(feat): add crypto stuff to ts-sdk

src/sdk/index.ts

@@ -26,6 +26,8 @@ export type ParsedFrame = RawBindings.ParsedFrame;
 
 export type Ed25519GenerateResult = ReturnType<typeof bindings.ed25519_generate>;
 
+export type WasmEncapsulated = RawBindings.WasmEncapsulated;
+
 export interface MTPCrypto {
   generateKeyring(): Uint8Array;
   generateEd25519(): Ed25519GenerateResult;
@@ -35,6 +37,13 @@ export interface MTPCrypto {
   hkdfExpand(ikm: Uint8Array, salt: Uint8Array, info: Uint8Array, len: number): Uint8Array;
   sha256(data: Uint8Array): Uint8Array;
   sha256Double(data: Uint8Array): Uint8Array;
+  encrypt(secret: string, input: Uint8Array): Promise<Uint8Array>;
+  decrypt(secret: string, input: Uint8Array): Promise<Uint8Array>;
+  encryptText(secret: string, plaintext: string): Promise<string>;
+  decryptText(secret: string, ciphertext: string): Promise<string>;
+  encapsulate(otherPublicKey: Uint8Array): WasmEncapsulated;
+  decapsulate(ownPrivateKey: Uint8Array, ciphertext: Uint8Array): Uint8Array;
+  getSharedSecret(ownPrivateKey: string, ownPublicKey: string, otherPublicKey: string): Promise<string>;
 }
 
 export const crypto: MTPCrypto = {
@@ -46,6 +55,67 @@ export const crypto: MTPCrypto = {
   hkdfExpand: (ikm, salt, info, len) => bindings.wasm_hkdf_expand(ikm, salt, info, len),
   sha256: (data) => bindings.wasm_sha256(data),
   sha256Double: (data) => bindings.wasm_sha256_double(data),
+
+  encrypt: async (secret, input) => {
+    const key = secretKeyFromString(secret);
+    const cipher = new bindings.WasmChaCha20Poly1305(key);
+    try {
+      return cipher.encrypt(input, new Uint8Array(0));
+    } finally {
+      cipher.free();
+    }
+  },
+
+  decrypt: async (secret, input) => {
+    const key = secretKeyFromString(secret);
+    const cipher = new bindings.WasmChaCha20Poly1305(key);
+    try {
+      return cipher.decrypt(input, new Uint8Array(0));
+    } finally {
+      cipher.free();
+    }
+  },
+
+  encryptText: async (secret, plaintext) => {
+    const key = secretKeyFromString(secret);
+    const cipher = new bindings.WasmChaCha20Poly1305(key);
+    try {
+      const ciphertext = cipher.encrypt(utf8Encode(plaintext), new Uint8Array(0));
+      return bytesToBase64(ciphertext);
+    } finally {
+      cipher.free();
+    }
+  },
+
+  decryptText: async (secret, ciphertext) => {
+    const key = secretKeyFromString(secret);
+    const cipher = new bindings.WasmChaCha20Poly1305(key);
+    try {
+      const decoded = bytesFromString(ciphertext, "ciphertext");
+      const plaintext = cipher.decrypt(decoded, new Uint8Array(0));
+      return utf8Decode(plaintext);
+    } finally {
+      cipher.free();
+    }
+  },
+
+  encapsulate: (otherPublicKey) => bindings.wasm_kem_encapsulate(otherPublicKey),
+
+  decapsulate: (ownPrivateKey, ciphertext) =>
+    bindings.wasm_kem_decapsulate(ownPrivateKey, ciphertext),
+
+  getSharedSecret: async (ownPrivateKey, ownPublicKey, otherPublicKey) => {
+    const ownPub = bytesFromString(ownPublicKey, "ownPublicKey");
+    const otherPub = bytesFromString(otherPublicKey, "otherPublicKey");
+    const enc = bindings.wasm_kem_encapsulate(otherPub);
+    try {
+      const sharedSecret = enc.shared_secret;
+      const derived = bindings.wasm_hkdf_expand(sharedSecret, ownPub, otherPub, 32);
+      return bytesToHex(derived);
+    } finally {
+      enc.free();
+    }
+  },
 };
 
 export type MTPRawBindings = typeof bindings;
@@ -250,6 +320,130 @@ function bytesFromString(value, name) {
   throw new TypeError(`${name} must be bytes, hex, or base64`);
 }
 
