Add PKCS#8 ECPrivateKey export/import functions.

crypto/ec_private_key.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "crypto/ec_private_key.h"
 
 #include <openssl/bytestring.h>
 #include <openssl/ec.h>
 #include <openssl/evp.h>
 #include <openssl/mem.h>
@@ skipping 72 matching lines @@
   std::unique_ptr<ECPrivateKey> result(new ECPrivateKey());
   result->key_ = EVP_PKEY_new();
   if (!result->key_ || !EVP_PKEY_set1_EC_KEY(result->key_, ec_key.get()))
     return NULL;
 
   CHECK_EQ(EVP_PKEY_EC, EVP_PKEY_type(result->key_->type));
   return result.release();
 }
 
 // static
+std::unique_ptr<ECPrivateKey> ECPrivateKey::CreateFromPrivateKeyInfo(
+    const std::vector<uint8_t>& input) {
+  OpenSSLErrStackTracer err_tracer(FROM_HERE);
+
+  CBS cbs;
+  CBS_init(&cbs, input.data(), input.size());
+  ScopedEVP_PKEY pkey(EVP_parse_private_key(&cbs));
+  if (!pkey || CBS_len(&cbs) != 0)
+    return nullptr;
+
+  // Check this is a P-256 key.
+  EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(pkey.get());
+  if (!ec_key ||
+      EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) !=
+          NID_X9_62_prime256v1) {

[Ryan Sleevi, 2016/05/02 23:26:56]

Why? We don't enforce this elsewhere, AFAICT. It's implicit in
ExportPublicKeyRaw, but my point here is that this isn't documented in the
header as part of the API contract, nor consistently enforced. I have no
objections to enforcing this consistently, and to clearly documenting that
contract - but this feels asymmetric and underspecified in the present form.

[davidben, 2016/06/01 17:19:39]

I think it's a little poor to have parsing be able to create keys that we would
never parse. But, fair enough, if we're to limit it to P-256, it should be done
uniformly and with tests. Took that bit out. We can sort it out separately.

[davidben, 2016/06/01 17:19:58]

s/would never parse/would never create/

+    return nullptr;
+  }
+
+  std::unique_ptr<ECPrivateKey> result(new ECPrivateKey);
+  result->key_ = pkey.release();
+  return result;
+}
+
+// static
 ECPrivateKey* ECPrivateKey::CreateFromEncryptedPrivateKeyInfo(
     const std::string& password,
     const std::vector<uint8_t>& encrypted_private_key_info,
     const std::vector<uint8_t>& subject_public_key_info) {
   // NOTE: The |subject_public_key_info| can be ignored here, it is only
   // useful for the NSS implementation (which uses the public key's SHA1
   // as a lookup key when storing the private one in its store).
   if (encrypted_private_key_info.empty())
     return NULL;
 
@@ skipping 27 matching lines @@
 
   // Create a new EVP_PKEY for it.
   std::unique_ptr<ECPrivateKey> result(new ECPrivateKey);
   result->key_ = EVP_PKCS82PKEY(p8_decrypted.get());
   if (!result->key_ || EVP_PKEY_type(result->key_->type) != EVP_PKEY_EC)
     return NULL;
 
   return result.release();
 }
 
-bool ECPrivateKey::ExportEncryptedPrivateKey(const std::string& password,
-                                             int iterations,
-                                             std::vector<uint8_t>* output) {
+bool ECPrivateKey::ExportPrivateKey(std::vector<uint8_t>* output) const {
+  OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  uint8_t* der;
+  size_t der_len;
+  AutoCBB cbb;
+  if (!CBB_init(cbb.get(), 0) || !EVP_marshal_private_key(cbb.get(), key_) ||
+      !CBB_finish(cbb.get(), &der, &der_len)) {
+    return false;
+  }
+  output->assign(der, der + der_len);
+  OPENSSL_free(der);
+  return true;
+}
+
+bool ECPrivateKey::ExportEncryptedPrivateKey(
+    const std::string& password,
+    int iterations,
+    std::vector<uint8_t>* output) const {
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   // Convert into a PKCS#8 object.
   ScopedPKCS8_PRIV_KEY_INFO pkcs8(EVP_PKEY2PKCS8(key_));
   if (!pkcs8.get())
     return false;
 
   // Encrypt the object.
   // NOTE: NSS uses SEC_OID_PKCS12_V2_PBE_WITH_SHA1_AND_3KEY_TRIPLE_DES_CBC
   // so use NID_pbe_WithSHA1And3_Key_TripleDES_CBC which should be the OpenSSL
   // equivalent.
   ScopedX509_SIG encrypted(PKCS8_encrypt_pbe(
       NID_pbe_WithSHA1And3_Key_TripleDES_CBC,
       nullptr,
       reinterpret_cast<const uint8_t*>(password.data()),
       password.size(),
       nullptr,
       0,
       iterations,
       pkcs8.get()));
   if (!encrypted.get())
     return false;
 
   // Write it into |*output|
   return ExportKeyWithBio(encrypted.get(),
                           reinterpret_cast<ExportBioFunction>(i2d_PKCS8_bio),
                           output);
 }
 
-bool ECPrivateKey::ExportPublicKey(std::vector<uint8_t>* output) {
+bool ECPrivateKey::ExportPublicKey(std::vector<uint8_t>* output) const {
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   uint8_t *der;
   size_t der_len;
   AutoCBB cbb;
   if (!CBB_init(cbb.get(), 0) ||
       !EVP_marshal_public_key(cbb.get(), key_) ||
       !CBB_finish(cbb.get(), &der, &der_len)) {
     return false;
   }
   output->assign(der, der + der_len);
   OPENSSL_free(der);
   return true;
 }
 
-bool ECPrivateKey::ExportRawPublicKey(std::string* output) {
+bool ECPrivateKey::ExportRawPublicKey(std::string* output) const {
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
 
   // Export the x and y field elements as 32-byte, big-endian numbers. (This is
   // the same as X9.62 uncompressed form without the leading 0x04 byte.)
   EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(key_);
   ScopedBIGNUM x(BN_new());
   ScopedBIGNUM y(BN_new());
   uint8_t buf[64];
   if (!x || !y ||
       !EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(ec_key),
                                            EC_KEY_get0_public_key(ec_key),
                                            x.get(), y.get(), nullptr) ||
       !BN_bn2bin_padded(buf, 32, x.get()) ||
       !BN_bn2bin_padded(buf + 32, 32, y.get())) {
     return false;
   }
 
   output->assign(reinterpret_cast<const char*>(buf), sizeof(buf));
   return true;
 }
 
-bool ECPrivateKey::ExportValueForTesting(std::vector<uint8_t>* output) {
-  OpenSSLErrStackTracer err_tracer(FROM_HERE);
-  EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(key_);
-  uint8_t *der;
-  size_t der_len;
-  AutoCBB cbb;
-  if (!CBB_init(cbb.get(), 0) ||
-      !EC_KEY_marshal_private_key(cbb.get(), ec_key, 0 /* enc_flags */) ||
-      !CBB_finish(cbb.get(), &der, &der_len)) {
-    return false;
-  }
-  output->assign(der, der + der_len);
-  OPENSSL_free(der);
-  return true;
-}
-
 ECPrivateKey::ECPrivateKey() : key_(NULL) {}
 
 }  // namespace crypto