crypto: add DH support to generateKeyPair

This allows using the generateKeyPair API for DH instead of the old stateful DH APIs. PR-URL: #31178 Reviewed-By: Sam Roberts <[email protected]>
nodejs · Feb 17, 2020 · 0d3e095 · 0d3e095
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diff --git a/doc/api/crypto.md b/doc/api/crypto.md
@@ -2093,6 +2093,9 @@ algorithm names.
 <!-- YAML
 added: v10.12.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/31178
+    description: Add support for Diffie-Hellman.
   - version: v12.0.0
     pr-url: https://github.com/nodejs/node/pull/26774
     description: Add ability to generate X25519 and X448 key pairs.
@@ -2106,21 +2109,26 @@ changes:
 -->
 
 * `type`: {string} Must be `'rsa'`, `'dsa'`, `'ec'`, `'ed25519'`, `'ed448'`,
-  `'x25519'`, or `'x448'`.
+  `'x25519'`, `'x448'`, or `'dh'`.
 * `options`: {Object}
   * `modulusLength`: {number} Key size in bits (RSA, DSA).
   * `publicExponent`: {number} Public exponent (RSA). **Default:** `0x10001`.
   * `divisorLength`: {number} Size of `q` in bits (DSA).
   * `namedCurve`: {string} Name of the curve to use (EC).
+  * `prime`: {Buffer} The prime parameter (DH).
+  * `primeLength`: {number} Prime length in bits (DH).
+  * `generator`: {number} Custom generator (DH). **Default:** `2`.
+  * `groupName`: {string} Diffie-Hellman group name (DH). See
+    [`crypto.getDiffieHellman()`][].
   * `publicKeyEncoding`: {Object} See [`keyObject.export()`][].
   * `privateKeyEncoding`: {Object} See [`keyObject.export()`][].
 * `callback`: {Function}
   * `err`: {Error}
   * `publicKey`: {string | Buffer | KeyObject}
   * `privateKey`: {string | Buffer | KeyObject}
 
-Generates a new asymmetric key pair of the given `type`. RSA, DSA, EC, Ed25519
-and Ed448 are currently supported.
+Generates a new asymmetric key pair of the given `type`. RSA, DSA, EC, Ed25519,
+Ed448, X25519, X448, and DH are currently supported.
 
 If a `publicKeyEncoding` or `privateKeyEncoding` was specified, this function
 behaves as if [`keyObject.export()`][] had been called on its result. Otherwise,
@@ -2158,6 +2166,9 @@ a `Promise` for an `Object` with `publicKey` and `privateKey` properties.
 <!-- YAML
 added: v10.12.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/31178
+    description: Add support for Diffie-Hellman.
   - version: v12.0.0
     pr-url: https://github.com/nodejs/node/pull/26554
     description: Add ability to generate Ed25519 and Ed448 key pairs.
@@ -2167,20 +2178,26 @@ changes:
                  produce key objects if no encoding was specified.
 -->
 
-* `type`: {string} Must be `'rsa'`, `'dsa'`, `'ec'`, `'ed25519'`, or `'ed448'`.
+* `type`: {string} Must be `'rsa'`, `'dsa'`, `'ec'`, `'ed25519'`, `'ed448'`,
+  `'x25519'`, `'x448'`, or `'dh'`.
 * `options`: {Object}
   * `modulusLength`: {number} Key size in bits (RSA, DSA).
   * `publicExponent`: {number} Public exponent (RSA). **Default:** `0x10001`.
   * `divisorLength`: {number} Size of `q` in bits (DSA).
   * `namedCurve`: {string} Name of the curve to use (EC).
+  * `prime`: {Buffer} The prime parameter (DH).
+  * `primeLength`: {number} Prime length in bits (DH).
+  * `generator`: {number} Custom generator (DH). **Default:** `2`.
+  * `groupName`: {string} Diffie-Hellman group name (DH). See
+    [`crypto.getDiffieHellman()`][].
   * `publicKeyEncoding`: {Object} See [`keyObject.export()`][].
   * `privateKeyEncoding`: {Object} See [`keyObject.export()`][].
 * Returns: {Object}
   * `publicKey`: {string | Buffer | KeyObject}
   * `privateKey`: {string | Buffer | KeyObject}
 
-Generates a new asymmetric key pair of the given `type`. RSA, DSA, EC, Ed25519
-and Ed448 are currently supported.
+Generates a new asymmetric key pair of the given `type`. RSA, DSA, EC, Ed25519,
+Ed448, X25519, X448, and DH are currently supported.
 
