Add ability to import exported public key

src/client/crypto/index.test.ts

@@ -1,4 +1,4 @@
-import { encrypt, decrypt, generateECDHKeyPair, deriveECDHKey } from './index'
+import { exportPublicKey, encrypt, decrypt, generateECDHKeyPair, deriveECDHKey, hasWebCryptoAPI, importPublicKey } from './index'
 
 describe('crypto', () => {
 
@@ -21,6 +21,22 @@ describe('crypto', () => {
     })
   })
 
+  describe('hasWebCryptoAPI', () => {
+    it('returns true when crypto.subtle api is available', () => {
+      expect(hasWebCryptoAPI()).toBe(true)
+    })
+  })
+
+  describe('exportPublicKey and importPublicKey', () => {
+    it('exports public key', async () => {
+      const value = await exportPublicKey(keypair1.publicKey)
+      console.log(value)
+      const key = await importPublicKey(value)
+      expect(key).toBeTruthy()
+      expect(key).toEqual(keypair1.publicKey)
+    })
+  })
+
   describe('encrypt and decrypt', () => {
     it('can be encrypted with one pair and decrypted with other', async () => {
       const message = 'test message'

src/client/crypto/index.ts

@@ -1,3 +1,12 @@
+
+export function hasWebCryptoAPI(): boolean {
+  return !!(window && window.crypto && window.crypto.subtle)
+}
+
+export function hasWebCryptoAPI2(): boolean {
+  return !!(window?.crypto?.subtle)
+}
+
 export async function generateECDHKeyPair() {
   const key = await window.crypto.subtle.generateKey(
     {
@@ -59,10 +68,38 @@ export async function decrypt(key: CryptoKey, data: string): Promise<string> {
   return ab2str(decrypted)
 }
 
+export async function exportPublicKey(key: CryptoKey) {
+  return await window.crypto.subtle.exportKey('jwk', key)
+  // const pkcs8 = await window.crypto.subtle.exportKey('pkcs8', key)
+  // const base64 = window.btoa(ab2str(pkcs8, Uint8Array))
+  // const value =
+  //   `-----BEGIN PUBLIC KEY-----\n${base64}\n-----END PUBLIC KEY-----`
+  // return value
+}
 
-function ab2str(buf: ArrayBuffer): string {
+function ab2str(
+  buf: ArrayBuffer,
+  ArrayType: typeof Uint16Array | typeof Uint8Array = Uint16Array,
+): string {
   return String.fromCharCode.apply(
-    null, new Uint16Array(buf) as unknown as number[])
+    null, new ArrayType(buf) as unknown as number[])
+}
+
+export async function importPublicKey(keyData: JsonWebKey) {
+  if (keyData.kty !== 'EC' || keyData.crv !== 'P-256') {
+    throw new Error(`Unsupported key type: ${keyData.kty}, crv: ${keyData.crv}`)
+  }
+  const key = await window.crypto.subtle.importKey(
+    'jwk',
+    keyData,
+    {
+      name: 'ECDH',
+      namedCurve: keyData.crv,
+    },
+    /* extractable */ true,
+    [],
+  )
+  return key
 }
 
 function str2ab(str: string): ArrayBuffer {