Update: export EC keys as PEM

Author: linuxwolf

lib/jwk/eckey.js

@@ -26,6 +26,32 @@ var WRAP_ALGS = [
   "ECDH-ES+A256KW"
 ];
 
+var EC_OID = "1.2.840.10045.2.1";
+function oidToCurveName(oid) {
+  switch (oid) {
+    case "1.2.840.10045.3.1.7":
+      return "P-256";
+    case "1.3.132.0.34":
+      return "P-384";
+    case "1.3.132.0.35":
+      return "P-521";
+    default:
+      return null;
+  }
+}
+function curveNameToOid(crv) {
+  switch (crv) {
+    case "P-256":
+      return "1.2.840.10045.3.1.7";
+    case "P-384":
+      return "1.3.132.0.34";
+    case "P-521":
+      return "1.3.132.0.35";
+    default:
+      return null;
+  }
+}
+
 var JWKEcCfg = {
   publicKey: function(props) {
     var fields = JWK.helpers.COMMON_PROPS.concat([
@@ -113,12 +139,62 @@ var JWKEcCfg = {
   },
   verifyKey: function(alg, keys) {
     return keys.public;
+  },
+
+  convertToPEM: function(key, isPrivate) {
+    // curveName to OID
+    var oid = key.crv;
+    oid = curveNameToOid(oid);
+    oid = forge.asn1.oidToDer(oid);
+    // key as bytes
+    var type,
+        pub,
+        asn1;
+    if (isPrivate) {
+      type = "EC PRIVATE KEY";
+      pub = Buffer.concat([
+        new Buffer([0x00, 0x04]),
+        key.x,
+        key.y
+      ]).toString("binary");
+      key = key.d.toString("binary");
+      asn1 = forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.SEQUENCE, true, [
+        forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.INTEGER, false, "\u0001"),
+        forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.OCTETSTRING, false, key),
+        forge.asn1.create(forge.asn1.Class.CONTEXT_SPECIFIC, 0, true, [
+          forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.OID, false, oid.bytes())
+        ]),
+        forge.asn1.create(forge.asn1.Class.CONTEXT_SPECIFIC, 1, true, [
+          forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.BITSTRING, false, pub)
+        ])
+      ]);
+    } else {
+      type = "PUBLIC KEY";
+      key = Buffer.concat([
+        new Buffer([0x00, 0x04]),
+        key.x,
+        key.y
+      ]).toString("binary");
+      asn1 = forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.SEQUENCE, true, [
+        forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.SEQUENCE, true, [
+          forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.OID, false, forge.asn1.oidToDer(EC_OID).bytes()),
+          forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.OID, false, oid.bytes())
+        ]),
+        forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.BITSTRING, false, key)
+      ]);
+    }
+    asn1 = forge.asn1.toDer(asn1).bytes();
+    var pem = forge.pem.encode({
+      type: type,
+      body: asn1
+    });
+    return pem;
   }
 };
 
 // Inspired by digitalbaazar/node-forge/js/rsa.js
 var validators = {
-  oid: "1.2.840.10045.2.1",
+  oid: EC_OID,
   privateKey: {
     // ECPrivateKey
     name: "ECPrivateKey",
@@ -215,19 +291,6 @@ var validators = {
   }
 };
 
-function oidToCurveName(oid) {
-  switch (oid) {
-    case "1.2.840.10045.3.1.7":
-      return "P-256";
-    case "1.3.132.0.34":
-      return "P-384";
-    case "1.3.132.0.35":
-      return "P-521";
-    default:
-      return null;
-  }
-}
-
 var JWKEcFactory = {
   kty: "EC",
   validators: validators,

test/jwk/eckey-test.js

@@ -233,6 +233,18 @@ describe("jwk/EC", function() {
       algs = JWK.EC.config.algorithms(keys, "verify");
       assert.deepEqual(algs, []);
     });
+    it("exports PEM for public key", function() {
+      var pem = JWK.EC.config.convertToPEM(keyPair.public, false);
+      assert.isString(pem);
+      assert.match(pem, /^-----BEGIN PUBLIC KEY-----\r\n/);
+      assert.match(pem, /\r\n-----END PUBLIC KEY-----\r\n$/);
+    });
+    it("exports PEM for private key", function() {
+      var pem = JWK.EC.config.convertToPEM(keyPair.private, true);
+      assert.isString(pem);
+      assert.match(pem, /^-----BEGIN EC PRIVATE KEY-----\r\n/);
+      assert.match(pem, /\r\n-----END EC PRIVATE KEY-----\r\n$/);
+    });
   });
   describe("keystore integration", function() {
     it("generates a 'EC' JWK", function() {

test/jwk/keystore-test.js

@@ -570,6 +570,11 @@ describe("jwk/keystore", function() {
           var promise = JWK.store.KeyStore.asKey(pem.rawPrivate, "pem");
           promise = promise.then(function(jwk) {
             assert.ok(JWK.store.KeyStore.asKey(jwk));
+            return jwk.toPEM(true);
+          });
+          promise = promise.then(function(pem) {
+            assert.match(pem, /^-----BEGIN EC PRIVATE KEY-----\r\n/);
+            assert.match(pem, /\r\n-----END EC PRIVATE KEY-----\r\n$/);
           });
 
           return promise;
@@ -594,6 +599,11 @@ describe("jwk/keystore", function() {
           var promise = JWK.store.KeyStore.asKey(pem.spki, "pem");
           promise = promise.then(function(jwk) {
             assert.ok(JWK.store.KeyStore.asKey(jwk));
+            return jwk.toPEM(false);
+          });
+          promise = promise.then(function(pem) {
+            assert.match(pem, /^-----BEGIN PUBLIC KEY-----\r\n/);
+            assert.match(pem, /\r\n-----END PUBLIC KEY-----\r\n$/);
           });
 
           return promise;