lob_t local_decrypt(local_t local, lob_t outer)
{
uint8_t key[uECC_BYTES*2], shared[uECC_BYTES], iv[16], hash[32];
lob_t inner, tmp;
// * `KEY` - 21 bytes, the sender's ephemeral exchange public key in compressed format
// * `IV` - 4 bytes, a random but unique value determined by the sender
// * `INNER` - (minimum 21+2 bytes) the AES-128-CTR encrypted inner packet ciphertext
// * `HMAC` - 4 bytes, the calculated HMAC of all of the previous KEY+INNER bytes
if(outer->body_len <= (21+4+0+4)) return NULL;
tmp = lob_new();
if(!lob_body(tmp,NULL,outer->body_len-(4+21+4))) return lob_free(tmp);
// get the shared secret to create the iv+key for the open aes
uECC_decompress(outer->body,key);
if(!uECC_shared_secret(key, local->secret, shared)) return lob_free(tmp);
e3x_hash(shared,uECC_BYTES,hash);
fold1(hash,hash);
memset(iv,0,16);
memcpy(iv,outer->body+21,4);
// decrypt the inner
aes_128_ctr(hash,tmp->body_len,iv,outer->body+4+21,tmp->body);
// load inner packet
inner = lob_parse(tmp->body,tmp->body_len);
lob_free(tmp);
return inner;
}
local_t local_new(lob_t keys, lob_t secrets)
{
local_t local = NULL;
lob_t key, secret;
if(!keys) keys = lob_linked(secrets); // for convenience
key = lob_get_base32(keys,"1c");
if(!key) return LOG("invalid key");
secret = lob_get_base32(secrets,"1c");
if(!secret) return LOG("invalid secret");
if(key->body_len == COMP_BYTES && secret->body_len == SECRET_BYTES)
{
if((local = malloc(sizeof(struct local_struct))))
{
memset(local,0,sizeof (struct local_struct));
// copy in key/secret data
uECC_decompress(key->body,local->key, curve);
memcpy(local->secret,secret->body,secret->body_len);
}else{
LOG("OOM");
}
}else{
LOG("invalid sizes key %d=%d secret %d=%d",key->body_len,COMP_BYTES,secret->body_len,SECRET_BYTES);
}
lob_free(key);
lob_free(secret);
return local;
}
ephemeral_t ephemeral_new(remote_t remote, lob_t outer)
{
uint8_t ekey[uECC_BYTES*2], shared[uECC_BYTES+((uECC_BYTES+1)*2)], hash[32];
ephemeral_t ephem;
if(!remote) return NULL;
if(!outer || outer->body_len < (uECC_BYTES+1)) return LOG("invalid outer");
if(!(ephem = malloc(sizeof(struct ephemeral_struct)))) return NULL;
memset(ephem,0,sizeof (struct ephemeral_struct));
// create and copy in the exchange routing token
e3x_hash(outer->body,16,hash);
memcpy(ephem->token,hash,16);
// generate a random seq starting point for channel IV's
e3x_rand((uint8_t*)&(ephem->seq),4);
// decompress the exchange key and get the shared secret
uECC_decompress(outer->body,ekey);
if(!uECC_shared_secret(ekey, remote->esecret, shared)) return LOG("ECDH failed");
// combine inputs to create the digest
memcpy(shared+uECC_BYTES,remote->ecomp,uECC_BYTES+1);
memcpy(shared+uECC_BYTES+uECC_BYTES+1,outer->body,uECC_BYTES+1);
e3x_hash(shared,uECC_BYTES+((uECC_BYTES+1)*2),hash);
fold1(hash,ephem->enckey);
memcpy(shared+uECC_BYTES,outer->body,uECC_BYTES+1);
memcpy(shared+uECC_BYTES+uECC_BYTES+1,remote->ecomp,uECC_BYTES+1);
e3x_hash(shared,uECC_BYTES+((uECC_BYTES+1)*2),hash);
fold1(hash,ephem->deckey);
return ephem;
}
int
joylink_encrypt_sub_dev_data(
uint8_t* pBuf,
int buflen,
E_EncType enctype,
uint8_t* key,
const uint8_t* payload,
int length)
{
char* psJson = (char*)payload;
uint8_t* pOut = pBuf;
int retlen;
uint8_t peerPubKey[uECC_BYTES * 2] = {0};
uint8_t secret[uECC_BYTES] = {0};
switch (enctype)
{
case ET_NOTHING:
break;
case ET_PSKAES:
break;
case ET_ACCESSKEYAES:
retlen = device_aes_encrypt(
key,
16,
key+16,
(uint8_t*)psJson,
length,
pOut,
length + 16);
break;
case ET_ECDH:
memcpy(pOut, __g_ekey.devPubKeyC, uECC_BYTES + 1);
pOut += (uECC_BYTES + 1);
uECC_decompress(key, peerPubKey);
uECC_shared_secret(
peerPubKey,
__g_ekey.priKey,
secret);
retlen = device_aes_encrypt(
secret,
16,
key + 4,
(const uint8_t*)psJson,
length,
pOut,
length + 16);
break;
default:
break;
}
return retlen;
}
local_t local_new(lob_t keys, lob_t secrets)
{
local_t local;
lob_t key, secret;
if(!keys) keys = lob_linked(secrets); // for convenience
key = lob_get_base32(keys,"1a");
if(!key || key->body_len != uECC_BYTES+1) return LOG("invalid key %d != %d",(key)?key->body_len:0,uECC_BYTES+1);
secret = lob_get_base32(secrets,"1a");
if(!secret || secret->body_len != uECC_BYTES) return LOG("invalid secret len %d",(secret)?secret->body_len:0);
if(!(local = malloc(sizeof(struct local_struct)))) return NULL;
memset(local,0,sizeof (struct local_struct));
// copy in key/secret data
uECC_decompress(key->body,local->key);
memcpy(local->secret,secret->body,secret->body_len);
lob_free(key);
lob_free(secret);
return local;
}
remote_t remote_new(lob_t key, uint8_t *token)
{
uint8_t hash[32];
remote_t remote;
if(!key || key->body_len != uECC_BYTES+1) return LOG("invalid key %d != %d",(key)?key->body_len:0,uECC_BYTES+1);
if(!(remote = malloc(sizeof(struct remote_struct)))) return NULL;
memset(remote,0,sizeof (struct remote_struct));
// copy in key and make ephemeral ones
uECC_decompress(key->body,remote->key);
uECC_make_key(remote->ekey, remote->esecret);
uECC_compress(remote->ekey, remote->ecomp);
if(token)
{
cipher_hash(remote->ecomp,16,hash);
memcpy(token,hash,16);
}
// generate a random seq starting point for message IV's
e3x_rand((uint8_t*)&(remote->seq),4);
return remote;
}
