draft tmk

package.json

@@ -55,7 +55,9 @@
   },
   "dependencies": {
     "@nucypher/nucypher-core": "^0.10.0",
+    "@types/crypto-js": "^4.1.1",
     "axios": "^0.21.1",
+    "crypto-js": "^4.1.1",
     "deep-equal": "^2.2.1",
     "ethers": "^5.4.1",
     "joi": "^17.7.0",

src/characters/enrico.ts

@@ -6,10 +6,17 @@ import {
   PublicKey,
   SecretKey,
 } from '@nucypher/nucypher-core';
+import { AES } from 'crypto-js';
 
-import { ConditionExpression } from '../conditions';
+import { ConditionExpression, ConditionExpressionJSON } from '../conditions';
 import { Keyring } from '../keyring';
-import { toBytes } from '../utils';
+import {
+  bytesEquals,
+  fromBase64,
+  fromBytes,
+  toBase64,
+  toBytes,
+} from '../utils';
 
 export class Enrico {
   public readonly encryptingKey: PublicKey | DkgPublicKey;
@@ -73,4 +80,125 @@ export class Enrico {
     );
     return { ciphertext, aad };
   }
+
+  public async encapsulateCbd(
+    message: string,
+    passphrase: string,
+    withConditions?: ConditionExpression
+  ): Promise<ThresholdMessageKit> {
+    const bulkCiphertext = AES.encrypt(message, passphrase).toString();
+
+    const { ciphertext, aad } = this.encryptMessageCbd(
+      passphrase,
+      withConditions
+    );
+
+    return new ThresholdMessageKit(
+      ciphertext,
+      aad,
+      bulkCiphertext,
+      withConditions || this.conditions
+    );
+  }
+}
+
+export class ThresholdMessageKit {
+  private static readonly SEPARATOR = ';';
+
+  constructor(
+    public keyCiphertext: Ciphertext,
+    public keyAad: Uint8Array,
+    public bulkCiphertext: string,
+    public conditions?: ConditionExpression,
+    public metadata: Record<string, string> = {}
+  ) {}
+
+  public toObj(): ThresholdMessageKitJSON {
+    return {
+      keyCiphertext: toBase64(this.keyCiphertext.toBytes()),
+      keyAad: toBase64(this.keyAad),
+      bulkCiphertext: this.bulkCiphertext,
+      conditions: this.conditions ? this.conditions.toObj() : undefined,
+      metadata: this.metadata,
+    };
+  }
+
+  public toJson(): string {
+    return JSON.stringify(this.toObj());
+  }
+
+  public toBytes(): Uint8Array {
+    const bulkCiphertextBytes = toBytes(this.bulkCiphertext);
+    const separator = toBytes(ThresholdMessageKit.SEPARATOR);
+    // bulkCiphertext will be serialized separately
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    const { bulkCiphertext: _, ...tmkMeta } = this.toObj();
+    const tmkMetaBytes = toBytes(JSON.stringify(tmkMeta));
+
+    return new Uint8Array([
+      ...tmkMetaBytes,
+      ...separator,
+      ...bulkCiphertextBytes,
+    ]);
+  }
+
+  public static fromObj({
+    keyCiphertext,
+    keyAad,
+    bulkCiphertext,
+    conditions,
+    metadata,
+  }: ThresholdMessageKitJSON): ThresholdMessageKit {
+    return new ThresholdMessageKit(
+      Ciphertext.fromBytes(fromBase64(keyCiphertext)),
+      fromBase64(keyAad),
+      bulkCiphertext,
+      conditions ? ConditionExpression.fromObj(conditions) : undefined,
+      metadata
+    );
+  }
+
+  public static fromJson(json: string): ThresholdMessageKit {
+    return ThresholdMessageKit.fromObj(JSON.parse(json));
+  }
+
+  public static fromBytes(bytes: Uint8Array): ThresholdMessageKit {
+    const separator = toBytes(ThresholdMessageKit.SEPARATOR);
+    const separatorIndex = bytes.indexOf(separator[0]);
+    const tmkMetaBytes = bytes.slice(0, separatorIndex);
+    const bulkCiphertextBytes = bytes.slice(separatorIndex + separator.length);
+
+    const tmkMeta: ThresholdMessageKitJSON = JSON.parse(
+      fromBytes(tmkMetaBytes)
+    );
+    const { keyCiphertext, keyAad, conditions, metadata } = tmkMeta;
+
+    return new ThresholdMessageKit(
+      Ciphertext.fromBytes(fromBase64(keyCiphertext)),
+      toBytes(keyAad),
+      bulkCiphertextBytes.toString(),
+      conditions ? ConditionExpression.fromObj(conditions) : undefined,
+      metadata
+    );
+  }
+
+  public equals(other: ThresholdMessageKit): boolean {
+    return [
+      this.keyCiphertext.equals(other.keyCiphertext),
+      bytesEquals(this.keyAad, other.keyAad),
+      this.bulkCiphertext === other.bulkCiphertext,
+      other.conditions
+        ? this.conditions?.equals(other.conditions)
+        : !this.conditions,
+      JSON.stringify(this.metadata) === JSON.stringify(other.metadata),
+    ].every(Boolean);
+  }
 }
+
+export type ThresholdMessageKitJSON = {
+  keyCiphertext: string;
+  keyAad: string;
+  bulkCiphertext: string;
+  conditions?: ConditionExpressionJSON;
+  metadata: Record<string, string>;
+};