+const HEX_DIGITS = "0123456789abcdef";
+
+function bytesToHex(bytes) {
+  let out = "";
+  for (let i = 0; i < bytes.length; i += 1) {
+    out += HEX_DIGITS[(bytes[i] >> 4) & 0xf] + HEX_DIGITS[bytes[i] & 0xf];
+  }
+  return out;
+}
+
+function bytesToBase64(bytes) {
+  if (typeof btoa === "function") {
+    let binary = "";
+    for (let i = 0; i < bytes.length; i += 1) {
+      binary += String.fromCharCode(bytes[i]);
+    }
+    return btoa(binary);
+  }
+  if (typeof Buffer !== "undefined") {
+    return Buffer.from(bytes).toString("base64");
+  }
+  throw new TypeError("base64 encoding is not available in this environment");
+}
+
+function utf8Encode(text) {
+  if (typeof TextEncoder !== "undefined") {
+    return new TextEncoder().encode(text);
+  }
+  if (typeof Buffer !== "undefined") {
+    return new Uint8Array(Buffer.from(text, "utf-8"));
+  }
+  const bytes = new Uint8Array(text.length * 4);
+  let len = 0;
+  for (let i = 0; i < text.length; i += 1) {
+    const code = text.codePointAt(i);
+    if (code < 0x80) {
+      bytes[len++] = code;
+    } else if (code < 0x800) {
+      bytes[len++] = 0xc0 | (code >> 6);
+      bytes[len++] = 0x80 | (code & 0x3f);
+    } else if (code < 0x10000) {
+      bytes[len++] = 0xe0 | (code >> 12);
+      bytes[len++] = 0x80 | ((code >> 6) & 0x3f);
+      bytes[len++] = 0x80 | (code & 0x3f);
+    } else {
+      bytes[len++] = 0xf0 | (code >> 18);
+      bytes[len++] = 0x80 | ((code >> 12) & 0x3f);
+      bytes[len++] = 0x80 | ((code >> 6) & 0x3f);
+      bytes[len++] = 0x80 | (code & 0x3f);
+      i += 1;
+    }
+  }
+  return bytes.subarray(0, len);
+}
+
+function utf8Decode(bytes) {
+  if (typeof TextDecoder !== "undefined") {
+    return new TextDecoder().decode(bytes);
+  }
+  if (typeof Buffer !== "undefined") {
+    return Buffer.from(bytes).toString("utf-8");
+  }
+  let out = "";
+  let i = 0;
+  while (i < bytes.length) {
+    const b = bytes[i];
+    if (b < 0x80) {
+      out += String.fromCharCode(b);
+      i += 1;
+    } else if (b < 0xc0) {
+      i += 1;
+    } else if (b < 0xe0) {
+      out += String.fromCharCode(((b & 0x1f) << 6) | (bytes[i + 1] & 0x3f));
+      i += 2;
+    } else if (b < 0xf0) {
+      out += String.fromCharCode(
+        ((b & 0x0f) << 12) | ((bytes[i + 1] & 0x3f) << 6) | (bytes[i + 2] & 0x3f),
+      );
+      i += 3;
+    } else {
+      const cp =
+        ((b & 0x07) << 18) |
+        ((bytes[i + 1] & 0x3f) << 12) |
+        ((bytes[i + 2] & 0x3f) << 6) |
+        (bytes[i + 3] & 0x3f);
+      out += String.fromCodePoint(cp);
+      i += 4;
+    }
+  }
+  return out;
+}
+
+const SYMMETRIC_KEY_SALT = utf8Encode("mtp-symmetric-key");
+
+function secretKeyFromString(secret) {
+  if (typeof secret !== "string" || !secret.trim()) {
+    throw new TypeError("secret must be a non-empty string");
+  }
+
+  const trimmed = secret.trim();
+  const hex = trimmed.replace(/^(0x)/i, "").replace(/[\s:_-]/g, "");
+  if (/^[0-9a-fA-F]+$/.test(hex) && hex.length === 64) {
+    const bytes = new Uint8Array(32);
+    for (let i = 0; i < 32; i += 1) {
+      bytes[i] = Number.parseInt(hex.slice(i * 2, i * 2 + 2), 16);
+    }
+    return bytes;
+  }
+
+  if (typeof atob === "function" || typeof Buffer !== "undefined") {
+    try {
+      const decoded = bytesFromString(trimmed, "secret");
+      if (decoded.length === 32) {
+        return decoded;
+      }
+    } catch {
+      // fall through to HKDF derivation
+    }
+  }
+
+  const ikm = utf8Encode(trimmed);
+  return bindings.wasm_derive_encryption_key(ikm, SYMMETRIC_KEY_SALT, SYMMETRIC_KEY_SALT);
+}
+
 function normalizeBytes(value, name) {
   if (typeof value === "string") {
     return bytesFromString(value, name);

