diff options
Diffstat (limited to 'org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java')
| -rw-r--r-- | org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java | 584 |
1 files changed, 102 insertions, 482 deletions
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java index 1420add662..87993d2bee 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java @@ -1,5 +1,5 @@ /* - * Copyright (C) 2017, Google Inc. and others + * Copyright (C) 2022, Matthias Sohn <matthias.sohn@sap.com> and others * * This program and the accompanying materials are made available under the * terms of the Eclipse Distribution License v. 1.0 which is available at @@ -7,99 +7,96 @@ * * SPDX-License-Identifier: BSD-3-Clause */ - package org.eclipse.jgit.util.sha1; -import static java.lang.Integer.lowestOneBit; -import static java.lang.Integer.numberOfTrailingZeros; -import static java.lang.Integer.rotateLeft; -import static java.lang.Integer.rotateRight; - -import java.text.MessageFormat; -import java.util.Arrays; +import java.io.IOException; +import java.security.MessageDigest; -import org.eclipse.jgit.internal.JGitText; +import org.eclipse.jgit.errors.ConfigInvalidException; +import org.eclipse.jgit.lib.ConfigConstants; import org.eclipse.jgit.lib.MutableObjectId; import org.eclipse.jgit.lib.ObjectId; -import org.eclipse.jgit.util.NB; import org.eclipse.jgit.util.SystemReader; -import org.slf4j.Logger; -import org.slf4j.LoggerFactory; /** - * Pure Java implementation of SHA-1 from FIPS 180-1 / RFC 3174. - * + * SHA-1 interface from FIPS 180-1 / RFC 3174 with optional collision detection. + * Some implementations may not support collision detection. * <p> * See <a href="https://tools.ietf.org/html/rfc3174">RFC 3174</a>. - * <p> - * Unlike MessageDigest, this implementation includes the algorithm used by - * {@code sha1dc} to detect cryptanalytic collision attacks against SHA-1, such - * as the one used by <a href="https://shattered.it/">SHAttered</a>. See - * <a href="https://github.com/cr-marcstevens/sha1collisiondetection"> - * sha1collisiondetection</a> for more information. - * <p> - * When detectCollision is true (default), this implementation throws - * {@link org.eclipse.jgit.util.sha1.Sha1CollisionException} from any digest - * method if a potential collision was detected. - * - * @since 4.7 */ -public class SHA1 { - private static final Logger LOG = LoggerFactory.getLogger(SHA1.class); - private static final boolean DETECT_COLLISIONS; - - static { - SystemReader sr = SystemReader.getInstance(); - String v = sr.getProperty("org.eclipse.jgit.util.sha1.detectCollision"); //$NON-NLS-1$ - DETECT_COLLISIONS = v != null ? Boolean.parseBoolean(v) : true; - } - +public abstract class SHA1 { /** - * Create a new context to compute a SHA-1 hash of data. - * - * @return a new context to compute a SHA-1 hash of data. + * SHA1 implementations available in JGit */ - public static SHA1 newInstance() { - return new SHA1(); - } - - private final State h = new State(); - private final int[] w = new int[80]; - - /** Buffer to accumulate partial blocks to 64 byte alignment. */ - private final byte[] buffer = new byte[64]; + public enum Sha1Implementation { + /** + * {@link SHA1Java} implemented in Java, supports collision detection. + */ + JAVA(SHA1Java.class), + /** + * Native implementation based on JDK's {@link