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