wasm/src/crypto.rs

@@ -1,9 +1,9 @@
 use wasm_bindgen::prelude::*;
 
 use mtp_crypto::{
-    AeadDecrypt, AeadEncrypt, ChaCha20Poly1305, Ed25519Signer, KemPrivateKey, KemPublicKey,
-    Keyring, PublicKeyBundle, SignaturePqPrivateKey, SignaturePqPublicKey, SignaturePrivateKey,
-    SignaturePublicKey, SignatureScheme, sha256, sha256_double,
+    AeadDecrypt, AeadEncrypt, ChaCha20Poly1305, Ed25519Signer, HybridKem, KemPrivateKey,
+    KemPublicKey, Keyring, PublicKeyBundle, SignaturePqPrivateKey, SignaturePqPublicKey,
+    SignaturePrivateKey, SignaturePublicKey, SignatureScheme, sha256, sha256_double,
 };
 
 use crate::error::js_error;
@@ -110,6 +110,66 @@ impl WasmPublicKeyBundle {
     }
 }
 
+// ===========================================================================
+// Hybrid KEM (X25519 + ML-KEM-768)
+// ===========================================================================
+
+/// KEM encapsulation result returned to JavaScript.
+///
+/// `shared_secret` is the symmetric key both parties will derive; `ciphertext`
+/// is the KEM ciphertext that must be sent to the recipient so they can
+/// decapsulate and recover the same shared secret.
+#[wasm_bindgen]
+pub struct WasmEncapsulated {
+    inner_shared_secret: Vec<u8>,
+    inner_ciphertext: Vec<u8>,
+}
+
+#[wasm_bindgen]
+impl WasmEncapsulated {
+    /// Symmetric secret derived during encapsulation.
+    #[wasm_bindgen(getter)]
+    pub fn shared_secret(&self) -> Vec<u8> {
+        self.inner_shared_secret.clone()
+    }
+
+    /// KEM ciphertext to transmit to the recipient.
+    #[wasm_bindgen(getter)]
+    pub fn ciphertext(&self) -> Vec<u8> {
+        self.inner_ciphertext.clone()
+    }
+}
+
+/// Encapsulate a fresh shared secret for `recipient_public_key`.
+///
+/// Returns a [`WasmEncapsulated`] containing the shared secret and the KEM
+/// ciphertext that the recipient needs to recover it via
+/// [`wasm_kem_decapsulate`].
+#[wasm_bindgen]
+pub fn wasm_kem_encapsulate(recipient_public_key: &[u8]) -> Result<WasmEncapsulated, JsValue> {
+    let pk = KemPublicKey::new(recipient_public_key.to_vec());
+    let enc = HybridKem::encapsulate(&pk)
+        .map_err(|e| js_error(&format!("kem_encapsulate failed: {}", e)))?;
+    Ok(WasmEncapsulated {
+        inner_shared_secret: enc.shared_secret,
+        inner_ciphertext: enc.ciphertext,
+    })
+}
+
+/// Decapsulate a KEM `ciphertext` with the recipient's `private_key`.
+///
+/// Returns the same shared secret the initiator obtained from
+/// [`wasm_kem_encapsulate`].
+#[wasm_bindgen]
+pub fn wasm_kem_decapsulate(
+    recipient_private_key: &[u8],
+    ciphertext: &[u8],
+) -> Result<Vec<u8>, JsValue> {
+    let sk = KemPrivateKey::new(recipient_private_key.to_vec());
+    HybridKem::decapsulate(&sk, ciphertext)
+        .map_err(|e| js_error(&format!("kem_decapsulate failed: {}", e)))
+}
+
 // ===========================================================================
 // ChaCha20-Poly1305 AEAD
 // ===========================================================================
@@ -326,6 +386,31 @@ mod tests {
         assert_eq!(restored.sig_cl_public_key(), pk);
     }
 