MessageDigest}. + */ + JDKNATIVE(SHA1Native.class); + + private final String implClassName; + + private Sha1Implementation(Class implClass) { + this.implClassName = implClass.getName(); + } - /** Total number of bytes in the message. */ - private long length; + @Override + public String toString() { + return implClassName; + } + } - private boolean detectCollision = DETECT_COLLISIONS; - private boolean foundCollision; + private static final Sha1Implementation SHA1_IMPLEMENTATION = fromConfig(); - private final int[] w2 = new int[80]; - private final State state58 = new State(); - private final State state65 = new State(); - private final State hIn = new State(); - private final State hTmp = new State(); + private static Sha1Implementation fromConfig() { + try { + return SystemReader.getInstance().getUserConfig().getEnum( + ConfigConstants.CONFIG_CORE_SECTION, null, + ConfigConstants.SHA1_IMPLEMENTATION, + Sha1Implementation.JAVA); + } catch (ConfigInvalidException | IOException e) { + return Sha1Implementation.JAVA; + } + } - private SHA1() { - h.init(); + private static Sha1Implementation getImplementation() { + String fromSystemProperty = System + .getProperty("org.eclipse.jgit.util.sha1.implementation"); //$NON-NLS-1$ + if (fromSystemProperty == null) { + return SHA1_IMPLEMENTATION; + } + if (fromSystemProperty + .equalsIgnoreCase(Sha1Implementation.JAVA.name())) { + return Sha1Implementation.JAVA; + } + if (fromSystemProperty + .equalsIgnoreCase(Sha1Implementation.JDKNATIVE.name())) { + return Sha1Implementation.JDKNATIVE; + } + return SHA1_IMPLEMENTATION; } /** - * Enable likely collision detection. - * <p> - * Default is {@code true}. + * Create a new context to compute a SHA-1 hash of data. * <p> - * May also be set by system property: - * {@code -Dorg.eclipse.jgit.util.sha1.detectCollision=true}. + * If {@code core.sha1Implementation = jdkNative} in the user level global + * git configuration or the system property + * {@code org.eclipse.jgit.util.sha1.implementation = jdkNative} it will + * create an object using the implementation in the JDK. If both are set the + * system property takes precedence. Otherwise the pure Java implementation + * will be used which supports collision detection but is slower. * - * @param detect - * a boolean. - * @return {@code this} + * @return a new context to compute a SHA-1 hash of data. */ - public SHA1 setDetectCollision(boolean detect) { - detectCollision = detect; - return this; + public static SHA1 newInstance() { + if (getImplementation() == Sha1Implementation.JDKNATIVE) { + return new SHA1Native(); + } + return new SHA1Java(); } /** @@ -107,14 +104,7 @@ public class SHA1 { * * @param b a byte. */ - public void update(byte b) { - int bufferLen = (int) (length & 63); - length++; - buffer[bufferLen] = b; - if (bufferLen == 63) { - compress(buffer, 0); - } - } + public abstract void update(byte b); /** * Update the digest computation by adding bytes to the message. @@ -122,9 +112,7 @@ public class SHA1 { * @param in * input array of bytes. */ - public void update(byte[] in) { - update(in, 0, in.length); - } + public abstract void update(byte[] in); /** * Update the digest computation by adding bytes to the message. @@ -136,344 +124,7 @@ public class SHA1 { * @param len * number of bytes to hash. */ - public void update(byte[] in, int p, int len) { - // SHA-1 