sha1.c

00001 // Copyright (c) Microsoft. All rights reserved.
00002 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
00003 
00004 /**************************** sha1.c ****************************/
00005 /******************** See RFC 4634 for details ******************/
00006 /*
00007 *  Description:
00008 *      This file implements the Secure Hash Signature Standard
00009 *      algorithms as defined in the National Institute of Standards
00010 *      and Technology Federal Information Processing Standards
00011 *      Publication (FIPS PUB) 180-1 published on April 17, 1995, 180-2
00012 *      published on August 1, 2002, and the FIPS PUB 180-2 Change
00013 *      Notice published on February 28, 2004.
00014 *
00015 *      A combined document showing all algorithms is available at
00016 *              http://csrc.nist.gov/publications/fips/
00017 *              fips180-2/fips180-2withchangenotice.pdf
00018 *
00019 *      The SHA-1 algorithm produces a 160-bit message digest for a
00020 *      given data stream.  It should take about 2**n steps to find a
00021 *      message with the same digest as a given message and
00022 *      2**(n/2) to find any two messages with the same digest,
00023 *      when n is the digest size in bits.  Therefore, this
00024 *      algorithm can serve as a means of providing a
00025 *      "fingerprint" for a message.
00026 *
00027 *  Portability Issues:
00028 *      SHA-1 is defined in terms of 32-bit "words".  This code
00029 *      uses <stdint.h> (included via "sha.h") to define 32 and 8
00030 *      bit unsigned integer types.  If your C compiler does not
00031 *      support 32 bit unsigned integers, this code is not
00032 *      appropriate.
00033 *
00034 *  Caveats:
00035 *      SHA-1 is designed to work with messages less than 2^64 bits
00036 *      long. This implementation uses SHA1Input() to hash the bits
00037 *      that are a multiple of the size of an 8-bit character, and then
00038 *      uses SHA1FinalBits() to hash the final few bits of the input.
00039 */
00040 
00041 #include <stdlib.h>
00042 #ifdef _CRTDBG_MAP_ALLOC
00043 #include <crtdbg.h>
00044 #endif
00045 #include "azure_c_shared_utility/gballoc.h"
00046 
00047 #include "azure_c_shared_utility/sha.h"
00048 #include "azure_c_shared_utility/sha-private.h"
00049 
00050 /*
00051 *  Define the SHA1 circular left shift macro
00052 */
00053 #define SHA1_ROTL(bits,word) \
00054                 (((word) << (bits)) | ((word) >> (32-(bits))))
00055 
00056 /*
00057 * add "length" to the length
00058 */
00059 #define SHA1AddLength(context, length)                     \
00060     (addTemp = (context)->Length_Low,                      \
00061      (context)->Corrupted =                                \
00062         (((context)->Length_Low += (length)) < addTemp) && \
00063         (++(context)->Length_High == 0) ? 1 : 0)
00064 
00065 /* Local Function Prototypes */
00066 static void SHA1Finalize(SHA1Context *context, uint8_t Pad_Byte);
00067 static void SHA1PadMessage(SHA1Context *, uint8_t Pad_Byte);
00068 static void SHA1ProcessMessageBlock(SHA1Context *);
00069 
00070 /*
00071 *  SHA1Reset
00072 *
00073 *  Description:
00074 *      This function will initialize the SHA1Context in preparation
00075 *      for computing a new SHA1 message digest.
00076 *
00077 *  Parameters:
00078 *      context: [in/out]
00079 *          The context to reset.
00080 *
00081 *  Returns:
00082 *      sha Error Code.
00083 *
00084 */
00085 int SHA1Reset(SHA1Context *context)
00086 {
00087     if (!context)
00088         return shaNull;
00089 
00090     context->Length_Low = 0;
00091     context->Length_High = 0;
00092     context->Message_Block_Index = 0;
00093 
00094 
00095     /* Initial Hash Values: FIPS-180-2 section 5.3.1 */
00096     context->Intermediate_Hash[0] = 0x67452301;
00097     context->Intermediate_Hash[1] = 0xEFCDAB89;
00098     context->Intermediate_Hash[2] = 0x98BADCFE;
00099     context->Intermediate_Hash[3] = 0x10325476;
00100     context->Intermediate_Hash[4] = 0xC3D2E1F0;
00101 
00102     context->Computed = 0;
00103     context->Corrupted = 0;
00104 
00105     return shaSuccess;
00106 }
00107 
00108 /*
00109 *  SHA1Input
00110 *
00111 *  Description:
00112 *      This function accepts an array of octets as the next portion
00113 *      of the message.
