_key: {
-      type: pubkeyType.secp256k1,
-      value: toBase64(Secp256k1.compressPubkey(pubkey)),
-    },
+    pub_key: encodeSecp256k1Pubkey(pubkey),
     // Recovery seems to be unused
     signature: toBase64(Secp256k1.trimRecoveryByte(signature)),
   };
diff --git a/packages/sdk/src/index.ts b/packages/sdk/src/index.ts
index 271e6a18..1908af35 100644
--- a/packages/sdk/src/index.ts
+++ b/packages/sdk/src/index.ts
@@ -7,3 +7,4 @@ export { unmarshalTx } from "./decoding";
 export { encodeSecp256k1Signature, makeSignBytes, marshalTx } from "./encoding";
 export { RestClient, TxsResponse } from "./restclient";
 export { makeCosmoshubPath, Pen, PrehashType, Secp256k1Pen } from "./pen";
+export { encodeSecp256k1Pubkey } from "./pubkey";
diff --git a/packages/sdk/src/pubkey.spec.ts b/packages/sdk/src/pubkey.spec.ts
new file mode 100644
index 00000000..0b700496
--- /dev/null
+++ b/packages/sdk/src/pubkey.spec.ts
@@ -0,0 +1,27 @@
+import { Encoding } from "@iov/encoding";
+
+import { encodeSecp256k1Pubkey } from "./pubkey";
+
+const { fromBase64 } = Encoding;
+
+describe("pubkey", () => {
+  describe("encodeSecp256k1Pubkey", () => {
+    it("encodes a full signature", () => {
+      const pubkey = fromBase64("AtQaCqFnshaZQp6rIkvAPyzThvCvXSDO+9AzbxVErqJP");
+      expect(encodeSecp256k1Pubkey(pubkey)).toEqual({
+        type: "tendermint/PubKeySecp256k1",
+        value: "AtQaCqFnshaZQp6rIkvAPyzThvCvXSDO+9AzbxVErqJP",
+      });
+    });
+
+    it("compresses uncompressed public keys", () => {
+      const pubkey = fromBase64(
+        "BE8EGB7ro1ORuFhjOnZcSgwYlpe0DSFjVNUIkNNQxwKQE7WHpoHoNswYeoFkuYpYSKK4mzFzMV/dB0DVAy4lnNU=",
+      );
+      expect(encodeSecp256k1Pubkey(pubkey)).toEqual({
+        type: "tendermint/PubKeySecp256k1",
+        value: "A08EGB7ro1ORuFhjOnZcSgwYlpe0DSFjVNUIkNNQxwKQ",
+      });
+    });
+  });
+});
diff --git a/packages/sdk/src/pubkey.ts b/packages/sdk/src/pubkey.ts
new file mode 100644
index 00000000..73b10695
--- /dev/null
+++ b/packages/sdk/src/pubkey.ts
@@ -0,0 +1,11 @@
+import { Secp256k1 } from "@iov/crypto";
+import { Encoding } from "@iov/encoding";
+
+import { PubKey, pubkeyType } from "./types";
+
+export function encodeSecp256k1Pubkey(pubkey: Uint8Array): PubKey {
+  return {
+    type: pubkeyType.secp256k1,
+    value: Encoding.toBase64(Secp256k1.compressPubkey(pubkey)),
+  };
+}
diff --git a/packages/sdk/types/index.d.ts b/packages/sdk/types/index.d.ts
index 084a2cfb..abe78f64 100644
--- a/packages/sdk/types/index.d.ts
+++ b/packages/sdk/types/index.d.ts
@@ -6,3 +6,4 @@ export { unmarshalTx } from "./decoding";
 export { encodeSecp256k1Signature, makeSignBytes, marshalTx } from "./encoding";
 export { RestClient, TxsResponse } from "./restclient";
 export { makeCosmoshubPath, Pen, PrehashType, Secp256k1Pen } from "./pen";
+export { encodeSecp256k1Pubkey } from "./pubkey";
diff --git a/packages/sdk/types/pubkey.d.ts b/packages/sdk/types/pubkey.d.ts
new file mode 100644
index 00000000..72188ff7
--- /dev/null
+++ b/packages/sdk/types/pubkey.d.ts
@@ -0,0 +1,2 @@
+import { PubKey } from "./types";
+export declare function encodeSecp256k1Pubkey(pubkey: Uint8Array): PubKey;