Crypto: allow to retreive salt & encrypted data and to derive raw key for AES encryption

include/opendht/crypto.h

@@ -793,7 +793,7 @@ OPENDHT_PUBLIC void hash(const uint8_t* data, size_t data_length, uint8_t* hash,
  * that can be transmitted in clear, and will be generated if
  * not provided (32 bytes).
  */
-OPENDHT_PUBLIC Blob stretchKey(const std::string& password, Blob& salt, size_t key_length = 512/8);
+OPENDHT_PUBLIC Blob stretchKey(std::string_view password, Blob& salt, size_t key_length = 512/8);
 
 /**
  * AES-GCM encryption. Key must be 128, 192 or 256 bits long (16, 24 or 32 bytes).
@@ -802,15 +802,37 @@ OPENDHT_PUBLIC Blob aesEncrypt(const uint8_t* data, size_t data_length, const Bl
 OPENDHT_PUBLIC inline Blob aesEncrypt(const Blob& data, const Blob& key) {
     return aesEncrypt(data.data(), data.size(), key);
 }
-OPENDHT_PUBLIC Blob aesEncrypt(const Blob& data, const std::string& password);
+OPENDHT_PUBLIC Blob aesEncrypt(const Blob& data, std::string_view password);
 
 /**
  * AES-GCM decryption.
  */
 OPENDHT_PUBLIC Blob aesDecrypt(const uint8_t* data, size_t data_length, const Blob& key);
 OPENDHT_PUBLIC inline Blob aesDecrypt(const Blob& data, const Blob& key) { return aesDecrypt(data.data(), data.size(), key); }
-OPENDHT_PUBLIC Blob aesDecrypt(const uint8_t* data, size_t data_length, const std::string& password);
-OPENDHT_PUBLIC inline Blob aesDecrypt(const Blob& data, const std::string& password) { return aesDecrypt(data.data(), data.size(), password); }
+OPENDHT_PUBLIC inline Blob aesDecrypt(std::string_view data, const Blob& key) { return aesDecrypt((uint8_t*)data.data(), data.size(), key); }
+
+OPENDHT_PUBLIC Blob aesDecrypt(const uint8_t* data, size_t data_length, std::string_view password);
+OPENDHT_PUBLIC inline Blob aesDecrypt(const Blob& data, std::string_view password) { return aesDecrypt(data.data(), data.size(), password); }
+OPENDHT_PUBLIC inline Blob aesDecrypt(std::string_view data, std::string_view password) { return aesDecrypt((uint8_t*)data.data(), data.size(), password); }
+
+/**
+ * Get raw AES key from password and salt stored with the encrypted data.
+ */
+OPENDHT_PUBLIC Blob aesGetKey(const uint8_t* data, size_t data_length, std::string_view password);
+OPENDHT_PUBLIC Blob inline aesGetKey(const Blob& data, std::string_view password) {
+    return aesGetKey(data.data(), data.size(), password);
+}
+/** Get the salt part of data password-encrypted with `aesEncrypt(data, password)` */
+OPENDHT_PUBLIC Blob aesGetSalt(const uint8_t* data, size_t data_length);
+OPENDHT_PUBLIC Blob inline aesGetSalt(const Blob& data) {
+    return aesGetSalt(data.data(), data.size());
+}
+/** Get the salt part of data password-encrypted with `aesEncrypt(data, password)` */
+OPENDHT_PUBLIC std::string_view aesGetEncrypted(const uint8_t* data, size_t data_length);
+OPENDHT_PUBLIC std::string_view inline aesGetEncrypted(const Blob& data) {
+    return aesGetEncrypted(data.data(), data.size());
+}
+
 
 }
 }

python/opendht.pyx

@@ -462,6 +462,26 @@ cdef class Identity(object):
             k._key = self._id.first
             return k
 
+def aesEncrypt(bytes data, str password) -> bytes :
+    cdef size_t d_len = len(data)
+    cdef cpp.uint8_t* d_ptr = <cpp.uint8_t*>data
+    cdef cpp.Blob indat
+    indat.assign(d_ptr, <cpp.uint8_t*>(d_ptr + d_len))
+    cdef cpp.Blob encrypted = cpp.aesEncrypt(indat, password.encode())
+    cdef char* encrypted_c_str = <char *>encrypted.data()
+    cdef Py_ssize_t length = encrypted.size()
+    return encrypted_c_str[:length]
+
+def aesDecrypt(bytes data, str password) -> bytes :
+    cdef size_t d_len = len(data)
+    cdef cpp.uint8_t* d_ptr = <cpp.uint8_t*>data
+    cdef cpp.Blob indat
+    indat.assign(d_ptr, <cpp.uint8_t*>(d_ptr + d_len))
+    cdef cpp.Blob decrypted = cpp.aesDecrypt(indat, password.encode())
+    cdef char* decrypted_c_str = <char *>decrypted.data()
+    cdef Py_ssize_t length = decrypted.size()
+    return decrypted_c_str[:length]
+
 cdef class DhtConfig(object):
     cdef cpp.DhtRunnerConfig _config
     def __init__(self):

python/opendht_cpp.pxd

@@ -94,6 +94,8 @@ ctypedef vector[uint8_t] Blob
 cdef extern from "opendht/crypto.h" namespace "dht::crypto":
     ctypedef pair[shared_ptr[PrivateKey], shared_ptr[Certificate]] Identity
     cdef Identity generateIdentity(string name, Identity ca, unsigned bits)
+    cdef Blob aesEncrypt(Blob data, string password) except +
+    cdef Blob aesDecrypt(Blob encrypted, string password) except +
 
     cdef cppclass PrivateKey:
         PrivateKey()

src/crypto.cpp

@@ -103,7 +103,7 @@ Blob aesEncrypt(const uint8_t* data, size_t data_length, const Blob& key)
     return ret;
 }
 
