diff --git a/Cargo.lock b/Cargo.lock
index 49dcd69..624e0c1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -318,7 +318,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1aa79e62e7697b8e29b513a68abacf485adcd1fe8284a4316c5ae868e6633327"
 dependencies = [
  "iana-time-zone",
+ "js-sys",
  "num-traits",
+ "wasm-bindgen",
  "windows-link",
 ]
 
@@ -1709,6 +1711,7 @@ dependencies = [
  "base64",
  "bcrypt",
  "bytes",
+ "chrono",
  "futures",
  "getrandom 0.2.17",
  "hex",
diff --git a/Cargo.toml b/Cargo.toml
index 3df0c7b..7a63da8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -28,6 +28,8 @@ aes-gcm = "0.10"
 hkdf = "0.12"
 bcrypt = "0.17"
 pgp = "0.16"
+# Match the chrono line rPGP pulls in; used to stamp detached-signature subpackets.
+chrono = "0.4"
 tracing = "0.1"
 num-bigint = "0.4"
 num-traits = "0.2"
diff --git a/crates/proton-drive-sdk/tests/common/mod.rs b/crates/proton-drive-sdk/tests/common/mod.rs
new file mode 100644
index 0000000..e9f30f4
--- /dev/null
+++ b/crates/proton-drive-sdk/tests/common/mod.rs
@@ -0,0 +1,180 @@
+//! Shared harness for live integration tests against a real Proton account.
+//!
+//! Tests are `#[ignore]` by default and run only with `cargo test -- --ignored`.
+//! When credentials are absent they **skip cleanly** (return `None`) rather than
+//! fail, so `--ignored` runs stay green in CI without secrets.
+//!
+//! Required env / `.env` (repo root):
+//!   `username=`, `password=`   (in `.env`)
+//!   `PROTON_TOTP_SECRET=`      (base32 2FA secret; env var)
+//!
+//! Read-only `live_login` example duplicates the TOTP/dotenv logic; this is the
+//! authenticated-client factory for the mutating integration suite.
+
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use hmac::{Hmac, Mac};
+use proton_drive_sdk::ProtonDriveClient;
+use proton_sdk::config::ProtonClientConfiguration;
+use proton_sdk::session::ProtonApiSession;
+use sha1::Sha1;
+
+// Must follow Proton's required shape (sdk/README.md "Operational requirements").
+// A malformed channel fails honest-identification → 422 "unusual activity".
+const APP_VERSION: &str = "external-drive-rust@0.1.0-alpha";
+const USER_AGENT: &str = "external-drive-rust/0.1.0";
+
+/// An authenticated Drive client plus the data password it was built with.
+pub struct LiveClient {
+    pub client: ProtonDriveClient,
+    // Kept alive: the session backs the client's token store.
+    pub _session: ProtonApiSession,
+}
+
+/// Build an authenticated `ProtonDriveClient`, or `None` when credentials are
+/// not configured (skip, don't fail).
+///
+/// Call from a test like:
+/// ```ignore
+/// let Some(live) = common::live_client().await else { return };
+/// ```
+pub async fn live_client() -> Option<LiveClient> {
+    let (username, password) = match read_dotenv() {
+        Ok(creds) => creds,
+        Err(e) => {
+            eprintln!("[skip] no .env credentials: {e}");
+            return None;
+        }
+    };
+    let totp_secret = match read_totp_secret() {
+        Some(s) => s,
+        None => {
+            eprintln!("[skip] PROTON_TOTP_SECRET not set (env or .env)");
+            return None;
+        }
+    };
+
+    let config = ProtonClientConfiguration::new(APP_VERSION).with_user_agent(USER_AGENT);
+
+    let mut session = ProtonApiSession::begin(config, &username, password.as_bytes())
+        .await
+        .expect("SRP login failed");
+
+    if session.is_waiting_for_second_factor() {
+        let code = totp_now(&totp_secret).expect("TOTP compute failed");
+        session
+            .apply_second_factor_code(&code)
+            .await
+            .expect("2FA submission failed");
+    }
+
+    let client = ProtonDriveClient::new(&session, password.into_bytes());
+    Some(LiveClient {
+        client,
+        _session: session,
+    })
+}
+
+/// Minimal `.env` reader: `key=value` lines, trims whitespace, ignores `#`.
