sha1.c

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/*! \file
 *
 * \brief Based on the RFC 6234
 *
 * Copyright (c) 2011 IETF Trust and the persons identified as
 * authors of the code. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above
 * copyright notice, this list of conditions and
 * the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided
 * with the distribution.
 *
 * - Neither the name of Internet Society, IETF or IETF Trust, nor
 * the names of specific contributors, may be used to endorse or
 * promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Description:
 * This file implements the Secure Hash Algorithm SHA-1
 * as defined in the U.S. National Institute of Standards
 * and Technology Federal Information Processing Standards
 * Publication (FIPS PUB) 180-3 published in October 2008
 * and formerly defined in its predecessors, FIPS PUB 180-1
 * and FIP PUB 180-2.
 *
 * A combined document showing all algorithms is available at
 * http://csrc.nist.gov/publications/fips/
 * fips180-3/fips180-3_final.pdf
 *
 * The SHA-1 algorithm produces a 160-bit message digest for a
 * given data stream that can serve as a means of providing a
 * "fingerprint" for a message.
 *
 * Portability Issues:
 * SHA-1 is defined in terms of 32-bit "words". This code
 * uses <stdint.h> (included via "sha.h") to define 32- and
 * 8-bit unsigned integer types. If your C compiler does
 * not support 32-bit unsigned integers, this code is not
 * appropriate.
 *
 * Caveats:
 * SHA-1 is designed to work with messages less than 2^64 bits
 * long. This implementation uses SHA1Input() to hash the bits
 * that are a multiple of the size of an 8-bit octet, and then
 * optionally uses SHA1FinalBits() to hash the final few bits of
 * the input.
 */

#include <asterisk/sha1.h>

/*! Define the SHA1 circular left shift macro */
#define SHA1_ROTL(bits,word) \
 (((word) << (bits)) | ((word) >> (32-(bits))))

/*
 * Add "length" to the length.
 * Set Corrupted when overflow has occurred.
 */
static uint32_t addTemp;
#define SHA1AddLength(context, length) \
 (addTemp = (context)->Length_Low, \
 (context)->Corrupted = \
 (((context)->Length_Low += (length)) < addTemp) && \
 (++(context)->Length_High == 0) ? shaInputTooLong \
 : (context)->Corrupted )

/* Local Function Prototypes */
static void SHA1ProcessMessageBlock(SHA1Context * context);
static void SHA1Finalize(SHA1Context * context, uint8_t Pad_Byte);
static void SHA1PadMessage(SHA1Context * context, uint8_t Pad_Byte);

/*!
 * \brief SHA1Reset
 * \param context the context to be reset.
 * This function will initialize the SHA1Context in preparation
 * for computing a new SHA1 message digest.
 * \return sha Error Code.
 */
int SHA1Reset(SHA1Context *context)
{
 if (!context) {
 return shaNull;
 }

 context->Length_High = context->Length_Low = 0;
 context->Message_Block_Index = 0;

 /* Initial Hash Values: FIPS 180-3 section 5.3.1 */
 context->Intermediate_Hash[0] = 0x67452301;
 context->Intermediate_Hash[1] = 0xEFCDAB89;
 context->Intermediate_Hash[2] = 0x98BADCFE;
 context->Intermediate_Hash[3] = 0x10325476;
 context->Intermediate_Hash[4] = 0xC3D2E1F0;

 context->Computed = 0;
 context->Corrupted = shaSuccess;

 return shaSuccess;
}

/*!
 * \brief SHA1Input
 * \param context [in/out] The SHA context to update
 * \param message_array [in] An array of characters representing the next portion of
 * the message.
 * \param length [in] The length of the message in message_array.
 * This function accepts an array of octets as the next portion
 * of the message.
 * \return sha Error Code.
 */
int SHA1Input(SHA1Context *context,
 const uint8_t *message_array, unsigned length)
{
 if (!context) {
 return shaNull;
 }
 if (!length) {
 return shaSuccess;
 }
 if (!message_array) {
 return shaNull;
 }

 if (context->Computed) {
 context->Corrupted = shaStateError;
 return shaStateError;
 }

 if (context->Corrupted) {
 return context->Corrupted;
 }

 while (length--) {
 context->Message_Block[context->Message_Block_Index++] =
 *message_array;

 if ((SHA1AddLength(context, 8) == shaSuccess) &&
 (context->Message_Block_Index == SHA1_Message_Block_Size))
 SHA1ProcessMessageBlock(context);

