Sat Mar 10 01:54:26 2012

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sha1.c

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00001 /*! \file
00002  *
00003  * \brief Based on the RFC 6234
00004  * 
00005  * Copyright (c) 2011 IETF Trust and the persons identified as
00006  * authors of the code.  All rights reserved.
00007  *
00008  * Redistribution and use in source and binary forms, with or
00009  * without modification, are permitted provided that the following
00010  * conditions are met:
00011  *
00012  * - Redistributions of source code must retain the above
00013  *   copyright notice, this list of conditions and
00014  *   the following disclaimer.
00015  *
00016  * - Redistributions in binary form must reproduce the above
00017  *   copyright notice, this list of conditions and the following
00018  *   disclaimer in the documentation and/or other materials provided
00019  *   with the distribution.
00020  *
00021  * - Neither the name of Internet Society, IETF or IETF Trust, nor
00022  *   the names of specific contributors, may be used to endorse or
00023  *   promote products derived from this software without specific
00024  *   prior written permission.
00025  *
00026  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
00027  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
00028  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00029  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
00030  * DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
00031  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00032  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00033  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00035  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00036  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
00037  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
00038  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00039  *
00040  *  Description:
00041  *      This file implements the Secure Hash Algorithm SHA-1
00042  *      as defined in the U.S. National Institute of Standards
00043  *      and Technology Federal Information Processing Standards
00044  *      Publication (FIPS PUB) 180-3 published in October 2008
00045  *      and formerly defined in its predecessors, FIPS PUB 180-1
00046  *      and FIP PUB 180-2.
00047  *
00048  *      A combined document showing all algorithms is available at
00049  *              http://csrc.nist.gov/publications/fips/
00050  *                     fips180-3/fips180-3_final.pdf
00051  *
00052  *      The SHA-1 algorithm produces a 160-bit message digest for a
00053  *      given data stream that can serve as a means of providing a
00054  *      "fingerprint" for a message.
00055  *
00056  *  Portability Issues:
00057  *      SHA-1 is defined in terms of 32-bit "words".  This code
00058  *      uses <stdint.h> (included via "sha.h") to define 32- and
00059  *      8-bit unsigned integer types.  If your C compiler does
00060  *      not support 32-bit unsigned integers, this code is not
00061  *      appropriate.
00062  *
00063  *  Caveats:
00064  *      SHA-1 is designed to work with messages less than 2^64 bits
00065  *      long.  This implementation uses SHA1Input() to hash the bits
00066  *      that are a multiple of the size of an 8-bit octet, and then
00067  *      optionally uses SHA1FinalBits() to hash the final few bits of
00068  *      the input.
00069  */
00070 
00071 #include <asterisk/sha1.h>
00072 
00073 /*! Define the SHA1 circular left shift macro */
00074 #define SHA1_ROTL(bits,word) \
00075                 (((word) << (bits)) | ((word) >> (32-(bits))))
00076 
00077 /*
00078  * Add "length" to the length.
00079  * Set Corrupted when overflow has occurred.
00080  */
00081 static uint32_t addTemp;
00082 #define SHA1AddLength(context, length)                     \
00083     (addTemp = (context)->Length_Low,                      \
00084      (context)->Corrupted =                                \
00085         (((context)->Length_Low += (length)) < addTemp) && \
00086         (++(context)->Length_High == 0) ? shaInputTooLong  \
00087                                         : (context)->Corrupted )
00088 
00089 /* Local Function Prototypes */
00090 static void SHA1ProcessMessageBlock(SHA1Context * context);
00091 static void SHA1Finalize(SHA1Context * context, uint8_t Pad_Byte);
00092 static void SHA1PadMessage(SHA1Context * context, uint8_t Pad_Byte);
00093 
00094 /*!
00095  * \brief SHA1Reset
00096  * \param context the context to be reset.
00097  * This function will initialize the SHA1Context in preparation
00098  * for computing a new SHA1 message digest.
00099  * \return sha Error Code.