00114 *
00115 *  Parameters:
00116 *      context: [in/out]
00117 *          The SHA context to update
00118 *      message_array: [in]
00119 *          An array of characters representing the next portion of
00120 *          the message.
00121 *      length: [in]
00122 *          The length of the message in message_array
00123 *
00124 *  Returns:
00125 *      sha Error Code.
00126 *
00127 */
00128 int SHA1Input(SHA1Context *context,
00129     const uint8_t *message_array, unsigned length)
00130 {
00131     uint32_t addTemp;
00132     if (!length)
00133         return shaSuccess;
00134 
00135     if (!context || !message_array)
00136         return shaNull;
00137 
00138     if (context->Computed) {
00139         context->Corrupted = shaStateError;
00140         return shaStateError;
00141     }
00142 
00143     if (context->Corrupted)
00144         return context->Corrupted;
00145 
00146     while (length-- && !context->Corrupted) {
00147         context->Message_Block[context->Message_Block_Index++] =
00148             (*message_array & 0xFF);
00149 
00150         if (!SHA1AddLength(context, 8) &&
00151             (context->Message_Block_Index == SHA1_Message_Block_Size))
00152             SHA1ProcessMessageBlock(context);
00153 
00154         message_array++;
00155     }
00156 
00157     return shaSuccess;
00158 }
00159 
00160 /*
00161 * SHA1FinalBits
00162 *
00163 * Description:
00164 *   This function will add in any final bits of the message.
00165 *
00166 * Parameters:
00167 *   context: [in/out]
00168 *     The SHA context to update
00169 *   message_bits: [in]
00170 *     The final bits of the message, in the upper portion of the
00171 *     byte. (Use 0b###00000 instead of 0b00000### to input the
00172 *     three bits ###.)
00173 *   length: [in]
00174 *     The number of bits in message_bits, between 1 and 7.
00175 *
00176 * Returns:
00177 *   sha Error Code.
00178 */
00179 int SHA1FinalBits(SHA1Context *context, const uint8_t message_bits,
00180     unsigned int length)
00181 {
00182     uint32_t addTemp;
00183 
00184     uint8_t masks[8] = {
00185         /* 0 0b00000000 */ 0x00, /* 1 0b10000000 */ 0x80,
00186         /* 2 0b11000000 */ 0xC0, /* 3 0b11100000 */ 0xE0,
00187         /* 4 0b11110000 */ 0xF0, /* 5 0b11111000 */ 0xF8,
00188         /* 6 0b11111100 */ 0xFC, /* 7 0b11111110 */ 0xFE
00189     };
00190     uint8_t markbit[8] = {
00191         /* 0 0b10000000 */ 0x80, /* 1 0b01000000 */ 0x40,
00192         /* 2 0b00100000 */ 0x20, /* 3 0b00010000 */ 0x10,
00193         /* 4 0b00001000 */ 0x08, /* 5 0b00000100 */ 0x04,
00194         /* 6 0b00000010 */ 0x02, /* 7 0b00000001 */ 0x01
00195     };
00196 
00197     if (!length)
00198         return shaSuccess;
00199 
00200     if (!context)
00201         return shaNull;
00202 
00203     if (context->Computed || (length >= 8) || (length == 0)) {
00204         context->Corrupted = shaStateError;
00205         return shaStateError;
00206     }
00207 
00208     if (context->Corrupted)
00209         return context->Corrupted;
00210 
00211     SHA1AddLength(context, length);
00212     SHA1Finalize(context,
00213         (uint8_t)((message_bits & masks[length]) | markbit[length]));
00214 
00215     return shaSuccess;
00216 }
00217 
00218 /*
00219 * SHA1Result
00220 *
00221 * Description:
00222 *   This function will return the 160-bit message digest into the
00223 *   Message_Digest array provided by the caller.