 If a `publicKeyEncoding` or `privateKeyEncoding` was specified, this function
 behaves as if [`keyObject.export()`][] had been called on its result. Otherwise,

diff --git a/doc/api/errors.md b/doc/api/errors.md
@@ -826,6 +826,12 @@ A signing `key` was not provided to the [`sign.sign()`][] method.
 [`crypto.timingSafeEqual()`][] was called with `Buffer`, `TypedArray`, or
 `DataView` arguments of different lengths.
 
+<a id="ERR_CRYPTO_UNKNOWN_DH_GROUP"></a>
+### `ERR_CRYPTO_UNKNOWN_DH_GROUP`
+
+An unknown Diffie-Hellman group name was given. See
+[`crypto.getDiffieHellman()`][] for a list of valid group names.
+
 <a id="ERR_DIR_CLOSED"></a>
 ### `ERR_DIR_CLOSED`
 
@@ -1514,6 +1520,12 @@ strict compliance with the API specification (which in some cases may accept
 An [ES Module][] loader hook specified `format: 'dynamic'` but did not provide
 a `dynamicInstantiate` hook.
 
+<a id="ERR_MISSING_OPTION"></a>
+### `ERR_MISSING_OPTION`
+
+For APIs that accept options objects, some options might be mandatory. This code
+is thrown if a required option is missing.
+
 <a id="ERR_MISSING_MESSAGE_PORT_IN_TRANSFER_LIST"></a>
 ### `ERR_MISSING_MESSAGE_PORT_IN_TRANSFER_LIST`
 
@@ -2423,6 +2435,7 @@ such as `process.stdout.on('data')`.
 [`Writable`]: stream.html#stream_class_stream_writable
 [`child_process`]: child_process.html
 [`cipher.getAuthTag()`]: crypto.html#crypto_cipher_getauthtag
+[`crypto.getDiffieHellman()`]: crypto.html#crypto_crypto_getdiffiehellman_groupname
 [`crypto.scrypt()`]: crypto.html#crypto_crypto_scrypt_password_salt_keylen_options_callback
 [`crypto.scryptSync()`]: crypto.html#crypto_crypto_scryptsync_password_salt_keylen_options
 [`crypto.timingSafeEqual()`]: crypto.html#crypto_crypto_timingsafeequal_a_b

diff --git a/lib/internal/crypto/keygen.js b/lib/internal/crypto/keygen.js
@@ -11,6 +11,7 @@ const {
   generateKeyPairDSA,
   generateKeyPairEC,
   generateKeyPairNid,
+  generateKeyPairDH,
   EVP_PKEY_ED25519,
   EVP_PKEY_ED448,
   EVP_PKEY_X25519,
@@ -28,10 +29,12 @@ const {
 const { customPromisifyArgs } = require('internal/util');
 const { isUint32, validateString } = require('internal/validators');
 const {
+  ERR_INCOMPATIBLE_OPTION_PAIR,
   ERR_INVALID_ARG_TYPE,
   ERR_INVALID_ARG_VALUE,
   ERR_INVALID_CALLBACK,
-  ERR_INVALID_OPT_VALUE
+  ERR_INVALID_OPT_VALUE,
+  ERR_MISSING_OPTION
 } = require('internal/errors').codes;
 
