Media and attachments

Images and other files use the same conversation key as text. Encrypt bytes with the Chat XDK (encrypt_stream / decrypt_stream), upload via the /2/chat/media/upload routes (sidebar API reference → Media), then attach media_hash_key on encrypt_message. Include media.write with your DM scopes when uploading. Use hyphenated conversation ids in paths (: → -). Prefer MIME/dimensions from decrypted bytes. This path is not the Posts media model (expansions=attachments.media_keys, media.fields=variants, etc.). Those parameters apply to Posts; E2EE X Chat blobs are addressed by media_hash_key and X Chat media download.

Encrypt

from chat_xdk import detect_mime_type, detect_image_dimensions

with open("photo.jpg", "rb") as f:
    plaintext = f.read()

mime = detect_mime_type(plaintext)
dims = detect_image_dimensions(plaintext)
width, height = dims if dims else (0, 0)

encrypted_blob = chat.encrypt_stream(plaintext, raw_conv_key)

import { detectMimeType, detectImageDimensions } from '@xdevplatform/chat-xdk';
import { readFile } from 'fs/promises';

const plaintext = await readFile('photo.jpg');
const mime = detectMimeType(plaintext);
const dims = detectImageDimensions(plaintext);
const width = dims?.width ?? 0;
const height = dims?.height ?? 0;

const encryptedBlob = chat.encryptStream(plaintext, rawConvKey);

use chat_xdk_core::{detect_image_dimensions, detect_mime_type};

let plaintext = std::fs::read("photo.jpg")?;
let _mime = detect_mime_type(&plaintext);
let dims = detect_image_dimensions(&plaintext);
let (width, height) = dims.map(|d| (d.width as i64, d.height as i64)).unwrap_or((0, 0));
// conv_key: &XChatConversationKey from extract_conversation_keys / decrypt_conversation_key
let encrypted_blob = chat.encrypt_stream(&plaintext, &conv_key)?;

plaintext, err := os.ReadFile("photo.jpg")
mime, _ := chatxdk.DetectMimeType(plaintext)
dims, _ := chatxdk.DetectImageDimensions(plaintext)
_ = mime
encrypted, err := chat.EncryptStream(plaintext, rawConvKey)
_ = dims
_ = encrypted

using ChatXdk;

byte[] plaintext = await File.ReadAllBytesAsync("photo.jpg");
string? mime = ChatXdkUtilities.DetectMimeType(plaintext);
var dims = ChatXdkUtilities.DetectImageDimensions(plaintext);
int width = (int)(dims?.Width ?? 0);
int height = (int)(dims?.Height ?? 0);
byte[] encryptedBlob = chat.EncryptStream(plaintext, rawConvKey);

import com.xdevplatform.chatxdk.ChatXdkUtilities;
import com.xdevplatform.chatxdk.Types.ImageDimensions;

byte[] plaintext = Files.readAllBytes(Path.of("photo.jpg"));
String mime = ChatXdkUtilities.detectMimeType(plaintext);
ImageDimensions dims = ChatXdkUtilities.detectImageDimensions(plaintext);
int width = dims != null ? (int) dims.width : 0;
int height = dims != null ? (int) dims.height : 0;
byte[] encryptedBlob = chat.encryptStream(plaintext, rawConvKey);

encrypt_stream / decrypt_stream process the whole payload in memory. For large files, stream_encryptor() / stream_decryptor() return incremental objects (StreamEncryptor / StreamDecryptor): feed chunks with push, then call finish once—finish errors if the stream was truncated.

Upload

Step	Method	Path
Initialize	`POST`	`/2/chat/media/upload/initialize`
Append	`POST`	`/2/chat/media/upload/{id}/append`
Finalize	`POST`	`/2/chat/media/upload/{id}/finalize`

Use the request bodies on the OpenAPI pages under API reference → Media. Prefer encrypted blob size where size is required. Finalize yields media_hash_key for attachments and download. Retry transient 5xx with backoff. Python/TypeScript may use the XDK when media helpers exist; otherwise POST with a Bearer token in any language.