00224 *   NOTE: The first octet of hash is stored in the 0th element,
00225 *      the last octet of hash in the 19th element.
00226 *
00227 * Parameters:
00228 *   context: [in/out]
00229 *     The context to use to calculate the SHA-1 hash.
00230 *   Message_Digest: [out]
00231 *     Where the digest is returned.
00232 *
00233 * Returns:
00234 *   sha Error Code.
00235 *
00236 */
00237 int SHA1Result(SHA1Context *context,
00238     uint8_t Message_Digest[SHA1HashSize])
00239 {
00240     int i;
00241 
00242     if (!context || !Message_Digest)
00243         return shaNull;
00244 
00245     if (context->Corrupted)
00246         return context->Corrupted;
00247 
00248     if (!context->Computed)
00249         SHA1Finalize(context, 0x80);
00250 
00251     for (i = 0; i < SHA1HashSize; ++i)
00252         Message_Digest[i] = (uint8_t)(context->Intermediate_Hash[i >> 2]
00253         >> 8 * (3 - (i & 0x03)));
00254 
00255     return shaSuccess;
00256 }
00257 
00258 /*
00259 * SHA1Finalize
00260 *
00261 * Description:
00262 *   This helper function finishes off the digest calculations.
00263 *
00264 * Parameters:
00265 *   context: [in/out]
00266 *     The SHA context to update
00267 *   Pad_Byte: [in]
00268 *     The last byte to add to the digest before the 0-padding
00269 *     and length. This will contain the last bits of the message
00270 *     followed by another single bit. If the message was an
00271 *     exact multiple of 8-bits long, Pad_Byte will be 0x80.
00272 *
00273 * Returns:
00274 *   sha Error Code.
00275 *
00276 */
00277 static void SHA1Finalize(SHA1Context *context, uint8_t Pad_Byte)
00278 {
00279     int i;
00280     SHA1PadMessage(context, Pad_Byte);
00281     /* message may be sensitive, clear it out */
00282     for (i = 0; i < SHA1_Message_Block_Size; ++i)
00283         context->Message_Block[i] = 0;
00284     context->Length_Low = 0;  /* and clear length */
00285     context->Length_High = 0;
00286     context->Computed = 1;
00287 }
00288 
00289 /*
00290 * SHA1PadMessage
00291 *
00292 * Description:
00293 *   According to the standard, the message must be padded to an
00294 *   even 512 bits. The first padding bit must be a '1'. The last
00295 *   64 bits represent the length of the original message. All bits
00296 *   in between should be 0. This helper function will pad the
00297 *   message according to those rules by filling the Message_Block
00298 *   array accordingly. When it returns, it can be assumed that the
00299 *   message digest has been computed.
00300 *
00301 * Parameters:
00302 *   context: [in/out]
00303 *     The context to pad
00304 *   Pad_Byte: [in]
00305 *     The last byte to add to the digest before the 0-padding
00306 *     and length. This will contain the last bits of the message
00307 *     followed by another single bit. If the message was an
00308 *     exact multiple of 8-bits long, Pad_Byte will be 0x80.
00309 *
00310 * Returns:
00311 *   Nothing.
00312 */
00313 static void SHA1PadMessage(SHA1Context *context, uint8_t Pad_Byte)
00314 {
00315     /*
00316     * Check to see if the current message block is too small to hold
00317     * the initial padding bits and length. If so, we will pad the
00318     * block, process it, and then continue padding into a second
00319     * block.
