Hack to allow ec_private_key_openssl loading keys generated with NSS.

crypto/ec_private_key_openssl.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/ec.h>
 #include <openssl/evp.h>
 #include <openssl/pkcs12.h>
 #include <openssl/x509.h>
@@ skipping 114 matching lines @@
   // Convert it, then decrypt it into a PKCS#8 object.
   ScopedOpenSSL<X509_SIG, X509_SIG_free> p8_encrypted(
       d2i_PKCS8_bio(bio.get(), NULL));
   if (!p8_encrypted.get())
     return NULL;
 
   ScopedOpenSSL<PKCS8_PRIV_KEY_INFO, PKCS8_PRIV_KEY_INFO_free> p8_decrypted(
       PKCS8_decrypt(p8_encrypted.get(),
                     password.c_str(),
                     static_cast<int>(password.size())));
+  if (!p8_decrypted.get() && password.empty()) {
+    // Hack for reading keys generated by ec_private_key_nss. Passing NULL
+    // causes OpenSSL to use an empty password instead of "\0\0".

[wtc, 2014/03/22 03:13:45]

Does NSS have a bug?

[mattm, 2014/03/22 04:01:34]

I don't know I'd call it a bug in NSS, other than perhaps of lacking
documentation.
NSS takes a SECItem for the password and uses it directly, so it's up to the app
to use an appropriately formatted password. (In ec_private_key_nss.cc, we pass
in a 0-length pwitem.)

OpenSSL interprets the password input as ASCII and converts it to 2-byte unicode
string with included null termination (Unless you #define PBE_UNICODE when
building OpenSSL, in which case it's like NSS and you can pass in whatever you
want without it being changed.)

PKCS 12 section B.1 says the password should be a 2-byte big-endian unicode
string with included 2 bytes of null termination, but then B.2.3 says that if
the password is the empty string, P should also be empty. I guess taken
literally, "\0\0" is not an empty string, but I dunno if that's what was
intended.

+    p8_decrypted.reset(PKCS8_decrypt(p8_encrypted.get(), NULL, 0));
+  }
   if (!p8_decrypted.get())
     return NULL;
 
   // Create a new EVP_PKEY for it.
   scoped_ptr<ECPrivateKey> result(new ECPrivateKey);
   result->key_ = EVP_PKCS82PKEY(p8_decrypted.get());
   if (!result->key_)
     return NULL;
 
   return result.release();
@@ skipping 50 matching lines @@
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   ScopedOpenSSL<EC_KEY, EC_KEY_free> ec_key(EVP_PKEY_get1_EC_KEY(key_));
   return ExportKey(ec_key.get(),
                    reinterpret_cast<ExportDataFunction>(i2d_ECParameters),
                    output);
 }
 
 ECPrivateKey::ECPrivateKey() : key_(NULL) {}
 
 }  // namespace crypto