crypto: Begin SubtleCrypto implementation (#33628)

* Update IDLs and Bindings conf

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Add AES crate

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Implement DOM interfaces

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* IDL tidy

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Remove deriveKey from inRealms for now until implemented

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Fix CryptoKey rustdoc comments

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Move string constants to top of file

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Use properly rooted CryptoKey

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Code clarity

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Rework NormalizedAlgorithm to not hold a DOMString

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Add Rustdoc for CryptoKey interface

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Move ignore mallocsizeof to rand crate, remove from crypto

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Update cargo lock

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Fix key handling, implement exportKey with JWK TODO

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Add missing spec link

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Use create_buffer_source, remove aes dep from libservo

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Fix crash when running in worker

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Update expectations

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* fmt

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Move CryptoKey and SubtleCrypto behind pref for now

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Update expectations

Signed-off-by: Daniel Adams <msub2official@gmail.com>

* Readd timeout expectation

Signed-off-by: Daniel Adams <msub2official@gmail.com>

---------

Signed-off-by: Daniel Adams <msub2official@gmail.com>

12 files changed, 607 insertions, 4 deletions

diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index d6da7d0e5d9..fe169317341 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -249,6 +249,11 @@ mod gen {
                     #[serde(rename = "dom.compositionevent.enabled")]
                     enabled: bool,
                 },
+                crypto: {
+                    subtle: {
+                        enabled: bool,
+                    }
+                },
                 custom_elements: {
                     #[serde(rename = "dom.customelements.enabled")]
                     enabled: bool,
diff --git a/components/rand/Cargo.toml b/components/rand/Cargo.toml
index 44606ff218d..46910f5e3f1 100644
--- a/components/rand/Cargo.toml
+++ b/components/rand/Cargo.toml
@@ -13,6 +13,8 @@ path = "lib.rs"
 
 [dependencies]
 log = { workspace = true }
+malloc_size_of = { workspace = true }
+malloc_size_of_derive = { workspace = true }
 rand = { workspace = true }
 rand_core = { workspace = true }
 rand_isaac = { workspace = true }
diff --git a/components/rand/lib.rs b/components/rand/lib.rs
index c5669a8cc4b..89af575c0f3 100644
--- a/components/rand/lib.rs
+++ b/components/rand/lib.rs
@@ -7,6 +7,7 @@ use std::rc::Rc;
 use std::sync::Mutex;
 
 use log::trace;
+use malloc_size_of_derive::MallocSizeOf;
 /// A random number generator which shares one instance of an `OsRng`.
 ///
 /// A problem with `OsRng`, which is inherited by `StdRng` and so
@@ -31,7 +32,9 @@ static OS_RNG: Mutex<OsRng> = Mutex::new(OsRng);
 const RESEED_THRESHOLD: u64 = 32_768;
 
 // An in-memory RNG that only uses the shared file descriptor for seeding and reseeding.
+#[derive(MallocSizeOf)]
 pub struct ServoRng {
+    #[ignore_malloc_size_of = "Defined in rand"]
     rng: ReseedingRng<IsaacCore, ServoReseeder>,
 }
 
diff --git a/components/script/Cargo.toml b/components/script/Cargo.toml
index cc731066180..c5b64d5a675 100644
--- a/components/script/Cargo.toml
+++ b/components/script/Cargo.toml
@@ -26,6 +26,7 @@ phf_shared = "0.11"
 serde_json = { workspace = true }
 
 [dependencies]
+aes = { workspace = true }
 accountable-refcell = { workspace = true, optional = true }
 app_units = { workspace = true }
 arrayvec = { workspace = true }
diff --git a/components/script/dom/bindings/codegen/Bindings.conf b/components/script/dom/bindings/codegen/Bindings.conf
index fa5b0755e79..2fee063b753 100644
--- a/components/script/dom/bindings/codegen/Bindings.conf
+++ b/components/script/dom/bindings/codegen/Bindings.conf
@@ -218,4 +218,8 @@ DOMInterfaces = {
     'inRealms': ['RequestSession', 'SupportsSessionMode'],
 },
 
