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decrypt and handle Layer 2 of encrypted LeaseSet 2

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orignal 2019-03-04 15:47:35 -05:00
parent 9b64be07a9
commit 9aaba49a9f
1 changed files with 28 additions and 4 deletions
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32
libi2pd/LeaseSet.cpp
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@ -463,9 +463,11 @@ namespace data
// handle ciphertext // handle ciphertext
if (verified && identity && lenOuterCiphertext >= 32) if (verified && identity && lenOuterCiphertext >= 32)
{ {
SetIsValid (false); // we must verify it again in Layer 2
size_t l = identity->GetFullLen(); size_t l = identity->GetFullLen();
std::vector<uint8_t> destination (l); std::vector<uint8_t> destination (l);
l = identity->ToBuffer (destination.data(), l); l = identity->ToBuffer (destination.data(), l);
// outer key
uint8_t credential[32], subcredential[36]; uint8_t credential[32], subcredential[36];
// credential = H("credential", Destination) // credential = H("credential", Destination)
H ("credential", { {destination.data(), l} }, credential); H ("credential", { {destination.data(), l} }, credential);
@ -475,13 +477,35 @@ namespace data
memcpy (subcredential + 32, publishedTimestamp, 4); memcpy (subcredential + 32, publishedTimestamp, 4);
// outerSalt = outerCiphertext[0:32] // outerSalt = outerCiphertext[0:32]
// keys = HKDF(outerSalt, outerInput, "ELS2_L1K", 44) // keys = HKDF(outerSalt, outerInput, "ELS2_L1K", 44)
uint8_t outerKey[44]; uint8_t keys[44];
HKDF (outerCiphertext, {subcredential, 36}, "ELS2_L1K", outerKey, 44); HKDF (outerCiphertext, {subcredential, 36}, "ELS2_L1K", keys, 44);
// decrypt Layer 1 // decrypt Layer 1
// outerKey = keys[0:31] // outerKey = keys[0:31]
// outerIV = keys[32:43] // outerIV = keys[32:43]
std::vector<uint8_t> outerPlainText (lenOuterCiphertext - 32); size_t lenOuterPlaintext = lenOuterCiphertext - 32;
i2p::crypto::ChaCha20 (outerCiphertext + 32, lenOuterCiphertext - 32, outerKey, outerKey + 32, outerPlainText.data ()); std::vector<uint8_t> outerPlainText (lenOuterPlaintext);
i2p::crypto::ChaCha20 (outerCiphertext + 32, lenOuterPlaintext, keys, keys + 32, outerPlainText.data ());
// inner key
// innerSalt = innerCiphertext[0:32]
// keys = HKDF(innerSalt, innerInput, "ELS2_L2K", 44)
// skip 1 byte flags
HKDF (outerPlainText.data () + 1, {subcredential, 36}, "ELS2_L2K", keys, 44); // no authCookie
// decrypt Layer 2
// innerKey = keys[0:31]
// innerIV = keys[32:43]
size_t lenInnerPlaintext = lenOuterPlaintext - 32 - 1;
std::vector<uint8_t> innerPlainText (lenInnerPlaintext);
i2p::crypto::ChaCha20 (outerPlainText.data () + 32 + 1, lenInnerPlaintext, keys, keys + 32, innerPlainText.data ());
if (innerPlainText[0] == NETDB_STORE_TYPE_STANDARD_LEASESET2 || innerPlainText[0] == NETDB_STORE_TYPE_META_LEASESET2)
{
// override store type and buffer
m_StoreType = innerPlainText[0];
SetBuffer (innerPlainText.data () + 1, lenInnerPlaintext - 1);
// parse and verify Layer 2
ReadFromBuffer (innerPlainText.data () + 1, lenInnerPlaintext - 1);
}
else
LogPrint (eLogError, "LeaseSet2: unxpected LeaseSet type ", (int)innerPlainText[0], " inside encrypted LeaseSet");
} }
} }