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8238804: Enhance key handling process

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Reviewed-by: rriggs, mullan, ahgross, rhalade
This commit is contained in:
Weijun Wang 2020-03-18 13:35:16 +08:00
parent c90e523e0a
commit 6ac3892e16
1 changed files with 16 additions and 6 deletions
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22
src/java.base/share/classes/java/security/MessageDigest.java
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@ -465,8 +465,10 @@ public abstract class MessageDigest extends MessageDigestSpi {
* the same length and all bytes at corresponding positions are equal.
*
* @implNote
* If the digests are the same length, all bytes are examined to
* determine equality.
* All bytes in {@code digesta} are examined to determine equality.
* The calculation time depends only on the length of {@code digesta}.
* It does not depend on the length of {@code digestb} or the contents
* of {@code digesta} and {@code digestb}.
*
* @param digesta one of the digests to compare.
*
@ -479,14 +481,22 @@ public abstract class MessageDigest extends MessageDigestSpi {
if (digesta == null || digestb == null) {
return false;
}
if (digesta.length != digestb.length) {
return false;
int lenA = digesta.length;
int lenB = digestb.length;
if (lenB == 0) {
return lenA == 0;
}
int result = 0;
result |= lenA - lenB;
// time-constant comparison
for (int i = 0; i < digesta.length; i++) {
result |= digesta[i] ^ digestb[i];
for (int i = 0; i < lenA; i++) {
// If i >= lenB, indexB is 0; otherwise, i.
int indexB = ((i - lenB) >>> 31) * i;
result |= digesta[i] ^ digestb[indexB];
}
return result == 0;
}