+    // ------------------------------------------------------------------
+    // KEM encapsulate / decapsulate
+    // ------------------------------------------------------------------
+
+    #[wasm_bindgen_test]
+    fn kem_encapsulate_decapsulate_roundtrip() {
+        let (sk, pk) = HybridKem::generate_keypair();
+        let enc = wasm_kem_encapsulate(pk.as_bytes()).expect("encapsulate failed");
+        let ss = wasm_kem_decapsulate(sk.as_bytes(), &enc.ciphertext()).expect("decapsulate failed");
+        assert_eq!(enc.shared_secret(), ss);
+    }
+
+    #[wasm_bindgen_test]
+    fn kem_encapsulate_invalid_public_key_fails() {
+        let bad = vec![0u8; 16];
+        assert!(wasm_kem_encapsulate(&bad).is_err());
+    }
+
+    #[wasm_bindgen_test]
+    fn kem_decapsulate_invalid_ciphertext_fails() {
+        let (sk, _pk) = HybridKem::generate_keypair();
+        let bad = vec![0u8; 32];
+        assert!(wasm_kem_decapsulate(sk.as_bytes(), &bad).is_err());
+    }
+
     // ------------------------------------------------------------------
     // ChaCha20-Poly1305
     // ------------------------------------------------------------------

wasm/types/mtp_wasm.d.ts

@@ -75,6 +75,19 @@ export class WasmChaCha20Poly1305 implements DisposableWasmObject {
   encrypt(plaintext: Uint8Array, aad: Uint8Array): Uint8Array;
 }
 
+export interface KemEncapsulateResult {
+  shared_secret: Uint8Array;
+  ciphertext: Uint8Array;
+}
+
+export class WasmEncapsulated implements DisposableWasmObject {
+  private constructor();
+  free(): void;
+  [Symbol.dispose](): void;
+  readonly shared_secret: Uint8Array;
+  readonly ciphertext: Uint8Array;
+}
+
 export class WasmClient implements DisposableWasmObject {
   constructor(
     on_state_change: StateChangeCallback,
@@ -166,6 +179,8 @@ export function parse_auth_response(response: Uint8Array): AuthResponse;
 export function parse_frame(frame: Uint8Array): ParsedFrame;
 export function wasm_derive_encryption_key(ikm: Uint8Array, salt: Uint8Array, context: Uint8Array): Uint8Array;
 export function wasm_hkdf_expand(ikm: Uint8Array, salt: Uint8Array, info: Uint8Array, len: number): Uint8Array;
+export function wasm_kem_decapsulate(recipient_private_key: Uint8Array, ciphertext: Uint8Array): Uint8Array;
+export function wasm_kem_encapsulate(recipient_public_key: Uint8Array): WasmEncapsulated;
 export function wasm_sha256(data: Uint8Array): Uint8Array;
 export function wasm_sha256_double(data: Uint8Array): Uint8Array;