1 /*

     2 * Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of the License "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: 

    15 * ** IMPORTANT ** PublishedPartner API's in this file are published to 3rd party developers via the 

    16 * Symbian website. Changes to these API's should be treated as PublishedAll API changes and the Security TA should be consulted.

    17 *

    18 */

    19 

    20 

    21 /**

    22  @file

    23  @publishedPartner

    24  @released

    25 */

    26 

    27 #ifndef __PKCS5KDF_H__

    28 #define __PKCS5KDF_H__

    29 

    30 #include <hash.h>

    31 

    32 /** The number of times the hashing algorithm is run. */

    33 const TUint KDefaultIterations = 1000;

    34 

    35 /**

    36  * A PKCS#5 compliant Key Derivation Function (KDF).

    37  *

    38  * This class allows the derivation of deterministic arbitrary length byte 

    39  * streams from an input string. The output byte stream is generated using 

    40  * multiple iterations of a CSHA1 message digest and is suitable for use 

    41  * as a cryptographic symmetric key.

    42  *

    43  * @since v7.0s

    44  */

    45 class TPKCS5KDF

    46 	{

    47 public:

    48 	/** 

    49 	 * Derives deterministic arbitrary length byte streams (aKey) from an input

    50 	 * string (aPasswd) and a randomly chosen salt (aSalt) for use as a

    51 	 * symmetric key.

    52 	 *

    53 	 * Attention -- Improperly chosen values for these parameters will seriously

    54 	 * impact the security of the derived key and as a result the security of 

    55 	 * your application. 

    56 	 *

    57 	 * See the Cryptography api-guide documentation for more information and 

    58 	 * recommended usage patterns.

    59 	 * 

    60 	 * @param aKey			Output Value. The key resulting from the operation.

    61 	 * 						The length of the key will be equal to the length of

    62 	 * 						the input descriptor. All data, from the first byte 

    63 	 * 						to the set length, will be overwritten with the resulting

    64 	 *						byte stream.

    65 	 * @param aPasswd		Input Value. The password you wish to derive a key from.

    66 	 * @param aSalt			Input Value. A <B><I>randomly</I></B> selected second

    67 	 * 						input to the key derivation function to discourage certain

    68 	 * 						attacks. PKCS5 recommends a minimum of 8 randomly chosen bytes.

    69 	 * @param aIterations	Input Value. The number of times the internal hashing

    70 	 * 						function should be run over the password and salt.

    71 	 *						Minimum recommendation is KDefaultIterations.

    72 	 */

    73 	IMPORT_C static void DeriveKeyL(TDes8& aKey, const TDesC8& aPasswd, 

    74 		const TDesC8& aSalt, TUint aIterations = KDefaultIterations);

    75 private:

    76 	/** 

    77 	 * Internal iterative function that performs the actual hashing. 

    78 	 */

    79 	static void F(CMessageDigest& aDigest, TUint32* aAccumulator, TUint32* S,

    80 	TUint32* Ui, TUint aHashBytes, const TUint32* aSalt, TUint aSaltBytes, 

    81 	TUint c, TUint i);

    82 	

    83 	/** 

    84 	 * XOR's the values of two equal length descriptors.  Internally, it

    85 	 * operates on a word by word basis.  Data stored beyond the end of the

    86 	 * descriptor, but before the end of the final word, will be xored as well.

    87 	 */

    88 	static inline void XORString(const TUint32* aOp1, TUint32* aOp2,

    89 		TUint aLength);

    90 	};

    91 

    92 #endif