hash01.ipynb

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   "source": [
    "# Cryptographic hash functions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
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     "name": "stdout",
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     "text": [
      "The two messages differ by 1 characters\n"
     ]
    }
   ],
   "source": [
    "# Begin by importing some necessary modules\n",
    "from cryptography.hazmat.backends import default_backend\n",
    "from cryptography.hazmat.primitives import hashes\n",
    "\n",
    "#Helper function that returns the number of characters different in two strings\n",
    "def char_diff(str1, str2):\n",
    "    return sum ( str1[i] != str2[i] for i in range(len(str1)) )\n",
    "\n",
    "# Messages to be hashed\n",
    "message_1 = b\"Buy 10000 shares of WXYZ stock now!\"\n",
    "message_2 = b\"Buy 10000 shares of VXYZ stock now!\"\n",
    "\n",
    "print(f\"The two messages differ by { char_diff(message_1, message_2)} characters\")"
   ]
  },
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   "cell_type": "code",
   "execution_count": 2,
   "id": "9d6c70e7-0557-468a-8007-fc9b5f2d83c7",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "digest-1: 6e0e6261b7131bd80ffdb2a4d42f9d042636350e45e184b92fcbcc9646eaf1e7\n",
      "digest-2: 6b0abb368c3a1730f935b68105e3f3ae7fd43d7e786d3ed3503dbb45c74ada46\n",
      "The two digests differ by 57 characters\n"
     ]
    }
   ],
   "source": [
    "# Create new SHA-256 hash objects, one for each message\n",
    "chf_1 = hashes.Hash(hashes.SHA256(), backend=default_backend())\n",
    "chf_2 = hashes.Hash(hashes.SHA256(), backend=default_backend())\n",
    "\n",
    "# Update each hash object with the bytes of the corresponding message\n",
    "chf_1.update(message_1)\n",
    "chf_2.update(message_2)\n",
    "\n",
    "# Finalize the hash process and obtain the digests\n",
    "digest_1 = chf_1.finalize()\n",
    "digest_2 = chf_2.finalize()\n",
    "\n",
    "#Convert the resulting hash to hexadecimal strings for convenient printing\n",
    "digest_1_str = digest_1.hex()\n",
    "digest_2_str = digest_2.hex()\n",
    "\n",
    "#Print out the digests as strings \n",
    "print(f\"digest-1: {digest_1_str}\")\n",
    "print(f\"digest-2: {digest_2_str}\")\n",
    "\n",
    "print(f\"The two digests differ by { char_diff(digest_1_str, digest_2_str)} characters\")"
   ]
  }
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