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125 lines
2.9 KiB
C++
125 lines
2.9 KiB
C++
#include <crypto.hpp>
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#include <encrypted_frame.hpp>
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#include <logger.hpp>
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#include <mem.hpp>
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namespace llarp
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{
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bool
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EncryptedFrame::EncryptInPlace(const byte_t* ourSecretKey,
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const byte_t* otherPubkey,
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llarp::Crypto* crypto)
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{
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// format of frame is
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// <32 bytes keyed hash of following data>
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// <32 bytes nonce>
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// <32 bytes pubkey>
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// <N bytes encrypted payload>
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//
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byte_t* hash = data();
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byte_t* nonce = hash + SHORTHASHSIZE;
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byte_t* pubkey = nonce + TUNNONCESIZE;
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byte_t* body = pubkey + PUBKEYSIZE;
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SharedSecret shared;
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auto DH = crypto->dh_client;
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auto Encrypt = crypto->xchacha20;
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auto MDS = crypto->hmac;
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llarp_buffer_t buf;
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buf.base = body;
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buf.cur = buf.base;
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buf.sz = size() - EncryptedFrameOverheadSize;
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// set our pubkey
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memcpy(pubkey, llarp::seckey_topublic(ourSecretKey), PUBKEYSIZE);
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// randomize nonce
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crypto->randbytes(nonce, TUNNONCESIZE);
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// derive shared key
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if(!DH(shared, otherPubkey, ourSecretKey, nonce))
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{
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llarp::LogError("DH failed");
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return false;
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}
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// encrypt body
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if(!Encrypt(buf, shared, nonce))
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{
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llarp::LogError("encrypt failed");
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return false;
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}
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// generate message auth
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buf.base = nonce;
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buf.cur = buf.base;
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buf.sz = size() - SHORTHASHSIZE;
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if(!MDS(hash, buf, shared))
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{
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llarp::LogError("Failed to generate messgae auth");
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return false;
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}
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return true;
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}
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bool
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EncryptedFrame::DecryptInPlace(const byte_t* ourSecretKey,
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llarp::Crypto* crypto)
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{
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// format of frame is
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// <32 bytes keyed hash of following data>
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// <32 bytes nonce>
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// <32 bytes pubkey>
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// <N bytes encrypted payload>
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//
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byte_t* hash = data();
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byte_t* nonce = hash + SHORTHASHSIZE;
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byte_t* otherPubkey = nonce + TUNNONCESIZE;
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byte_t* body = otherPubkey + PUBKEYSIZE;
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// use dh_server becuase we are not the creator of this message
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auto DH = crypto->dh_server;
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auto Decrypt = crypto->xchacha20;
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auto MDS = crypto->hmac;
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llarp_buffer_t buf;
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buf.base = nonce;
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buf.cur = buf.base;
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buf.sz = size() - SHORTHASHSIZE;
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SharedSecret shared;
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ShortHash digest;
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if(!DH(shared, otherPubkey, ourSecretKey, nonce))
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{
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llarp::LogError("DH failed");
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return false;
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}
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if(!MDS(digest, buf, shared))
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{
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llarp::LogError("Digest failed");
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return false;
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}
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if(memcmp(digest, hash, digest.size()))
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{
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llarp::LogError("message authentication failed");
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return false;
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}
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buf.base = body;
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buf.cur = body;
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buf.sz = size() - EncryptedFrameOverheadSize;
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if(!Decrypt(buf, shared, nonce))
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{
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llarp::LogError("decrypt failed");
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return false;
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}
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return true;
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}
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} // namespace llarp
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