$ cat ai6.py
#!/usr/bin/env python3
import sys
import json
import base64
import struct
from Crypto.Cipher import AES

def url_b64_to_bytes(s):
    s = s.replace('-', '+').replace('_', '/')
    pad = (-len(s)) % 4
    s += '=' * pad
    return base64.b64decode(s)

def bytes_to_url_b64(b):
    s = base64.b64encode(b).decode('ascii')
    return s.replace('+', '-').replace('/', '_').rstrip('=')

def xor_bytes(a, b):
    return bytes(x ^ y for x, y in zip(a, b))

def decrypt_node_key(node_key_bin, folder_key_bin):
    # node_key_bin: 16 or 32 bytes; folder_key_bin: 16 bytes AES key
    cipher = AES.new(folder_key_bin, AES.MODE_ECB)
    if len(node_key_bin) == 16:
        return cipher.decrypt(node_key_bin)
    elif len(node_key_bin) == 32:
        a = cipher.decrypt(node_key_bin[:16])
        b = cipher.decrypt(node_key_bin[16:])
        return xor_bytes(a, b)
    else:
        raise ValueError("unexpected node_key_bin length: %d" % len(node_key_bin))

def decrypt_attributes(attr_b64url, node_key_bin):
    if not attr_b64url:
        return None
    try:
        data = url_b64_to_bytes(attr_b64url)
    except Exception:
        return None
    key = node_key_bin[:16]
    iv = b'\x00' * 16
    cipher = AES.new(key, AES.MODE_CBC, iv)
    try:
        dec = cipher.decrypt(data)
    except Exception:
        return None
    dec = dec.rstrip(b'\x00')
    try:
        text = dec.decode('utf-8', errors='ignore')
        idx = text.find('{')
        if idx != -1:
            text = text[idx:]
        return json.loads(text)
    except Exception:
        return None

def safe_url_b64_to_bytes_try(s):
    # try direct decode, else replace URL-safe variants
    try:
        return url_b64_to_bytes(s)
    except Exception:
        s2 = s.replace(' ', '').replace('\n', '')
        return url_b64_to_bytes(s2)

def process(cache_path, folder_key_str):
    with open(cache_path, 'r', encoding='utf-8') as f:
        raw = f.read()
    data = json.loads(raw)
    if isinstance(data, list):
        res0 = data[0]
    else:
        res0 = data
    entries = res0.get('f', [])
    folder_key_bin = safe_url_b64_to_bytes_try(folder_key_str)
    out = {}
    total = len(entries)
    for idx, node in enumerate(entries, 1):
        full_k = node.get('k')
        if not full_k:
            continue
        segments = full_k.split('/')
        valid_dec_node_key = None
        valid_at = None
        for segment in segments:
            parts = segment.split(':')
            if len(parts) >= 2:
                potential_k_b64 = parts[-1]
                try:
                    node_key_bin = safe_url_b64_to_bytes_try(potential_k_b64)
                except Exception:
                    continue
                try:
                    dec_key = decrypt_node_key(node_key_bin, folder_key_bin)
                except Exception:
                    continue
                at = decrypt_attributes(node.get('a'), dec_key)
                if at is not None and at.get('n') is not None:
                    valid_dec_node_key = dec_key
                    valid_at = at
                    break
        if valid_at is not None:
            the_node = {
                'h': node.get('h'),
                'type': node.get('t'),
                'parent': node.get('p'),
                'key': bytes_to_url_b64(valid_dec_node_key),
                'name': valid_at.get('n'),
                'size': int(node.get('s')) if node.get('s') is not None else 0
            }
            out[node.get('h')] = the_node
    return out

def main():
    if len(sys.argv) < 3:
        print("Usage: decode_megabasterd_cache.py <cache_file> <folder_key>")
        sys.exit(1)
    cache_path = sys.argv[1]
    folder_key_str = sys.argv[2]
    out = process(cache_path, folder_key_str)
    print(json.dumps(out, ensure_ascii=False, indent=2))

if __name__ == '__main__':
    main()
$ ###################
$ ###################
$ ###################
$ cat ~/Downloads/forums/duck.ai_2026-04-24_09-26-54.txt
This conversation was generated with Duck.ai (https://duck.ai) using OpenAI's GPT-5 mini Model. AI chats may display inaccurate or offensive information (see https://duckduckgo.com/duckai/privacy-terms for more info).

