--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/sun/security/ssl/HKDF.java Fri May 11 15:53:12 2018 -0700
@@ -0,0 +1,232 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package sun.security.ssl;
+
+import java.security.NoSuchAlgorithmException;
+import java.security.InvalidKeyException;
+import javax.crypto.Mac;
+import javax.crypto.SecretKey;
+import javax.crypto.ShortBufferException;
+import javax.crypto.spec.SecretKeySpec;
+import java.util.Objects;
+
+/**
+ * An implementation of the HKDF key derivation algorithm outlined in RFC 5869,
+ * specific to the needs of TLS 1.3 key derivation in JSSE. This is not a
+ * general purpose HKDF implementation and is suited only to single-key output
+ * derivations.
+ *
+ * HKDF objects are created by specifying a message digest algorithm. That
+ * digest algorithm will be used by the HMAC function as part of the HKDF
+ * derivation process.
+ */
+class HKDF {
+ private final String hmacAlg;
+ private final Mac hmacObj;
+ private final int hmacLen;
+
+ /**
+ * Create an HDKF object, specifying the underlying message digest
+ * algorithm.
+ *
+ * @param hashAlg a standard name corresponding to a supported message
+ * digest algorithm.
+ *
+ * @throws NoSuchAlgorithmException if that message digest algorithm does
+ * not have an HMAC variant supported on any available provider.
+ */
+ HKDF(String hashAlg) throws NoSuchAlgorithmException {
+ Objects.requireNonNull(hashAlg,
+ "Must provide underlying HKDF Digest algorithm.");
+ hmacAlg = "Hmac" + hashAlg.replace("-", "");
+ hmacObj = Mac.getInstance(hmacAlg);
+ hmacLen = hmacObj.getMacLength();
+ }
+
+ /**
+ * Perform the HMAC-Extract derivation.
+ *
+ * @param salt a salt value, implemented as a {@code SecretKey}. A
+ * {@code null} value is allowed, which will internally use an array of
+ * zero bytes the same size as the underlying hash output length.
+ * @param inputKey the input keying material provided as a
+ * {@code SecretKey}.
+ * @param keyAlg the algorithm name assigned to the resulting
+ * {@code SecretKey} object.
+ *
+ * @return a {@code SecretKey} that is the result of the HKDF extract
+ * operation.
+ *
+ * @throws InvalidKeyException if the {@code salt} parameter cannot be
+ * used to initialize the underlying HMAC.
+ */
+ SecretKey extract(SecretKey salt, SecretKey inputKey, String keyAlg)
+ throws InvalidKeyException {
+ if (salt == null) {
+ salt = new SecretKeySpec(new byte[hmacLen], "HKDF-Salt");
+ }
+ hmacObj.init(salt);
+
+ return new SecretKeySpec(hmacObj.doFinal(inputKey.getEncoded()),
+ keyAlg);
+ }
+
+ /**
+ * Perform the HMAC-Extract derivation.
+ *
+ * @param salt a salt value as cleartext bytes. A {@code null} value is
+ * allowed, which will internally use an array of zero bytes the same
+ * size as the underlying hash output length.
+ * @param inputKey the input keying material provided as a
+ * {@code SecretKey}.
+ * @param keyAlg the algorithm name assigned to the resulting
+ * {@code SecretKey} object.
+ *
+ * @return a {@code SecretKey} that is the result of the HKDF extract
+ * operation.
+ *
+ * @throws InvalidKeyException if the {@code salt} parameter cannot be
+ * used to initialize the underlying HMAC.
+ */
+ SecretKey extract(byte[] salt, SecretKey inputKey, String keyAlg)
+ throws InvalidKeyException {
+ if (salt == null) {
+ salt = new byte[hmacLen];
+ }
+ return extract(new SecretKeySpec(salt, "HKDF-Salt"), inputKey, keyAlg);
+ }
+
+ /**
+ * Perform the HKDF-Expand derivation for a single-key output.
+ *
+ * @param pseudoRandKey the pseudo random key (PRK).
+ * @param info optional context-specific info. A {@code null} value is
+ * allowed in which case a zero-length byte array will be used.
+ * @param outLen the length of the resulting {@code SecretKey}
+ * @param keyAlg the algorithm name applied to the resulting
+ * {@code SecretKey}
+ *
+ * @return the resulting key derivation as a {@code SecretKey} object
+ *
+ * @throws InvalidKeyException if the underlying HMAC operation cannot
+ * be initialized using the provided {@code pseudoRandKey} object.
