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app_vue/node_modules/node-forge/lib/hmac.js

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+/**
+ * Hash-based Message Authentication Code implementation. Requires a message
+ * digest object that can be obtained, for example, from forge.md.sha1 or
+ * forge.md.md5.
+ *
+ * @author Dave Longley
+ *
+ * Copyright (c) 2010-2012 Digital Bazaar, Inc. All rights reserved.
+ */
+var forge = require('./forge');
+require('./md');
+require('./util');
+
+/* HMAC API */
+var hmac = module.exports = forge.hmac = forge.hmac || {};
+
+/**
+ * Creates an HMAC object that uses the given message digest object.
+ *
+ * @return an HMAC object.
+ */
+hmac.create = function() {
+  // the hmac key to use
+  var _key = null;
+
+  // the message digest to use
+  var _md = null;
+
+  // the inner padding
+  var _ipadding = null;
+
+  // the outer padding
+  var _opadding = null;
+
+  // hmac context
+  var ctx = {};
+
+  /**
+   * Starts or restarts the HMAC with the given key and message digest.
+   *
+   * @param md the message digest to use, null to reuse the previous one,
+   *           a string to use builtin 'sha1', 'md5', 'sha256'.
+   * @param key the key to use as a string, array of bytes, byte buffer,
+   *           or null to reuse the previous key.
+   */
+  ctx.start = function(md, key) {
+    if(md !== null) {
+      if(typeof md === 'string') {
+        // create builtin message digest
+        md = md.toLowerCase();
+        if(md in forge.md.algorithms) {
+          _md = forge.md.algorithms[md].create();
+        } else {
+          throw new Error('Unknown hash algorithm "' + md + '"');
+        }
+      } else {
+        // store message digest
+        _md = md;
+      }
+    }
+
+    if(key === null) {
+      // reuse previous key
+      key = _key;
+    } else {
+      if(typeof key === 'string') {
+        // convert string into byte buffer
+        key = forge.util.createBuffer(key);
+      } else if(forge.util.isArray(key)) {
+        // convert byte array into byte buffer
+        var tmp = key;
+        key = forge.util.createBuffer();
+        for(var i = 0; i < tmp.length; ++i) {
+          key.putByte(tmp[i]);
+        }
+      }
+
+      // if key is longer than blocksize, hash it
+      var keylen = key.length();
+      if(keylen > _md.blockLength) {
+        _md.start();
+        _md.update(key.bytes());
+        key = _md.digest();
+      }
+
+      // mix key into inner and outer padding
+      // ipadding = [0x36 * blocksize] ^ key
+      // opadding = [0x5C * blocksize] ^ key
+      _ipadding = forge.util.createBuffer();
+      _opadding = forge.util.createBuffer();
+      keylen = key.length();
+      for(var i = 0; i < keylen; ++i) {
+        var tmp = key.at(i);
+        _ipadding.putByte(0x36 ^ tmp);
+        _opadding.putByte(0x5C ^ tmp);
+      }
+
+      // if key is shorter than blocksize, add additional padding
+      if(keylen < _md.blockLength) {
+        var tmp = _md.blockLength - keylen;
+        for(var i = 0; i < tmp; ++i) {
+          _ipadding.putByte(0x36);
+          _opadding.putByte(0x5C);
+        }
+      }
+      _key = key;
+      _ipadding = _ipadding.bytes();
+      _opadding = _opadding.bytes();
+    }
+
+    // digest is done like so: hash(opadding | hash(ipadding | message))
+
+    // prepare to do inner hash
+    // hash(ipadding | message)
+    _md.start();
+    _md.update(_ipadding);
+  };
+
+  /**
+   * Updates the HMAC with the given message bytes.
+   *
+   * @param bytes the bytes to update with.
+   */
+  ctx.update = function(bytes) {
+    _md.update(bytes);
+  };
+
+  /**
+   * Produces the Message Authentication Code (MAC).
+   *
+   * @return a byte buffer containing the digest value.
+   */
+  ctx.getMac = function() {
+    // digest is done like so: hash(opadding | hash(ipadding | message))
+    // here we do the outer hashing
+    var inner = _md.digest().bytes();
+    _md.start();
+    _md.update(_opadding);
+    _md.update(inner);
+    return _md.digest();
+  };
+  // alias for getMac
+  ctx.digest = ctx.getMac;
+
+  return ctx;
+};