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ponaromixxx, posted Sat Sep 01, 2018 4:43 pm (38024)

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Can help?

Code:

    /* check SNGW (Capcom's MT Framework PC games), may be encrypted */
    if (is_sngw) {
        if (read_32bitBE(0x00,streamFile) != 0x4f676753) { /* "OggS" */
            ovmi.xor_value = read_32bitBE(0x00,streamFile);
            ovmi.decryption_callback = sngw_ogg_decryption_callback;
        }
        ovmi.meta_type = meta_OGG_SNGW;
    }

Code:

static void sngw_ogg_decryption_callback(void *ptr, size_t size, size_t nmemb, void *datasource) {
    size_t bytes_read = size*nmemb;
    ogg_vorbis_streamfile * const ov_streamfile = datasource;
    int i;
    char *header_id = "OggS";
    uint8_t key[4];

    put_32bitBE(key, ov_streamfile->xor_value);

    /* bytes are xor'd with key and nibble-swapped, first "OggS" is changed */
    for (i = 0; i < bytes_read; i  ) {
        if (ov_streamfile->offset i < 0x04) {
            ((uint8_t*)ptr)[i] = (uint8_t)header_id[(ov_streamfile->offset   i) % 4];
        }
        else {
            uint8_t val = ((uint8_t*)ptr)[i] ^ key[(ov_streamfile->offset   i) % 4];
            ((uint8_t*)ptr)[i] = ((val << 4) & 0xf0) | ((val >> 4) & 0x0f);
        }
    }
}