From 65064eb1472f98c9d496041ee44a1bb2ad3d874b Mon Sep 17 00:00:00 2001
From: RSoraM <soramephisto@gmail.com>
Date: Sun, 29 Dec 2024 04:19:37 +0800
Subject: [PATCH] =?UTF-8?q?chore:=20=F0=9F=A4=96=20x25519=20&=20x448=20?=
 =?UTF-8?q?=E5=9F=BA=E7=A1=80?=
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我还没想好怎么封装这两个怪东西
---
 src/cipher/pkcs/ecc.ts | 32 ++++++++++++++++++++++++++++++++
 test/pkcs.test.ts      | 22 +++++++++++++++++++++-
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/cipher/pkcs/ecc.ts b/src/cipher/pkcs/ecc.ts
index 25bee04..1ee0550 100644
--- a/src/cipher/pkcs/ecc.ts
+++ b/src/cipher/pkcs/ecc.ts
@@ -496,6 +496,38 @@ export function FpECC(curve: FpWECParams | FpMECParams): FpECCrypto {
   }
 }
 
+export function clampX25519(k: Uint8Array, little_endian: boolean = false): U8 {
+  if (k.length !== 32) {
+    throw new KitError('Invalid X25519 private key')
+  }
+  const _ = U8.from(k.slice())
+  if (little_endian) {
+    _[0] &= 0xF8
+    _[31] = (_[31] & 0x7F) | 0x40
+  }
+  else {
+    _[31] &= 0xF8
+    _[0] = (_[0] & 0x7F) | 0x40
+  }
+  return _
+}
+
+export function clampX448(k: Uint8Array, little_endian: boolean = false): U8 {
+  if (k.length !== 56) {
+    throw new KitError('Invalid X448 private key')
+  }
+  const _ = U8.from(k.slice())
+  if (little_endian) {
+    _[0] &= 0xFC
+    _[55] |= 0x80
+  }
+  else {
+    _[55] &= 0xFC
+    _[0] |= 0x80
+  }
+  return _
+}
+
 // * Algorithms for Test
 
 /**
diff --git a/test/pkcs.test.ts b/test/pkcs.test.ts
index eb7c62d..827003a 100644
--- a/test/pkcs.test.ts
+++ b/test/pkcs.test.ts
@@ -5,7 +5,7 @@ import { NO_PAD, ecb } from '../src/core/cipher'
 import { hkdf, pbkdf2, x963kdf } from '../src/core/kdf'
 import * as ecParams from '../src/core/ecParams'
 import { rsa } from '../src/cipher/pkcs/rsa'
-import { FpECC, es_xor } from '../src/cipher/pkcs/ecc'
+import { FpECC, clampX25519, clampX448, es_xor } from '../src/cipher/pkcs/ecc'
 import { hmac } from '../src/hash/hmac'
 import { sha1 } from '../src/hash/sha1'
 import { sha256 } from '../src/hash/sha256'
@@ -17,6 +17,7 @@ const { pkcs1_es_1_5, pkcs1_es_oaep } = pkcs1
 const { pkcs1_ssa_1_5, pkcs1_ssa_pss } = pkcs1
 
 const { secp160r1 } = ecParams
+const { curve25519, curve448 } = ecParams
 
 describe('pkcs#1', () => {
   const m = UTF8('meow, 喵， 🐱')
@@ -206,6 +207,25 @@ describe('ecc', () => {
     expect(P).toMatchObject(P_outside)
     expect(Q.y).toBe(R.y)
   })
+  // vector source: https://tools.ietf.org/html/rfc7748
+  it('x25519', () => {
+    const ec = FpECC(curve25519)
+
+    const k_a = HEX('77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a').toReversed()
+    const p_a = ec.utils.mulPoint(curve25519.G, clampX25519(k_a).toBI())
+    const p_a_x = U8.fromBI(p_a.x)
+    const p_a_x_outside = HEX('8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a').toReversed()
+    expect(p_a_x).toMatchObject(p_a_x_outside)
+  })
+  it('x448', () => {
+    const ec = FpECC(curve448)
+
+    const k_a = HEX('9a8f4925d1519f5775cf46b04b5800d4ee9ee8bae8bc5565d498c28dd9c9baf574a9419744897391006382a6f127ab1d9ac2d8c0a598726b').toReversed()
+    const p_a = ec.utils.mulPoint(curve448.G, clampX448(k_a).toBI())
+    const p_a_x = U8.fromBI(p_a.x)
+    const p_a_x_outside = HEX('9b08f7cc31b7e3e67d22d5aea121074a273bd2b83de09c63faa73d2c22c5d9bbc836647241d953d40c5b12da88120d53177f80e532c41fa0').toReversed()
+    expect(p_a_x).toMatchObject(p_a_x_outside)
+  })
 })
 
 describe('kdf', () => {