00100  */
00101 int SHA1Reset(SHA1Context *context)
00102 {
00103    if (!context) {
00104       return shaNull;
00105    }
00106 
00107    context->Length_High = context->Length_Low = 0;
00108    context->Message_Block_Index = 0;
00109 
00110    /* Initial Hash Values: FIPS 180-3 section 5.3.1 */
00111    context->Intermediate_Hash[0] = 0x67452301;
00112    context->Intermediate_Hash[1] = 0xEFCDAB89;
00113    context->Intermediate_Hash[2] = 0x98BADCFE;
00114    context->Intermediate_Hash[3] = 0x10325476;
00115    context->Intermediate_Hash[4] = 0xC3D2E1F0;
00116 
00117    context->Computed = 0;
00118    context->Corrupted = shaSuccess;
00119 
00120    return shaSuccess;
00121 }
00122 
00123 /*!
00124  *  \brief SHA1Input
00125  * \param context [in/out] The SHA context to update
00126  * \param message_array [in] An array of characters representing the next portion of
00127  *       the message.
00128  * \param length [in] The length of the message in message_array.
00129  *  This function accepts an array of octets as the next portion
00130  *  of the message.
00131  * \return sha Error Code.
00132  */
00133 int SHA1Input(SHA1Context *context,
00134            const uint8_t *message_array, unsigned length)
00135 {
00136    if (!context) {
00137       return shaNull;
00138    }
00139    if (!length) {
00140       return shaSuccess;
00141    }
00142    if (!message_array) {
00143       return shaNull;
00144    }
00145 
00146    if (context->Computed) {
00147       context->Corrupted = shaStateError;
00148       return shaStateError;
00149    }
00150 
00151    if (context->Corrupted) {
00152       return context->Corrupted;
00153    }
00154 
00155    while (length--) {
00156       context->Message_Block[context->Message_Block_Index++] =
00157          *message_array;
00158 
00159       if ((SHA1AddLength(context, 8) == shaSuccess) &&
00160          (context->Message_Block_Index == SHA1_Message_Block_Size))
00161          SHA1ProcessMessageBlock(context);
00162 
00163       message_array++;
00164    }
00165 
00166    return context->Corrupted;
00167 }
00168 
00169 /*!
00170  * \brief SHA1FinalBits Add in any final bits of the message.
00171  *
00172  * \param context [in/out] The SHA context to update.
00173  * \param message_bits [in] The final bits of the message, in the upper portion of the
00174  *     byte.  (Use 0b###00000 instead of 0b00000### to input the
00175  *     three bits ###.)
00176  * \param length [in] *     The number of bits in message_bits, between 1 and 7.
00177  * \returns sha Error Code.
00178  */
00179 int SHA1FinalBits(SHA1Context * context, uint8_t message_bits,
00180               unsigned int length)
00181 {
00182    static uint8_t masks[8] = {
00183       /* 0 0b00000000 */ 0x00, /* 1 0b10000000 */ 0x80,
00184       /* 2 0b11000000 */ 0xC0, /* 3 0b11100000 */ 0xE0,
00185       /* 4 0b11110000 */ 0xF0, /* 5 0b11111000 */ 0xF8,
00186       /* 6 0b11111100 */ 0xFC, /* 7 0b11111110 */ 0xFE
00187    };
00188 
00189    static uint8_t markbit[8] = {
00190       /* 0 0b10000000 */ 0x80, /* 1 0b01000000 */ 0x40,
00191       /* 2 0b00100000 */ 0x20, /* 3 0b00010000 */ 0x10,
00192       /* 4 0b00001000 */ 0x08, /* 5 0b00000100 */ 0x04,
00193       /* 6 0b00000010 */ 0x02, /* 7 0b00000001 */ 0x01
00194    };
00195 
00196    if (!context)
00197       return shaNull;
00198    if (!length)
00199       return shaSuccess;
00200    if (context->Corrupted)
00201       return context->Corrupted;
00202    if (context->Computed)
00203       return context->Corrupted = shaStateError;
00204    if (length >= 8)
00205       return context->Corrupted = shaBadParam;
00206 
00207    SHA1AddLength(context, length);
00208    SHA1Finalize(context,
00209              (uint8_t) ((message_bits & masks[length]) |
00210                      markbit[length]));
00211 
00212    return context->Corrupted;
00213 }
00214 
00215 /*
00216  * \brief SHA1Result Returns the resulting 160-bit digest
00217  * \param context [in/out] The SHA context to update.