+fn read_dotenv() -> Result<(String, String), Box<dyn std::error::Error>> {
+    let path = concat!(env!("CARGO_MANIFEST_DIR"), "/../../.env");
+    let text = std::fs::read_to_string(path).map_err(|e| format!("read {path}: {e}"))?;
+    let mut username = None;
+    let mut password = None;
+    for line in text.lines() {
+        let line = line.trim();
+        if line.is_empty() || line.starts_with('#') {
+            continue;
+        }
+        let Some((k, v)) = line.split_once('=') else {
+            continue;
+        };
+        match k.trim() {
+            "username" => username = Some(v.trim().to_owned()),
+            "password" => password = Some(v.trim().to_owned()),
+            _ => {}
+        }
+    }
+    Ok((
+        username.ok_or("username missing in .env")?,
+        password.ok_or("password missing in .env")?,
+    ))
+}
+
+/// TOTP secret from `PROTON_TOTP_SECRET` env var, falling back to a
+/// `PROTON_TOTP_SECRET=` line in `.env`.
+fn read_totp_secret() -> Option<String> {
+    if let Ok(s) = std::env::var("PROTON_TOTP_SECRET") {
+        if !s.trim().is_empty() {
+            return Some(s.trim().to_owned());
+        }
+    }
+    let path = concat!(env!("CARGO_MANIFEST_DIR"), "/../../.env");
+    let text = std::fs::read_to_string(path).ok()?;
+    for line in text.lines() {
+        let line = line.trim();
+        if line.is_empty() || line.starts_with('#') {
+            continue;
+        }
+        if let Some((k, v)) = line.split_once('=') {
+            if k.trim() == "PROTON_TOTP_SECRET" {
+                let v = v.trim();
+                if !v.is_empty() {
+                    return Some(v.to_owned());
+                }
+            }
+        }
+    }
+    None
+}
+
+/// RFC 6238 TOTP (SHA-1, 6 digits, 30s step) for the current time.
+fn totp_now(secret_b32: &str) -> Result<String, Box<dyn std::error::Error>> {
+    let key = base32_decode(secret_b32)?;
+    let counter = SystemTime::now().duration_since(UNIX_EPOCH)?.as_secs() / 30;
+
+    let mut mac = Hmac::<Sha1>::new_from_slice(&key)?;
+    mac.update(&counter.to_be_bytes());
+    let digest = mac.finalize().into_bytes();
+
+    let offset = (digest[19] & 0x0f) as usize;
+    let bin = ((digest[offset] as u32 & 0x7f) << 24)
+        | ((digest[offset + 1] as u32) << 16)
+        | ((digest[offset + 2] as u32) << 8)
+        | (digest[offset + 3] as u32);
+    Ok(format!("{:06}", bin % 1_000_000))
+}
+
+/// RFC 4648 base32 decode (uppercase, padding optional).
+fn base32_decode(s: &str) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
+    const ALPHA: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
+    let mut buf = 0u64;
+    let mut bits = 0u32;
+    let mut out = Vec::new();
+    for c in s.trim().bytes() {
+        if c == b'=' || c == b' ' {
+            continue;
+        }
+        let up = c.to_ascii_uppercase();
+        let val = ALPHA
+            .iter()
+            .position(|&a| a == up)
+            .ok_or("invalid base32 char")? as u64;
+        buf = (buf << 5) | val;
+        bits += 5;
+        if bits >= 8 {
+            bits -= 8;
+            out.push((buf >> bits) as u8);
+        }
+    }
+    Ok(out)
+}
+
+/// A unique-ish suffix for test artifact names, so reruns don't collide.
+pub fn unique_suffix() -> String {
+    let nanos = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap()
+        .as_nanos();
+    format!("{nanos}")
+}
diff --git a/crates/proton-drive-sdk/tests/live_upload_download.rs b/crates/proton-drive-sdk/tests/live_upload_download.rs
new file mode 100644
index 0000000..c36aeae
--- /dev/null
+++ b/crates/proton-drive-sdk/tests/live_upload_download.rs
@@ -0,0 +1,131 @@
+//! Live integration: upload → download → byte-equality round-trips.
+//!
+//! Skipped by default. Run against the test account with:
+//!   PROTON_TOTP_SECRET=... cargo test -p proton-drive-sdk --test live_upload_download -- --ignored --nocapture
+//!