+ */
+ SecretKey expand(SecretKey pseudoRandKey, byte[] info, int outLen,
+ String keyAlg) throws InvalidKeyException {
+ byte[] kdfOutput;
+
+ // Calculate the number of rounds of HMAC that are needed to
+ // meet the requested data. Then set up the buffers we will need.
+ Objects.requireNonNull(pseudoRandKey, "A null PRK is not allowed.");
+ hmacObj.init(pseudoRandKey);
+ if (info == null) {
+ info = new byte[0];
+ }
+ int rounds = (outLen + hmacLen - 1) / hmacLen;
+ kdfOutput = new byte[rounds * hmacLen];
+ int offset = 0;
+ int tLength = 0;
+
+ for (int i = 0; i < rounds ; i++) {
+
+ // Calculate this round
+ try {
+ // Add T(i). This will be an empty string on the first
+ // iteration since tLength starts at zero. After the first
+ // iteration, tLength is changed to the HMAC length for the
+ // rest of the loop.
+ hmacObj.update(kdfOutput,
+ Math.max(0, offset - hmacLen), tLength);
+ hmacObj.update(info); // Add info
+ hmacObj.update((byte)(i + 1)); // Add round number
+ hmacObj.doFinal(kdfOutput, offset);
+
+ tLength = hmacLen;
+ offset += hmacLen; // For next iteration
+ } catch (ShortBufferException sbe) {
+ // This really shouldn't happen given that we've
+ // sized the buffers to their largest possible size up-front,
+ // but just in case...
+ throw new RuntimeException(sbe);
+ }
+ }
+
+ return new SecretKeySpec(kdfOutput, 0, outLen, keyAlg);
+ }
+
+ /**
+ * Perform the HKDF Extract-then-Expand operation.
+ *
+ * @param inputKey the input keying material provided as a
+ * {@code SecretKey}.
+ * @param salt a salt value, implemented as a {@code SecretKey}. A
+ * {@code null} value is allowed, which will internally use an array of
+ * zero bytes the same size as the underlying hash output length.
+ * @param info optional context-specific info. A {@code null} value is
+ * allowed in which case a zero-length byte array will be used.
+ * @param outLen the length of the resulting {@code SecretKey}
+ * @param keyAlg the algorithm name applied to the resulting
+ * {@code SecretKey}
+ *
+ * @return the resulting derivation stored in a {@code SecretKey} object.
+ *
+ * @throws InvalidKeyException if initialization of the underlying HMAC
+ * process fails with the salt during the extract phase, or with the
+ * resulting PRK during the expand phase.
+ */
+ SecretKey extractExpand(SecretKey inputKey, SecretKey salt, byte[] info,
+ int outLen, String keyAlg) throws InvalidKeyException {
+ SecretKey prk = extract(salt, inputKey, "HKDF-PRK");
+ return expand(prk, info, outLen, keyAlg);
+ }
+
+ /**
+ * Perform the HKDF Extract-then-Expand operation.
+ *
+ * @param inputKey the input keying material provided as a
+ * {@code SecretKey}.
+ * @param salt a salt value as cleartext bytes. A {@code null} value is
+ * allowed, which will internally use an array of zero bytes the same
+ * size as the underlying hash output length.
+ * @param info optional context-specific info. A {@code null} value is
+ * allowed in which case a zero-length byte array will be used.
+ * @param outLen the length of the resulting {@code SecretKey}
+ * @param keyAlg the algorithm name applied to the resulting
+ * {@code SecretKey}
+ *
+ * @return the resulting derivation stored in a {@code SecretKey} object.
+ *
+ * @throws InvalidKeyException if initialization of the underlying HMAC
+ * process fails with the salt during the extract phase, or with the
+ * resulting PRK during the expand phase.
+ */
+ SecretKey extractExpand(SecretKey inputKey, byte[] salt, byte[] info,
+ int outLen, String keyAlg) throws InvalidKeyException {
+ byte[] saltBytes = (salt != null) ? salt : new byte[hmacLen];
+ return extractExpand(inputKey,
+ new SecretKeySpec(saltBytes, "HKDF-PRK"), info, outLen, keyAlg);
+ }
+}
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