Send with an attachment

Encrypt with a media attachment, then POST the send-message body (same field mapping as Getting Started).

import uuid
from xdk.chat.models import SendMessageRequest

message_id = str(uuid.uuid4())
payload = chat.encrypt_message(
    message_id,
    sender_id,
    conversation_id,
    raw_conv_key,
    caption or "",
    conversation_key_version,
    signing_key_version,
    attachments=[{
        "attachment_type": "media",
        "media_hash_key": media_hash_key,
        "width": width,
        "height": height,
        "filesize_bytes": len(plaintext),
        "filename": "photo.jpg",
    }],
)
client.chat.send_message(
    conversation_id.replace(":", "-"),
    SendMessageRequest(
        message_id=message_id,
        encoded_message_create_event=payload.encrypted_content,
        encoded_message_event_signature=payload.encoded_event_signature,
    ),
)

const messageId = crypto.randomUUID();
const payload = chat.encryptMessage({
  messageId,
  senderId,
  conversationId,
  conversationKey: rawConvKey,
  text: caption || '',
  conversationKeyVersion,
  signingKeyVersion,
  attachments: [{
    attachmentType: 'media',
    mediaHashKey: mediaHashKey,
    width,
    height,
    filesizeBytes: plaintext.byteLength,
    filename: 'photo.jpg',
  }],
});
await client.chat.sendMessage(conversationId.replace(/:/g, '-'), {
  message_id: messageId,
  encoded_message_create_event: payload.encryptedContent,
  encoded_message_event_signature: payload.encodedEventSignature,
});

// Set attachments on EncryptMessageParams per chat_xdk_core AttachmentDescriptor::Media
let payload = chat.encrypt_message(params_with_media_attachment)?;
let body = serde_json::json!({
    "message_id": message_id,
    "encoded_message_create_event": payload.encrypted_content,
    "encoded_message_event_signature": payload.encoded_event_signature,
});
let path_id = conversation_id.replace(':', "-");
http.post(format!("https://api.x.com/2/chat/conversations/{path_id}/messages"))
    .header("Authorization", &auth)
    .json(&body)
    .send()?;

payload, err := chat.EncryptMessage(chatxdk.EncryptMessageParams{
    MessageID: messageID, SenderID: senderID, ConversationID: conversationID,
    ConversationKey: rawConvKey, Text: caption,
    ConversationKeyVersion: conversationKeyVersion, SigningKeyVersion: signingKeyVersion,
    Attachments: []chatxdk.AttachmentDescriptor{{
        AttachmentType: "media",
        MediaHashKey:   mediaHashKey,
        Width:          width,
        Height:         height,
        FilesizeBytes:  int64(len(plaintext)),
        Filename:       "photo.jpg",
    }},
})
// POST payload.EncryptedContent / EncodedEventSignature to /2/chat/conversations/{id}/messages

var payload = chat.EncryptMessage(new EncryptMessageParams {
    MessageId = messageId,
    SenderId = senderId,
    ConversationId = conversationId,
    ConversationKey = rawConvKey,
    Text = caption ?? "",
    ConversationKeyVersion = conversationKeyVersion,
    SigningKeyVersion = signingKeyVersion,
    // Attachments = media descriptor with MediaHashKey, Width, Height,
    // FilesizeBytes, and Filename (as in the Go tab above)
});
// POST EncryptedContent / EncodedEventSignature as for text messages

EncryptMessageParams params = new EncryptMessageParams();
params.messageId = messageId;
params.senderId = senderId;
params.conversationId = conversationId;
params.conversationKey = rawConvKey;
params.text = caption != null ? caption : "";
params.conversationKeyVersion = conversationKeyVersion;
params.signingKeyVersion = signingKeyVersion;
// params.attachments — media type with mediaHashKey, width, height, filename
SendPayload payload = chat.encryptMessage(params);
// POST to /2/chat/conversations/{id}/messages

Download and decrypt

Path: GET /2/chat/media/{conversation_id}/{media_hash_key}. Response body is ciphertext. On inbound messages, read media_hash_key from decrypted attachments / media_hashes. Pick the key by the event’s key version. Each decrypted message event carries the keyVersion (JS; key_version in the other bindings) its content was encrypted under. Decrypt an attachment with the conversation key for that version—conversationKeys.keys[event.keyVersion]—not the latest. After a key rotation (for example a member add), the latest key cannot decrypt media attached to older messages.

