From e3e3caed6aa77067d389635c9577e3a62a4315db Mon Sep 17 00:00:00 2001
From: imbytecat <imbytecat@gmail.com>
Date: Thu, 19 Mar 2026 16:16:07 +0800
Subject: [PATCH] =?UTF-8?q?feat(crypto):=20=E6=96=B0=E5=A2=9E=20RSA=20?=
 =?UTF-8?q?=E9=AA=8C=E7=AD=BE=E5=B7=A5=E5=85=B7?=
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---
 packages/crypto/src/index.ts              |  1 +
 packages/crypto/src/rsa-signature.test.ts | 24 +++++++++++++++++++++++
 packages/crypto/src/rsa-signature.ts      | 19 ++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 packages/crypto/src/rsa-signature.test.ts
 create mode 100644 packages/crypto/src/rsa-signature.ts

diff --git a/packages/crypto/src/index.ts b/packages/crypto/src/index.ts
index b8bd01b..d9c9b6c 100644
--- a/packages/crypto/src/index.ts
+++ b/packages/crypto/src/index.ts
@@ -4,3 +4,4 @@ export { hkdfSha256 } from './hkdf'
 export { hmacSha256, hmacSha256Base64 } from './hmac'
 export { generatePgpKeyPair, pgpSignDetached, pgpVerifyDetached, validatePgpPrivateKey } from './pgp'
 export { rsaOaepEncrypt } from './rsa-oaep'
+export { rsaVerifySignature, validateRsaPublicKey } from './rsa-signature'
diff --git a/packages/crypto/src/rsa-signature.test.ts b/packages/crypto/src/rsa-signature.test.ts
new file mode 100644
index 0000000..481e16b
--- /dev/null
+++ b/packages/crypto/src/rsa-signature.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'bun:test'
+import { constants, createSign, generateKeyPairSync } from 'node:crypto'
+import { rsaVerifySignature, validateRsaPublicKey } from './rsa-signature'
+
+describe('rsaVerifySignature', () => {
+  it('verifies SHA256withRSA signatures over raw payload bytes', () => {
+    const { privateKey, publicKey } = generateKeyPairSync('rsa', { modulusLength: 2048 })
+    const payload = Buffer.from('eyJsaWNlbmNlX2lkIjoiTElDLTAwMSIsImV4cGlyZV90aW1lIjoiMjAyNy0wMy0xOSJ9', 'utf-8')
+
+    const signer = createSign('RSA-SHA256')
+    signer.update(payload)
+    signer.end()
+
+    const signature = signer.sign({ key: privateKey, padding: constants.RSA_PKCS1_PADDING })
+    const publicKeyBase64 = publicKey.export({ format: 'der', type: 'spki' }).toString('base64')
+
+    expect(rsaVerifySignature(payload, signature, publicKeyBase64)).toBe(true)
+    expect(rsaVerifySignature(Buffer.from(`${payload}x`, 'utf-8'), signature, publicKeyBase64)).toBe(false)
+  })
+
+  it('rejects malformed SPKI public keys', () => {
+    expect(() => validateRsaPublicKey('not-a-public-key')).toThrow()
+  })
+})
diff --git a/packages/crypto/src/rsa-signature.ts b/packages/crypto/src/rsa-signature.ts
new file mode 100644
index 0000000..4fc2701
--- /dev/null
+++ b/packages/crypto/src/rsa-signature.ts
@@ -0,0 +1,19 @@
+import { constants, createPublicKey, verify } from 'node:crypto'
+
+const createSpkiPublicKey = (publicKeyBase64: string) => {
+  return createPublicKey({
+    key: Buffer.from(publicKeyBase64, 'base64'),
+    format: 'der',
+    type: 'spki',
+  })
+}
+
+export const validateRsaPublicKey = (publicKeyBase64: string): void => {
+  createSpkiPublicKey(publicKeyBase64)
+}
+
+export const rsaVerifySignature = (data: Uint8Array, signature: Uint8Array, publicKeyBase64: string): boolean => {
+  const publicKey = createSpkiPublicKey(publicKeyBase64)
+
+  return verify('RSA-SHA256', data, { key: publicKey, padding: constants.RSA_PKCS1_PADDING }, signature)
+}