+'SubtleCrypto': {
+    'inRealms': ['GenerateKey', 'ExportKey']
+}
+
 }
diff --git a/components/script/dom/crypto.rs b/components/script/dom/crypto.rs
index 8a2fa81fd36..4d1ead530c2 100644
--- a/components/script/dom/crypto.rs
+++ b/components/script/dom/crypto.rs
@@ -12,19 +12,20 @@ use uuid::Uuid;
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::CryptoBinding::CryptoMethods;
 use crate::dom::bindings::error::{Error, Fallible};
-use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
-use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
+use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::bindings::str::USVString;
 use crate::dom::globalscope::GlobalScope;
+use crate::dom::subtlecrypto::SubtleCrypto;
 use crate::script_runtime::JSContext;
 
 // https://developer.mozilla.org/en-US/docs/Web/API/Crypto
 #[dom_struct]
 pub struct Crypto {
     reflector_: Reflector,
-    #[ignore_malloc_size_of = "Defined in rand"]
     #[no_trace]
     rng: DomRefCell<ServoRng>,
+    subtle: MutNullableDom<SubtleCrypto>,
 }
 
 impl Crypto {
@@ -32,6 +33,7 @@ impl Crypto {
         Crypto {
             reflector_: Reflector::new(),
             rng: DomRefCell::new(ServoRng::default()),
+            subtle: MutNullableDom::default(),
         }
     }
 
