/*
 * Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * Copyright (C) 2019-2020 by Sukchan Lee <acetcom@gmail.com>
 *
 * This file is part of Open5GS.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 *  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 "ogs-crypt.h"

/*
 *  Define the circular shift macro
 */
#define SHA1CircularShift(bits,word) \
                ((((word) << (bits)) & 0xFFFFFFFF) | \
                ((word) >> (32-(bits))))

/* Function prototypes */
static void SHA1ProcessMessageBlock(ogs_sha1_ctx *);
static void SHA1PadMessage(ogs_sha1_ctx *);

/*  
 *  sha1_init
 *
 *  Description:
 *      This function will initialize the ogs_sha1_ctx in preparation
 *      for computing a new message digest.
 *
 *  Parameters:
 *      context: [in/out]
 *          The context to reset.
 *
 *  Returns:
 *      Nothing.
 *
 *  Comments:
 *
 */
void ogs_sha1_init(ogs_sha1_ctx *ctx)
{
    ctx->Length_Low             = 0;
    ctx->Length_High            = 0;
    ctx->Message_Block_Index    = 0;

    ctx->Message_Digest[0]      = 0x67452301;
    ctx->Message_Digest[1]      = 0xEFCDAB89;
    ctx->Message_Digest[2]      = 0x98BADCFE;
    ctx->Message_Digest[3]      = 0x10325476;
    ctx->Message_Digest[4]      = 0xC3D2E1F0;

    ctx->Computed   = 0;
    ctx->Corrupted  = 0;
}

/*  
 *  sha1_final
 *
 *  Description:
 *      This function will return the 160-bit message digest into the
 *      Message_Digest array within the ogs_sha1_ctx provided
 *
 *  Parameters:
 *      context: [in/out]
 *          The context to use to calculate the SHA-1 hash.
 *
 *  Returns:
 *      1 if successful, 0 if it failed.
 *
 *  Comments:
 *
 */
#if 0 /* modifed by anoveth */
void ogs_sha1_final(ogs_sha1_ctx *ctx)
#else
void ogs_sha1_final(ogs_sha1_ctx *ctx, uint8_t *digest)
#endif
{
#if 0 /* blocked by anoveth */
    if (ctx->Corrupted)
    {
        return 0;
    }
#endif

    if (!ctx->Computed)
    {
        SHA1PadMessage(ctx);
        ctx->Computed = 1;
    }

#if 0 /* modified by anoveth */
    return 1;
#else
    {
#if OGS_BYTE_ORDER == OGS_BIG_ENDIAN
        memcpy(digest, ctx->Message_Digest, OGS_SHA1_DIGEST_SIZE);
#else
#define ROTR(a) ((((unsigned)(a))>>8)|((a)<<24))
#define ROTL(a) (((a)<<8)|(((unsigned)(a))>>24))
#define SWAP32(a) (ROTL((a)&0xff00ff00)|ROTR((a)&0x00ff00ff))
        uint32_t n[5];
        n[0] = SWAP32(ctx->Message_Digest[0]);
        n[1] = SWAP32(ctx->Message_Digest[1]);
        n[2] = SWAP32(ctx->Message_Digest[2]);
        n[3] = SWAP32(ctx->Message_Digest[3]);
        n[4] = SWAP32(ctx->Message_Digest[4]);

        memcpy(digest, n, OGS_SHA1_DIGEST_SIZE);
    }
#endif
#endif
}

/*  
 *  sha1_update
 *
 *  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 ogs_sha1_update(ogs_sha1_ctx *ctx, const uint8_t *message_array,
        uint32_t length)
{
    if (!length)
    {
        return;
    }

    if (ctx->Computed || ctx->Corrupted)
    {
        ctx->Corrupted = 1;
        return;
    }

    while(length-- && !ctx->Corrupted)
    {
        ctx->Message_Block[ctx->Message_Block_Index++] =
                                                (*message_array & 0xFF);

        ctx->Length_Low += 8;
        /* Force it to 32 bits */
        ctx->Length_Low &= 0xFFFFFFFF;
        if (ctx->Length_Low == 0)
        {
            ctx->Length_High++;
            /* Force it to 32 bits */
            ctx->Length_High &= 0xFFFFFFFF;
            if (ctx->Length_High == 0)
            {
                /* Message is too long */
                ctx->Corrupted = 1;
            }
        }

        if (ctx->Message_Block_Index == 64)
        {
            SHA1ProcessMessageBlock(ctx);
        }

        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.
 *         
 *
 */
static void SHA1ProcessMessageBlock(ogs_sha1_ctx *ctx)
{
    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) ctx->Message_Block[t * 4]) << 24;
        W[t] |= ((unsigned) ctx->Message_Block[t * 4 + 1]) << 16;
        W[t] |= ((unsigned) ctx->Message_Block[t * 4 + 2]) << 8;
        W[t] |= ((unsigned) ctx->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 = ctx->Message_Digest[0];
    B = ctx->Message_Digest[1];
    C = ctx->Message_Digest[2];
    D = ctx->Message_Digest[3];
    E = ctx->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;
    }

    ctx->Message_Digest[0] =
                        (ctx->Message_Digest[0] + A) & 0xFFFFFFFF;
    ctx->Message_Digest[1] =
                        (ctx->Message_Digest[1] + B) & 0xFFFFFFFF;
    ctx->Message_Digest[2] =
                        (ctx->Message_Digest[2] + C) & 0xFFFFFFFF;
    ctx->Message_Digest[3] =
                        (ctx->Message_Digest[3] + D) & 0xFFFFFFFF;
    ctx->Message_Digest[4] =
                        (ctx->Message_Digest[4] + E) & 0xFFFFFFFF;

    ctx->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:
 *
 */
static void SHA1PadMessage(ogs_sha1_ctx *ctx)
{
    /*
     *  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 (ctx->Message_Block_Index > 55)
    {
        ctx->Message_Block[ctx->Message_Block_Index++] = 0x80;
        while(ctx->Message_Block_Index < 64)
        {
            ctx->Message_Block[ctx->Message_Block_Index++] = 0;
        }

        SHA1ProcessMessageBlock(ctx);

        while(ctx->Message_Block_Index < 56)
        {
            ctx->Message_Block[ctx->Message_Block_Index++] = 0;
        }
    }
    else
    {
        ctx->Message_Block[ctx->Message_Block_Index++] = 0x80;
        while(ctx->Message_Block_Index < 56)
        {
            ctx->Message_Block[ctx->Message_Block_Index++] = 0;
        }
    }

    /*
     *  Store the message length as the last 8 octets
     */
    ctx->Message_Block[56] = (ctx->Length_High >> 24) & 0xFF;
    ctx->Message_Block[57] = (ctx->Length_High >> 16) & 0xFF;
    ctx->Message_Block[58] = (ctx->Length_High >> 8) & 0xFF;
    ctx->Message_Block[59] = (ctx->Length_High) & 0xFF;
    ctx->Message_Block[60] = (ctx->Length_Low >> 24) & 0xFF;
    ctx->Message_Block[61] = (ctx->Length_Low >> 16) & 0xFF;
    ctx->Message_Block[62] = (ctx->Length_Low >> 8) & 0xFF;
    ctx->Message_Block[63] = (ctx->Length_Low) & 0xFF;

    SHA1ProcessMessageBlock(ctx);
}

void ogs_sha1(const uint8_t *message, uint32_t len, uint8_t *digest)
{
    ogs_sha1_ctx ctx;

    ogs_sha1_init(&ctx);
    ogs_sha1_update(&ctx, message, len);
    ogs_sha1_final(&ctx, digest);
}