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Remove unnecessary memcpy for PKI crypto #5608

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merged 4 commits into from
Dec 20, 2024
Merged

Remove unnecessary memcpy for PKI crypto #5608

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fc44c6b
Remove unnecessary memcpy for PKI crypto
esev Dec 19, 2024
3a8b175
Merge branch 'master' into remove_memcpy
jp-bennett Dec 19, 2024
42c8eaf
Update comment s/packet_id/id/
esev Dec 19, 2024
a597384
Create a copy of bytes for each channel decrypt
esev Dec 19, 2024
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24 changes: 17 additions & 7 deletions src/mesh/CryptoEngine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -58,10 +58,16 @@ void CryptoEngine::clearKeys()
* Encrypt a packet's payload using a key generated with Curve25519 and SHA256
* for a specific node.
*
* @param bytes is updated in place
* @param toNode The MeshPacket `to` field.
* @param fromNode The MeshPacket `from` field.
* @param remotePublic The remote node's Curve25519 public key.
* @param packetId The MeshPacket `packet_id` field.
* @param numBytes Number of bytes of plaintext in the bytes buffer.
* @param bytes Buffer containing plaintext input.
* @param bytesOut Output buffer to be populated with encrypted ciphertext.
*/
bool CryptoEngine::encryptCurve25519(uint32_t toNode, uint32_t fromNode, meshtastic_UserLite_public_key_t remotePublic,
uint64_t packetNum, size_t numBytes, uint8_t *bytes, uint8_t *bytesOut)
uint64_t packetNum, size_t numBytes, const uint8_t *bytes, uint8_t *bytesOut)
{
uint8_t *auth;
long extraNonceTmp = random();
Expand Down Expand Up @@ -93,14 +99,18 @@ bool CryptoEngine::encryptCurve25519(uint32_t toNode, uint32_t fromNode, meshtas
* Decrypt a packet's payload using a key generated with Curve25519 and SHA256
* for a specific node.
*
* @param bytes is updated in place
* @param fromNode The MeshPacket `from` field.
* @param remotePublic The remote node's Curve25519 public key.
* @param packetId The MeshPacket `packet_id` field.
* @param numBytes Number of bytes of ciphertext in the bytes buffer.
* @param bytes Buffer containing ciphertext input.
* @param bytesOut Output buffer to be populated with decrypted plaintext.
*/
bool CryptoEngine::decryptCurve25519(uint32_t fromNode, meshtastic_UserLite_public_key_t remotePublic, uint64_t packetNum,
size_t numBytes, uint8_t *bytes, uint8_t *bytesOut)
size_t numBytes, const uint8_t *bytes, uint8_t *bytesOut)
{
uint8_t *auth; // set to last 8 bytes of text?
uint32_t extraNonce; // pointer was not really used
auth = bytes + numBytes - 12;
const uint8_t *auth = bytes + numBytes - 12; // set to last 8 bytes of text?
uint32_t extraNonce; // pointer was not really used
memcpy(&extraNonce, auth + 8,
sizeof(uint32_t)); // do not use dereference on potential non aligned pointers : (uint32_t *)(auth + 8);
LOG_INFO("Random nonce value: %d", extraNonce);
Expand Down
4 changes: 2 additions & 2 deletions src/mesh/CryptoEngine.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,9 +40,9 @@ class CryptoEngine
void clearKeys();
void setDHPrivateKey(uint8_t *_private_key);
virtual bool encryptCurve25519(uint32_t toNode, uint32_t fromNode, meshtastic_UserLite_public_key_t remotePublic,
uint64_t packetNum, size_t numBytes, uint8_t *bytes, uint8_t *bytesOut);
uint64_t packetNum, size_t numBytes, const uint8_t *bytes, uint8_t *bytesOut);
virtual bool decryptCurve25519(uint32_t fromNode, meshtastic_UserLite_public_key_t remotePublic, uint64_t packetNum,
size_t numBytes, uint8_t *bytes, uint8_t *bytesOut);
size_t numBytes, const uint8_t *bytes, uint8_t *bytesOut);
virtual bool setDHPublicKey(uint8_t *publicKey);
virtual void hash(uint8_t *bytes, size_t numBytes);