Python
TypeScript

keys = result["conversation_keys"]["keys"]
key_for_media = keys[event["key_version"]]   # not the latest version
plaintext = chat.decrypt_stream(encrypted_blob, key_for_media)

const keys = result.conversationKeys.keys;
const keyForMedia = keys[event.keyVersion]; // not the latest version
const plaintext = chat.decryptStream(encryptedBlob, keyForMedia);

import requests
from chat_xdk import detect_mime_type

api_id = conversation_id.replace(":", "-")
url = f"https://api.x.com/2/chat/media/{api_id}/{media_hash_key}"
r = requests.get(url, headers={"Authorization": f"Bearer {access_token}"})
r.raise_for_status()

plaintext = chat.decrypt_stream(r.content, raw_conv_key)
mime = detect_mime_type(plaintext) or "application/octet-stream"

import { detectMimeType } from '@xdevplatform/chat-xdk';

const apiId = conversationId.replace(/:/g, '-');
const res = await fetch(
  `https://api.x.com/2/chat/media/${apiId}/${mediaHashKey}`,
  { headers: { Authorization: `Bearer ${accessToken}` } },
);
const encryptedBlob = new Uint8Array(await res.arrayBuffer());
const plaintext = chat.decryptStream(encryptedBlob, rawConvKey);
const mime = detectMimeType(plaintext) ?? 'application/octet-stream';

let api_id = conversation_id.replace(':', "-");
let encrypted_blob = http
    .get(format!("https://api.x.com/2/chat/media/{api_id}/{media_hash_key}"))
    .header("Authorization", &auth)
    .send()?
    .bytes()?;
// conv_key: &XChatConversationKey from extract_conversation_keys / decrypt_conversation_key
let plaintext = chat.decrypt_stream(&encrypted_blob, &conv_key)?;

url := fmt.Sprintf("https://api.x.com/2/chat/media/%s/%s",
    strings.ReplaceAll(conversationID, ":", "-"), mediaHashKey)
req, _ := http.NewRequest(http.MethodGet, url, nil)
req.Header.Set("Authorization", "Bearer "+accessToken)
resp, err := http.DefaultClient.Do(req)
// read body into []byte → chat.DecryptStream(encryptedBlob, rawConvKey)
_ = resp
_ = err

var apiId = conversationId.Replace(':', '-');
byte[] encryptedBlob = await http.GetByteArrayAsync(
    $"https://api.x.com/2/chat/media/{apiId}/{mediaHashKey}");
byte[] plaintext = chat.DecryptStream(encryptedBlob, rawConvKey);
string? mime = ChatXdkUtilities.DetectMimeType(plaintext);

String apiId = conversationId.replace(':', '-');
HttpRequest req = HttpRequest.newBuilder()
    .uri(URI.create("https://api.x.com/2/chat/media/" + apiId + "/" + mediaHashKey))
    .header("Authorization", "Bearer " + accessToken)
    .GET()
    .build();
byte[] encryptedBlob = http.send(req, HttpResponse.BodyHandlers.ofByteArray()).body();
byte[] plaintext = chat.decryptStream(encryptedBlob, rawConvKey);
String mime = ChatXdkUtilities.detectMimeType(plaintext);

Tips

Use the same conversation key version as when the media was encrypted
Do not log plaintext media or raw keys
Detect MIME after decrypt
Web clients: encrypt/decrypt on the client when possible; keep OAuth tokens on your server

Full request and response schemas for each media route are under API reference → Media in the sidebar (initialize upload, append chunk, finalize upload, and download media).

​Encrypt

​Upload

​Send with an attachment

​Download and decrypt

​Tips

Encrypt

Upload

Send with an attachment

Download and decrypt

Tips