Support decrypting empty ciphertext

src/jwe/compact/decrypt.ts

@@ -77,7 +77,7 @@ export async function compactDecrypt(
 
   const decrypted = await flattenedDecrypt(
     {
-      ciphertext: <string>(ciphertext || undefined),
+      ciphertext,
       iv: <string>(iv || undefined),
       protected: protectedHeader || undefined,
       tag: <string>(tag || undefined),

test/jwe/compact.decrypt.test.mjs

@@ -1,7 +1,7 @@
 import test from 'ava'
 
 const root = !('WEBCRYPTO' in process.env) ? '#dist' : '#dist/webcrypto'
-const { compactDecrypt } = await import(root)
+const { CompactEncrypt, compactDecrypt } = await import(root)
 
 test('JWE format validation', async (t) => {
   await t.throwsAsync(compactDecrypt(null, new Uint8Array(0)), {
@@ -13,3 +13,14 @@ test('JWE format validation', async (t) => {
     code: 'ERR_JWE_INVALID',
   })
 })
+
+test('decrypt empty data', async (t) => {
+  const jwe = await new CompactEncrypt(new Uint8Array(0))
+    .setProtectedHeader({ alg: 'dir', enc: 'A128GCM' })
+    .encrypt(new Uint8Array(16))
+
+  t.is(jwe.split('.')[3], '')
+
+  const { plaintext } = await compactDecrypt(jwe, new Uint8Array(16))
+  t.is(plaintext.byteLength, 0)
+})

test/jwe/flattened.decrypt.test.mjs

@@ -217,3 +217,14 @@ test('AES CBC + HMAC', async (t) => {
     })
   }
 })
+
+test('decrypt empty data', async (t) => {
+  const jwe = await new FlattenedEncrypt(new Uint8Array(0))
+    .setProtectedHeader({ alg: 'dir', enc: 'A128GCM' })
+    .encrypt(new Uint8Array(16))
+
+  t.is(jwe.ciphertext, '')
+
+  const { plaintext } = await flattenedDecrypt(jwe, new Uint8Array(16))
+  t.is(plaintext.byteLength, 0)
+})

test/jwe/general.test.mjs

@@ -170,3 +170,15 @@ test('General JWE format validation', async (t) => {
     await t.notThrowsAsync(generalDecrypt(jwe, t.context.secret))
   }
 })
+
+test('decrypt empty data', async (t) => {
+  const jwe = await new GeneralEncrypt(new Uint8Array(0))
+    .setProtectedHeader({ alg: 'dir', enc: 'A128GCM' })
+    .addRecipient(new Uint8Array(16))
+    .encrypt()
+
+  t.is(jwe.ciphertext, '')
+
+  const { plaintext } = await generalDecrypt(jwe, new Uint8Array(16))
+  t.is(plaintext.byteLength, 0)
+})