From bf72a5e52e2b31386fa39e79fe7e7ee011cb3d0d Mon Sep 17 00:00:00 2001
From: Filip Skokan <panva.ip@gmail.com>
Date: Sun, 27 Jan 2019 20:47:05 +0100
Subject: [PATCH] refactor: dry and fix key.algorithms when key has alg

---
 lib/jwk/key/ec.js  | 36 +++++++++---------------------------
 lib/jwk/key/oct.js | 35 +++++++----------------------------
 lib/jwk/key/rsa.js | 30 +++++++++---------------------
 3 files changed, 25 insertions(+), 76 deletions(-)

diff --git a/lib/jwk/key/ec.js b/lib/jwk/key/ec.js
index e52c16f6..fb626bf4 100644
--- a/lib/jwk/key/ec.js
+++ b/lib/jwk/key/ec.js
@@ -3,12 +3,6 @@ const generateKeyPair = promisify(require('crypto').generateKeyPair)
 
 const Key = require('./base')
 
-const SIG_ALGS = new Set([
-  'ES256',
-  'ES384',
-  'ES512'
-])
-
 const WRAP_ALGS = new Set([
   'ECDH-ES',
   'ECDH-ES+A128KW',
@@ -38,50 +32,38 @@ class ECKey extends Key {
     return { crv: this.crv, kty: 'EC', x: this.x, y: this.y }
   }
 
-  algorithms (operation) {
+  algorithms (operation, { use = this.use, alg = this.alg } = {}) {
+    if (alg) {
+      return new Set(this.algorithms(operation, { alg: null, use }).has(alg) ? [alg] : undefined)
+    }
+
     switch (operation) {
       case 'encrypt':
       case 'decrypt':
         return new Set()
       case 'sign':
-        if (this.public || this.use === 'enc') {
+        if (this.public || use === 'enc') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(SIG_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set([`ES${this.length === 521 ? 512 : this.length}`])
       case 'verify':
-        if (this.use === 'enc') {
+        if (use === 'enc') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(SIG_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set([`ES${this.length === 521 ? 512 : this.length}`])
       case 'wrapKey':
-        if (this.use === 'sig') {
+        if (use === 'sig') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(WRAP_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(WRAP_ALGS)
       case 'unwrapKey':
-        if (this.public || this.use === 'sig') {
+        if (this.public || use === 'sig') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(WRAP_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(WRAP_ALGS)
       case undefined:
         return new Set([
diff --git a/lib/jwk/key/oct.js b/lib/jwk/key/oct.js
index 354e4856..db5d96cb 100644
--- a/lib/jwk/key/oct.js
+++ b/lib/jwk/key/oct.js
@@ -32,19 +32,6 @@ const WRAP_LEN = new Set([
   256
 ])
 
-const WRAP_ALGS = new Set([
-  'A128KW',
-  'A192KW',
-  'A256KW',
-  'A128GCMKW',
-  'A192GCMKW',
-  'A256GCMKW',
-  'PBES2-HS256+A128KW',
-  'PBES2-HS384+A192KW',
-  'PBES2-HS512+A256KW',
-  'dir'
-])
-
 class OctKey extends Key {
   constructor (...args) {
     super(...args)
@@ -71,7 +58,11 @@ class OctKey extends Key {
     return { k: this.k, kty: 'oct' }
   }
 
-  algorithms (operation) {
+  algorithms (operation, { use = this.use, alg = this.alg } = {}) {
+    if (alg) {
+      return new Set(this.algorithms(operation, { alg: null, use }).has(alg) ? [alg] : undefined)
+    }
+
     switch (operation) {
       case 'encrypt':
       case 'decrypt':
@@ -79,32 +70,20 @@ class OctKey extends Key {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(ENC_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set([`A${this.length / 2}CBC-HS${this.length}`, `A${this.length}GCM`].filter(a => ENC_ALGS.has(a)))
       case 'sign':
       case 'verify':
-        if (this.use === 'enc') {
+        if (use === 'enc') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(SIG_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(SIG_ALGS)
       case 'wrapKey':
       case 'unwrapKey':
-        if (this.use === 'sig') {
+        if (use === 'sig') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(WRAP_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         const algs = new Set(['dir', 'PBES2-HS256+A128KW', 'PBES2-HS384+A192KW', 'PBES2-HS512+A256KW'])
 
         if (WRAP_LEN.has(this.length)) {
diff --git a/lib/jwk/key/rsa.js b/lib/jwk/key/rsa.js
index 85569e91..be0153e9 100644
--- a/lib/jwk/key/rsa.js
+++ b/lib/jwk/key/rsa.js
@@ -39,50 +39,38 @@ class RSAKey extends Key {
     return { e: this.e, kty: 'RSA', n: this.n }
   }
 
-  algorithms (operation) {
+  algorithms (operation, { use = this.use, alg = this.alg } = {}) {
+    if (alg) {
+      return new Set(this.algorithms(operation, { alg: null, use }).has(alg) ? [alg] : undefined)
+    }
+
     switch (operation) {
       case 'encrypt':
       case 'decrypt':
         return new Set()
       case 'sign':
-        if (this.public || this.use === 'enc') {
+        if (this.public || use === 'enc') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(SIG_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(SIG_ALGS)
       case 'verify':
-        if (this.use === 'enc') {
+        if (use === 'enc') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(SIG_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(SIG_ALGS)
       case 'wrapKey':
-        if (this.use === 'sig') {
+        if (use === 'sig') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(WRAP_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(WRAP_ALGS)
       case 'unwrapKey':
-        if (this.public || this.use === 'sig') {
+        if (this.public || use === 'sig') {
           return new Set()
         }
 
-        if (this.alg) {
-          return new Set(WRAP_ALGS.has(this.alg) ? [this.alg] : undefined)
-        }
-
         return new Set(WRAP_ALGS)
       case undefined:
         return new Set([