@@ -41,6 +43,11 @@ impl Crypto {
 }
 
 impl CryptoMethods for Crypto {
+    /// <https://w3c.github.io/webcrypto/#dfn-Crypto-attribute-subtle>
+    fn Subtle(&self) -> DomRoot<SubtleCrypto> {
+        self.subtle.or_init(|| SubtleCrypto::new(&self.global()))
+    }
+
     #[allow(unsafe_code)]
     // https://w3c.github.io/webcrypto/#Crypto-method-getRandomValues
     fn GetRandomValues(
diff --git a/components/script/dom/cryptokey.rs b/components/script/dom/cryptokey.rs
new file mode 100644
index 00000000000..a9fd0471301
--- /dev/null
+++ b/components/script/dom/cryptokey.rs
@@ -0,0 +1,140 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::cell::Cell;
+use std::ptr::NonNull;
+
+use dom_struct::dom_struct;
+use js::jsapi::{JSObject, Value};
+
+use crate::dom::bindings::cell::DomRefCell;
+use crate::dom::bindings::codegen::Bindings::CryptoKeyBinding::{
+    CryptoKeyMethods, KeyType, KeyUsage,
+};
+use crate::dom::bindings::codegen::Bindings::SubtleCryptoBinding::{AesKeyAlgorithm, KeyAlgorithm};
+use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::str::DOMString;
+use crate::dom::globalscope::GlobalScope;
+use crate::js::conversions::ToJSValConvertible;
+use crate::script_runtime::JSContext;
+
+/// The underlying cryptographic data this key represents
+#[allow(dead_code)]
+pub enum Handle {
+    Aes128(Vec<u8>),
+    Aes192(Vec<u8>),
+    Aes256(Vec<u8>),
+}
+
+/// <https://w3c.github.io/webcrypto/#cryptokey-interface>
+#[dom_struct]
+pub struct CryptoKey {
+    reflector_: Reflector,
+    key_type: KeyType,
+    extractable: Cell<bool>,
+    // This would normally be KeyAlgorithm but we cannot Send DOMString, which
+    // is a member of Algorithm
+    algorithm: DomRefCell<String>,
+    usages: Vec<KeyUsage>,
+    #[ignore_malloc_size_of = "Defined in external cryptography crates"]
+    #[no_trace]
+    handle: Handle,
+}
+
+impl CryptoKey {
+    fn new_inherited(
+        key_type: KeyType,
+        extractable: bool,
+        algorithm: KeyAlgorithm,
+        usages: Vec<KeyUsage>,
+        handle: Handle,
+    ) -> CryptoKey {
+        CryptoKey {
+            reflector_: Reflector::new(),
+            key_type,
+            extractable: Cell::new(extractable),
+            algorithm: DomRefCell::new(algorithm.name.to_string()),
+            usages,
+            handle,
+        }
+    }
+
+    pub fn new(
+        global: &GlobalScope,
+        key_type: KeyType,
+        extractable: bool,
+        algorithm: KeyAlgorithm,
+        usages: Vec<KeyUsage>,
+        handle: Handle,
+    ) -> DomRoot<CryptoKey> {
+        reflect_dom_object(
+            Box::new(CryptoKey::new_inherited(
+                key_type,
+                extractable,
+                algorithm,
+                usages,
+                handle,
+            )),
+            global,
+        )
+    }
+
+    pub fn algorithm(&self) -> String {
+        self.algorithm.borrow().to_string()
+    }
+
+    pub fn handle(&self) -> &Handle {
+        &self.handle
+    }
+}
+
+impl CryptoKeyMethods for CryptoKey {
+    /// <https://w3c.github.io/webcrypto/#cryptokey-interface-members>
+    fn Type(&self) -> KeyType {
+        self.key_type.clone()
+    }
+
+    /// <https://w3c.github.io/webcrypto/#cryptokey-interface-members>
+    fn Extractable(&self) -> bool {
+        self.extractable.get()
+    }
+
+    #[allow(unsafe_code)]
+    /// <https://w3c.github.io/webcrypto/#cryptokey-interface-members>
+    fn Algorithm(&self, cx: JSContext) -> NonNull<JSObject> {
+        let parent = KeyAlgorithm {
+            name: DOMString::from_string(self.algorithm()),
+        };
+        let algorithm = match self.handle() {
+            Handle::Aes128(_) => AesKeyAlgorithm {
+                parent,
+                length: 128,
+            },
+            Handle::Aes192(_) => AesKeyAlgorithm {
+                parent,
+                length: 192,
+            },
+            Handle::Aes256(_) => AesKeyAlgorithm {
+                parent,
+                length: 256,
+            },
+        };
+        unsafe {
+            rooted!(in(*cx) let mut alg: Value);
+            algorithm.to_jsval(*cx, alg.handle_mut());
+            NonNull::new(alg.to_object()).unwrap()
+        }
+    }
+
+    #[allow(unsafe_code)]
+    /// <https://w3c.github.io/webcrypto/#cryptokey-interface-members>