====================

User prompt 1 of 5 - 4/24/2026, 9:13:13 AM:
Part of src/main/java/com/tonikelope/megabasterd/MegaAPI.java where res = /tmp/megabasterd_folder_cache_uz410RTR :

    public HashMap<String, Object> getFolderNodes(String folder_id, String folder_key, JProgressBar bar, boolean cache) throws Exception {

        HashMap<String, Object> folder_nodes = null;
        String res = null;

        if (cache) {
            res = getCachedFolderNodes(folder_id);
        }

        if (res == null) {
            String request = "[{\"a\":\"f\", \"c\":\"1\", \"r\":\"1\", \"ca\":\"1\"}]";
            URL url_api = new URL(API_URL + "/cs?id=" + String.valueOf(_seqno) + "&n=" + folder_id);
            res = RAW_REQUEST(request, url_api);

            if (res != null) {
                writeCachedFolderNodes(folder_id, res);
            }
        }

        if (res == null) {
            throw new Exception("No response from MEGA");
        }

        LOG.log(Level.INFO, "MEGA FOLDER {0} JSON FILE TREE SIZE -> {1}", new Object[]{folder_id, MiscTools.formatBytes((long) res.length())});

        ObjectMapper objectMapper = new ObjectMapper();
        HashMap[] res_map = objectMapper.readValue(res, HashMap[].class);
        folder_nodes = new HashMap<>();

        List folder_entries = (List) res_map[0].get("f");

        if (bar != null) {
            int s = folder_entries.size();
            MiscTools.GUIRun(() -> {
                bar.setIndeterminate(false);
                bar.setMaximum(s);
                bar.setValue(0);
            });
        }

        int conta_nodo = 0;
        byte[] decodedFolderKey = _urlBase64KeyDecode(folder_key);

        for (Object o : (Iterable<? extends Object>) folder_entries) {
            conta_nodo++;
            final int c = conta_nodo;

            if (bar != null) {
                MiscTools.GUIRun(() -> bar.setValue(c));
            }

            HashMap<String, Object> node = (HashMap<String, Object>) o;
            String full_k = (String) node.get("k");
            if (full_k == null || full_k.isEmpty()) {
                continue;
            }

            String[] segments = full_k.split("/");
            String valid_dec_node_k = null;
            HashMap valid_at = null;

            // Bucle Yellowstone: Probamos segmentos hasta dar con la llave que desencripta el nombre
            for (String segment : segments) {
                String[] node_k_parts = segment.split(":");
                if (node_k_parts.length >= 2) {
                    String potential_k_b64 = node_k_parts[node_k_parts.length - 1];

                    try {
                        byte[] nodeKeyBin = UrlBASE642Bin(potential_k_b64);
                        byte[] decryptedKeyBin = decryptKey(nodeKeyBin, decodedFolderKey);
                        String dec_node_k = Bin2UrlBASE64(decryptedKeyBin);

                        HashMap at = _decAttr((String) node.get("a"), _urlBase64KeyDecode(dec_node_k));

                        if (at != null && at.get("n") != null) {
                            valid_dec_node_k = dec_node_k;
                            valid_at = at;
                            break;
                        }
                    } catch (Exception e) {
                    }
                }
            }

            if (valid_at != null) {
                HashMap<String, Object> the_node = new HashMap<>();
                the_node.put("h", node.get("h"));
                the_node.put("type", node.get("t"));
                the_node.put("parent", node.get("p"));
                the_node.put("key", valid_dec_node_k);
                the_node.put("name", valid_at.get("n"));