src/utils.ts

@@ -4,6 +4,9 @@ import deepEqual from 'deep-equal';
 export const toBytes = (str: string): Uint8Array =>
   new TextEncoder().encode(str);
 
+export const fromBytes = (bytes: Uint8Array): string =>
+  new TextDecoder().decode(bytes);
+
 export const fromHexString = (hexString: string): Uint8Array => {
   if (hexString.startsWith('0x')) {
     hexString = hexString.slice(2);

test/integration/enrico.test.ts

@@ -1,6 +1,9 @@
 // Disabling because we want to access Alice.keyring which is a private property
 /* eslint-disable @typescript-eslint/no-explicit-any */
+import { DkgPublicKey } from '@nucypher/nucypher-core';
+
 import { conditions, Enrico, PolicyMessageKit } from '../../src';
+import { ThresholdMessageKit } from '../../src/characters/enrico';
 import { RetrievalResult } from '../../src/kits/retrieval';
 import { toBytes } from '../../src/utils';
 import {
@@ -150,3 +153,32 @@ describe('enrico', () => {
     expect(alicePlaintext).toEqual(alicePlaintext);
   });
 });
+
+describe('enrico with cbd encapsulation', () => {
+  it('encapsulates a plaintext message', async () => {
+    const message = 'fake-message';
+    const encryptingKey = DkgPublicKey.random();
+    const ownsBufficornNFT = ERC721Ownership.fromObj({
+      contractAddress: '0x1e988ba4692e52Bc50b375bcC8585b95c48AaD77',
+      parameters: [3591],
+      chain: 5,
+    });
+    const conditions = new ConditionExpression(ownsBufficornNFT);
+    const enrico = new Enrico(encryptingKey, undefined, conditions);
+
+    const passphrase = "I'm a passphrase";
+    const tmk = await enrico.encapsulateCbd(message, passphrase, conditions);
+
+    const asObject = tmk.toObj();
+    const fromObject = ThresholdMessageKit.fromObj(asObject);
+    expect(fromObject.equals(tmk)).toBeTruthy();
+
+    const asJson = tmk.toJson();
+    const fromJson = ThresholdMessageKit.fromJson(asJson);
+    expect(fromJson.equals(tmk)).toBeTruthy();
+
+    const asBytes = tmk.toBytes();
+    const fromBytes = ThresholdMessageKit.fromBytes(asBytes);
+    expect(fromBytes.equals(tmk)).toBeTruthy();
+  });
+});