/*

* sha1.c

*

* Copyright (C) 1998, 2009

* Paul E. Jones <paulej@packetizer.com>

* All Rights Reserved

*

*****************************************************************************

* $Id: sha1.c 12 2009-06-22 19:34:25Z paulej $

*****************************************************************************

*

* Description:

* This file 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 the size of an 8-bit character.

*

*/

#include "sha1.h"

/*

* Define the circular shift macro

*/

#define SHA1CircularShift(bits,word) \

((((word) << (bits)) & 0xFFFFFFFF) | \

((word) >> (32-(bits))))

/* Function prototypes */

void SHA1ProcessMessageBlock(SHA1Context *);

void SHA1PadMessage(SHA1Context *);

/*

* SHA1Reset

*

* Description:

* This function will initialize the SHA1Context in preparation

* for computing a new message digest.

*

* Parameters:

* context: [in/out]

* The context to reset.

*

* Returns:

* Nothing.

*

* Comments:

*

*/

void SHA1Reset(SHA1Context *context)

{

context->Length_Low = 0;

context->Length_High = 0;

context->Message_Block_Index = 0;

context->Message_Digest[0] = 0x67452301;

context->Message_Digest[1] = 0xEFCDAB89;

context->Message_Digest[2] = 0x98BADCFE;

context->Message_Digest[3] = 0x10325476;

context->Message_Digest[4] = 0xC3D2E1F0;

context->Computed = 0;

context->Corrupted = 0;

}

/*

* SHA1Result

*

* Description:

* This function will return the 160-bit message digest into the

* Message_Digest array within the SHA1Context provided

*

* Parameters:

* context: [in/out]

* The context to use to calculate the SHA-1 hash.

*

* Returns:

* 1 if successful, 0 if it failed.

*

* Comments:

*

*/

int SHA1Result(SHA1Context *context)

{

if (context->Corrupted)

{

return 0;

}

if (!context->Computed)

{

SHA1PadMessage(context);

context->Computed = 1;

}

return 1;

}

/*

* SHA1Input

*

* Description:

* This function accepts an array of octets as the next portion of

* the message.

*

* Parameters:

* context: [in/out]

* The SHA-1 context to update

* message_array: [in]

* An array of characters representing the next portion of the

* message.

* length: [in]

* The length of the message in message_array

*

* Returns:

* Nothing.

*

* Comments:

*

*/

void SHA1Input( SHA1Context *context,

const unsigned char *message_array,

unsigned length)

{

if (!length)

{

return;

}

if (context->Computed || context->Corrupted)

{

context->Corrupted = 1;

return;

}

while(length-- && !context->Corrupted)

{

context->Message_Block[context->Message_Block_Index++] =

(*message_array & 0xFF);

context->Length_Low += 8;

/* Force it to 32 bits */

context->Length_Low &= 0xFFFFFFFF;

if (context->Length_Low == 0)

{

context->Length_High++;

/* Force it to 32 bits */

context->Length_High &= 0xFFFFFFFF;

if (context->Length_High == 0)

{

/* Message is too long */

context->Corrupted = 1;

}

}

if (context->Message_Block_Index == 64)

{

SHA1ProcessMessageBlock(context);

}

message_array++;

}

}

/*

* SHA1ProcessMessageBlock

*

* 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 the SHAContext, especially the

* single character names, were used because those were the names

* used in the publication.

*

*

*/

void SHA1ProcessMessageBlock(SHA1Context *context)

{

const unsigned K[] = /* Constants defined in 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) context->Message_Block[t * 4]) << 24;

W[t] |= ((unsigned) context->Message_Block[t * 4 + 1]) << 16;

W[t] |= ((unsigned) context->Message_Block[t * 4 + 2]) << 8;

W[t] |= ((unsigned) context->Message_Block[t * 4 + 3]);

}

for(t = 16; t < 80; t++)

{

W[t] = SHA1CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);

}

A = context->Message_Digest[0];

B = context->Message_Digest[1];

C = context->Message_Digest[2];

D = context->Message_Digest[3];

E = context->Message_Digest[4];

for(t = 0; t < 20; t++)

{

temp = SHA1CircularShift(5,A) +

((B & C) | ((~B) & D)) + E + W[t] + K[0];

temp &= 0xFFFFFFFF;

E = D;

D = C;

C = SHA1CircularShift(30,B);

B = A;

A = temp;

}

for(t = 20; t < 40; t++)

{

temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];

temp &= 0xFFFFFFFF;

E = D;

D = C;

C = SHA1CircularShift(30,B);

B = A;

A = temp;

}

for(t = 40; t < 60; t++)

{

temp = SHA1CircularShift(5,A) +

((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];

temp &= 0xFFFFFFFF;

E = D;

D = C;

C = SHA1CircularShift(30,B);

B = A;

A = temp;

}

for(t = 60; t < 80; t++)

{

temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];

temp &= 0xFFFFFFFF;

E = D;

D = C;

C = SHA1CircularShift(30,B);

B = A;

A = temp;

}

context->Message_Digest[0] =

(context->Message_Digest[0] + A) & 0xFFFFFFFF;

context->Message_Digest[1] =

(context->Message_Digest[1] + B) & 0xFFFFFFFF;

context->Message_Digest[2] =

(context->Message_Digest[2] + C) & 0xFFFFFFFF;

context->Message_Digest[3] =

(context->Message_Digest[3] + D) & 0xFFFFFFFF;

context->Message_Digest[4] =

(context->Message_Digest[4] + E) & 0xFFFFFFFF;

context->Message_Block_Index = 0;

}

/*

* SHA1PadMessage

*

* 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 SHA1ProcessMessageBlock()

* appropriately. When it returns, it can be assumed that the

* message digest has been computed.

*

* Parameters:

* context: [in/out]

* The context to pad

*

* Returns:

* Nothing.

*

* Comments:

*

*/

void SHA1PadMessage(SHA1Context *context)

{

/*

* 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 > 55)

{

context->Message_Block[context->Message_Block_Index++] = 0x80;

while(context->Message_Block_Index < 64)

{

context->Message_Block[context->Message_Block_Index++] = 0;

}

SHA1ProcessMessageBlock(context);

while(context->Message_Block_Index < 56)

{

context->Message_Block[context->Message_Block_Index++] = 0;

}

}

else

{

context->Message_Block[context->Message_Block_Index++] = 0x80;

while(context->Message_Block_Index < 56)

{

context->Message_Block[context->Message_Block_Index++] = 0;

}

}

/*

* Store the message length as the last 8 octets

*/

context->Message_Block[56] = (context->Length_High >> 24) & 0xFF;

context->Message_Block[57] = (context->Length_High >> 16) & 0xFF;

context->Message_Block[58] = (context->Length_High >> 8) & 0xFF;

context->Message_Block[59] = (context->Length_High) & 0xFF;

context->Message_Block[60] = (context->Length_Low >> 24) & 0xFF;

context->Message_Block[61] = (context->Length_Low >> 16) & 0xFF;

context->Message_Block[62] = (context->Length_Low >> 8) & 0xFF;

context->Message_Block[63] = (context->Length_Low) & 0xFF;

SHA1ProcessMessageBlock(context);

}