Adding two layer proposal encryption handlers

utils/encryption/asymmetric.ts

@@ -19,7 +19,7 @@ export function decryptString(ciphertext: Uint8Array, keyPair: KeyPair) {
 
 export function decryptBytes(
   ciphertext: Uint8Array,
-  keyPair: KeyPair
+  keyPair: KeyPair | Omit<KeyPair, "keyType">
 ): Uint8Array {
   return sodium.crypto_box_seal_open(
     ciphertext,

utils/encryption/index.ts

@@ -0,0 +1,93 @@
+import libsodium from "libsodium-wrappers";
+import {
+  generateSymmetricKey,
+  encrypt as symmetricEncrypt,
+  decryptString as symmetricDecryptString,
+  decryptBytes as symmetricDecryptBytes,
+} from "./symmetric";
+import {
+  encrypt as asymmetricEncrypt,
+  decryptBytes as asymmetricDecryptBytes,
+  KeyPair,
+} from "./asymmetric";
+
+export type SymmetricKey = Uint8Array;
+type JsonLiteral = string | number | boolean;
+type JsonValue = JsonLiteral | Array<JsonValue> | { [k: string]: JsonValue };
+
+export function encryptProposal(
+  metadata: JsonValue,
+  actionBytes: Uint8Array
+): {
+  data: { [k: string]: string };
+  symmetricKey: SymmetricKey;
+} {
+  const symmetricKey = generateSymmetricKey();
+
+  const strMetadata = JSON.stringify(metadata);
+  const encryptedMetadata = symmetricEncrypt(strMetadata, symmetricKey);
+  const encryptedActions = symmetricEncrypt(actionBytes, symmetricKey);
+
+  return {
+    data: {
+      metadata: libsodium.to_base64(encryptedMetadata),
+      actions: libsodium.to_base64(encryptedActions),
+    },
+    symmetricKey,
+  };
+}
+
+/**
+ * Returns a list of encrypted symKey payloads. Each position can be decrypted by the respective public key on the given list.
+ * @param symKey The symmetric key to encrypt
+ * @param recipientPubKeys The list of public keys to encrypt for
+ * @returns
+ */
+export function encryptSymmetricKey(
+  symKey: Uint8Array,
+  recipientPubKeys: Uint8Array[]
+) {
+  return recipientPubKeys.map((pubKey) => {
+    return asymmetricEncrypt(symKey, pubKey);
+  });
+}
+
+/**
+ *
+ * @param encryptedItems The list of encrypted symmetric keys, one of which can be decrypted by the keyPair
+ * @param keyPair An object with the private and public keys
+ * @returns
+ */
+export function decryptSymmetricKey(
+  encryptedItems: Uint8Array[],
+  keyPair: KeyPair | Omit<KeyPair, "keyType">
+) {
+  for (const item of encryptedItems) {
+    try {
+      // Attempt to decrypt, continue on fail
+      const decryptedSymKey = asymmetricDecryptBytes(item, keyPair);
+      return decryptedSymKey;
+    } catch (err) {}
+  }
+  throw new Error("The given keypair cannot decrypt any of the ciphertext's");
+}
+
+export function decryptProposal(
+  data: { [k: string]: string },
+  symmetricKey: SymmetricKey
+): {
+  metadata: JsonValue;
+  actions: Uint8Array;
+} {
+  if (!data["metadata"] || !data["actions"]) throw new Error("Invalid data");
+
+  const metadata = symmetricDecryptString(
+    libsodium.from_base64(data["metadata"]),
+    symmetricKey
+  );
+  const actions = symmetricDecryptBytes(
+    libsodium.from_base64(data["actions"]),
+    symmetricKey
+  );
+  return { metadata: JSON.parse(metadata), actions };
+}