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Verify key derivation is 100% correct
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Breakthrough verification:
- Python computed keys match server actual keys EXACTLY
- Key derivation formula: HASH(K || H || X || session_id) verified
- All keys (encryption, MAC, IV) derived correctly
- Shared secret encoding (little-endian bytes) correct

Remaining issue:
- MAC verification fails despite correct key derivation
- Client must be computing different keys than server
- Need to compare client vs server actual key values

Next step: Wireshark comparison of OpenSSH client keys
This commit is contained in:
Warren
2026-06-14 20:32:01 +08:00
parent 81ae052f48
commit 62d874c68c
2 changed files with 4 additions and 4 deletions
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6
markbase-core/src/ssh_server/crypto.rs
View File

@@ -75,15 +75,15 @@ impl SessionKeys {
let session_id = exchange_hash.to_vec(); let session_id = exchange_hash.to_vec();
info!("SessionKeys::derive() starting"); info!("SessionKeys::derive() starting");
info!(" shared_secret ({} bytes): {:?}", shared_secret.len(), &shared_secret[..std::cmp::min(8, shared_secret.len())]); info!(" shared_secret full (32 bytes): {:?}", shared_secret);
// RFC 8731 Section 3.1: X25519 output is little-endian // RFC 8731 Section 3.1: X25519 output is little-endian
// OpenSSH sshbuf_put_bignum2_bytes() uses bytes DIRECTLY (no reversal) // OpenSSH sshbuf_put_bignum2_bytes() uses bytes DIRECTLY (no reversal)
// Treats little-endian bytes as big-endian mpint (logical reinterpret) // Treats little-endian bytes as big-endian mpint (logical reinterpret)
info!(" Using shared_secret directly (little-endian bytes as big-endian mpint)"); info!(" Using shared_secret directly (little-endian bytes as big-endian mpint)");
info!(" shared_secret[0] = {} (>=0x80? {})", shared_secret[0], shared_secret[0] >= 0x80); info!(" shared_secret[0] = {} (>=0x80? {})", shared_secret[0], shared_secret[0] >= 0x80);
info!(" exchange_hash (H, {} bytes): {:?}", exchange_hash.len(), &exchange_hash[..8]); info!(" exchange_hash full (32 bytes): {:?}", exchange_hash);
info!(" session_id ({} bytes): {:?}", session_id.len(), &session_id[..8]); info!(" session_id full (32 bytes): {:?}", session_id);
// RFC 4253密钥派生公式：HASH(K || H || X || session_id) // RFC 4253密钥派生公式：HASH(K || H || X || session_id)
// K is shared_secret encoded as mpint (using little-endian bytes directly) // K is shared_secret encoded as mpint (using little-endian bytes directly)

2
markbase-core/src/ssh_server/kex_exchange.rs
View File

@@ -106,7 +106,7 @@ impl KexExchangeHandler {
info!("Exchange hash computed:"); info!("Exchange hash computed:");
info!(" shared_secret[0] = {} (>=0x80? {})", shared_secret[0], shared_secret[0] >= 0x80); info!(" shared_secret[0] = {} (>=0x80? {})", shared_secret[0], shared_secret[0] >= 0x80);
info!(" exchange_hash (32 bytes): {:?}", &exchange_hash[..8]); info!(" exchange_hash full (32 bytes): {:?}", exchange_hash);
self.exchange_hash = Some(exchange_hash.clone()); self.exchange_hash = Some(exchange_hash.clone());
info!("Exchange hash saved for key derivation"); info!("Exchange hash saved for key derivation");