File	Doc	Category	Size	Date	Package
SHA1_MessageDigestImpl.java	API Doc	Android 1.5 API	11055	Wed May 06 22:41:06 BST 2009	org.apache.harmony.security.provider.crypto

SHA1_MessageDigestImpl

• java.lang.Object
  • java.security.MessageDigestSpi

Fields Summary
private int[]	buffer
private byte[]	oneByte
private int	messageLength

Constructors Summary
public SHA1_MessageDigestImpl() The constructor creates needed buffers and sets the engine at initial state // BYTES_OFFSET +6 is minimal length required by methods in SHA1Impl buffer = new int[BYTES_OFFSET +6]; oneByte = new byte[1]; engineReset();

Methods Summary
public java.lang.Object	clone() Returns a "deep" copy of this SHA1MDImpl object. The method overrides "clone()" in class Object. return a clone of this object SHA1_MessageDigestImpl cloneObj = (SHA1_MessageDigestImpl) super.clone(); cloneObj.buffer = ( int[])buffer.clone(); cloneObj.oneByte = (byte[])oneByte.clone(); return cloneObj;
protected byte[]	engineDigest() Computes a message digest value. The method resets the engine. The method overrides "engineDigest()" in class MessageDigestSpi. return byte array containing message digest value byte[] hash = new byte[DIGEST_LENGTH]; processDigest(hash, 0); return hash;
protected int	engineDigest(byte[] buf, int offset, int len) Computes message digest value. Upon return, the value is stored in "buf" buffer beginning "offset" byte. The method resets the engine. The method overrides "engineDigest(byte[],int,int) in class MessageDigestSpi. param buf byte array to store a message digest returned param offset a position in the array for first byte of the message digest param len number of bytes within buffer allotted for the message digest; as this implementation doesn't provide partial digests, len should be >= 20, DigestException is thrown otherwise return the length of the message digest stored in the "buf" buffer; in this implementation the length=20 throws IllegalArgumentException if null is passed to the "buf" argument if offset + len > buf.length if offset > buf.length or len > buf.length throws DigestException if len < 20 throws ArrayIndexOutOfBoundsException if offset < 0 if ( buf == null ) { throw new IllegalArgumentException(Messages.getString("security.162")); //$NON-NLS-1$ } if ( offset > buf.length || len > buf.length || (len + offset) > buf.length ) { throw new IllegalArgumentException( Messages.getString("security.163")); //$NON-NLS-1$ } if ( len < DIGEST_LENGTH ) { throw new DigestException(Messages.getString("security.164")); //$NON-NLS-1$ } if ( offset < 0 ) { throw new ArrayIndexOutOfBoundsException(Messages.getString("security.165", offset)); //$NON-NLS-1$ } processDigest(buf, offset); return DIGEST_LENGTH;
protected int	engineGetDigestLength() Returns a message digest length. The method overrides "engineGetDigestLength()" in class MessageDigestSpi. return total length of current message digest as an int value return DIGEST_LENGTH;
protected void	engineReset() Resets the engine. The method overrides "engineReset()" in class MessageDigestSpi. messageLength = 0; buffer[BYTES_OFFSET] = 0; buffer[HASH_OFFSET ] = H0; buffer[HASH_OFFSET +1] = H1; buffer[HASH_OFFSET +2] = H2; buffer[HASH_OFFSET +3] = H3; buffer[HASH_OFFSET +4] = H4;
protected void	engineUpdate(byte input) Supplements a byte to current message. The method overrides "engineUpdate(byte)" in class MessageDigestSpi. param input byte to add to current message oneByte[0] = input; SHA1Impl.updateHash( buffer, oneByte, 0, 0 ); messageLength++;
protected void	engineUpdate(byte[] input, int offset, int len) Updates current message. The method overrides "engineUpdate(byte[],int,int)" in class MessageDigestSpi. The method silently returns if "len" <= 0. param input a byte array param offset a number of first byte in the "input" array to use for updating param len a number of bytes to use throws NullPointerException if null is passed to the "buf" argument throws IllegalArgumentException if offset > buf.length or len > buf.length or (len + offset) > buf.length throws ArrayIndexOutOfBoundsException offset < 0 if ( input == null ) { throw new IllegalArgumentException(Messages.getString("security.166")); //$NON-NLS-1$ } if ( len <= 0 ) { return; } if ( offset < 0 ) { throw new ArrayIndexOutOfBoundsException(Messages.getString("security.165", offset)); //$NON-NLS-1$ } if ( offset > input.length || len > input.length || (len + offset) > input.length ) { throw new IllegalArgumentException( Messages.getString("security.167")); //$NON-NLS-1$ } SHA1Impl.updateHash(buffer, input, offset, offset + len -1 ); messageLength += len;
private void	processDigest(byte[] digest, int offset) The method performs final actions and invokes the "computeHash(int[])" method. In case if there is no enough words in current frame after processing its data, extra frame is prepared and the "computeHash(int[])" method is invoked second time. After processing, the method resets engine's state param digest - byte array param offset - offset in digest int i, j; // implementation variables int lastWord; // long nBits = messageLength <<3 ; // length has to be calculated before padding engineUpdate( (byte) 0x80 ); // beginning byte in padding i = 0; // i contains number of beginning word for following loop lastWord = (buffer[BYTES_OFFSET] + 3)>>2 ; // computing of # of full words by shifting // # of bytes // possible cases: // // - buffer[BYTES_OFFSET] == 0 - buffer frame is empty, // padding byte was 64th in previous frame // current frame should contain only message's length // // - lastWord < 14 - two last, these are 14 & 15, words in 16 word frame are free; // no extra frame needed // - lastWord = 14 - only one last, namely 15-th, word in frame doesn't contain bytes; // extra frame is needed // - lastWord > 14 - last word in frame is not full; // extra frame is needed if ( buffer[BYTES_OFFSET] != 0 ) { if ( lastWord < 15 ) { i = lastWord; } else { if ( lastWord == 15 ) { buffer[15] = 0; // last word in frame is set to "0" } SHA1Impl.computeHash(buffer); i = 0; } } Arrays.fill(buffer, i, 14, 0); buffer[14] = (int)( nBits >>>32 ); buffer[15] = (int)( nBits & 0xFFFFFFFF ); SHA1Impl.computeHash(buffer); // converting 5-word frame into 20 bytes j = offset; for ( i = HASH_OFFSET; i < HASH_OFFSET +5; i++ ) { int k = buffer[i]; digest[j ] = (byte) ( k >>>24 ); // getting first byte from left digest[j+1] = (byte) ( k >>>16 ); // getting second byte from left digest[j+2] = (byte) ( k >>> 8 ); // getting third byte from left digest[j+3] = (byte) ( k ); // getting fourth byte from left j += 4; } engineReset();