Class SHA1

java.lang.Object
org.eclipse.jgit.util.sha1.SHA1
public class SHA1 extends 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

  • Method Summary

    Modifier and Type
    Method
    Description
    byte[]
    digest()
    Finish the digest and return the resulting hash.
    void
    digest(MutableObjectId id)
    Finish the digest and return the resulting hash.
    boolean
    hasCollision()
    Check if a collision was detected.
    static SHA1
    newInstance()
    Create a new context to compute a SHA-1 hash of data.
    SHA1
    reset()
    Reset this instance to compute another hash.
    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.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • 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.

    • 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

    • update

      public void update(byte b)
      Update the digest computation by adding a byte.
      Parameters:
      b - a byte.

    • update

      public void update(byte[] in)
      Update the digest computation by adding bytes to the message.
      Parameters:
      in - input array of bytes.

    • 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 from in.
      len - number of bytes to hash.

    • 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.

    • 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.

    • 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.

    • 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) or toObjectId(), as the hashing function must finish processing to know the final state.

      Returns:
      true if a likely collision was detected.

    • reset

      public SHA1 reset()
      Reset this instance to compute another hash.
      Returns:
      this.