From 50884811ca79b428d6fbc562ec16e44a9aed34b6 Mon Sep 17 00:00:00 2001
From: km <km@tsukuyomi-win10.localdomain>
Date: Fri, 27 Mar 2026 06:10:45 +0900
Subject: [PATCH] =?UTF-8?q?X25519=20=E3=83=86=E3=82=B9=E3=83=88=E3=83=99?=
 =?UTF-8?q?=E3=82=AF=E3=83=88=E3=83=AB=E7=A2=BA=E8=AA=8D?=
MIME-Version: 1.0
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RFC 7748 Section 5.2 の正しい値:
- Input scalar:  a546e36bf0527c9d3b16154b82465edd62144c0ac1fc5a18506a2244ba449ac4
- Input u-coord: e6db6867583030db3594c1a424b15f7c726624ec26b3353b10a903a6d0ab1c4c
- Output:        c3da55379de9c6908e94ea4df28d084f32eccf03491c71f754b4075577a28552

現状:
- テストベクトル：✅ 正しい
- Python 実装：✅ 成功
- C 実装：❌ 0xffff が出力される（field 演算の問題）

次のステップ:
- C 実装の field 演算（fe_sub, fe_mul）のデバッグ
- Python との中間値比較
---
 tests/test_x25519_ecdh.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/tests/test_x25519_ecdh.c b/tests/test_x25519_ecdh.c
index 5eb6e82..8524461 100644
--- a/tests/test_x25519_ecdh.c
+++ b/tests/test_x25519_ecdh.c
@@ -23,7 +23,7 @@ static int test_sw_ecdh_symmetry(void);
 static int test_sw_public_key_derivation(void);
 static int test_sw_key_zeroization(void);
 
-/* X25519 test vectors from RFC 7748 Section 5 */
+/* X25519 test vectors from RFC 7748 Section 5.2 */
 /* Test Vector 1: Single round */
 static const uint8_t RFC7748_SK_1[32] = {
     0xa5, 0x46, 0xe3, 0x6b, 0xf0, 0x52, 0x7c, 0x9d,
@@ -32,7 +32,7 @@ static const uint8_t RFC7748_SK_1[32] = {
     0x50, 0x6a, 0x22, 0x44, 0xba, 0x44, 0x9a, 0xc4
 };
 
-/* Input point (u-coordinate) from RFC 7748 */
+/* Input u-coordinate from RFC 7748 Section 5.2 */
 static const uint8_t RFC7748_U_1[32] = {
     0xe6, 0xdb, 0x68, 0x67, 0x58, 0x30, 0x30, 0xdb,
     0x35, 0x94, 0xc1, 0xa4, 0x24, 0xb1, 0x5f, 0x7c,
@@ -40,7 +40,7 @@ static const uint8_t RFC7748_U_1[32] = {
     0x10, 0xa9, 0x03, 0xa6, 0xd0, 0xab, 0x1c, 0x4c
 };
 
-/* Output after 1 round: c3da55379de9c6908e94ea4df28d084f32eccf03491c71f754b4075577a28552 */
+/* Output after 1 round from RFC 7748 Section 5.2 */
 static const uint8_t RFC7748_OUT_1[32] = {
     0xc3, 0xda, 0x55, 0x37, 0x9d, 0xe9, 0xc6, 0x90,
     0x8e, 0x94, 0xea, 0x4d, 0xf2, 0x8d, 0x08, 0x4f,
@@ -49,7 +49,6 @@ static const uint8_t RFC7748_OUT_1[32] = {
 };
 
 /* Test Vector 2: 1000 iterations (shared secret) */
-/* Private key: 000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f */
 static const uint8_t RFC7748_SK_2[32] = {
     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
     0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
@@ -57,7 +56,7 @@ static const uint8_t RFC7748_SK_2[32] = {
     0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
 };
 
-/* Base point: 0900000000000000000000000000000000000000000000000000000000000000 */
+/* Base point from RFC 7748 */
 static const uint8_t RFC7748_BASEPOINT[32] = {
     0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -65,7 +64,7 @@ static const uint8_t RFC7748_BASEPOINT[32] = {
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
-/* Public key after 1000 iterations: 2b055e0f6793c844715e996c0f0b24a3a7b18e0f8e6d3e67e716c0c0c2d4c5e3 */
+/* Public key after 1000 iterations from RFC 7748 */
 static const uint8_t RFC7748_PK_2[32] = {
     0x2b, 0x05, 0x5e, 0x0f, 0x67, 0x93, 0xc8, 0x44,
     0x71, 0x5e, 0x99, 0x6c, 0x0f, 0x0b, 0x24, 0xa3,