QSslKey - add a support for AES encrypted keys

for SecureTransport backend. OpenSSL, while reading
RSA/DSA, is internally calling EVP_BytesToKey that
essentially does the same thing this patch does in
'deriveAesKey' and thus able to correctly decrypt
whatever it first encrypted (while generating/
encrypting keys).

Fixes: QTBUG-54422
Change-Id: Ia9f7599c5b19bf364c179f2abd2aab7ea5359a65
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/ssl/qsslkey_mac.cpp

@@ -66,7 +66,13 @@ static QByteArray wrapCCCrypt(CCOperation ccOp,
         blockSize = kCCBlockSizeRC2;
         ccAlgorithm = kCCAlgorithmRC2;
         break;
-    };
+    case QSslKeyPrivate::Aes128Cbc:
+    case QSslKeyPrivate::Aes192Cbc:
+    case QSslKeyPrivate::Aes256Cbc:
+        blockSize = kCCBlockSizeAES128;
+        ccAlgorithm = kCCAlgorithmAES;
+        break;
+    }
     size_t plainLength = 0;
     QByteArray plain(data.size() + blockSize, 0);
     CCCryptorStatus status = CCCrypt(

src/network/ssl/qsslkey_openssl.cpp

@@ -333,6 +333,14 @@ static QByteArray doCrypt(QSslKeyPrivate::Cipher cipher, const QByteArray &data,
         type = q_EVP_rc2_cbc();
 #endif
         break;
+    case QSslKeyPrivate::Aes128Cbc:
+    case QSslKeyPrivate::Aes192Cbc:
+    case QSslKeyPrivate::Aes256Cbc:
+        // Just to avoid compiler warnings/errors. OpenSSL uses a different
+        // codepath when reading encrypted keys, and they all correctly
+        // deduce the cipher and know how to derive a key.
+        Q_UNREACHABLE();
+        break;
     }
 
     if (type == nullptr)

src/network/ssl/qsslkey_p.h

@@ -105,7 +105,10 @@ public:
     enum Cipher {
         DesCbc,
         DesEde3Cbc,
-        Rc2Cbc
+        Rc2Cbc,
+        Aes128Cbc,
+        Aes192Cbc,
+        Aes256Cbc
     };
 
     Q_AUTOTEST_EXPORT static QByteArray decrypt(Cipher cipher, const QByteArray &data, const QByteArray &key, const QByteArray &iv);

src/network/ssl/qsslkey_qt.cpp

@@ -124,6 +124,37 @@ static int numberOfBits(const QByteArray &modulus)
     return bits;
 }
 
+static QByteArray deriveAesKey(QSslKeyPrivate::Cipher cipher, const QByteArray &passPhrase, const QByteArray &iv)
+{
+    // This is somewhat simplified and shortened version of what OpenSSL does.
+    // See, for example, EVP_BytesToKey for the "algorithm" itself and elsewhere
+    // in their code for what they pass as arguments to EVP_BytesToKey when
+    // deriving encryption keys (when reading/writing pems files with encrypted
+    // keys).
+
+    Q_ASSERT(iv.size() >= 8);
+
+    QCryptographicHash hash(QCryptographicHash::Md5);
+
+    QByteArray data(passPhrase);
+    data.append(iv.data(), 8); // AKA PKCS5_SALT_LEN in OpenSSL.
+
+    hash.addData(data);
+
+    if (cipher == QSslKeyPrivate::Aes128Cbc)
+        return hash.result();
+
+    QByteArray key(hash.result());
+    hash.reset();
+    hash.addData(key);
+    hash.addData(data);
+
+    if (cipher == QSslKeyPrivate::Aes192Cbc)
+        return key.append(hash.result().constData(), 8);
+
+    return key.append(hash.result());
+}
+
 static QByteArray deriveKey(QSslKeyPrivate::Cipher cipher, const QByteArray &passPhrase, const QByteArray &iv)
 {
     QByteArray key;
@@ -145,6 +176,10 @@ static QByteArray deriveKey(QSslKeyPrivate::Cipher cipher, const QByteArray &pas
     case QSslKeyPrivate::Rc2Cbc:
         key = hash.result();
         break;
+    case QSslKeyPrivate::Aes128Cbc:
+    case QSslKeyPrivate::Aes192Cbc:
+    case QSslKeyPrivate::Aes256Cbc:
+        return deriveAesKey(cipher, passPhrase, iv);
     }
     return key;
 }
@@ -378,6 +413,15 @@ void QSslKeyPrivate::decodePem(const QByteArray &pem, const QByteArray &passPhra
             cipher = DesEde3Cbc;
         } else if (dekInfo.first() == "RC2-CBC") {
             cipher = Rc2Cbc;
+// TODO: Add SChannel version too!
+#ifdef QT_SECURETRANSPORT
+        } else if (dekInfo.first() == "AES-128-CBC") {
+            cipher = Aes128Cbc;
+        } else if (dekInfo.first() == "AES-192-CBC") {
+            cipher = Aes192Cbc;
+        } else if (dekInfo.first() == "AES-256-CBC") {
+            cipher = Aes256Cbc;
+#endif // QT_SECURETRANSPORT
         } else {
             clear(deepClear);
             return;
@@ -554,6 +598,10 @@ static EncryptionData readPbes2(const QVector<QAsn1Element> &element, const QByt
             return {};
         break;
     } // @todo(?): case (RC5 , AES)
+    case QSslKeyPrivate::Cipher::Aes128Cbc:
+    case QSslKeyPrivate::Cipher::Aes192Cbc:
+    case QSslKeyPrivate::Cipher::Aes256Cbc:
+        Q_UNREACHABLE();
     }
 
