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   "id": "40f1de36-e79b-448b-84ae-b3c5d3cabf4e",
   "metadata": {
    "tags": []
   },
   "source": [
    "# Generic and Short Hashing"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "80a1d42e-5c83-4388-b549-1fe2460b9f53",
   "metadata": {},
   "source": [
    "libsodium provides functions for \"generic\" and \"short\" hashing.  \n",
    "\n",
    "Generic hashing is suitable for cryptographic purposes using the BLAKE2b algorithm."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "7f249352-fbd2-4a00-b94a-6e836366e111",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "%load_ext sql"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "eb8fa7ea-e634-42a1-8519-9add7844c019",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "%config SqlMagic.feedback=False\n",
    "%config SqlMagic.displaycon=False\n",
    "%sql postgresql://postgres@/"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "6a6fc4d4-f0fd-4431-8640-85a524f5cd32",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[]"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%%sql \n",
    "CREATE EXTENSION IF NOT EXISTS pgsodium;"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "857d49ef-f874-474f-a076-a020ed22b2ae",
   "metadata": {},
   "source": [
    "### `crypto_generichash_keygen()`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "01f03749-e98e-41d2-a816-71a6f96c64b7",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'\\xf2\\xcc\\xc18\\x8f)\\x93\\x0b^\\x12\\x13\\xa3q\\x9e\\x83\\x03\\xb7\\xb0\\xe9z+/\\x1b\\xd4\\xae\\x1fO\\xa4pj\\xab\\xef'\n"
     ]
    }
   ],
   "source": [
    "k = %sql select pgsodium.crypto_generichash_keygen()\n",
    "generichash_key = k[0][0].tobytes()\n",
    "print(generichash_key)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "bc5faade-d3de-47d7-949d-14ffd6c46b73",
   "metadata": {},
   "source": [
    "### `crypto_generichash(message bytea, key bytea = NULL)`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "923831fc-1557-4f43-9b3e-340bdeb5dc70",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'\\x9dJc\\xe5\\xdc\\x1dw\\xed\\x99\\xb6\\xf7V\\x92\\x0e\\xdb\\x89\\xdf\\xda\\xd2|J!\\xf2\\xa9j\\x85\\x82K\\x8f\\xdb_\\xe1'\n"
     ]
    }
   ],
   "source": [
    "signature = %sql select pgsodium.crypto_generichash('this is a message')\n",
    "print(signature[0][0].tobytes())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "4fa44307-63ef-4e96-bf15-991320969774",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'Y\\xc6\"\\x97\\xa5\\x16\\xa4\\xa3\\xaay8\\xe4\\xad)XS\\xa1~UDO)X\\x0bl\\x82\\xa0\\x87\\xba|\\x1al'\n"
     ]
    }
   ],
   "source": [
    "signature = %sql select pgsodium.crypto_generichash('this is a message', :generichash_key)\n",
    "print(signature[0][0].tobytes())"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a6d1a008-a5ea-4c80-8c3c-ed67d565b0aa",
   "metadata": {},
   "source": [
    "## Short Hashing"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "991bfd3c-8398-4694-b60b-12417d9b474d",
   "metadata": {},
   "source": [
    "Many applications and programming language implementations were recently found to be vulnerable to denial-of-service (DoS) attacks when a hash function with weak security guarantees, such as MurmurHash3, was used to construct a hash table.\n",
    "\n",
    "To address this, Sodium provides the crypto_shorthash() function, which outputs short but unpredictable (without knowing the secret key) values suitable for picking a list in a hash table for a given key.\n",
    "\n",
    "This function is optimized for short inputs.\n",
    "\n",
    "The output of this function is only 64 bits. Therefore, it should not be considered collision-resistant.\n",
    "\n",
    "Use cases:\n",
    "- Hash tables\n",
    "- Probabilistic data structures, such as Bloom filters\n",
    "- Integrity checking in interactive protocols"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "0fc90170-fcca-4417-9d02-2b8faf49eb1d",
   "metadata": {},
   "source": [
    "### `crypto_shorthash_keygen()`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "6086244d-8a17-4c36-8405-01c172e02b14",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'%\\x9a\\xedN\\xad\\xa3\\xf5php\\xa5\\x93\\rd\\xe3\\xa2'\n"
     ]
    }
   ],
   "source": [
    "k = %sql select pgsodium.crypto_shorthash_keygen()\n",
    "shorthash_key = k[0][0].tobytes()\n",
    "print(shorthash_key)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e0f52ba7-8fa7-4fcb-bd43-003cd5420aa7",
   "metadata": {},
   "source": [
    "### `crypto_shorthash(message bytea, key bytea)`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "ad0367eb-6dfc-4c0e-b609-e5726b69c57c",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'\\xb1\\xfd\\xa4VAjg\\xcc'\n"
     ]
    }
   ],
   "source": [
    "short_signature = %sql select pgsodium.crypto_shorthash('this is a message', :shorthash_key)\n",
    "print(short_signature[0][0].tobytes())"
   ]
  }
 ],
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