Port shared secret encryption from nucypher-core

packages/shared/package.json

@@ -42,6 +42,8 @@
   "dependencies": {
     "@ethersproject/abi": "^5.8.0",
     "@ethersproject/providers": "^5.8.0",
+    "@noble/ciphers": "^1.2.1",
+    "@noble/hashes": "^1.7.1",
     "@nucypher/nucypher-contracts": "^0.23.0",
     "@nucypher/nucypher-core": "^0.14.5",
     "axios": "^1.8.4",

packages/shared/src/encryption/errors.ts

@@ -0,0 +1,66 @@
+/**
+ * Errors during encryption.
+ */
+export class EncryptionError extends Error {
+    readonly code: EncryptionErrorCode;
+
+    constructor(code: EncryptionErrorCode) {
+        let message: string;
+        switch (code) {
+            case EncryptionErrorCode.PlaintextTooLarge:
+                message = 'Plaintext is too large to encrypt';
+                break;
+            default:
+                message = 'Unknown encryption error';
+        }
+        super(message);
+        this.name = 'EncryptionError';
+        this.code = code;
+    }
+}
+
+/**
+ * Error codes for encryption operations.
+ */
+export enum EncryptionErrorCode {
+    PlaintextTooLarge = 'PlaintextTooLarge',
+}
+
+/**
+ * Errors during decryption.
+ */
+export class DecryptionError extends Error {
+    readonly code: DecryptionErrorCode;
+    readonly details?: string;
+
+    constructor(code: DecryptionErrorCode, details?: string) {
+        let message: string;
+        switch (code) {
+            case DecryptionErrorCode.CiphertextTooShort:
+                message = 'The ciphertext must include the nonce';
+                break;
+            case DecryptionErrorCode.AuthenticationFailed:
+                message = 'Decryption of ciphertext failed: ' +
+                    'either someone tampered with the ciphertext or ' +
+                    'you are using an incorrect decryption key.';
+                break;
+            case DecryptionErrorCode.DeserializationFailed:
+                message = details ? `deserialization failed: ${details}` : 'deserialization failed';
+                break;
+            default:
+                message = 'Unknown decryption error';
+        }
+        super(message);
+        this.name = 'DecryptionError';
+        this.code = code;
+    }
+}
+
+/**
+ * Error codes for decryption operations.
+ */
+export enum DecryptionErrorCode {
+    CiphertextTooShort = 'CiphertextTooShort',
+    AuthenticationFailed = 'AuthenticationFailed',
+    DeserializationFailed = 'DeserializationFailed',
+}

packages/shared/src/encryption/index.ts

@@ -0,0 +1,2 @@
+export * from './errors';
+export * from './shared-secret';

packages/shared/src/encryption/shared-secret.ts

@@ -0,0 +1,47 @@
+import { chacha20poly1305 } from '@noble/ciphers/chacha';
+import { randomBytes } from '@noble/hashes/utils';
+
+import {
+  DecryptionError,
+  DecryptionErrorCode,
+  EncryptionError,
+  EncryptionErrorCode,
+} from './errors';
+
+export const CHACHA20POLY1305_NONCE_LENGTH = 12; // bytes
+
+export function encryptWithSharedSecret(
+  sharedSecret: Uint8Array,
+  plaintext: Uint8Array,
+): Uint8Array {
+  const nonce = randomBytes(CHACHA20POLY1305_NONCE_LENGTH); // Generate a 12-byte nonce
+  const cipher = chacha20poly1305(sharedSecret, nonce); // Use an object with key
+  try {
+    const ciphertext = cipher.encrypt(plaintext);
+    const result = new Uint8Array(
+      CHACHA20POLY1305_NONCE_LENGTH + ciphertext.length,
+    );
+    result.set(nonce);
+    result.set(ciphertext, CHACHA20POLY1305_NONCE_LENGTH);
+    return result;
+  } catch (error) {
+    throw new EncryptionError(EncryptionErrorCode.PlaintextTooLarge);
+  }
+}
+
+export function decryptWithSharedSecret(
+  sharedSecret: Uint8Array,
+  ciphertext: Uint8Array,
+): Uint8Array {
+  if (ciphertext.length < CHACHA20POLY1305_NONCE_LENGTH) {
+    throw new DecryptionError(DecryptionErrorCode.CiphertextTooShort);
+  }
+  const nonce = ciphertext.slice(0, CHACHA20POLY1305_NONCE_LENGTH);
+  const encryptedData = ciphertext.slice(CHACHA20POLY1305_NONCE_LENGTH);
+  const cipher = chacha20poly1305(sharedSecret, nonce); // Use an object with key
+  try {
+    return cipher.decrypt(encryptedData);
+  } catch (error) {
+    throw new DecryptionError(DecryptionErrorCode.AuthenticationFailed);
+  }
+}