                // FIX: Prevenir NullPointerException en JTree para carpetas
                if (node.get("s") != null) {
                    the_node.put("size", ((Number) node.get("s")).longValue());
                } else {
                    the_node.put("size", 0L);
                }

                folder_nodes.put((String) node.get("h"), the_node);
            }
        }

        //String content0 = folder_nodes.toString();
        //Files.writeString(outPath, content0, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
        return folder_nodes;
    }


GPT-5 mini:
What do you want me to do with this code? Options I can do (pick one):

1) Explain what this method does and key parts briefly.  
2) Find bugs, race conditions, or style problems and suggest fixes.  
3) Provide a cleaned/modernized Java version (better generics, try-with-resources, logging).  
4) Add null-safety and defensive checks + unit-testable refactor.  
5) Convert to Kotlin.  
6) Something else — specify exactly.

Which option?

--------------------

User prompt 2 of 5 - 4/24/2026, 9:14:15 AM:
Use a language other than Java to take that megabasterd_folder_cache_uz410RTR (JSON) file and decode it. It can be decoded with .java but I don't want that.

GPT-5 mini:
Got it — I'll provide a self-contained Python script that reads the cached JSON file (e.g., /tmp/megabasterd_folder_cache_uz410RTR), parses it, and performs the same decoding steps as the Java method (base64/url-safe conversions, node key decryption with the folder key, and attribute decryption) to output a map of nodes with h, type, parent, key, name, size.

I need two pieces of information to produce a working script:
1. The folder key (the same string passed as folder_key in the Java method).  
2. Whether the cache file is exactly at /tmp/megabasterd_folder_cache_uz410RTR or a different path.

If you want, I can assume the cache file path is /tmp/megabasterd_folder_cache_uz410RTR and show a script that accepts the path and folder key as command-line arguments. Which do you prefer?

--------------------

User prompt 3 of 5 - 4/24/2026, 9:15:22 AM:
It's https://mega.nz/folder/uz410RTR#a7AIQml9TZdUzuxL2l5_fQ so the folder ID is uz410RTR and the folder key is probably a7AIQml9TZdUzuxL2l5_fQ

GPT-5 mini:
Below is a self-contained Python 3 script that reads the cached JSON file, takes the folder ID/key (from the URL fragment) and replicates the Java decoding steps: URL-safe base64 conversions, Mega AES ECB key decryption, and attribute (AES-CBC-ish) decryption used by Mega to extract node names. It expects the cache file path and the folder key string (the part after '#')Here's a Python 3 script. Save as decode_megabasterd_cache.py and run:

python3 decode_megabasterd_cache.py /tmp/megabasterd_folder_cache_uz410RTR a7AIQml9TZdUzuxL2l5_fQ