00218  * \param Message_Digest [out] Where the digest is returned.
00219  *
00220  *   This function will return the 160-bit message digest
00221  *   into the Message_Digest array provided by the caller.
00222  * \note The first octet of hash is stored in the element with index 0,
00223  *       the last octet of hash in the element with index 19.
00224  * \returns sha Error Code.
00225  */
00226 int SHA1Result(SHA1Context * context, uint8_t Message_Digest[SHA1HashSize])
00227 {
00228    int i;
00229 
00230    if (!context) {
00231       return shaNull;
00232    }
00233    if (!Message_Digest) {
00234       return shaNull;
00235    }
00236    if (context->Corrupted) {
00237       return context->Corrupted;
00238    }
00239 
00240    if (!context->Computed) {
00241       SHA1Finalize(context, 0x80);
00242    }
00243 
00244    for (i = 0; i < SHA1HashSize; ++i) {
00245       Message_Digest[i] = (uint8_t) (context->Intermediate_Hash[i >> 2]
00246             >> (8 * (3 - (i & 0x03))));
00247    }
00248 
00249    return shaSuccess;
00250 }
00251 
00252 /*!
00253  * \brief Process the next 512 bits of the message stored in the Message_Block array.
00254  * \param context [in/out] The SHA context to update
00255  * \note  Many of the variable names in this code, especially the
00256  *   single character names, were used because those were the
00257  *   names used in the publication.
00258  * \returns nothing.
00259  */
00260 static void SHA1ProcessMessageBlock(SHA1Context *context)
00261 {
00262    /* Constants defined in FIPS 180-3, section 4.2.1 */
00263    const uint32_t K[4] = {
00264       0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6
00265    };
00266    int t;                  /* Loop counter */
00267    uint32_t temp;          /* Temporary word value */
00268    uint32_t W[80];            /* Word sequence */
00269    uint32_t A, B, C, D, E;    /* Word buffers */
00270 
00271    /*
00272     * Initialize the first 16 words in the array W
00273     */
00274    for (t = 0; t < 16; t++) {
00275       W[t] = ((uint32_t) context->Message_Block[t * 4]) << 24;
00276       W[t] |= ((uint32_t) context->Message_Block[t * 4 + 1]) << 16;
00277       W[t] |= ((uint32_t) context->Message_Block[t * 4 + 2]) << 8;
00278       W[t] |= ((uint32_t) context->Message_Block[t * 4 + 3]);
00279    }
00280 
00281    for (t = 16; t < 80; t++) {
00282       W[t] = SHA1_ROTL(1, W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]);
00283    }
00284 
00285    A = context->Intermediate_Hash[0];
00286    B = context->Intermediate_Hash[1];
00287    C = context->Intermediate_Hash[2];
00288    D = context->Intermediate_Hash[3];
00289    E = context->Intermediate_Hash[4];
00290 
00291    for (t = 0; t < 20; t++) {
00292       temp = SHA1_ROTL(5, A) + SHA_Ch(B, C, D) + E + W[t] + K[0];
00293       E = D;
00294       D = C;
00295       C = SHA1_ROTL(30, B);
00296       B = A;
00297       A = temp;
00298    }
00299 
00300    for (t = 20; t < 40; t++) {
00301       temp = SHA1_ROTL(5, A) + SHA_Parity(B, C, D) + E + W[t] + K[1];
00302       E = D;
00303       D = C;
00304       C = SHA1_ROTL(30, B);
00305       B = A;
00306       A = temp;
00307    }
00308 
00309    for (t = 40; t < 60; t++) {
00310       temp = SHA1_ROTL(5, A) + SHA_Maj(B, C, D) + E + W[t] + K[2];
00311       E = D;
00312       D = C;
00313       C = SHA1_ROTL(30, B);
00314       B = A;
00315       A = temp;
00316    }
00317 
00318    for (t = 60; t < 80; t++) {
00319       temp = SHA1_ROTL(5, A) + SHA_Parity(B, C, D) + E + W[t] + K[3];
00320       E = D;
00321       D = C;
00322       C = SHA1_ROTL(30, B);
00323       B = A;
00324       A = temp;
00325    }
00326 
00327    context->Intermediate_Hash[0] += A;
00328    context->Intermediate_Hash[1] += B;
00329    context->Intermediate_Hash[2] += C;
00330    context->Intermediate_Hash[3] += D;
00331    context->Intermediate_Hash[4] += E;
00332 
00333    context->Message_Block_Index = 0;
00334 }
00335 
00336 /*!