 message_array++;
 }

 return context->Corrupted;
}

/*!
 * \brief SHA1FinalBits Add in any final bits of the message.
 *
 * \param context [in/out] The SHA context to update.
 * \param message_bits [in] The final bits of the message, in the upper portion of the
 * byte. (Use 0b###00000 instead of 0b00000### to input the
 * three bits ###.)
 * \param length [in] * The number of bits in message_bits, between 1 and 7.
 * \returns sha Error Code.
 */
int SHA1FinalBits(SHA1Context * context, uint8_t message_bits,
 unsigned int length)
{
 static uint8_t masks[8] = {
 /* 0 0b00000000 */ 0x00, /* 1 0b10000000 */ 0x80,
 /* 2 0b11000000 */ 0xC0, /* 3 0b11100000 */ 0xE0,
 /* 4 0b11110000 */ 0xF0, /* 5 0b11111000 */ 0xF8,
 /* 6 0b11111100 */ 0xFC, /* 7 0b11111110 */ 0xFE
 };

 static uint8_t markbit[8] = {
 /* 0 0b10000000 */ 0x80, /* 1 0b01000000 */ 0x40,
 /* 2 0b00100000 */ 0x20, /* 3 0b00010000 */ 0x10,
 /* 4 0b00001000 */ 0x08, /* 5 0b00000100 */ 0x04,
 /* 6 0b00000010 */ 0x02, /* 7 0b00000001 */ 0x01
 };

 if (!context)
 return shaNull;
 if (!length)
 return shaSuccess;
 if (context->Corrupted)
 return context->Corrupted;
 if (context->Computed)
 return context->Corrupted = shaStateError;
 if (length >= 8)
 return context->Corrupted = shaBadParam;

 SHA1AddLength(context, length);
 SHA1Finalize(context,
 (uint8_t) ((message_bits & masks[length]) |
 markbit[length]));

 return context->Corrupted;
}

/*
 * \brief SHA1Result Returns the resulting 160-bit digest
 * \param context [in/out] The SHA context to update.
 * \param Message_Digest [out] Where the digest is returned.
 *
 * This function will return the 160-bit message digest
 * into the Message_Digest array provided by the caller.
 * \note The first octet of hash is stored in the element with index 0,
 * the last octet of hash in the element with index 19.
 * \returns sha Error Code.
 */
int SHA1Result(SHA1Context * context, uint8_t Message_Digest[SHA1HashSize])
{
 int i;

 if (!context) {
 return shaNull;
 }
 if (!Message_Digest) {
 return shaNull;
 }
 if (context->Corrupted) {
 return context->Corrupted;
 }

 if (!context->Computed) {
 SHA1Finalize(context, 0x80);
 }

 for (i = 0; i < SHA1HashSize; ++i) {
 Message_Digest[i] = (uint8_t) (context->Intermediate_Hash[i >> 2]
 >> (8 * (3 - (i & 0x03))));
 }

 return shaSuccess;
}

/*!
 * \brief Process the next 512 bits of the message stored in the Message_Block array.
 * \param context [in/out] The SHA context to update
 * \note Many of the variable names in this code, especially the
 * single character names, were used because those were the
 * names used in the publication.
 * \returns nothing.
 */
static void SHA1ProcessMessageBlock(SHA1Context *context)
{
 /* Constants defined in FIPS 180-3, section 4.2.1 */
 const uint32_t K[4] = {
 0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6
 };
 int t; /* Loop counter */
 uint32_t temp; /* Temporary word value */
 uint32_t W[80]; /* Word sequence */
 uint32_t A, B, C, D, E; /* Word buffers */

 /*
 * Initialize the first 16 words in the array W
 */
 for (t = 0; t < 16; t++) {
 W[t] = ((uint32_t) context->Message_Block[t * 4]) << 24;
 W[t] |= ((uint32_t) context->Message_Block[t * 4 + 1]) << 16;
 W[t] |= ((uint32_t) context->Message_Block[t * 4 + 2]) << 8;
 W[t] |= ((uint32_t) context->Message_Block[t * 4 + 3]);
 }

 for (t = 16; t < 80; t++) {
 W[t] = SHA1_ROTL(1, W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]);
 }