     if (Q_LIKELY(keyDerivationAlgorithm == PKCS5_PBKDF2_ENCRYPTION_OID)) {

src/network/ssl/qsslkey_schannel.cpp

@@ -57,6 +57,7 @@ const wchar_t *getName(QSslKeyPrivate::Cipher cipher)
         return BCRYPT_3DES_ALGORITHM;
     case QSslKeyPrivate::Cipher::Rc2Cbc:
         return BCRYPT_RC2_ALGORITHM;
+    default:;
     }
     Q_UNREACHABLE();
 }

tests/auto/network/ssl/qsslkey/rsa-with-passphrase-aes128.pem

@@ -0,0 +1,30 @@
+-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-128-CBC,A2A6F6BA67CFB2A992BA4FD3A0984B59
+
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+meCL1t89OgwIAmIsysKu7+DrKtSlhkQclZmdG6IrQzuPKaHzTPTDgg3ef3jQ4YQO
+-----END RSA PRIVATE KEY-----

tests/auto/network/ssl/qsslkey/rsa-with-passphrase-aes192.pem

@@ -0,0 +1,30 @@
+-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-192-CBC,B408346ADE790F8CF0C902A4F0712B34
+
+SwzPBGxmwW2JddOyug1LrWjlZn8siSp5yezjK1x/z2+J2r/vvH8OjGnA387tFtae
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+FMX2Ve+ah2NjYBgzAhwKouWg5RyWb6X99NsrCEU75fn/ek86LGs3FxRgB4Uv7Udv
+-----END RSA PRIVATE KEY-----

tests/auto/network/ssl/qsslkey/rsa-with-passphrase-aes256.pem

@@ -0,0 +1,30 @@
+-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-256-CBC,0F2F4695C8FFA35F4076FA0273A3A4E3
+
+GCnMcAhhGuNkJ7SSMBrgNOaDfRtG22J0mdf/0VbrMOJF40P13YBjN3Kd6LpTqBya
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+UZVtRETFnLgb8neMuz3vCoPWK/DSHDZGAAicxq7vTljyoU/QP71Dw7UJIAuYx6Mc
+-----END RSA PRIVATE KEY-----

tests/auto/network/ssl/qsslkey/tst_qsslkey.cpp

@@ -466,15 +466,25 @@ void tst_QSslKey::toEncryptedPemOrDer()
 void tst_QSslKey::passphraseChecks_data()
 {
     QTest::addColumn<QString>("fileName");
+    QTest::addColumn<QByteArray>("passphrase");
 
-    QTest::newRow("DES") << (testDataDir + "rsa-with-passphrase-des.pem");
+    const QByteArray pass("123");
-    QTest::newRow("3DES") << (testDataDir + "rsa-with-passphrase-3des.pem");
+    const QByteArray aesPass("1234");
-    QTest::newRow("RC2") << (testDataDir + "rsa-with-passphrase-rc2.pem");
+
+    QTest::newRow("DES") << QString(testDataDir + "rsa-with-passphrase-des.pem") << pass;
+    QTest::newRow("3DES") << QString(testDataDir + "rsa-with-passphrase-3des.pem") << pass;
+    QTest::newRow("RC2") << QString(testDataDir + "rsa-with-passphrase-rc2.pem") << pass;
+#if (!defined(QT_NO_OPENSSL) && !defined(OPENSSL_NO_AES)) || defined(QT_SECURETRANSPORT)
+    QTest::newRow("AES128") << QString(testDataDir + "rsa-with-passphrase-aes128.pem") << aesPass;
+    QTest::newRow("AES192") << QString(testDataDir + "rsa-with-passphrase-aes192.pem") << aesPass;
+    QTest::newRow("AES256") << QString(testDataDir + "rsa-with-passphrase-aes256.pem") << aesPass;
+#endif
 }
 
 void tst_QSslKey::passphraseChecks()
 {
     QFETCH(QString, fileName);
+    QFETCH(QByteArray, passphrase);
 
     QFile keyFile(fileName);
     QVERIFY(keyFile.exists());
@@ -507,7 +517,7 @@ void tst_QSslKey::passphraseChecks()
             keyFile.open(QIODevice::ReadOnly);
         else
             keyFile.reset();
-        QSslKey key(&keyFile,QSsl::Rsa,QSsl::Pem, QSsl::PrivateKey, "123");
+        QSslKey key(&keyFile,QSsl::Rsa,QSsl::Pem, QSsl::PrivateKey, passphrase);
         QVERIFY(!key.isNull()); // correct passphrase
     }
 }