00337  * \brief This helper function finishes off the digest calculations.
00338  * \param context [in/out]  The context to pad.
00339  * \param Pad_byte [in]  The last byte to add to the message block
00340  *     before the 0-padding and length.  This will contain the last
00341  *     bits of the message followed by another single bit.  If the
00342  *     message was an exact multiple of 8-bits long, Pad_Byte will
00343  *     be 0x80.
00344  * \returns sha Error Code.
00345  */
00346 static void SHA1Finalize(SHA1Context * context, uint8_t Pad_Byte)
00347 {
00348    int i;
00349    SHA1PadMessage(context, Pad_Byte);
00350    /* message may be sensitive, clear it out */
00351    for (i = 0; i < SHA1_Message_Block_Size; ++i) {
00352       context->Message_Block[i] = 0;
00353    }
00354    context->Length_High = 0;  /* and clear length */
00355    context->Length_Low = 0;
00356    context->Computed = 1;
00357 }
00358 
00359 /*!
00360  * \brief Pad message to be 512 bits.
00361  * \param context [in/out]  The context to pad.
00362  * \param Pad_byte [in]  Last padding byte.
00363  *
00364  *  According to the standard, the message must be padded to the next
00365  *  even multiple of 512 bits.  The first padding bit must be a '1'.
00366  *  The last 64 bits represent the length of the original message.
00367  *  All bits in between should be 0.  This helper function will pad
00368  *  the message according to those rules by filling the Message_Block
00369  *  array accordingly.  When it returns, it can be assumed that the
00370  *  message digest has been computed.
00371  *
00372  * \returns nothing.
00373  */
00374 static void SHA1PadMessage(SHA1Context * context, uint8_t Pad_Byte)
00375 {
00376    /*
00377     *  Check to see if the current message block is too small to hold
00378     *  the initial padding bits and length.  If so, we will pad the
00379     *  block, process it, and then continue padding into a second
00380     *  block.
00381     */
00382    if (context->Message_Block_Index >= (SHA1_Message_Block_Size - 8)) {
00383       context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
00384       while (context->Message_Block_Index < SHA1_Message_Block_Size) {
00385          context->Message_Block[context->Message_Block_Index++] = 0;
00386       }
00387 
00388       SHA1ProcessMessageBlock(context);
00389    } else
00390       context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
00391 
00392    while (context->Message_Block_Index < (SHA1_Message_Block_Size - 8)) {
00393       context->Message_Block[context->Message_Block_Index++] = 0;
00394    }
00395 
00396    /*
00397     *  Store the message length as the last 8 octets
00398     */
00399    context->Message_Block[56] = (uint8_t) (context->Length_High >> 24);
00400    context->Message_Block[57] = (uint8_t) (context->Length_High >> 16);
00401    context->Message_Block[58] = (uint8_t) (context->Length_High >> 8);
00402    context->Message_Block[59] = (uint8_t) (context->Length_High);
00403    context->Message_Block[60] = (uint8_t) (context->Length_Low >> 24);
00404    context->Message_Block[61] = (uint8_t) (context->Length_Low >> 16);
00405    context->Message_Block[62] = (uint8_t) (context->Length_Low >> 8);
00406    context->Message_Block[63] = (uint8_t) (context->Length_Low);
00407 
00408    SHA1ProcessMessageBlock(context);
00409 }

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