 const { isArrayBufferView } = require('internal/util/types');
@@ -245,6 +248,49 @@ function check(type, options, callback) {
                                             cipher, passphrase, wrap);
       }
       break;
+    case 'dh':
+      {
+        const { group, primeLength, prime, generator } = needOptions();
+        let args;
+        if (group != null) {
+          if (prime != null)
+            throw new ERR_INCOMPATIBLE_OPTION_PAIR('group', 'prime');
+          if (primeLength != null)
+            throw new ERR_INCOMPATIBLE_OPTION_PAIR('group', 'primeLength');
+          if (generator != null)
+            throw new ERR_INCOMPATIBLE_OPTION_PAIR('group', 'generator');
+          if (typeof group !== 'string')
+            throw new ERR_INVALID_OPT_VALUE('group', group);
+          args = [group];
+        } else {
+          if (prime != null) {
+            if (primeLength != null)
+              throw new ERR_INCOMPATIBLE_OPTION_PAIR('prime', 'primeLength');
+            if (!isArrayBufferView(prime))
+              throw new ERR_INVALID_OPT_VALUE('prime', prime);
+          } else if (primeLength != null) {
+            if (!isUint32(primeLength))
+              throw new ERR_INVALID_OPT_VALUE('primeLength', primeLength);
+          } else {
+            throw new ERR_MISSING_OPTION(
+              'At least one of the group, prime, or primeLength options');
+          }
+
+          if (generator != null) {
+            if (!isUint32(generator))
+              throw new ERR_INVALID_OPT_VALUE('generator', generator);
+          }
+
+          args = [prime != null ? prime : primeLength,
+                  generator == null ? 2 : generator];
+        }
+
+        impl = (wrap) => generateKeyPairDH(...args,
+                                           publicFormat, publicType,
+                                           privateFormat, privateType,
+                                           cipher, passphrase, wrap);
+      }
+      break;
     default:
       throw new ERR_INVALID_ARG_VALUE('type', type,
                                       'must be a supported key type');

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
@@ -1187,6 +1187,7 @@ E('ERR_MISSING_ARGS',
 E('ERR_MISSING_DYNAMIC_INSTANTIATE_HOOK',
   'The ES Module loader may not return a format of \'dynamic\' when no ' +
   'dynamicInstantiate function was provided', Error);
+E('ERR_MISSING_OPTION', '%s is required', TypeError);
 E('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times', Error);
 E('ERR_NAPI_CONS_FUNCTION', 'Constructor must be a function', TypeError);
 E('ERR_NAPI_INVALID_DATAVIEW_ARGS',

diff --git a/src/node_crypto.cc b/src/node_crypto.cc
@@ -6628,6 +6628,71 @@ class NidKeyPairGenerationConfig : public KeyPairGenerationConfig {
   const int id_;
 };
 
+// TODO(tniessen): Use std::variant instead.
+// Diffie-Hellman can either generate keys using a fixed prime, or by first
+// generating a random prime of a given size (in bits). Only one of both options
+// may be specified.
+struct PrimeInfo {
+  BignumPointer fixed_value_;
+  unsigned int prime_size_;
+};
+
+class DHKeyPairGenerationConfig : public KeyPairGenerationConfig {
+ public:
+  explicit DHKeyPairGenerationConfig(PrimeInfo&& prime_info,
+                                     unsigned int generator)
+      : prime_info_(std::move(prime_info)),
+        generator_(generator) {}
+
+  EVPKeyCtxPointer Setup() override {
+    EVPKeyPointer params;
+    if (prime_info_.fixed_value_) {
+      DHPointer dh(DH_new());
+      if (!dh)
+        return nullptr;
+
+      BIGNUM* prime = prime_info_.fixed_value_.get();
+      BignumPointer bn_g(BN_new());
+      if (!BN_set_word(bn_g.get(), generator_) ||
+          !DH_set0_pqg(dh.get(), prime, nullptr, bn_g.get()))
+        return nullptr;
+
+      prime_info_.fixed_value_.release();
+      bn_g.release();
+
+      params = EVPKeyPointer(EVP_PKEY_new());
+      CHECK(params);
+      EVP_PKEY_assign_DH(params.get(), dh.release());
+    } else {
+      EVPKeyCtxPointer param_ctx(EVP_PKEY_CTX_new_id(EVP_PKEY_DH, nullptr));
+      if (!param_ctx)
+        return nullptr;
+
+      if (EVP_PKEY_paramgen_init(param_ctx.get()) <= 0)
+        return nullptr;
+
+      if (EVP_PKEY_CTX_set_dh_paramgen_prime_len(param_ctx.get(),
+                                                 prime_info_.prime_size_) <= 0)
+        return nullptr;
+
+      if (EVP_PKEY_CTX_set_dh_paramgen_generator(param_ctx.get(),
+                                                 generator_) <= 0)
+        return nullptr;
+
+      EVP_PKEY* raw_params = nullptr;
+      if (EVP_PKEY_paramgen(param_ctx.get(), &raw_params) <= 0)
+        return nullptr;
+      params = EVPKeyPointer(raw_params);
+    }
+
+    return EVPKeyCtxPointer(EVP_PKEY_CTX_new(params.get(), nullptr));
+  }
+
+ private:
+  PrimeInfo prime_info_;
+  unsigned int generator_;
+};
+
 class GenerateKeyPairJob : public CryptoJob {
  public:
   GenerateKeyPairJob(Environment* env,
@@ -6847,6 +6912,39 @@ void GenerateKeyPairNid(const FunctionCallbackInfo<Value>& args) {
   GenerateKeyPair(args, 1, std::move(config));
 }
 