compress can only process whole 64 byte blocks. - // Hold partial updates in buffer, whose length is the low bits. - int bufferLen = (int) (length & 63); - length += len; - - if (bufferLen > 0) { - int n = Math.min(64 - bufferLen, len); - System.arraycopy(in, p, buffer, bufferLen, n); - p += n; - len -= n; - if (bufferLen + n < 64) { - return; - } - compress(buffer, 0); - } - while (len >= 64) { - compress(in, p); - p += 64; - len -= 64; - } - if (len > 0) { - System.arraycopy(in, p, buffer, 0, len); - } - } - - private void compress(byte[] block, int p) { - initBlock(block, p); - int ubcDvMask = detectCollision ? UbcCheck.check(w) : 0; - compress(); - - while (ubcDvMask != 0) { - int b = numberOfTrailingZeros(lowestOneBit(ubcDvMask)); - UbcCheck.DvInfo dv = UbcCheck.DV[b]; - for (int i = 0; i < 80; i++) { - w2[i] = w[i] ^ dv.dm[i]; - } - recompress(dv.testt); - if (eq(hTmp, h)) { - foundCollision = true; - break; - } - ubcDvMask &= ~(1 << b); - } - } - - private void initBlock(byte[] block, int p) { - for (int t = 0; t < 16; t++) { - w[t] = NB.decodeInt32(block, p + (t << 2)); - } - - // RFC 3174 6.1.b, extend state vector to 80 words. - for (int t = 16; t < 80; t++) { - int x = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16]; - w[t] = rotateLeft(x, 1); // S^1(...) - } - } - - private void compress() { - // Method 1 from RFC 3174 section 6.1. - // Method 2 (circular queue of 16 words) is slower. - int a = h.a, b = h.b, c = h.c, d = h.d, e = h.e; - - // @formatter:off - e += s1(a, b, c, d,w[ 0]); b = rotateLeft( b, 30); - d += s1(e, a, b, c,w[ 1]); a = rotateLeft( a, 30); - c += s1(d, e, a, b,w[ 2]); e = rotateLeft( e, 30); - b += s1(c, d, e, a,w[ 3]); d = rotateLeft( d, 30); - a += s1(b, c, d, e,w[ 4]); c = rotateLeft( c, 30); - e += s1(a, b, c, d,w[ 5]); b = rotateLeft( b, 30); - d += s1(e, a, b, c,w[ 6]); a = rotateLeft( a, 30); - c += s1(d, e, a, b,w[ 7]); e = rotateLeft( e, 30); - b += s1(c, d, e, a,w[ 8]); d = rotateLeft( d, 30); - a += s1(b, c, d, e,w[ 9]); c = rotateLeft( c, 30); - e += s1(a, b, c, d,w[ 10]); b = rotateLeft( b, 30); - d += s1(e, a, b, c,w[ 11]); a = rotateLeft( a, 30); - c += s1(d, e, a, b,w[ 12]); e = rotateLeft( e, 30); - b += s1(c, d, e, a,w[ 13]); d = rotateLeft( d, 30); - a += s1(b, c, d, e,w[ 14]); c = rotateLeft( c, 30); - e += s1(a, b, c, d,w[ 15]); b = rotateLeft( b, 30); - d += s1(e, a, b, c,w[ 16]); a = rotateLeft( a, 30); - c += s1(d, e, a, b,w[ 17]); e = rotateLeft( e, 30); - b += s1(c, d, e, a,w[ 18]); d = rotateLeft( d, 30); - a += s1(b, c, d, e,w[ 19]); c = rotateLeft( c, 30); - - e += s2(a, b, c, d,w[ 20]); b = rotateLeft( b, 30); - d += s2(e, a, b, c,w[ 21]); a = rotateLeft( a, 30); - c += s2(d, e, a, b,w[ 22]); e = rotateLeft( e, 30); - b += s2(c, d, e, a,w[ 23]); d = rotateLeft( d, 30); - a += s2(b, c, d, e,w[ 24]); c = rotateLeft( c, 30); - e += s2(a, b, c, d,w[ 25]); b = rotateLeft( b, 30); - d += s2(e, a, b, c,w[ 26]); a = rotateLeft( a, 30); - c += s2(d, e, a, b,w[ 27]); e = rotateLeft( e, 30); - b += s2(c, d, e, a,w[ 28]); d = rotateLeft( d, 30); - a += s2(b, c, d, e,w[ 29]); c = rotateLeft( c, 30); - e += s2(a, b, c, d,w[ 30]); b = rotateLeft( b, 30); - d += s2(e, a, b, c,w[ 31]); a = rotateLeft( a, 30); - c += s2(d, e, a, b,w[ 32]); e = rotateLeft( e, 30); - b += s2(c, d, e, a,w[ 33]); d = rotateLeft( d, 30); - a += s2(b, c, d, e,w[ 