-Blob aesEncrypt(const Blob& data, const std::string& password)
+Blob aesEncrypt(const Blob& data, std::string_view password)
 {
     Blob salt;
     Blob key = stretchKey(password, salt, 256 / 8);
@@ -152,16 +152,35 @@ Blob aesDecrypt(const uint8_t* data, size_t data_length, const Blob& key)
     return ret;
 }
 
-Blob aesDecrypt(const uint8_t* data, size_t data_len, const std::string& password)
+Blob aesDecrypt(const uint8_t* data, size_t data_length, std::string_view password)
 {
-    if (data_len <= PASSWORD_SALT_LENGTH)
+    return aesDecrypt(
+        aesGetEncrypted(data, data_length),
+        aesGetKey(data, data_length, password)
+    );
+}
+
+Blob aesGetSalt(const uint8_t* data, size_t data_length)
+{
+    if (data_length <= PASSWORD_SALT_LENGTH)
+        throw DecryptError("Wrong data size");
+    return Blob {data, data+PASSWORD_SALT_LENGTH};
+}
+
+std::string_view aesGetEncrypted(const uint8_t* data, size_t data_length)
+{
+    if (data_length <= PASSWORD_SALT_LENGTH)
         throw DecryptError("Wrong data size");
-    Blob salt {data, data+PASSWORD_SALT_LENGTH};
-    Blob key = stretchKey(password, salt, 256/8);
-    return aesDecrypt(data+PASSWORD_SALT_LENGTH, data_len - PASSWORD_SALT_LENGTH, key);
+    return std::string_view((const char*)(data+PASSWORD_SALT_LENGTH), data_length - PASSWORD_SALT_LENGTH);
+}
+
+Blob aesGetKey(const uint8_t* data, size_t data_length, std::string_view password)
+{
+    Blob salt = aesGetSalt(data, data_length);
+    return stretchKey(password, salt, 256/8);
 }
 
-Blob stretchKey(const std::string& password, Blob& salt, size_t key_length)
+Blob stretchKey(std::string_view password, Blob& salt, size_t key_length)
 {
     if (salt.empty()) {
         salt.resize(PASSWORD_SALT_LENGTH);

tests/cryptotester.cpp

@@ -173,6 +173,54 @@ void CryptoTester::testOcsp() {
     CPPUNIT_ASSERT(ocspRequest.second == req.getNonce());
 }
 
+void CryptoTester::testAesEncryption() {
+    auto password = "this is a password 123414!@#%@#$?" + std::to_string(rand());
+
+    std::vector<uint8_t> data1 {5, 10};
+    std::vector<uint8_t> data2(128 * 1024 + 13, 10);
+
+    auto encrypted1 = dht::crypto::aesEncrypt(data1, password);
+    auto encrypted2 = dht::crypto::aesEncrypt(data2, password);
+
+    auto decrypted1 = dht::crypto::aesDecrypt(encrypted1, password);
+    auto decrypted2 = dht::crypto::aesDecrypt(encrypted2, password);
+
+    CPPUNIT_ASSERT(data1 != encrypted1);
+    CPPUNIT_ASSERT(data2 != encrypted2);
+    CPPUNIT_ASSERT(data1 == decrypted1);
+    CPPUNIT_ASSERT(data2 == decrypted2);
+
+    auto key1 = dht::crypto::aesGetKey(encrypted1, password);
+    auto key2 = dht::crypto::aesGetKey(encrypted2, password);
+    auto encrypted1_data = dht::crypto::aesGetEncrypted(encrypted1);
+    auto encrypted2_data = dht::crypto::aesGetEncrypted(encrypted2);
+
+    CPPUNIT_ASSERT(key1 != key2);
+
+    decrypted1 = dht::crypto::aesDecrypt(encrypted1_data, key1);
+    decrypted2 = dht::crypto::aesDecrypt(encrypted2_data, key2);
+
+    CPPUNIT_ASSERT(data1 == decrypted1);
+    CPPUNIT_ASSERT(data2 == decrypted2);
+
+    auto salt1 = dht::crypto::aesGetSalt(encrypted1);
+    auto salt2 = dht::crypto::aesGetSalt(encrypted2);
+
+    CPPUNIT_ASSERT(salt1 != salt2);
+
+    auto key12 = dht::crypto::stretchKey(password, salt1, 256/8);
+    auto key22 = dht::crypto::stretchKey(password, salt2, 256/8);
+
+    CPPUNIT_ASSERT(key1 == key12);
+    CPPUNIT_ASSERT(key2 == key22);
+
+    decrypted1 = dht::crypto::aesDecrypt(encrypted1_data, key12);
+    decrypted2 = dht::crypto::aesDecrypt(encrypted2_data, key22);
+
+    CPPUNIT_ASSERT(data1 == decrypted1);
+    CPPUNIT_ASSERT(data2 == decrypted2);
+}
+
 void
 CryptoTester::tearDown() {
 

tests/cryptotester.h

@@ -33,6 +33,7 @@ class CryptoTester : public CppUnit::TestFixture {
     CPPUNIT_TEST(testCertificateRequest);
     CPPUNIT_TEST(testCertificateSerialNumber);
     CPPUNIT_TEST(testOcsp);
+    CPPUNIT_TEST(testAesEncryption);
     CPPUNIT_TEST_SUITE_END();
 
  public:
@@ -64,6 +65,10 @@ class CryptoTester : public CppUnit::TestFixture {
      * Test OCSP
      */
     void testOcsp();
+    /**
+     * Test key streching and aes encryption/decryption
+     */
+    void testAesEncryption();
 };
 
 }  // namespace test