Session 46: Noise IK peer authentication implementation

Implement Noise Protocol Framework for peer authentication using the IK
pattern, which allows responders to learn initiator identity from the
encrypted handshake message.

Protocol: Noise_IK_secp256k1_ChaChaPoly_SHA256
- Message 1: 82 bytes (ephemeral + encrypted static)
- Message 2: 33 bytes (ephemeral only)

New noise.rs module (~600 lines):
- HandshakeState: Manages handshake for both initiator/responder roles
- NoiseSession: Post-handshake symmetric encryption
- CipherState: ChaCha20-Poly1305 with nonce counter
- SymmetricState: HKDF-SHA256 key derivation

PeerConnection integration:
- Simplified HandshakeState enum (Initial/SentMsg1/ReceivedMsg1/Complete/Failed)
- start_handshake(): Initiator generates msg1
- receive_handshake_init(): Responder processes msg1, discovers identity
- complete_handshake(): Initiator completes with msg2
- take_session(): Extract NoiseSession for ActivePeer

Identity helpers:
- Identity::keypair() for Noise operations
- PeerIdentity::from_pubkey_full() preserves parity for ECDH
- PeerIdentity::pubkey_full() returns full key or derives with even parity

Node changes:
- initiate_peer_connection() now starts handshake and sends msg1
- Method is async to use transport's async send

All 219 tests pass.

Cargo.lock

@@ -2,6 +2,16 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "aead"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d122413f284cf2d62fb1b7db97e02edb8cda96d769b16e443a4f6195e35662b0"
+dependencies = [
+ "crypto-common",
+ "generic-array",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "1.1.4"
@@ -201,6 +211,41 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
+[[package]]
+name = "chacha20"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3613f74bd2eac03dad61bd53dbe620703d4371614fe0bc3b9f04dd36fe4e818"
+dependencies = [
+ "cfg-if",
+ "cipher",
+ "cpufeatures",
+]
+
+[[package]]
+name = "chacha20poly1305"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10cd79432192d1c0f4e1a0fef9527696cc039165d729fb41b3f4f4f354c2dc35"
+dependencies = [
+ "aead",
+ "chacha20",
+ "cipher",
+ "poly1305",
+ "zeroize",
+]
+
+[[package]]
+name = "cipher"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773f3b9af64447d2ce9850330c473515014aa235e6a783b02db81ff39e4a3dad"
+dependencies = [
+ "crypto-common",
+ "inout",
+ "zeroize",
+]
+
 [[package]]
 name = "clap"
 version = "4.5.56"
@@ -278,6 +323,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
 dependencies = [
  "generic-array",
+ "rand_core",
  "typenum",
 ]
 
@@ -289,6 +335,7 @@ checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
 dependencies = [
  "block-buffer",
  "crypto-common",
+ "subtle",
 ]
 
 [[package]]
@@ -366,10 +413,12 @@ name = "fips"
 version = "0.1.0"
 dependencies = [
  "bech32",
+ "chacha20poly1305",
  "clap",
  "dirs",
  "futures",
  "hex",
+ "hkdf",
  "libc",
  "rand",
  "rtnetlink",
@@ -544,6 +593,24 @@ dependencies = [
  "arrayvec",
 ]
 
+[[package]]
+name = "hkdf"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b5f8eb2ad728638ea2c7d47a21db23b7b58a72ed6a38256b8a1849f15fbbdf7"
+dependencies = [
+ "hmac",
+]
+
+[[package]]
+name = "hmac"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c49c37c09c17a53d937dfbb742eb3a961d65a994e6bcdcf37e7399d0cc8ab5e"
+dependencies = [
+ "digest",
+]
+
 [[package]]
 name = "indexmap"
 version = "2.13.0"
@@ -554,6 +621,15 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inout"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "879f10e63c20629ecabbb64a8010319738c66a5cd0c29b02d63d272b03751d01"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "ipnet"
 version = "2.11.0"
@@ -750,6 +826,12 @@ version = "1.70.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
 
+[[package]]
+name = "opaque-debug"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
+
 [[package]]
 name = "option-ext"
 version = "0.2.0"
@@ -791,6 +873,17 @@ dependencies = [
  "futures-io",
 ]
 
+[[package]]
+name = "poly1305"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8159bd90725d2df49889a078b54f4f79e87f1f8a8444194cdca81d38f5393abf"
+dependencies = [
+ "cpufeatures",
+ "opaque-debug",
+ "universal-hash",
+]
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.21"
@@ -1046,6 +1139,12 @@ version = "0.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
+[[package]]
+name = "subtle"
+version = "2.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
+
 [[package]]
 name = "syn"
 version = "2.0.114"
@@ -1253,6 +1352,16 @@ version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9312f7c4f6ff9069b165498234ce8be658059c6728633667c526e27dc2cf1df5"
 
+[[package]]
+name = "universal-hash"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc1de2c688dc15305988b563c3854064043356019f97a4b46276fe734c4f07ea"
+dependencies = [
+ "crypto-common",
+ "subtle",
+]
+
 [[package]]
 name = "unsafe-libyaml"
 version = "0.2.11"
@@ -1505,3 +1614,9 @@ dependencies = [
  "quote",
  "syn",
 ]
+
+[[package]]
+name = "zeroize"
+version = "1.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b97154e67e32c85465826e8bcc1c59429aaaf107c1e4a9e53c8d8ccd5eff88d0"