packages/shared/test/fixtures/shared-secret-vectors.json

@@ -0,0 +1,50 @@
+{
+  "test_vectors": [
+    {
+      "id": "vector1",
+      "description": "Fixed nonce encryption with known plaintext",
+      "shared_secret": [
+        0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+        20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31
+      ],
+      "plaintext": "This is a test message",
+      "fixed_nonce": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+      "expected_ciphertext": [
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 76, 208, 43, 66, 141, 143, 213, 241,
+        114, 65, 40, 4, 220, 55, 110, 74, 157, 194, 128, 148, 134, 200, 181, 72,
+        212, 7, 218, 216, 247, 94, 232, 77, 109, 158, 146, 164, 44, 74
+      ]
+    },
+    {
+      "id": "vector2",
+      "description": "Fixed nonce encryption with alternative values",
+      "shared_secret": [
+        31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14,
+        13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
+      ],
+      "plaintext": "",
+      "fixed_nonce": [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
+      "expected_ciphertext": [
+        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 135, 38, 197, 242, 213, 184, 24,
+        114, 168, 100, 147, 239, 82, 50, 170, 161
+      ]
+    },
+    {
+      "id": "vector3",
+      "description": "Rust-generated ciphertext for TypeScript compatibility check",
+      "shared_secret": [
+        0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+        20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31
+      ],
+      "plaintext": "This is a message encrypted by the Rust implementation",
+      "expected_ciphertext": [
+        100, 196, 241, 204, 119, 208, 40, 31, 29, 138, 199, 108, 168, 89, 32,
+        208, 157, 93, 80, 94, 60, 106, 168, 38, 62, 206, 143, 135, 56, 12, 142,
+        15, 156, 9, 227, 26, 97, 154, 204, 11, 179, 200, 3, 180, 203, 200, 221,
+        190, 122, 118, 154, 147, 180, 170, 1, 23, 168, 86, 226, 78, 224, 176,
+        218, 159, 127, 47, 55, 28, 193, 231, 42, 92, 118, 112, 139, 150, 73,
+        205, 155, 90, 66, 172
+      ]
+    }
+  ]
+}