+void GenerateKeyPairDH(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+
+  PrimeInfo prime_info = {};
+  unsigned int generator;
+  if (args[0]->IsString()) {
+    String::Utf8Value group_name(args.GetIsolate(), args[0].As<String>());
+    const modp_group* group = FindDiffieHellmanGroup(*group_name);
+    if (group == nullptr)
+      return THROW_ERR_CRYPTO_UNKNOWN_DH_GROUP(env);
+
+    prime_info.fixed_value_ = BignumPointer(
+        BN_bin2bn(reinterpret_cast<const unsigned char*>(group->prime),
+                  group->prime_size, nullptr));
+    generator = group->gen;
+  } else {
+    if (args[0]->IsInt32()) {
+      prime_info.prime_size_ = args[0].As<Int32>()->Value();
+    } else {
+      ArrayBufferViewContents<unsigned char> input(args[0]);
+      prime_info.fixed_value_ = BignumPointer(
+          BN_bin2bn(input.data(), input.length(), nullptr));
+    }
+
+    CHECK(args[1]->IsInt32());
+    generator = args[1].As<Int32>()->Value();
+  }
+
+  std::unique_ptr<KeyPairGenerationConfig> config(
+      new DHKeyPairGenerationConfig(std::move(prime_info), generator));
+  GenerateKeyPair(args, 2, std::move(config));
+}
+
 
 void GetSSLCiphers(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
@@ -7253,6 +7351,7 @@ void Initialize(Local<Object> target,
   env->SetMethod(target, "generateKeyPairDSA", GenerateKeyPairDSA);
   env->SetMethod(target, "generateKeyPairEC", GenerateKeyPairEC);
   env->SetMethod(target, "generateKeyPairNid", GenerateKeyPairNid);
+  env->SetMethod(target, "generateKeyPairDH", GenerateKeyPairDH);
   NODE_DEFINE_CONSTANT(target, EVP_PKEY_ED25519);
   NODE_DEFINE_CONSTANT(target, EVP_PKEY_ED448);
   NODE_DEFINE_CONSTANT(target, EVP_PKEY_X25519);

diff --git a/src/node_errors.h b/src/node_errors.h
@@ -39,6 +39,7 @@ void PrintErrorString(const char* format, ...);
   V(ERR_BUFFER_TOO_LARGE, Error)                                             \
   V(ERR_CONSTRUCT_CALL_REQUIRED, TypeError)                                  \
   V(ERR_CONSTRUCT_CALL_INVALID, TypeError)                                   \
+  V(ERR_CRYPTO_UNKNOWN_DH_GROUP, Error)                                      \
   V(ERR_INVALID_ARG_VALUE, TypeError)                                        \
   V(ERR_OSSL_EVP_INVALID_DIGEST, Error)                                      \
   V(ERR_INVALID_ARG_TYPE, TypeError)                                         \
@@ -89,6 +90,7 @@ void PrintErrorString(const char* format, ...);
     "Buffer is not available for the current Context")                       \
   V(ERR_CONSTRUCT_CALL_INVALID, "Constructor cannot be called")              \
   V(ERR_CONSTRUCT_CALL_REQUIRED, "Cannot call constructor without `new`")    \
+  V(ERR_CRYPTO_UNKNOWN_DH_GROUP, "Unknown DH group")                         \
   V(ERR_INVALID_TRANSFER_OBJECT, "Found invalid object in transferList")     \
   V(ERR_MEMORY_ALLOCATION_FAILED, "Failed to allocate memory")               \
   V(ERR_OSSL_EVP_INVALID_DIGEST, "Invalid digest used")                      \