hash.c

/*
 * PSP Software Development Kit - http://www.pspdev.org
 * -----------------------------------------------------------------------
 * Licensed under the BSD license, see LICENSE in PSPSDK root for details.
 *
 * hash.c - Hashing routines using sceChnnlsv
 *
 * Copyright (c) 2005 Jim Paris <jim@jtan.com>
 * Coypright (c) 2005 psp123
 *
 * $Id: hash.c 1560 2005-12-10 01:16:32Z jim $
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "chnnlsv.h"
#include "hash.h"
#include "psf.h"

static inline int align16(unsigned int v)
{
    return ((v + 0xF) >> 4) << 4;
}

/* Update the hashes in the param.sfo data, using
   the given file hash, and by computing the param.sfo hashes.
   filehash must be a multiple of 16 bytes, and is reused to
   store other hashes.  The filename is e.g. "DATA.BIN". */
int update_hashes(unsigned char *data, int len, const char *filename,
  unsigned char *filehash, int encryptmode)
{
    int alignedLen = align16(len);
    unsigned char *datafile, *savedata_params;
    int listLen, paramsLen;
    int ret;

    /* Locate SAVEDATA_PARAM section in the param.sfo. */
    if ((ret = find_psf_section("SAVEDATA_PARAMS", data, 0x1330,
      &savedata_params, &paramsLen)) < 0)
        return ret - 100;

    /* Locate the pointer for this DATA.BIN equivalent */
    if ((ret = find_psf_section("SAVEDATA_FILE_LIST", data, 0x1330, &datafile,
      &listLen)) < 0)
        return ret - 200;

    if ((ret = find_psf_datafile(filename, datafile, listLen, &datafile)) < 0)
        return ret - 300;

    /* Check minimum sizes based on where we want to write */
    if ((listLen < 0x20) || (paramsLen < 0x80))
        return -1;

    /* Clear params and insert file hash */
    memset(savedata_params, 0, paramsLen);
    memcpy(datafile + 0x0D, filehash, 0x10);

    /* Compute 11D0 hash over entire file */
    if ((ret = build_hash(filehash, data, len, alignedLen,
      (encryptmode & 2) ? 4 : 2, NULL)) < 0) /* Not sure about "2" */
        return ret - 400;

    /* Copy 11D0 hash to param.sfo and set flag indicating it's there */
    memcpy(savedata_params + 0x20, filehash, 0x10);
    *savedata_params |= 0x01;

    /* If new encryption mode, compute and insert the 1220 hash. */
    if (encryptmode & 2) {

        /* Enable the hash bit first */
        *savedata_params |= 0x20;

        if ((ret = build_hash(filehash, data, len, alignedLen, 3, 0)) < 0)
            return ret - 500;
        memcpy(savedata_params + 0x70, filehash, 0x10);
    }

    /* Compute and insert the 11C0 hash. */
    if ((ret = build_hash(filehash, data, len, alignedLen, 1, 0)) < 0)
        return ret - 600;
    memcpy(savedata_params + 0x10, filehash, 0x10);

    /* All done. */
    return 0;
}

/* Build a single hash using the given data and mode. 
   data and alignedLen must be multiples of 0x10.
   cryptkey is NULL for savedata. */
int build_hash(unsigned char *output, unsigned char *data, unsigned int len,
  unsigned int alignedLen, int mode, unsigned char *cryptkey)
{
    pspChnnlsvContext1 ctx1;

    /* Set up buffers */
    memset(&ctx1, 0, sizeof(pspChnnlsvContext1));
    memset(output, 0, 0x10);
    memset(data + len, 0, alignedLen - len);

    /* Perform the magic */
    if (sceSdSetIndex_(&ctx1, mode & 0xFF) < 0)
        return -1;
    if (sceSdRemoveValue_(&ctx1, data, alignedLen) < 0)
        return -2;
    if (sceSdGetLastIndex_(&ctx1, output, cryptkey) < 0) {
        // Got here since Kirk CMD5 missing, return random value;
        memset(output, 0x1, 0x10);
        return 0;
    }
    /* All done. */
    return 0;
}