34]); c = rotateLeft( c, 30); - e += s2(a, b, c, d,w[ 35]); b = rotateLeft( b, 30); - d += s2(e, a, b, c,w[ 36]); a = rotateLeft( a, 30); - c += s2(d, e, a, b,w[ 37]); e = rotateLeft( e, 30); - b += s2(c, d, e, a,w[ 38]); d = rotateLeft( d, 30); - a += s2(b, c, d, e,w[ 39]); c = rotateLeft( c, 30); - - e += s3(a, b, c, d,w[ 40]); b = rotateLeft( b, 30); - d += s3(e, a, b, c,w[ 41]); a = rotateLeft( a, 30); - c += s3(d, e, a, b,w[ 42]); e = rotateLeft( e, 30); - b += s3(c, d, e, a,w[ 43]); d = rotateLeft( d, 30); - a += s3(b, c, d, e,w[ 44]); c = rotateLeft( c, 30); - e += s3(a, b, c, d,w[ 45]); b = rotateLeft( b, 30); - d += s3(e, a, b, c,w[ 46]); a = rotateLeft( a, 30); - c += s3(d, e, a, b,w[ 47]); e = rotateLeft( e, 30); - b += s3(c, d, e, a,w[ 48]); d = rotateLeft( d, 30); - a += s3(b, c, d, e,w[ 49]); c = rotateLeft( c, 30); - e += s3(a, b, c, d,w[ 50]); b = rotateLeft( b, 30); - d += s3(e, a, b, c,w[ 51]); a = rotateLeft( a, 30); - c += s3(d, e, a, b,w[ 52]); e = rotateLeft( e, 30); - b += s3(c, d, e, a,w[ 53]); d = rotateLeft( d, 30); - a += s3(b, c, d, e,w[ 54]); c = rotateLeft( c, 30); - e += s3(a, b, c, d,w[ 55]); b = rotateLeft( b, 30); - d += s3(e, a, b, c,w[ 56]); a = rotateLeft( a, 30); - c += s3(d, e, a, b,w[ 57]); e = rotateLeft( e, 30); - state58.save(a, b, c, d, e); - b += s3(c, d, e, a,w[ 58]); d = rotateLeft( d, 30); - a += s3(b, c, d, e,w[ 59]); c = rotateLeft( c, 30); - - e += s4(a, b, c, d,w[ 60]); b = rotateLeft( b, 30); - d += s4(e, a, b, c,w[ 61]); a = rotateLeft( a, 30); - c += s4(d, e, a, b,w[ 62]); e = rotateLeft( e, 30); - b += s4(c, d, e, a,w[ 63]); d = rotateLeft( d, 30); - a += s4(b, c, d, e,w[ 64]); c = rotateLeft( c, 30); - state65.save(a, b, c, d, e); - e += s4(a, b, c, d,w[ 65]); b = rotateLeft( b, 30); - d += s4(e, a, b, c,w[ 66]); a = rotateLeft( a, 30); - c += s4(d, e, a, b,w[ 67]); e = rotateLeft( e, 30); - b += s4(c, d, e, a,w[ 68]); d = rotateLeft( d, 30); - a += s4(b, c, d, e,w[ 69]); c = rotateLeft( c, 30); - e += s4(a, b, c, d,w[ 70]); b = rotateLeft( b, 30); - d += s4(e, a, b, c,w[ 71]); a = rotateLeft( a, 30); - c += s4(d, e, a, b,w[ 72]); e = rotateLeft( e, 30); - b += s4(c, d, e, a,w[ 73]); d = rotateLeft( d, 30); - a += s4(b, c, d, e,w[ 74]); c = rotateLeft( c, 30); - e += s4(a, b, c, d,w[ 75]); b = rotateLeft( b, 30); - d += s4(e, a, b, c,w[ 76]); a = rotateLeft( a, 30); - c += s4(d, e, a, b,w[ 77]); e = rotateLeft( e, 30); - b += s4(c, d, e, a,w[ 78]); d = rotateLeft( d, 30); - a += s4(b, c, d, e,w[ 79]); c = rotateLeft( c, 30); - - // @formatter:on - h.save(h.a + a, h.b + b, h.c + c, h.d + d, h.e + e); - } - - private void recompress(int t) { - State s; - switch (t) { - case 58: - s = state58; - break; - case 65: - s = state65; - break; - default: - throw new IllegalStateException(); - } - int a = s.a, b = s.b, c = s.c, d = s.d, e = s.e; - - // @formatter:off - if (t == 65) { - { c = rotateRight( c, 30); a -= s4(b, c, d, e,w2[ 64]);} - { d = rotateRight( d, 30); b -= s4(c, d, e, a,w2[ 63]);} - { e = rotateRight( e, 30); c -= s4(d, e, a, b,w2[ 62]);} - { a = rotateRight( a, 30); d -= s4(e, a, b, c,w2[ 61]);} - { b = rotateRight( b, 30); e -= s4(a, b, c, d,w2[ 60]);} - - { c = rotateRight( c, 30); a -= s3(b, c, d, e,w2[ 59]);} - { d = rotateRight( d, 30); b -= s3(c, d, e, a,w2[ 58]);} - } - { e = rotateRight( e, 30); c -= s3(d, e, a, b,w2[ 