Script:
```python
#!/usr/bin/env python3
import sys
import json
import base64
import struct
from Crypto.Cipher import AES

# Helpers: URL-safe base64 <-> binary (Mega uses URL-safe without padding)
def url_b64_to_bytes(s):
    s = s.replace('-', '+').replace('_', '/')
    # add padding
    pad = (-len(s)) % 4
    s += '=' * pad
    return base64.b64decode(s)

def bytes_to_url_b64(b):
    s = base64.b64encode(b).decode('ascii')
    return s.replace('+', '-').replace('/', '_').rstrip('=')

# Mega-specific: split 128-bit key into four 32-bit little-endian integers
def bytes_to_uint32_le_list(b):
    return list(struct.unpack('<4I', b))

def uint32_le_list_to_bytes(lst):
    return struct.pack('<4I', *lst)

# XOR two byte arrays
def xor_bytes(a, b):
    return bytes(x ^ y for x, y in zip(a, b))

# AES ECB decrypt 16-byte block with given 16/32/.. byte key
def aes_ecb_decrypt_block(block, key):
    cipher = AES.new(key, AES.MODE_ECB)
    return cipher.decrypt(block)

# AES-CTR style key decryption used in Mega for node keys:
# Actually nodes use AES-ECB with key = folderKey (128-bit) to decrypt node key (128-bit)
def decrypt_node_key(node_key_bin, folder_key_bin):
    # node_key_bin is 16 bytes (result of UrlBASE642Bin in Java)
    # folder_key_bin is 16 bytes (decoded folder key)
    # decrypt with AES-ECB using folder_key_bin
    return aes_ecb_decrypt_block(node_key_bin, folder_key_bin)

# Decrypt attributes: Mega stores attributes as base64-URL of AES-CBC with zero IV, then after decrypt it's NUL-padded JSON like {"n":"filename"}
def decrypt_attributes(attr_b64url, node_key_bin):
    if attr_b64url is None:
        return None
    try:
        data = url_b64_to_bytes(attr_b64url)
    except Exception:
        return None
    # attributes are encrypted with AES-ECB/CBC using first 16 bytes of node key as AES key and IV=0
    key = node_key_bin[:16]
    iv = b'\x00' * 16
    cipher = AES.new(key, AES.MODE_CBC, iv)
    try:
        dec = cipher.decrypt(data)
    except Exception:
        return None
    # strip trailing nulls
    dec = dec.rstrip(b'\x00')
    # attributes start with "MEGA" signature? In many clients it's raw JSON
    try:
        text = dec.decode('utf-8', errors='ignore')
        # Some implementations have a leading "\x00" or other padding; trim non-printable prefix
        # Find first '{'
        idx = text.find('{')
        if idx != -1:
            text = text[idx:]
        return json.loads(text)
    except Exception:
        return None

def main():
    if len(sys.argv) < 3:
        print("Usage: decode_megabasterd_cache.py <cache_file> <folder_key>")
        sys.exit(1)

    cache_path = sys.argv[1]
    folder_key_str = sys.argv[2]

    with open(cache_path, 'r', encoding='utf-8') as f:
        raw = f.read()

    # The cache content should be the JSON response (array with object containing "f")
    data = json.loads(raw)
    if isinstance(data, list):
        res0 = data[0]
    else:
        res0 = data

    entries = res0.get('f', [])
    # decode folder key (URL-safe base64)
    folder_key_bin = url_b64_to_bytes(folder_key_str)

    out = {}
    for node in entries:
        full_k = node.get('k')
        if not full_k:
            continue
        segments = full_k.split('/')
        valid_dec_node_k = None
        valid_at = None
        for segment in segments:
            parts = segment.split(':')
            if len(parts) >= 2:
                potential_k_b64 = parts[-1]
                try:
                    node_key_bin = url_b64_to_bytes(potential_k_b64)
                    # decrypt node key with folder_key_bin (AES-ECB)
                    dec_key = decrypt_node_key(node_key_bin, folder_key_bin)
                    dec_key_b64 = bytes_to_url_b64(dec_key)
                    # now try decrypt attributes using dec_key
                    at = decrypt_attributes(node.get('a'), url_b64_to_bytes(dec_key_b64))
                    if at is not None and at.get('n') is not None:
                        valid_dec_node_k = dec_key_b64
                        valid_at = at
                        break
                except Exception:
                    continue
        if valid_at is not None:
            the_node = {}
            the_node['h'] = node.get('h')
            the_node['type'] = node.get('t')
            the_node['parent'] = node.get('p')
            the_node['key'] = valid_dec_node_k
            the_node['name'] = valid_at.get('n')
            the_node['size'] = int(node.get('s')) if node.get('s') is not None else 0
            out[node.get('h')] = the_node

    print(json.dumps(out, ensure_ascii=False, indent=2))

if __name__ == '__main__':
    main()
```

Notes:
- Requires PyCryptodome (install with pip install pycryptodome).
- This mirrors the Java logic: try each segment's tail as a candidate node key, AES-decrypt it with the folder key, then use the decrypted key to decrypt attributes and check for "n" (name).
- If you want CSV or different output, tell me.