+//! Each test cleans up after itself (trash + delete-from-trash) so the account
+//! stays reusable across runs.
+
+mod common;
+
+use proton_sdk::ids::NodeUid;
+
+/// Trash then permanently delete the given nodes; best-effort, logs on failure.
+async fn cleanup(client: &proton_drive_sdk::ProtonDriveClient, uids: &[NodeUid]) {
+    if let Err(e) = client.trash_nodes(uids).await {
+        eprintln!("[cleanup] trash failed: {e}");
+        return;
+    }
+    if let Err(e) = client.delete_nodes(uids).await {
+        eprintln!("[cleanup] delete failed: {e}");
+    }
+}
+
+/// Small single-block legacy SEIPDv1 upload, downloaded back, bytes compared.
+#[tokio::test]
+#[ignore = "live: needs test-account credentials"]
+async fn upload_download_small_roundtrip() {
+    let Some(live) = common::live_client().await else {
+        return;
+    };
+    let client = live.client;
+
+    let root = client
+        .get_my_files_folder()
+        .await
+        .expect("get my-files root");
+
+    let name = format!("rt-small-{}.txt", common::unique_suffix());
+    let payload = b"hello proton drive integration test \x00\x01\x02 bytes".to_vec();
+
+    let uid = client
+        .upload_file(&root.uid, &name, "text/plain", &payload)
+        .await
+        .expect("upload_file");
+
+    let got = client.download_file(&uid).await.expect("download_file");
+    assert_eq!(got, payload, "downloaded bytes must match uploaded");
+
+    cleanup(&client, &[uid]).await;
+}
+
+/// Multi-block streaming upload (> 4 MiB) exercising `upload_file_from` and the
+/// paginated revision-block download path.
+#[tokio::test]
+#[ignore = "live: needs test-account credentials"]
+async fn upload_download_multiblock_roundtrip() {
+    let Some(live) = common::live_client().await else {
+        return;
+    };
+    let client = live.client;
+
+    let root = client
+        .get_my_files_folder()
+        .await
+        .expect("get my-files root");
+
+    // 10 MiB of non-trivial, non-repeating-friendly content (3 full 4 MiB blocks).
+    let size = 10 * 1024 * 1024;
+    let mut payload = vec![0u8; size];
+    for (i, b) in payload.iter_mut().enumerate() {
+        *b = (i as u32).wrapping_mul(2_654_435_761) as u8;
+    }
+
+    let name = format!("rt-multi-{}.bin", common::unique_suffix());
+    let reader = std::io::Cursor::new(payload.clone());
+
+    let uid = client
+        .upload_file_from(
+            &root.uid,
+            &name,
+            "application/octet-stream",
+            reader,
+            size as i64,
+            Vec::new(), // thumbnails
+            None,       // last_modification_time
+            false,      // aead
+        )
+        .await
+        .expect("upload_file_from");
+
+    let got = client.download_file(&uid).await.expect("download_file");
+    assert_eq!(got.len(), payload.len(), "size mismatch");
+    assert_eq!(got, payload, "multi-block bytes must match");
+
+    cleanup(&client, &[uid]).await;
+}
+
+/// New revision over an existing file: upload v1, replace with v2, download must
+/// yield v2.
