Пример #1
0
 /**
  * Creates a new {@code HKDF} instance.
  *
  * @param algorithm the MAC algorithm to use.
  * @param info optional context and application specific information, may be {@code null} or
  *     empty.
  * @param dkLen the desired length for derived keys, in bytes.
  * @throws NullPointerException if {@code algorithm} is {@code null}.
  * @throws IllegalArgumentException if {@code dkLen} is negative, or if the MAC algorithm is
  *     unknown, or if {@code dkLen} is greater than 255 * MAC algorithm's output length.
  */
 HKDF(Algorithm<MAC> algorithm, byte[] info, int dkLen) {
   Parameters.checkCondition(dkLen > 0);
   MAC mac = Factory.newMAC(algorithm, new byte[0]);
   Parameters.checkCondition(dkLen <= 255 * mac.length());
   this.algorithm = algorithm;
   this.dkLen = dkLen;
   this.info = info == null ? new byte[0] : XArrays.copyOf(info);
 }
Пример #2
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 private byte[] expand(byte[] key) {
   MAC mac = Factory.newMAC(algorithm, key);
   ByteBuffer t = new ByteBuffer(dkLen + mac.length());
   int n = (int) Math.ceil((double) dkLen / mac.length());
   byte[] u = new byte[0];
   for (int i = 1; i <= n; i++) {
     u = mac.update(u).update(info).digest((byte) i);
     t.append(u);
   }
   return t.toByteArray(0, dkLen);
 }
Пример #3
0
 private byte[] extract(byte[] key, byte[] salt) {
   return Factory.newMAC(algorithm, salt).digest(key);
 }