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{
"cells": [
{
"cell_type": "code",
"execution_count": 31,
"metadata": {},
"outputs": [],
"source": [
"import os\n",
"\n",
"import hashlib\n",
"import nacl.signing\n",
"from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes\n",
"from cryptography.hazmat.backends import default_backend"
]
},
{
"cell_type": "code",
"execution_count": 7,
"metadata": {},
"outputs": [],
"source": [
"sign_key = nacl.signing.SigningKey.generate()"
]
},
{
"cell_type": "code",
"execution_count": 44,
"metadata": {},
"outputs": [],
"source": [
"make_action_string = lambda group, index: f'reset idx={index:08x} g={group}'.encode()\n",
"def generate_presig(group, index):\n",
" action_string = make_action_string(group, index)\n",
" sig = sign_key.sign(action_string)[:64] # cut off original message\n",
" \n",
" key = os.urandom(16)\n",
" \n",
" cipher = Cipher(algorithms.AES(key), modes.CTR(b'\\0' * 16), backend=default_backend())\n",
" enc = cipher.encryptor()\n",
" ciphtertext = enc.update(sig)\n",
" assert len(enc.finalize()) == 0\n",
" \n",
" return key, ciphtertext\n",
"\n",
"presigs = { group: [ generate_presig(group, index) for index in range(64) ] for group in ['all', 'v=foo', 's=bar', 'l=somewhere'] }"
]
},
{
"cell_type": "code",
"execution_count": 46,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"(b'\\x9f\\n\\x8e\\xc9\\x1d\\xaf*\\xac\\x9e\\x1as\\xe8\\xf8\\xe6\\xe9z',\n",
" b'{\\xd8\\xb4\\xaf\\xb4PK1%*`\\\\\\x8e\\x93;\\x82\\xeaF\\x99\\xe0\\xbfB\\xf1\\x9d\\xae\\x02|\\xae\\\\?\\x97\\xb3\\xa5j.Y\\x83\\xddg\\x7f\\x06\\xd2\\xa47^\\xf3\\xdd\\x08n3\\x90\\x84~\\x96,tO#\\x8e$\\xdc\\xa2\\x1a\\r')"
]
},
"execution_count": 46,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"presigs['all'][0]"
]
},
{
"cell_type": "code",
"execution_count": 69,
"metadata": {},
"outputs": [],
"source": [
"def validate_presig(group, index, key, presig, verify_key=sign_key.verify_key):\n",
" \"\"\" Will raise an error for invalid signature or group/index \"\"\"\n",
" action_string = make_action_string(group, index)\n",
" \n",
" cipher = Cipher(algorithms.AES(key), modes.CTR(b'\\0' * 16), backend=default_backend())\n",
" dec = cipher.decryptor()\n",
" plaintext = dec.update(presig)\n",
" assert len(dec.finalize()) == 0\n",
" \n",
" return verify_key.verify(plaintext + action_string) == action_string"
]
},
{
"cell_type": "code",
"execution_count": 70,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"True"
]
},
"execution_count": 70,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"validate_presig('all', 0, *presigs['all'][0])"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "labenv",
"language": "python",
"name": "labenv"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.8.2"
}
},
"nbformat": 4,
"nbformat_minor": 4
}
|