--------------------

User prompt 4 of 5 - 4/24/2026, 9:23:53 AM:
This worked, but it only got folder names and not file names.

GPT-5 mini:
Likely cause: file nodes in MEGA use a different key layout—file node keys are XORed across two 16-byte halves (or stored as 32-byte JSON keys) and attribute decryption requires using the correct 16-byte AES key derived from that layout. The script treated every decrypted 16-byte block as the full node key, which works for folders but not files.

I'll give a minimal fix: detect when node key material is 32 bytes (two 16-byte parts), derive the actual AES key by XORing the two 16-byte halves (per MEGA spec / common clients), then use that 16-byte result to decrypt attributes. Replace decrypt_node_key and the place that builds dec_key_b64 with this corrected handling.

Patch to the earlier script — change these functions/blocks:

1) Replace decrypt_node_key with:

```python
def decrypt_node_key(node_key_bin, folder_key_bin):
    # node_key_bin may be 16 or 32 bytes.
    # Decrypt each 16-byte block with folder_key_bin (AES-ECB).
    cipher = AES.new(folder_key_bin, AES.MODE_ECB)
    if len(node_key_bin) == 16:
        return cipher.decrypt(node_key_bin)
    elif len(node_key_bin) == 32:
        a = cipher.decrypt(node_key_bin[:16])
        b = cipher.decrypt(node_key_bin[16:])
        # actual key = XOR(a, b)
        return xor_bytes(a, b)
    else:
        raise ValueError("unexpected node_key_bin length")
```

2) When computing dec_key_b64 and passing to decrypt_attributes, use the raw decrypted bytes directly (no extra encode/decode step). So replace:

```python
dec_key = decrypt_node_key(node_key_bin, folder_key_bin)
dec_key_b64 = bytes_to_url_b64(dec_key)
at = decrypt_attributes(node.get('a'), url_b64_to_bytes(dec_key_b64))
```

with:

```python
dec_key = decrypt_node_key(node_key_bin, folder_key_bin)
at = decrypt_attributes(node.get('a'), dec_key)
```

3) Update decrypt_attributes to accept node_key_bin directly (already treated as bytes in the version below). For clarity, use:

```python
def decrypt_attributes(attr_b64url, node_key_bin):
    if not attr_b64url:
        return None
    data = url_b64_to_bytes(attr_b64url)
    key = node_key_bin[:16]
    iv = b'\x00' * 16
    cipher = AES.new(key, AES.MODE_CBC, iv)
    dec = cipher.decrypt(data).rstrip(b'\x00')
    text = dec.decode('utf-8', errors='ignore')
    idx = text.find('{')
    if idx != -1:
        text = text[idx:]
    return json.loads(text)
```

With those three changes the script will correctly derive file keys and decrypt file attributes (names). Try updating the script accordingly; if you want, I can send you the fully patched script.

--------------------

User prompt 5 of 5 - 4/24/2026, 9:25:10 AM:
Amount of folder about 5,000. Amount of files:

$ cat ~/Downloads/megabasterd_folder_cache_uz410RTR.json | jq | grep '"h": "' | wc -l
32487

GPT-5 mini:
Here's the complete, updated Python 3 script that applies the fixes (handles 16- and 32-byte node keys, XOR combination for files) and can process large caches. It reads a cache file path and folder key, decodes all nodes (files + folders), and prints JSON mapping node-h -> metadata (h,type,parent,key,name,size).