Expand Down
13 changes: 4 additions & 9 deletions src/mesh/Router.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,6 @@ static MemoryDynamic<meshtastic_MeshPacket> staticPool;
Allocator<meshtastic_MeshPacket> &packetPool = staticPool;

static uint8_t bytes[MAX_LORA_PAYLOAD_LEN + 1] __attribute__((__aligned__));
static uint8_t ScratchEncrypted[MAX_LORA_PAYLOAD_LEN + 1] __attribute__((__aligned__));

/**
* Constructor
Expand Down Expand Up @@ -327,17 +326,14 @@ bool perhapsDecode(meshtastic_MeshPacket *p)
}
bool decrypted = false;
ChannelIndex chIndex = 0;
memcpy(bytes, p->encrypted.bytes,
rawSize); // we have to copy into a scratch buffer, because these bytes are a union with the decoded protobuf
memcpy(ScratchEncrypted, p->encrypted.bytes, rawSize);
#if !(MESHTASTIC_EXCLUDE_PKI)
// Attempt PKI decryption first
if (p->channel == 0 && isToUs(p) && p->to > 0 && !isBroadcast(p->to) && nodeDB->getMeshNode(p->from) != nullptr &&
nodeDB->getMeshNode(p->from)->user.public_key.size > 0 && nodeDB->getMeshNode(p->to)->user.public_key.size > 0 &&
rawSize > MESHTASTIC_PKC_OVERHEAD) {
LOG_DEBUG("Attempt PKI decryption");

if (crypto->decryptCurve25519(p->from, nodeDB->getMeshNode(p->from)->user.public_key, p->id, rawSize, ScratchEncrypted,
if (crypto->decryptCurve25519(p->from, nodeDB->getMeshNode(p->from)->user.public_key, p->id, rawSize, p->encrypted.bytes,
bytes)) {
LOG_INFO("PKI Decryption worked!");
memset(&p->decoded, 0, sizeof(p->decoded));
Expand All @@ -349,8 +345,6 @@ bool perhapsDecode(meshtastic_MeshPacket *p)
p->pki_encrypted = true;
memcpy(&p->public_key.bytes, nodeDB->getMeshNode(p->from)->user.public_key.bytes, 32);
p->public_key.size = 32;
// memcpy(bytes, ScratchEncrypted, rawSize); // TODO: Rename the bytes buffers
// chIndex = 8;
} else {
LOG_ERROR("PKC Decrypted, but pb_decode failed!");
return false;
Expand All @@ -363,6 +357,8 @@ bool perhapsDecode(meshtastic_MeshPacket *p)

// assert(p->which_payloadVariant == MeshPacket_encrypted_tag);
if (!decrypted) {
memcpy(bytes, p->encrypted.bytes,
rawSize); // we have to copy into a scratch buffer, because these bytes are a union with the decoded protobuf
// Try to find a channel that works with this hash
for (chIndex = 0; chIndex < channels.getNumChannels(); chIndex++) {
// Try to use this hash/channel pair
Expand Down Expand Up @@ -515,9 +511,8 @@ meshtastic_Routing_Error perhapsEncode(meshtastic_MeshPacket *p)
*node->user.public_key.bytes);
return meshtastic_Routing_Error_PKI_FAILED;
}
crypto->encryptCurve25519(p->to, getFrom(p), node->user.public_key, p->id, numbytes, bytes, ScratchEncrypted);
crypto->encryptCurve25519(p->to, getFrom(p), node->user.public_key, p->id, numbytes, bytes, p->encrypted.bytes);
numbytes += MESHTASTIC_PKC_OVERHEAD;
memcpy(p->encrypted.bytes, ScratchEncrypted, numbytes);
p->channel = 0;
p->pki_encrypted = true;
} else {
Expand Down
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