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165 lines
5.6 KiB
165 lines
5.6 KiB
// $Id: Digest.java 232 2010-06-17 14:19:24Z tp $ |
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package fr.cryptohash; |
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/** |
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* <p>This interface documents the API for a hash function. This |
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* interface somewhat mimics the standard {@code |
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* java.security.MessageDigest} class. We do not extend that class in |
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* order to provide compatibility with reduced Java implementations such |
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* as J2ME. Implementing a {@code java.security.Provider} compatible |
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* with Sun's JCA ought to be easy.</p> |
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* |
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* <p>A {@code Digest} object maintains a running state for a hash |
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* function computation. Data is inserted with {@code update()} calls; |
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* the result is obtained from a {@code digest()} method (where some |
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* final data can be inserted as well). When a digest output has been |
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* produced, the objet is automatically resetted, and can be used |
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* immediately for another digest operation. The state of a computation |
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* can be cloned with the {@link #copy} method; this can be used to get |
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* a partial hash result without interrupting the complete |
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* computation.</p> |
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* |
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* <p>{@code Digest} objects are stateful and hence not thread-safe; |
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* however, distinct {@code Digest} objects can be accessed concurrently |
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* without any problem.</p> |
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* |
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* <pre> |
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* ==========================(LICENSE BEGIN)============================ |
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* |
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* Copyright (c) 2007-2010 Projet RNRT SAPHIR |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining |
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* a copy of this software and associated documentation files (the |
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* "Software"), to deal in the Software without restriction, including |
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* without limitation the rights to use, copy, modify, merge, publish, |
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* distribute, sublicense, and/or sell copies of the Software, and to |
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* permit persons to whom the Software is furnished to do so, subject to |
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* the following conditions: |
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* |
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* The above copyright notice and this permission notice shall be |
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* included in all copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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* |
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* ===========================(LICENSE END)============================= |
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* </pre> |
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* |
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* @version $Revision: 232 $ |
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* @author Thomas Pornin <[email protected]> |
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*/ |
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public interface Digest { |
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/** |
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* Insert one more input data byte. |
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* |
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* @param in the input byte |
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*/ |
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public void update(byte in); |
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/** |
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* Insert some more bytes. |
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* |
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* @param inbuf the data bytes |
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*/ |
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public void update(byte[] inbuf); |
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/** |
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* Insert some more bytes. |
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* |
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* @param inbuf the data buffer |
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* @param off the data offset in {@code inbuf} |
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* @param len the data length (in bytes) |
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*/ |
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public void update(byte[] inbuf, int off, int len); |
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/** |
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* Finalize the current hash computation and return the hash value |
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* in a newly-allocated array. The object is resetted. |
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* |
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* @return the hash output |
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*/ |
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public byte[] digest(); |
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/** |
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* Input some bytes, then finalize the current hash computation |
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* and return the hash value in a newly-allocated array. The object |
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* is resetted. |
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* |
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* @param inbuf the input data |
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* @return the hash output |
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*/ |
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public byte[] digest(byte[] inbuf); |
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/** |
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* Finalize the current hash computation and store the hash value |
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* in the provided output buffer. The {@code len} parameter |
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* contains the maximum number of bytes that should be written; |
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* no more bytes than the natural hash function output length will |
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* be produced. If {@code len} is smaller than the natural |
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* hash output length, the hash output is truncated to its first |
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* {@code len} bytes. The object is resetted. |
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* |
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* @param outbuf the output buffer |
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* @param off the output offset within {@code outbuf} |
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* @param len the requested hash output length (in bytes) |
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* @return the number of bytes actually written in {@code outbuf} |
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*/ |
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public int digest(byte[] outbuf, int off, int len); |
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/** |
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* Get the natural hash function output length (in bytes). |
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* |
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* @return the digest output length (in bytes) |
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*/ |
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public int getDigestLength(); |
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/** |
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* Reset the object: this makes it suitable for a new hash |
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* computation. The current computation, if any, is discarded. |
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*/ |
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public void reset(); |
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/** |
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* Clone the current state. The returned object evolves independantly |
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* of this object. |
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* |
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* @return the clone |
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*/ |
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public Digest copy(); |
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/** |
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* <p>Return the "block length" for the hash function. This |
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* value is naturally defined for iterated hash functions |
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* (Merkle-Damgard). It is used in HMAC (that's what the |
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* <a href="http://tools.ietf.org/html/rfc2104">HMAC specification</a> |
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* names the "{@code B}" parameter).</p> |
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* |
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* <p>If the function is "block-less" then this function may |
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* return {@code -n} where {@code n} is an integer such that the |
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* block length for HMAC ("{@code B}") will be inferred from the |
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* key length, by selecting the smallest multiple of {@code n} |
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* which is no smaller than the key length. For instance, for |
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* the Fugue-xxx hash functions, this function returns -4: the |
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* virtual block length B is the HMAC key length, rounded up to |
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* the next multiple of 4.</p> |
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* |
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* @return the internal block length (in bytes), or {@code -n} |
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*/ |
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public int getBlockLength(); |
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/** |
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* <p>Get the display name for this function (e.g. {@code "SHA-1"} |
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* for SHA-1).</p> |
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* |
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* @see Object |
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*/ |
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public String toString(); |
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}
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