www.pudn.com > sha1.zip > sha1.cpp
/*
* sha1.cpp
*
* Copyright (C) 1998
* Paul E. Jones
* All Rights Reserved.
*
*****************************************************************************
* $Id: sha1.cpp,v 1.9 2004/03/27 18:02:20 paulej Exp $
*****************************************************************************
*
* Description:
* This class implements the Secure Hashing Standard as defined
* in FIPS PUB 180-1 published April 17, 1995.
*
* The Secure Hashing Standard, which uses the Secure Hashing
* Algorithm (SHA), produces a 160-bit message digest for a
* given data stream. In theory, it is highly improbable that
* two messages will produce the same message digest. Therefore,
* this algorithm 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 was
* written with the expectation that the processor has at least
* a 32-bit machine word size. If the machine word size is larger,
* the code should still function properly. One caveat to that
* is that the input functions taking characters and character arrays
* assume that only 8 bits of information are stored in each character.
*
* Caveats:
* SHA-1 is designed to work with messages less than 2^64 bits long.
* Although SHA-1 allows a message digest to be generated for
* messages of any number of bits less than 2^64, this implementation
* only works with messages with a length that is a multiple of 8
* bits.
*
*/
#include "sha1.h"
/*
* SHA1
*
* Description:
* This is the constructor for the sha1 class.
*
* Parameters:
* None.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
SHA1::SHA1()
{
Reset();
}
/*
* ~SHA1
*
* Description:
* This is the destructor for the sha1 class
*
* Parameters:
* None.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
SHA1::~SHA1()
{
// The destructor does nothing
}
/*
* Reset
*
* Description:
* This function will initialize the sha1 class member variables
* in preparation for computing a new message digest.
*
* Parameters:
* None.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
void SHA1::Reset()
{
Length_Low = 0;
Length_High = 0;
Message_Block_Index = 0;
H[0] = 0x67452301;
H[1] = 0xEFCDAB89;
H[2] = 0x98BADCFE;
H[3] = 0x10325476;
H[4] = 0xC3D2E1F0;
Computed = false;
Corrupted = false;
}
/*
* Result
*
* Description:
* This function will return the 160-bit message digest into the
* array provided.
*
* Parameters:
* message_digest_array: [out]
* This is an array of five unsigned integers which will be filled
* with the message digest that has been computed.
*
* Returns:
* True if successful, false if it failed.
*
* Comments:
*
*/
bool SHA1::Result(unsigned *message_digest_array)
{
int i; // Counter
if (Corrupted)
{
return false;
}
if (!Computed)
{
PadMessage();
Computed = true;
}
for(i = 0; i < 5; i++)
{
message_digest_array[i] = H[i];
}
return true;
}
/*
* Input
*
* Description:
* This function accepts an array of octets as the next portion of
* the message.
*
* Parameters:
* message_array: [in]
* An array of characters representing the next portion of the
* message.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
void SHA1::Input( const unsigned char *message_array,
unsigned length)
{
if (!length)
{
return;
}
if (Computed || Corrupted)
{
Corrupted = true;
return;
}
while(length-- && !Corrupted)
{
Message_Block[Message_Block_Index++] = (*message_array & 0xFF);
Length_Low += 8;
Length_Low &= 0xFFFFFFFF; // Force it to 32 bits
if (Length_Low == 0)
{
Length_High++;
Length_High &= 0xFFFFFFFF; // Force it to 32 bits
if (Length_High == 0)
{
Corrupted = true; // Message is too long
}
}
if (Message_Block_Index == 64)
{
ProcessMessageBlock();
}
message_array++;
}
}
/*
* Input
*
* Description:
* This function accepts an array of octets as the next portion of
* the message.
*
* Parameters:
* message_array: [in]
* An array of characters representing the next portion of the
* message.
* length: [in]
* The length of the message_array
*
* Returns:
* Nothing.
*
* Comments:
*
*/
void SHA1::Input( const char *message_array,
unsigned length)
{
Input((unsigned char *) message_array, length);
}
/*
* Input
*
* Description:
* This function accepts a single octets as the next message element.
*
* Parameters:
* message_element: [in]
* The next octet in the message.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
void SHA1::Input(unsigned char message_element)
{
Input(&message_element, 1);
}
/*
* Input
*
* Description:
* This function accepts a single octet as the next message element.
*
* Parameters:
* message_element: [in]
* The next octet in the message.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
void SHA1::Input(char message_element)
{
Input((unsigned char *) &message_element, 1);
}
/*
* operator<<
*
* Description:
* This operator makes it convenient to provide character strings to
* the SHA1 object for processing.
*
* Parameters:
* message_array: [in]
* The character array to take as input.
*
* Returns:
* A reference to the SHA1 object.
*
* Comments:
* Each character is assumed to hold 8 bits of information.
*
*/
SHA1& SHA1::operator<<(const char *message_array)
{
const char *p = message_array;
while(*p)
{
Input(*p);
p++;
}
return *this;
}
/*
* operator<<
*
* Description:
* This operator makes it convenient to provide character strings to
* the SHA1 object for processing.
*
* Parameters:
* message_array: [in]
* The character array to take as input.
*
* Returns:
* A reference to the SHA1 object.
*
* Comments:
* Each character is assumed to hold 8 bits of information.
*
*/
SHA1& SHA1::operator<<(const unsigned char *message_array)
{
const unsigned char *p = message_array;
while(*p)
{
Input(*p);
p++;
}
return *this;
}
/*
* operator<<
*
* Description:
* This function provides the next octet in the message.