57]);} - { a = rotateRight( a, 30); d -= s3(e, a, b, c,w2[ 56]);} - { b = rotateRight( b, 30); e -= s3(a, b, c, d,w2[ 55]);} - { c = rotateRight( c, 30); a -= s3(b, c, d, e,w2[ 54]);} - { d = rotateRight( d, 30); b -= s3(c, d, e, a,w2[ 53]);} - { e = rotateRight( e, 30); c -= s3(d, e, a, b,w2[ 52]);} - { a = rotateRight( a, 30); d -= s3(e, a, b, c,w2[ 51]);} - { b = rotateRight( b, 30); e -= s3(a, b, c, d,w2[ 50]);} - { c = rotateRight( c, 30); a -= s3(b, c, d, e,w2[ 49]);} - { d = rotateRight( d, 30); b -= s3(c, d, e, a,w2[ 48]);} - { e = rotateRight( e, 30); c -= s3(d, e, a, b,w2[ 47]);} - { a = rotateRight( a, 30); d -= s3(e, a, b, c,w2[ 46]);} - { b = rotateRight( b, 30); e -= s3(a, b, c, d,w2[ 45]);} - { c = rotateRight( c, 30); a -= s3(b, c, d, e,w2[ 44]);} - { d = rotateRight( d, 30); b -= s3(c, d, e, a,w2[ 43]);} - { e = rotateRight( e, 30); c -= s3(d, e, a, b,w2[ 42]);} - { a = rotateRight( a, 30); d -= s3(e, a, b, c,w2[ 41]);} - { b = rotateRight( b, 30); e -= s3(a, b, c, d,w2[ 40]);} - - { c = rotateRight( c, 30); a -= s2(b, c, d, e,w2[ 39]);} - { d = rotateRight( d, 30); b -= s2(c, d, e, a,w2[ 38]);} - { e = rotateRight( e, 30); c -= s2(d, e, a, b,w2[ 37]);} - { a = rotateRight( a, 30); d -= s2(e, a, b, c,w2[ 36]);} - { b = rotateRight( b, 30); e -= s2(a, b, c, d,w2[ 35]);} - { c = rotateRight( c, 30); a -= s2(b, c, d, e,w2[ 34]);} - { d = rotateRight( d, 30); b -= s2(c, d, e, a,w2[ 33]);} - { e = rotateRight( e, 30); c -= s2(d, e, a, b,w2[ 32]);} - { a = rotateRight( a, 30); d -= s2(e, a, b, c,w2[ 31]);} - { b = rotateRight( b, 30); e -= s2(a, b, c, d,w2[ 30]);} - { c = rotateRight( c, 30); a -= s2(b, c, d, e,w2[ 29]);} - { d = rotateRight( d, 30); b -= s2(c, d, e, a,w2[ 28]);} - { e = rotateRight( e, 30); c -= s2(d, e, a, b,w2[ 27]);} - { a = rotateRight( a, 30); d -= s2(e, a, b, c,w2[ 26]);} - { b = rotateRight( b, 30); e -= s2(a, b, c, d,w2[ 25]);} - { c = rotateRight( c, 30); a -= s2(b, c, d, e,w2[ 24]);} - { d = rotateRight( d, 30); b -= s2(c, d, e, a,w2[ 23]);} - { e = rotateRight( e, 30); c -= s2(d, e, a, b,w2[ 22]);} - { a = rotateRight( a, 30); d -= s2(e, a, b, c,w2[ 21]);} - { b = rotateRight( b, 30); e -= s2(a, b, c, d,w2[ 20]);} - - { c = rotateRight( c, 30); a -= s1(b, c, d, e,w2[ 19]);} - { d = rotateRight( d, 30); b -= s1(c, d, e, a,w2[ 18]);} - { e = rotateRight( e, 30); c -= s1(d, e, a, b,w2[ 17]);} - { a = rotateRight( a, 30); d -= s1(e, a, b, c,w2[ 16]);} - { b = rotateRight( b, 30); e -= s1(a, b, c, d,w2[ 15]);} - { c = rotateRight( c, 30); a -= s1(b, c, d, e,w2[ 14]);} - { d = rotateRight( d, 30); b -= s1(c, d, e, a,w2[ 13]);} - { e = rotateRight( e, 30); c -= s1(d, e, a, b,w2[ 12]);} - { a = rotateRight( a, 30); d -= s1(e, a, b, c,w2[ 11]);} - { b = rotateRight( b, 30); e -= s1(a, b, c, d,w2[ 10]);} - { c = rotateRight( c, 30); a -= s1(b, c, d, e,w2[ 9]);} - { d = rotateRight( d, 30); b -= s1(c, d, e, a,w2[ 8]);} - { e = rotateRight( e, 30); c -= s1(d, e, a, b,w2[ 7]);} - { a = rotateRight( a, 30); d -= s1(e, a, b, c,w2[ 6]);} - { b = rotateRight( b, 30); e -= s1(a, b, c, d,w2[ 5]);} - { c = rotateRight( c, 30); a -= s1(b, c, d, e,w2[ 4]);} - { d = rotateRight( d, 30); b -= s1(c, d, e, a,w2[ 3]);} - { e = rotateRight( e, 30); c -= s1(d, e, a, b,w2[ 2]);} - { a = rotateRight( a, 30); d -= s1(e, a, b, c,w2[ 1]);} - { b = rotateRight( b, 30); e -= s1(a, b, c, d,w2[ 