 A = context->Intermediate_Hash[0];
 B = context->Intermediate_Hash[1];
 C = context->Intermediate_Hash[2];
 D = context->Intermediate_Hash[3];
 E = context->Intermediate_Hash[4];

 for (t = 0; t < 20; t++) {
 temp = SHA1_ROTL(5, A) + SHA_Ch(B, C, D) + E + W[t] + K[0];
 E = D;
 D = C;
 C = SHA1_ROTL(30, B);
 B = A;
 A = temp;
 }

 for (t = 20; t < 40; t++) {
 temp = SHA1_ROTL(5, A) + SHA_Parity(B, C, D) + E + W[t] + K[1];
 E = D;
 D = C;
 C = SHA1_ROTL(30, B);
 B = A;
 A = temp;
 }

 for (t = 40; t < 60; t++) {
 temp = SHA1_ROTL(5, A) + SHA_Maj(B, C, D) + E + W[t] + K[2];
 E = D;
 D = C;
 C = SHA1_ROTL(30, B);
 B = A;
 A = temp;
 }

 for (t = 60; t < 80; t++) {
 temp = SHA1_ROTL(5, A) + SHA_Parity(B, C, D) + E + W[t] + K[3];
 E = D;
 D = C;
 C = SHA1_ROTL(30, B);
 B = A;
 A = temp;
 }

 context->Intermediate_Hash[0] += A;
 context->Intermediate_Hash[1] += B;
 context->Intermediate_Hash[2] += C;
 context->Intermediate_Hash[3] += D;
 context->Intermediate_Hash[4] += E;

 context->Message_Block_Index = 0;
}

/*!
 * \brief This helper function finishes off the digest calculations.
 * \param context [in/out] The context to pad.
 * \param Pad_Byte [in] The last byte to add to the message block
 * before the 0-padding and length. This will contain the last
 * bits of the message followed by another single bit. If the
 * message was an exact multiple of 8-bits long, Pad_Byte will
 * be 0x80.
 * \returns sha Error Code.
 */
static void SHA1Finalize(SHA1Context * context, uint8_t Pad_Byte)
{
 int i;
 SHA1PadMessage(context, Pad_Byte);
 /* message may be sensitive, clear it out */
 for (i = 0; i < SHA1_Message_Block_Size; ++i) {
 context->Message_Block[i] = 0;
 }
 context->Length_High = 0; /* and clear length */
 context->Length_Low = 0;
 context->Computed = 1;
}

/*!
 * \brief Pad message to be 512 bits.
 * \param context [in/out] The context to pad.
 * \param Pad_Byte [in] Last padding byte.
 *
 * According to the standard, the message must be padded to the next
 * even multiple of 512 bits. The first padding bit must be a '1'.
 * The last 64 bits represent the length of the original message.
 * All bits in between should be 0. This helper function will pad
 * the message according to those rules by filling the Message_Block
 * array accordingly. When it returns, it can be assumed that the
 * message digest has been computed.
 *
 * \returns nothing.
 */
static void SHA1PadMessage(SHA1Context * context, uint8_t Pad_Byte)
{
 /*
 * Check to see if the current message block is too small to hold
 * the initial padding bits and length. If so, we will pad the
 * block, process it, and then continue padding into a second
 * block.
 */
 if (context->Message_Block_Index >= (SHA1_Message_Block_Size - 8)) {
 context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
 while (context->Message_Block_Index < SHA1_Message_Block_Size) {
 context->Message_Block[context->Message_Block_Index++] = 0;
 }

 SHA1ProcessMessageBlock(context);
 } else
 context->Message_Block[context->Message_Block_Index++] = Pad_Byte;

 while (context->Message_Block_Index < (SHA1_Message_Block_Size - 8)) {
 context->Message_Block[context->Message_Block_Index++] = 0;
 }

 /*
 * Store the message length as the last 8 octets
 */
 context->Message_Block[56] = (uint8_t) (context->Length_High >> 24);
 context->Message_Block[57] = (uint8_t) (context->Length_High >> 16);
 context->Message_Block[58] = (uint8_t) (context->Length_High >> 8);
 context->Message_Block[59] = (uint8_t) (context->Length_High);
 context->Message_Block[60] = (uint8_t) (context->Length_Low >> 24);
 context->Message_Block[61] = (uint8_t) (context->Length_Low >> 16);
 context->Message_Block[62] = (uint8_t) (context->Length_Low >> 8);
 context->Message_Block[63] = (uint8_t) (context->Length_Low);

 SHA1ProcessMessageBlock(context);
}