00320     */
00321     if (context->Message_Block_Index >= (SHA1_Message_Block_Size - 8)) {
00322         context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
00323         while (context->Message_Block_Index < SHA1_Message_Block_Size)
00324             context->Message_Block[context->Message_Block_Index++] = 0;
00325 
00326         SHA1ProcessMessageBlock(context);
00327     }
00328     else
00329         context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
00330 
00331     while (context->Message_Block_Index < (SHA1_Message_Block_Size - 8))
00332         context->Message_Block[context->Message_Block_Index++] = 0;
00333 
00334     /*
00335     * Store the message length as the last 8 octets
00336     */
00337     context->Message_Block[56] = (uint8_t)(context->Length_High >> 24);
00338     context->Message_Block[57] = (uint8_t)(context->Length_High >> 16);
00339 
00340     context->Message_Block[58] = (uint8_t)(context->Length_High >> 8);
00341     context->Message_Block[59] = (uint8_t)(context->Length_High);
00342     context->Message_Block[60] = (uint8_t)(context->Length_Low >> 24);
00343     context->Message_Block[61] = (uint8_t)(context->Length_Low >> 16);
00344     context->Message_Block[62] = (uint8_t)(context->Length_Low >> 8);
00345     context->Message_Block[63] = (uint8_t)(context->Length_Low);
00346 
00347     SHA1ProcessMessageBlock(context);
00348 }
00349 
00350 /*
00351 * SHA1ProcessMessageBlock
00352 *
00353 * Description:
00354 *   This helper function will process the next 512 bits of the
00355 *   message stored in the Message_Block array.
00356 *
00357 * Parameters:
00358 *   None.
00359 *
00360 * Returns:
00361 *   Nothing.
00362 *
00363 * Comments:
00364 *   Many of the variable names in this code, especially the
00365 *   single character names, were used because those were the
00366 *   names used in the publication.
00367 */
00368 static void SHA1ProcessMessageBlock(SHA1Context *context)
00369 {
00370     /* Constants defined in FIPS-180-2, section 4.2.1 */
00371     const uint32_t K[4] = {
00372         0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6
00373     };
00374     int        t;               /* Loop counter */
00375     uint32_t   temp;            /* Temporary word value */
00376     uint32_t   W[80];           /* Word sequence */
00377     uint32_t   A, B, C, D, E;   /* Word buffers */
00378 
00379     /*
00380     * Initialize the first 16 words in the array W
00381     */
00382     for (t = 0; t < 16; t++) {
00383         W[t] = ((uint32_t)context->Message_Block[t * 4]) << 24;
00384         W[t] |= ((uint32_t)context->Message_Block[t * 4 + 1]) << 16;
00385         W[t] |= ((uint32_t)context->Message_Block[t * 4 + 2]) << 8;
00386         W[t] |= ((uint32_t)context->Message_Block[t * 4 + 3]);
00387     }
00388 
00389     for (t = 16; t < 80; t++)
00390         W[t] = SHA1_ROTL(1, W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]);
00391 
00392     A = context->Intermediate_Hash[0];
00393     B = context->Intermediate_Hash[1];
00394     C = context->Intermediate_Hash[2];
00395     D = context->Intermediate_Hash[3];
00396     E = context->Intermediate_Hash[4];
00397 
00398     for (t = 0; t < 20; t++) {
00399         temp = SHA1_ROTL(5, A) + SHA_Ch(B, C, D) + E + W[t] + K[0];
00400         E = D;
00401         D = C;
00402         C = SHA1_ROTL(30, B);
00403         B = A;
00404         A = temp;
00405     }
00406 
00407     for (t = 20; t < 40; t++) {
00408         temp = SHA1_ROTL(5, A) + SHA_Parity(B, C, D) + E + W[t] + K[1];
00409         E = D;
00410         D = C;
00411         C = SHA1_ROTL(30, B);
00412         B = A;
00413         A = temp;
00414     }
00415 
00416     for (t = 40; t < 60; t++) {
00417         temp = SHA1_ROTL(5, A) + SHA_Maj(B, C, D) + E + W[t] + K[2];
00418         E = D;
00419         D = C;
00420         C = SHA1_ROTL(30, B);
00421         B = A;
00422         A = temp;
00423     }
00424 
00425     for (t = 60; t < 80; t++) {
00426         temp = SHA1_ROTL(5, A) + SHA_Parity(B, C, D) + E + W[t] + K[3];
00427         E = D;
00428         D = C;
00429         C = SHA1_ROTL(30, B);
00430         B = A;
00431         A = temp;
00432     }
00433 
00434     context->Intermediate_Hash[0] += A;
00435     context->Intermediate_Hash[1] += B;
00436     context->Intermediate_Hash[2] += C;
00437 
00438     context->Intermediate_Hash[3] += D;
00439     context->Intermediate_Hash[4] += E;
00440 
00441     context->Message_Block_Index = 0;
00442 }
00443