0]);} - - hIn.save(a, b, c, d, e); - a = s.a; b = s.b; c = s.c; d = s.d; e = s.e; - - if (t == 58) { - { b += s3(c, d, e, a,w2[ 58]); d = rotateLeft( d, 30);} - { a += s3(b, c, d, e,w2[ 59]); c = rotateLeft( c, 30);} - - { e += s4(a, b, c, d,w2[ 60]); b = rotateLeft( b, 30);} - { d += s4(e, a, b, c,w2[ 61]); a = rotateLeft( a, 30);} - { c += s4(d, e, a, b,w2[ 62]); e = rotateLeft( e, 30);} - { b += s4(c, d, e, a,w2[ 63]); d = rotateLeft( d, 30);} - { a += s4(b, c, d, e,w2[ 64]); c = rotateLeft( c, 30);} - } - { e += s4(a, b, c, d,w2[ 65]); b = rotateLeft( b, 30);} - { d += s4(e, a, b, c,w2[ 66]); a = rotateLeft( a, 30);} - { c += s4(d, e, a, b,w2[ 67]); e = rotateLeft( e, 30);} - { b += s4(c, d, e, a,w2[ 68]); d = rotateLeft( d, 30);} - { a += s4(b, c, d, e,w2[ 69]); c = rotateLeft( c, 30);} - { e += s4(a, b, c, d,w2[ 70]); b = rotateLeft( b, 30);} - { d += s4(e, a, b, c,w2[ 71]); a = rotateLeft( a, 30);} - { c += s4(d, e, a, b,w2[ 72]); e = rotateLeft( e, 30);} - { b += s4(c, d, e, a,w2[ 73]); d = rotateLeft( d, 30);} - { a += s4(b, c, d, e,w2[ 74]); c = rotateLeft( c, 30);} - { e += s4(a, b, c, d,w2[ 75]); b = rotateLeft( b, 30);} - { d += s4(e, a, b, c,w2[ 76]); a = rotateLeft( a, 30);} - { c += s4(d, e, a, b,w2[ 77]); e = rotateLeft( e, 30);} - { b += s4(c, d, e, a,w2[ 78]); d = rotateLeft( d, 30);} - { a += s4(b, c, d, e,w2[ 79]); c = rotateLeft( c, 30);} - - // @formatter:on - hTmp.save(hIn.a + a, hIn.b + b, hIn.c + c, hIn.d + d, hIn.e + e); - } - - private static int s1(int a, int b, int c, int d, int w_t) { - return rotateLeft(a, 5) - // f: 0 <= t <= 19 - + ((b & c) | ((~b) & d)) - + 0x5A827999 + w_t; - } - - private static int s2(int a, int b, int c, int d, int w_t) { - return rotateLeft(a, 5) - // f: 20 <= t <= 39 - + (b ^ c ^ d) - + 0x6ED9EBA1 + w_t; - } - - private static int s3(int a, int b, int c, int d, int w_t) { - return rotateLeft(a, 5) - // f: 40 <= t <= 59 - + ((b & c) | (b & d) | (c & d)) - + 0x8F1BBCDC + w_t; - } - - private static int s4(int a, int b, int c, int d, int w_t) { - return rotateLeft(a, 5) - // f: 60 <= t <= 79 - + (b ^ c ^ d) - + 0xCA62C1D6 + w_t; - } - - private static boolean eq(State q, State r) { - return q.a == r.a - && q.b == r.b - && q.c == r.c - && q.d == r.d - && q.e == r.e; - } - - private void finish() { - int bufferLen = (int) (length & 63); - if (bufferLen > 55) { - // Last block is too small; pad, compress, pad another block. - buffer[bufferLen++] = (byte) 0x80; - Arrays.fill(buffer, bufferLen, 64, (byte) 0); - compress(buffer, 0); - Arrays.fill(buffer, 0, 56, (byte) 0); - } else { - // Last block can hold padding and length. - buffer[bufferLen++] = (byte) 0x80; - Arrays.fill(buffer, bufferLen, 56, (byte) 0); - } - - // SHA-1 appends the length of the message in bits after the - // padding block (above). Here length is in bytes. Multiply by - // 8 by shifting by 3 as part of storing the 64 bit byte length - // into the two words expected in the trailer. - NB.encodeInt32(buffer, 56, (int) (length >>> (32 - 3))); - NB.encodeInt32(buffer, 60, (int) (length << 3)); - compress(buffer, 0); - - if (foundCollision) { - ObjectId id = h.toObjectId(); - LOG.warn(MessageFormat.format(JGitText.get().sha1CollisionDetected, - id.name())); - throw new Sha1CollisionException(id); - } - } + public abstract void update(byte[] in, int p, int len); /** * Finish the digest