packages/shared/test/shared-secret-compatibility.test.ts

@@ -0,0 +1,163 @@
+import { describe, expect, it, vi } from 'vitest';
+import { DecryptionError, DecryptionErrorCode } from '../src/encryption/errors';
+import testVectorsFile from './fixtures/shared-secret-vectors.json';
+
+// Mock the randomBytes function from @noble/hashes/utils
+// This must be done before importing any modules that use it
+vi.mock('@noble/hashes/utils', () => {
+  return {
+    // Return a function that will be replaced in each test
+    randomBytes: vi.fn().mockImplementation((bytesLength?: number) => {
+      return new Uint8Array(bytesLength || 32);
+    }),
+  };
+});
+
+// Now import modules that depend on the mocked randomBytes
+import { randomBytes } from '@noble/hashes/utils';
+import {
+  decryptWithSharedSecret,
+  encryptWithSharedSecret,
+} from '../src/encryption/shared-secret';
+
+/**
+ * This test file contains fixed test vectors to verify compatibility
+ * between the TypeScript implementation and the original Rust implementation.
+ *
+ * Test vectors are loaded from a JSON file which makes it easier to:
+ * 1. Share vectors between different implementations (Rust, TypeScript)
+ * 2. Update or add vectors without changing test logic
+ * 3. Maintain expected inputs/outputs separately from test code
+ */
+describe('Shared Secret Compatibility Tests', () => {
+  // Parse test vectors from the loaded JSON file
+  const { test_vectors } = testVectorsFile as { test_vectors: any[] };
+
+  // Helper to convert test vector from JSON to usable objects
+  const prepareTestVector = (vector: any) => {
+    return {
+      id: vector.id,
+      description: vector.description,
+      sharedSecret: new Uint8Array(vector.shared_secret),
+      plaintext: new TextEncoder().encode(vector.plaintext),
+      fixedNonce: vector.fixed_nonce
+        ? new Uint8Array(vector.fixed_nonce)
+        : undefined,
+      expectedCiphertext: Buffer.from(vector.expected_ciphertext, 'hex'),
+    };
+  };
+
+  // Parse all test vectors into usable formats
+  const testVectors = test_vectors.map(prepareTestVector);
+
+  // Set up a fixed nonce for testing
+  function setupFixedNonceMock(fixedNonce: Uint8Array) {
+    // Get the mocked function
+    const mockedRandomBytes = vi.mocked(randomBytes);
+
+    // Clear previous implementations
+    mockedRandomBytes.mockReset();
+
+    // Configure it to return our fixed nonce
+    mockedRandomBytes.mockImplementation((bytesLength?: number) => {
+      // If length is undefined or matches our nonce length, return the fixed nonce
+      // Otherwise return a new array of the requested length
+      if (bytesLength === undefined || bytesLength === fixedNonce.length) {
+        return fixedNonce;
+      } else {
+        return new Uint8Array(bytesLength);
+      }
+    });
+
+    // Return a cleanup function
+    return () => {
+      mockedRandomBytes.mockReset();
+    };
+  }
+
+  describe('Vector-based compatibility tests', () => {
+    it.each(testVectors)(
+      'should correctly encrypt and decrypt test vector $id: $description',
+      (vector) => {
+        const { sharedSecret, plaintext, fixedNonce, expectedCiphertext } =
+          vector;
+
+        if (fixedNonce) {
+          // Set up our mock to return the fixed nonce
+          const cleanupMock = setupFixedNonceMock(fixedNonce);
+
+          // Encrypt with fixed nonce
+          const ciphertext = encryptWithSharedSecret(sharedSecret, plaintext);
+          // Always restore the original implementation
+          cleanupMock();
+
+          // Check against expected ciphertext from the JSON file
+          const ciphertextHex = Buffer.from(ciphertext).toString('hex');
+          const expectedHex = Buffer.from(expectedCiphertext).toString('hex');
+          expect(ciphertextHex).toEqual(expectedHex);
+        }
+
+        // Verify decryption works correctly
+        const decrypted = decryptWithSharedSecret(
+          sharedSecret,
+          expectedCiphertext,
+        );
+
+        expect(Buffer.from(decrypted).toString()).toEqual(
+          Buffer.from(plaintext).toString(),
+        );
+      },
+    );
+  });
+
+  describe('Error handling compatibility tests', () => {
+    // Using the first test vector's shared secret for error tests
+    const { expectedCiphertext, fixedNonce, sharedSecret } = testVectors[0];
+
+    it('should handle ciphertext too short error in the same way as Rust', () => {
+      const tooShortCiphertext = new Uint8Array([0x01, 0x02, 0x03]); // Less than nonce length
+
+      try {
+        decryptWithSharedSecret(sharedSecret, tooShortCiphertext);
+        expect.fail('Should have thrown an error');
+      } catch (error) {
+        expect(error).toBeInstanceOf(DecryptionError);
+        const decryptionError = error as DecryptionError;
+        expect(decryptionError.code).toBe(
+          DecryptionErrorCode.CiphertextTooShort,
+        );
+        expect(decryptionError.message).toContain(
+          'The ciphertext must include the nonce',
+        );
+      }
+    });
+
+    it('should handle tampered ciphertext in the same way as Rust', () => {
+      // Use the existing helper to setup the mock
+      const cleanupMock = setupFixedNonceMock(fixedNonce!);
+
+      try {
+        // Tamper with the ciphertext by changing one byte
+        const tamperedCiphertext = new Uint8Array(expectedCiphertext);
+        tamperedCiphertext[tamperedCiphertext.length - 1] ^= 0x01; // Flip one bit in the last byte
+
+        try {
+          decryptWithSharedSecret(sharedSecret, tamperedCiphertext);
+          expect.fail('Should have thrown an error');
+        } catch (error) {
+          expect(error).toBeInstanceOf(DecryptionError);
+          const decryptionError = error as DecryptionError;
+          expect(decryptionError.code).toBe(
+            DecryptionErrorCode.AuthenticationFailed,
+          );
+          expect(decryptionError.message).toContain(
+            'Decryption of ciphertext failed',
+          );
+        }
+      } finally {
+        // Always restore the original implementation
+        cleanupMock();
+      }
+    });
+  });
+});