*
* Parameters:
* message_element: [in]
* The next octet in the message
*
* Returns:
* A reference to the SHA1 object.
*
* Comments:
* The character is assumed to hold 8 bits of information.
*
*/
SHA1& SHA1::operator<<(const char message_element)
{
Input((unsigned char *) &message_element, 1);
return *this;
}
/*
* operator<<
*
* Description:
* This function provides the next octet in the message.
*
* Parameters:
* message_element: [in]
* The next octet in the message
*
* Returns:
* A reference to the SHA1 object.
*
* Comments:
* The character is assumed to hold 8 bits of information.
*
*/
SHA1& SHA1::operator<<(const unsigned char message_element)
{
Input(&message_element, 1);
return *this;
}
/*
* ProcessMessageBlock
*
* Description:
* This function will process the next 512 bits of the message
* stored in the Message_Block array.
*
* Parameters:
* None.
*
* Returns:
* Nothing.
*
* Comments:
* Many of the variable names in this function, especially the single
* character names, were used because those were the names used
* in the publication.
*
*/
void SHA1::ProcessMessageBlock()
{
const unsigned K[] = { // Constants defined for SHA-1
0x5A827999,
0x6ED9EBA1,
0x8F1BBCDC,
0xCA62C1D6
};
int t; // Loop counter
unsigned temp; // Temporary word value
unsigned W[80]; // Word sequence
unsigned A, B, C, D, E; // Word buffers
/*
* Initialize the first 16 words in the array W
*/
for(t = 0; t < 16; t++)
{
W[t] = ((unsigned) Message_Block[t * 4]) << 24;
W[t] |= ((unsigned) Message_Block[t * 4 + 1]) << 16;
W[t] |= ((unsigned) Message_Block[t * 4 + 2]) << 8;
W[t] |= ((unsigned) Message_Block[t * 4 + 3]);
}
for(t = 16; t < 80; t++)
{
W[t] = CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
}
A = H[0];
B = H[1];
C = H[2];
D = H[3];
E = H[4];
for(t = 0; t < 20; t++)
{
temp = CircularShift(5,A) + ((B & C) | ((~B) & D)) + E + W[t] + K[0];
temp &= 0xFFFFFFFF;
E = D;
D = C;
C = CircularShift(30,B);
B = A;
A = temp;
}
for(t = 20; t < 40; t++)
{
temp = CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
temp &= 0xFFFFFFFF;
E = D;
D = C;
C = CircularShift(30,B);
B = A;
A = temp;
}
for(t = 40; t < 60; t++)
{
temp = CircularShift(5,A) +
((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
temp &= 0xFFFFFFFF;
E = D;
D = C;
C = CircularShift(30,B);
B = A;
A = temp;
}
for(t = 60; t < 80; t++)
{
temp = CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
temp &= 0xFFFFFFFF;
E = D;
D = C;
C = CircularShift(30,B);
B = A;
A = temp;
}
H[0] = (H[0] + A) & 0xFFFFFFFF;
H[1] = (H[1] + B) & 0xFFFFFFFF;
H[2] = (H[2] + C) & 0xFFFFFFFF;
H[3] = (H[3] + D) & 0xFFFFFFFF;
H[4] = (H[4] + E) & 0xFFFFFFFF;
Message_Block_Index = 0;
}
/*
* PadMessage
*
* Description:
* According to the standard, the message must be padded to an even
* 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 function will pad the message according to those
* rules by filling the message_block array accordingly. It will also
* call ProcessMessageBlock() appropriately. When it returns, it
* can be assumed that the message digest has been computed.
*
* Parameters:
* None.
*
* Returns:
* Nothing.
*
* Comments:
*
*/
void SHA1::PadMessage()
{
/*
* 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 (Message_Block_Index > 55)
{
Message_Block[Message_Block_Index++] = 0x80;
while(Message_Block_Index < 64)
{
Message_Block[Message_Block_Index++] = 0;
}
ProcessMessageBlock();
while(Message_Block_Index < 56)
{
Message_Block[Message_Block_Index++] = 0;
}
}
else
{
Message_Block[Message_Block_Index++] = 0x80;
while(Message_Block_Index < 56)
{
Message_Block[Message_Block_Index++] = 0;
}
}
/*
* Store the message length as the last 8 octets
*/
Message_Block[56] = (Length_High >> 24) & 0xFF;
Message_Block[57] = (Length_High >> 16) & 0xFF;
Message_Block[58] = (Length_High >> 8) & 0xFF;
Message_Block[59] = (Length_High) & 0xFF;
Message_Block[60] = (Length_Low >> 24) & 0xFF;
Message_Block[61] = (Length_Low >> 16) & 0xFF;
Message_Block[62] = (Length_Low >> 8) & 0xFF;
Message_Block[63] = (Length_Low) & 0xFF;
ProcessMessageBlock();
}
/*
* CircularShift
*
* Description:
* This member function will perform a circular shifting operation.
*
* Parameters:
* bits: [in]
* The number of bits to shift (1-31)
* word: [in]
* The value to shift (assumes a 32-bit integer)
*
* Returns:
* The shifted value.
*
* Comments:
*
*/
unsigned SHA1::CircularShift(int bits, unsigned word)
{
return ((word << bits) & 0xFFFFFFFF) | ((word & 0xFFFFFFFF) >> (32-bits));
}