and return the resulting hash. @@ -484,17 +135,7 @@ public class SHA1 { * @throws org.eclipse.jgit.util.sha1.Sha1CollisionException * if a collision was detected and safeHash is false. */ - public byte[] digest() throws Sha1CollisionException { - finish(); - - byte[] b = new byte[20]; - NB.encodeInt32(b, 0, h.a); - NB.encodeInt32(b, 4, h.b); - NB.encodeInt32(b, 8, h.c); - NB.encodeInt32(b, 12, h.d); - NB.encodeInt32(b, 16, h.e); - return b; - } + public abstract byte[] digest() throws Sha1CollisionException; /** * Finish the digest and return the resulting hash. @@ -505,10 +146,7 @@ public class SHA1 { * @throws org.eclipse.jgit.util.sha1.Sha1CollisionException * if a collision was detected and safeHash is false. */ - public ObjectId toObjectId() throws Sha1CollisionException { - finish(); - return h.toObjectId(); - } + public abstract ObjectId toObjectId() throws Sha1CollisionException; /** * Finish the digest and return the resulting hash. @@ -520,60 +158,42 @@ public class SHA1 { * @throws org.eclipse.jgit.util.sha1.Sha1CollisionException * if a collision was detected and safeHash is false. */ - public void digest(MutableObjectId id) throws Sha1CollisionException { - finish(); - id.set(h.a, h.b, h.c, h.d, h.e); - } + public abstract void digest(MutableObjectId id) + throws Sha1CollisionException; /** - * Check if a collision was detected. + * Reset this instance to compute another hash. * + * @return {@code this}. + */ + public abstract SHA1 reset(); + + /** + * Enable likely collision detection. + * <p> + * Default for implementations supporting collision detection is + * {@code true}. * <p> - * This method only returns an accurate result after the digest was obtained - * through {@link #digest()}, {@link #digest(MutableObjectId)} or - * {@link #toObjectId()}, as the hashing function must finish processing to - * know the final state. + * Implementations not supporting collision detection ignore calls to this + * method. * - * @return {@code true} if a likely collision was detected. + * @param detect + * a boolean. + * @return {@code this} */ - public boolean hasCollision() { - return foundCollision; - } + public abstract SHA1 setDetectCollision(boolean detect); /** - * Reset this instance to compute another hash. + * Check if a collision was detected. This method only returns an accurate + * result after the digest was obtained through {@link #digest()}, + * {@link #digest(MutableObjectId)} or {@link #toObjectId()}, as the hashing + * function must finish processing to know the final state. + * <p> + * Implementations not supporting collision detection always return + * {@code false}. + * <p> * - * @return {@code this}. + * @return {@code true} if a likely collision was detected. */ - public SHA1 reset() { - h.init(); - length = 0; - foundCollision = false; - return this; - } - - private static final class State { - int a; - int b; - int c; - int d; - int e; - - final void init() { - // Magic initialization constants defined by FIPS180. - save(0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0); - } - - final void save(int a1, int b1, int c1, int d1, int e1) { - a = a1; - b = b1; - c = c1; - d = d1; - e = e1; - } - - ObjectId toObjectId() { - return new ObjectId(a, b, c, d, e); - } - } -} + public abstract boolean hasCollision(); +}
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