crypto: add ECDH.convertKey to convert public keys

ECDH.convertKey is used to convert public keys between different
formats.

PR-URL: https://github.com/nodejs/node/pull/19080
Fixes: https://github.com/nodejs/node/issues/18977
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 50 insertions, 32 deletions

diff --git a/lib/internal/crypto/diffiehellman.js b/lib/internal/crypto/diffiehellman.js
index f6d525c215..793f3fb351 100644
--- a/lib/internal/crypto/diffiehellman.js
+++ b/lib/internal/crypto/diffiehellman.js
@@ -14,7 +14,8 @@ const {
 const {
   DiffieHellman: _DiffieHellman,
   DiffieHellmanGroup: _DiffieHellmanGroup,
-  ECDH: _ECDH
+  ECDH: _ECDH,
+  ECDHConvertKey: _ECDHConvertKey
 } = process.binding('crypto');
 const {
   POINT_CONVERSION_COMPRESSED,
@@ -84,11 +85,9 @@ DiffieHellmanGroup.prototype.generateKeys =
     dhGenerateKeys;
 
 function dhGenerateKeys(encoding) {
-  var keys = this._handle.generateKeys();
+  const keys = this._handle.generateKeys();
   encoding = encoding || getDefaultEncoding();
-  if (encoding && encoding !== 'buffer')
-    keys = keys.toString(encoding);
-  return keys;
+  return encode(keys, encoding);
 }
 
 
@@ -100,12 +99,10 @@ function dhComputeSecret(key, inEnc, outEnc) {
   const encoding = getDefaultEncoding();
   inEnc = inEnc || encoding;
   outEnc = outEnc || encoding;
-  var ret = this._handle.computeSecret(toBuf(key, inEnc));
+  const ret = this._handle.computeSecret(toBuf(key, inEnc));
   if (typeof ret === 'string')
     throw new ERR_CRYPTO_ECDH_INVALID_PUBLIC_KEY();
-  if (outEnc && outEnc !== 'buffer')
-    ret = ret.toString(outEnc);
-  return ret;
+  return encode(ret, outEnc);
 }
 
 
@@ -114,11 +111,9 @@ DiffieHellmanGroup.prototype.getPrime =
     dhGetPrime;
 
 function dhGetPrime(encoding) {
-  var prime = this._handle.getPrime();
+  const prime = this._handle.getPrime();
   encoding = encoding || getDefaultEncoding();
-  if (encoding && encoding !== 'buffer')
-    prime = prime.toString(encoding);
-  return prime;
+  return encode(prime, encoding);
 }
 
 
@@ -127,11 +122,9 @@ DiffieHellmanGroup.prototype.getGenerator =
     dhGetGenerator;
 
 function dhGetGenerator(encoding) {
-  var generator = this._handle.getGenerator();
+  const generator = this._handle.getGenerator();
   encoding = encoding || getDefaultEncoding();
-  if (encoding && encoding !== 'buffer')
-    generator = generator.toString(encoding);
-  return generator;
+  return encode(generator, encoding);
 }
 
 
@@ -140,11 +133,9 @@ DiffieHellmanGroup.prototype.getPublicKey =
     dhGetPublicKey;
 
 function dhGetPublicKey(encoding) {
-  var key = this._handle.getPublicKey();
+  const key = this._handle.getPublicKey();
   encoding = encoding || getDefaultEncoding();
-  if (encoding && encoding !== 'buffer')
-    key = key.toString(encoding);
-  return key;
+  return encode(key, encoding);
 }
 
 
@@ -153,11 +144,9 @@ DiffieHellmanGroup.prototype.getPrivateKey =
     dhGetPrivateKey;
 
 function dhGetPrivateKey(encoding) {
-  var key = this._handle.getPrivateKey();
+  const key = this._handle.getPrivateKey();
   encoding = encoding || getDefaultEncoding();
-  if (encoding && encoding !== 'buffer')
-    key = key.toString(encoding);
-  return key;
+  return encode(key, encoding);
 }
 
 
@@ -197,7 +186,40 @@ ECDH.prototype.generateKeys = function generateKeys(encoding, format) {
 };
 
 ECDH.prototype.getPublicKey = function getPublicKey(encoding, format) {
-  var f;
+  const f = getFormat(format);
+  const key = this._handle.getPublicKey(f);
+  encoding = encoding || getDefaultEncoding();
+  return encode(key, encoding);
+};
+
+ECDH.convertKey = function convertKey(key, curve, inEnc, outEnc, format) {
+  if (typeof key !== 'string' && !isArrayBufferView(key)) {
+    throw new ERR_INVALID_ARG_TYPE(
+      'key',
+      ['string', 'Buffer', 'TypedArray', 'DataView']
+    );
+  }
+
+  if (typeof curve !== 'string') {
+    throw new ERR_INVALID_ARG_TYPE('curve', 'string');
+  }
+
+  const encoding = getDefaultEncoding();
+  inEnc = inEnc || encoding;
+  outEnc = outEnc || encoding;
+  const f = getFormat(format);
+  const convertedKey = _ECDHConvertKey(toBuf(key, inEnc), curve, f);
+  return encode(convertedKey, outEnc);
+};
+
+function encode(buffer, encoding) {
+  if (encoding && encoding !== 'buffer')
+    buffer = buffer.toString(encoding);
+  return buffer;
+}
+
+function getFormat(format) {
+  let f;
   if (format) {
     if (format === 'compressed')
       f = POINT_CONVERSION_COMPRESSED;
@@ -211,12 +233,8 @@ ECDH.prototype.getPublicKey = function getPublicKey(encoding, format) {
   } else {
     f = POINT_CONVERSION_UNCOMPRESSED;
   }
-  var key = this._handle.getPublicKey(f);
-  encoding = encoding || getDefaultEncoding();
-  if (encoding && encoding !== 'buffer')
-    key = key.toString(encoding);
-  return key;
-};
+  return f;
+}
 
 module.exports = {
   DiffieHellman,