Class SHA1
- java.lang.Object
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- org.eclipse.jgit.util.sha1.SHA1
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public class SHA1 extends java.lang.Object
Pure Java implementation of SHA-1 from FIPS 180-1 / RFC 3174.See RFC 3174.
Unlike MessageDigest, this implementation includes the algorithm used by
sha1dc
to detect cryptanalytic collision attacks against SHA-1, such as the one used by SHAttered. See sha1collisiondetection for more information.When detectCollision is true (default), this implementation throws
Sha1CollisionException
from any digest method if a potential collision was detected.- Since:
- 4.7
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Nested Class Summary
Nested Classes Modifier and Type Class Description private static class
SHA1.State
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Field Summary
Fields Modifier and Type Field Description private byte[]
buffer
Buffer to accumulate partial blocks to 64 byte alignment.private static boolean
DETECT_COLLISIONS
private boolean
detectCollision
private boolean
foundCollision
private SHA1.State
h
private SHA1.State
hIn
private SHA1.State
hTmp
private long
length
Total number of bytes in the message.private static org.slf4j.Logger
LOG
private SHA1.State
state58
private SHA1.State
state65
private int[]
w
private int[]
w2
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Constructor Summary
Constructors Modifier Constructor Description private
SHA1()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description private void
compress()
private void
compress(byte[] block, int p)
byte[]
digest()
Finish the digest and return the resulting hash.void
digest(MutableObjectId id)
Finish the digest and return the resulting hash.private static boolean
eq(SHA1.State q, SHA1.State r)
private void
finish()
boolean
hasCollision()
Check if a collision was detected.private void
initBlock(byte[] block, int p)
static SHA1
newInstance()
Create a new context to compute a SHA-1 hash of data.private void
recompress(int t)
SHA1
reset()
Reset this instance to compute another hash.private static int
s1(int a, int b, int c, int d, int w_t)
private static int
s2(int a, int b, int c, int d, int w_t)
private static int
s3(int a, int b, int c, int d, int w_t)
private static int
s4(int a, int b, int c, int d, int w_t)
SHA1
setDetectCollision(boolean detect)
Enable likely collision detection.ObjectId
toObjectId()
Finish the digest and return the resulting hash.void
update(byte b)
Update the digest computation by adding a byte.void
update(byte[] in)
Update the digest computation by adding bytes to the message.void
update(byte[] in, int p, int len)
Update the digest computation by adding bytes to the message.
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Field Detail
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LOG
private static final org.slf4j.Logger LOG
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DETECT_COLLISIONS
private static final boolean DETECT_COLLISIONS
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h
private final SHA1.State h
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w
private final int[] w
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buffer
private final byte[] buffer
Buffer to accumulate partial blocks to 64 byte alignment.
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length
private long length
Total number of bytes in the message.
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detectCollision
private boolean detectCollision
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foundCollision
private boolean foundCollision
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w2
private final int[] w2
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state58
private final SHA1.State state58
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state65
private final SHA1.State state65
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hIn
private final SHA1.State hIn
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hTmp
private final SHA1.State hTmp
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Method Detail
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newInstance
public static SHA1 newInstance()
Create a new context to compute a SHA-1 hash of data.- Returns:
- a new context to compute a SHA-1 hash of data.
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setDetectCollision
public SHA1 setDetectCollision(boolean detect)
Enable likely collision detection.Default is
true
.May also be set by system property:
-Dorg.eclipse.jgit.util.sha1.detectCollision=true
.- Parameters:
detect
- a boolean.- Returns:
this
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update
public void update(byte b)
Update the digest computation by adding a byte.- Parameters:
b
- a byte.
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update
public void update(byte[] in)
Update the digest computation by adding bytes to the message.- Parameters:
in
- input array of bytes.
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update
public void update(byte[] in, int p, int len)
Update the digest computation by adding bytes to the message.- Parameters:
in
- input array of bytes.p
- offset to start at fromin
.len
- number of bytes to hash.
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compress
private void compress(byte[] block, int p)
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initBlock
private void initBlock(byte[] block, int p)
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compress
private void compress()
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recompress
private void recompress(int t)
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s1
private static int s1(int a, int b, int c, int d, int w_t)
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s2
private static int s2(int a, int b, int c, int d, int w_t)
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s3
private static int s3(int a, int b, int c, int d, int w_t)
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s4
private static int s4(int a, int b, int c, int d, int w_t)
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eq
private static boolean eq(SHA1.State q, SHA1.State r)
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finish
private void finish()
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digest
public byte[] digest() throws Sha1CollisionException
Finish the digest and return the resulting hash.Once
digest()
is called, this instance should be discarded.- Returns:
- the bytes for the resulting hash.
- Throws:
Sha1CollisionException
- if a collision was detected and safeHash is false.
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toObjectId
public ObjectId toObjectId() throws Sha1CollisionException
Finish the digest and return the resulting hash.Once
digest()
is called, this instance should be discarded.- Returns:
- the ObjectId for the resulting hash.
- Throws:
Sha1CollisionException
- if a collision was detected and safeHash is false.
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digest
public void digest(MutableObjectId id) throws Sha1CollisionException
Finish the digest and return the resulting hash.Once
digest()
is called, this instance should be discarded.- Parameters:
id
- destination to copy the digest to.- Throws:
Sha1CollisionException
- if a collision was detected and safeHash is false.
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hasCollision
public boolean hasCollision()
Check if a collision was detected.This method only returns an accurate result after the digest was obtained through
digest()
,digest(MutableObjectId)
ortoObjectId()
, as the hashing function must finish processing to know the final state.- Returns:
true
if a likely collision was detected.
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reset
public SHA1 reset()
Reset this instance to compute another hash.- Returns:
this
.
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