Save as decode_megabasterd_cache.py and run:
python3 decode_megabasterd_cache.py /path/to/megabasterd_folder_cache_uz410RTR.json a7AIQml9TZdUzuxL2l5_fQ

Requires pycryptodome: pip install pycryptodome

Script:
```python
#!/usr/bin/env python3
import sys
import json
import base64
import struct
from Crypto.Cipher import AES

def url_b64_to_bytes(s):
    s = s.replace('-', '+').replace('_', '/')
    pad = (-len(s)) % 4
    s += '=' * pad
    return base64.b64decode(s)

def bytes_to_url_b64(b):
    s = base64.b64encode(b).decode('ascii')
    return s.replace('+', '-').replace('/', '_').rstrip('=')

def xor_bytes(a, b):
    return bytes(x ^ y for x, y in zip(a, b))

def decrypt_node_key(node_key_bin, folder_key_bin):
    # node_key_bin: 16 or 32 bytes; folder_key_bin: 16 bytes AES key
    cipher = AES.new(folder_key_bin, AES.MODE_ECB)
    if len(node_key_bin) == 16:
        return cipher.decrypt(node_key_bin)
    elif len(node_key_bin) == 32:
        a = cipher.decrypt(node_key_bin[:16])
        b = cipher.decrypt(node_key_bin[16:])
        return xor_bytes(a, b)
    else:
        raise ValueError("unexpected node_key_bin length: %d" % len(node_key_bin))

def decrypt_attributes(attr_b64url, node_key_bin):
    if not attr_b64url:
        return None
    try:
        data = url_b64_to_bytes(attr_b64url)
    except Exception:
        return None
    key = node_key_bin[:16]
    iv = b'\x00' * 16
    cipher = AES.new(key, AES.MODE_CBC, iv)
    try:
        dec = cipher.decrypt(data)
    except Exception:
        return None
    dec = dec.rstrip(b'\x00')
    try:
        text = dec.decode('utf-8', errors='ignore')
        idx = text.find('{')
        if idx != -1:
            text = text[idx:]
        return json.loads(text)
    except Exception:
        return None

def safe_url_b64_to_bytes_try(s):
    # try direct decode, else replace URL-safe variants
    try:
        return url_b64_to_bytes(s)
    except Exception:
        s2 = s.replace(' ', '').replace('\n', '')
        return url_b64_to_bytes(s2)

def process(cache_path, folder_key_str):
    with open(cache_path, 'r', encoding='utf-8') as f:
        raw = f.read()
    data = json.loads(raw)
    if isinstance(data, list):
        res0 = data[0]
    else:
        res0 = data
    entries = res0.get('f', [])
    folder_key_bin = safe_url_b64_to_bytes_try(folder_key_str)
    out = {}
    total = len(entries)
    for idx, node in enumerate(entries, 1):
        full_k = node.get('k')
        if not full_k:
            continue
        segments = full_k.split('/')
        valid_dec_node_key = None
        valid_at = None
        for segment in segments:
            parts = segment.split(':')
            if len(parts) >= 2:
                potential_k_b64 = parts[-1]
                try:
                    node_key_bin = safe_url_b64_to_bytes_try(potential_k_b64)
                except Exception:
                    continue
                try:
                    dec_key = decrypt_node_key(node_key_bin, folder_key_bin)
                except Exception:
                    continue
                at = decrypt_attributes(node.get('a'), dec_key)
                if at is not None and at.get('n') is not None:
                    valid_dec_node_key = dec_key
                    valid_at = at
                    break
        if valid_at is not None:
            the_node = {
                'h': node.get('h'),
                'type': node.get('t'),
                'parent': node.get('p'),
                'key': bytes_to_url_b64(valid_dec_node_key),
                'name': valid_at.get('n'),
                'size': int(node.get('s')) if node.get('s') is not None else 0
            }
            out[node.get('h')] = the_node
    return out

def main():
    if len(sys.argv) < 3:
        print("Usage: decode_megabasterd_cache.py <cache_file> <folder_key>")
        sys.exit(1)
    cache_path = sys.argv[1]
    folder_key_str = sys.argv[2]
    out = process(cache_path, folder_key_str)
    print(json.dumps(out, ensure_ascii=False, indent=2))

if __name__ == '__main__':
    main()
```

If you want:
- CSV output, or
- Progress printing for the ~32k nodes,
tell me which and I'll patch it.
$