+#[tokio::test]
+#[ignore = "live: needs test-account credentials"]
+async fn new_revision_roundtrip() {
+    let Some(live) = common::live_client().await else {
+        return;
+    };
+    let client = live.client;
+
+    let root = client
+        .get_my_files_folder()
+        .await
+        .expect("get my-files root");
+
+    let name = format!("rt-rev-{}.txt", common::unique_suffix());
+    let v1 = b"first revision".to_vec();
+    let v2 = b"second revision, longer than the first".to_vec();
+
+    let uid = client
+        .upload_file(&root.uid, &name, "text/plain", &v1)
+        .await
+        .expect("upload v1");
+
+    client
+        .upload_new_revision(&uid, &v2)
+        .await
+        .expect("upload v2");
+
+    let got = client.download_file(&uid).await.expect("download");
+    assert_eq!(got, v2, "active revision must be v2");
+
+    cleanup(&client, &[uid]).await;
+}
diff --git a/crates/proton-sdk/Cargo.toml b/crates/proton-sdk/Cargo.toml
index 472437d..df2235d 100644
--- a/crates/proton-sdk/Cargo.toml
+++ b/crates/proton-sdk/Cargo.toml
@@ -25,6 +25,7 @@ aes-gcm.workspace = true
 hkdf.workspace = true
 bcrypt.workspace = true
 pgp.workspace = true
+chrono.workspace = true
 tracing.workspace = true
 num-bigint.workspace = true
 num-traits.workspace = true
diff --git a/crates/proton-sdk/src/crypto/encrypt.rs b/crates/proton-sdk/src/crypto/encrypt.rs
index c15b165..ff3aaa4 100644
--- a/crates/proton-sdk/src/crypto/encrypt.rs
+++ b/crates/proton-sdk/src/crypto/encrypt.rs
@@ -15,8 +15,9 @@ use pgp::composed::{
 };
 use pgp::crypto::hash::HashAlgorithm;
 use pgp::crypto::sym::SymmetricKeyAlgorithm;
-use pgp::packet::{SignatureConfig, SignatureType};
-use pgp::types::{CompressionAlgorithm, KeyVersion, Password, PublicKeyTrait};
+use pgp::packet::{SignatureConfig, SignatureType, Subpacket, SubpacketData};
+use pgp::types::{CompressionAlgorithm, KeyDetails, KeyVersion, Password, PublicKeyTrait};
+use chrono::SubsecRound;
 use rand::RngCore;
 
 use super::errors::CryptoError;
@@ -244,8 +245,27 @@ pub(crate) fn sign_detached(signer: &PrivateKey, data: &[u8]) -> Result<String,
     let key = &signer.key().primary_key;
     let pw = signer.password();
 
-    let config = SignatureConfig::from_key(&mut rng, key, SignatureType::Binary)
+    let mut config = SignatureConfig::from_key(&mut rng, key, SignatureType::Binary)
         .map_err(|e| CryptoError::Encrypt(format!("signature config: {e}")))?;
+
+    // `from_key` leaves the subpacket lists empty, which produces a signature with
+    // a zero creation time and a zero (missing) issuer key id. GopenPGP — what the
+    // Proton server verifies with — rejects such signatures ("Invalid manifest
+    // signature"). Mirror rPGP's own MessageBuilder: stamp the issuer fingerprint +
+    // creation time in the hashed subpackets and the issuer key id in the unhashed.
+    config.hashed_subpackets = vec![
+        Subpacket::regular(SubpacketData::IssuerFingerprint(key.fingerprint()))
+            .map_err(|e| CryptoError::Encrypt(format!("issuer fingerprint subpacket: {e}")))?,
+        Subpacket::regular(SubpacketData::SignatureCreationTime(
+            chrono::Utc::now().trunc_subsecs(0),
+        ))
+        .map_err(|e| CryptoError::Encrypt(format!("creation-time subpacket: {e}")))?,
+    ];
+    if key.version() <= KeyVersion::V4 {
+        config.unhashed_subpackets = vec![Subpacket::regular(SubpacketData::Issuer(key.key_id()))
+            .map_err(|e| CryptoError::Encrypt(format!("issuer subpacket: {e}")))?];
+    }
+
     let signature = config
         .sign(key, &pw, data)
         .map_err(|e| CryptoError::Encrypt(format!("detached sign: {e}")))?;
@@ -328,6 +348,22 @@ mod tests {
             .key
             .verify_detached_signature(&sig, data)
             .expect("verify detached signature");
+
+        // Regression: the detached signature must carry a non-zero creation time
+        // and an issuer key id. `SignatureConfig::from_key` leaves both empty,
+        // which rPGP self-verify tolerates but GopenPGP (the Proton server)
+        // rejects with "Invalid manifest signature". rPGP self-verify above is not
+        // enough to catch that — assert the subpackets explicitly.
+        use pgp::composed::Deserializable as _;
+        let (parsed, _) = StandaloneSignature::from_string(&sig).expect("parse detached sig");
+        assert!(
+            parsed.signature.created().is_some(),
+            "detached signature missing creation time"
+        );
+        assert!(
+            !parsed.signature.issuer().is_empty(),
+            "detached signature missing issuer key id"
+        );
     }
 
     #[test]