+    fn Usages(&self, cx: JSContext) -> NonNull<JSObject> {
+        unsafe {
+            rooted!(in(*cx) let mut usages: Value);
+            self.usages.to_jsval(*cx, usages.handle_mut());
+            NonNull::new(usages.to_object()).unwrap()
+        }
+    }
+}
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index cc5a60c7ef9..059f706b373 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -257,6 +257,7 @@ pub mod console;
 pub mod constantsourcenode;
 mod create;
 pub mod crypto;
+pub mod cryptokey;
 pub mod css;
 pub mod cssconditionrule;
 pub mod cssfontfacerule;
@@ -543,6 +544,7 @@ pub mod stylepropertymapreadonly;
 pub mod stylesheet;
 pub mod stylesheetlist;
 pub mod submitevent;
+pub mod subtlecrypto;
 pub mod svgelement;
 pub mod svggraphicselement;
 pub mod svgsvgelement;
diff --git a/components/script/dom/subtlecrypto.rs b/components/script/dom/subtlecrypto.rs
new file mode 100644
index 00000000000..81291df87f4
--- /dev/null
+++ b/components/script/dom/subtlecrypto.rs
@@ -0,0 +1,335 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::ptr;
+use std::rc::Rc;
+
+use dom_struct::dom_struct;
+use js::conversions::ConversionResult;
+use js::jsapi::JSObject;
+use js::jsval::ObjectValue;
+use js::typedarray::ArrayBufferU8;
+use servo_rand::{RngCore, ServoRng};
+
+use crate::dom::bindings::buffer_source::create_buffer_source;
+use crate::dom::bindings::cell::DomRefCell;
+use crate::dom::bindings::codegen::Bindings::CryptoKeyBinding::{
+    CryptoKeyMethods, KeyType, KeyUsage,
+};
+use crate::dom::bindings::codegen::Bindings::SubtleCryptoBinding::{
+    AesKeyGenParams, Algorithm, AlgorithmIdentifier, KeyAlgorithm, KeyFormat, SubtleCryptoMethods,
+};
+use crate::dom::bindings::error::Error;
+use crate::dom::bindings::inheritance::Castable;
+use crate::dom::bindings::refcounted::{Trusted, TrustedPromise};
+use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::str::DOMString;
+use crate::dom::cryptokey::{CryptoKey, Handle};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::promise::Promise;
+use crate::dom::window::Window;
+use crate::dom::workerglobalscope::WorkerGlobalScope;
+use crate::realms::InRealm;
+use crate::script_runtime::JSContext;
+use crate::task::TaskCanceller;
+use crate::task_source::dom_manipulation::DOMManipulationTaskSource;
+use crate::task_source::TaskSource;
+
+// String constants for algorithms/curves
+const ALG_AES_CBC: &str = "AES-CBC";
+const ALG_AES_CTR: &str = "AES-CTR";
+const ALG_AES_GCM: &str = "AES-GCM";
+const ALG_AES_KW: &str = "AES-KW";
+const ALG_SHA1: &str = "SHA1";
+const ALG_SHA256: &str = "SHA256";
+const ALG_SHA384: &str = "SHA384";
+const ALG_SHA512: &str = "SHA512";
+const ALG_HMAC: &str = "HMAC";
+const ALG_HKDF: &str = "HKDF";
+const ALG_PBKDF2: &str = "PBKDF2";
+const ALG_RSASSA_PKCS1: &str = "RSASSA-PKCS1-v1_5";
+const ALG_RSA_OAEP: &str = "RSA-OAEP";
+const ALG_RSA_PSS: &str = "RSA-PSS";
+const ALG_ECDH: &str = "ECDH";
+const ALG_ECDSA: &str = "ECDSA";
+#[allow(dead_code)]
+static SUPPORTED_ALGORITHMS: &[&str] = &[
+    ALG_AES_CBC,
+    ALG_AES_CTR,
+    ALG_AES_GCM,
+    ALG_AES_KW,
+    ALG_SHA1,
+    ALG_SHA256,
+    ALG_SHA384,
+    ALG_SHA512,
+    ALG_HMAC,
+    ALG_HKDF,
+    ALG_PBKDF2,
+    ALG_RSASSA_PKCS1,
+    ALG_RSA_OAEP,
+    ALG_RSA_PSS,
+    ALG_ECDH,
+    ALG_ECDSA,
+];
+
+const NAMED_CURVE_P256: &str = "P-256";
+const NAMED_CURVE_P384: &str = "P-384";
+const NAMED_CURVE_P521: &str = "P-521";
+#[allow(dead_code)]
+static SUPPORTED_CURVES: &[&str] = &[NAMED_CURVE_P256, NAMED_CURVE_P384, NAMED_CURVE_P521];
+
+#[dom_struct]
+pub struct SubtleCrypto {
+    reflector_: Reflector,
+    #[no_trace]
+    rng: DomRefCell<ServoRng>,
+}
+
+impl SubtleCrypto {
+    fn new_inherited() -> SubtleCrypto {
+        SubtleCrypto {
+            reflector_: Reflector::new(),
+            rng: DomRefCell::new(ServoRng::default()),
+        }
+    }
+
+    pub(crate) fn new(global: &GlobalScope) -> DomRoot<SubtleCrypto> {
+        reflect_dom_object(Box::new(SubtleCrypto::new_inherited()), global)
+    }
+
+    fn task_source_with_canceller(&self) -> (DOMManipulationTaskSource, TaskCanceller) {
+        if let Some(window) = self.global().downcast::<Window>() {
+            window
+                .task_manager()
+                .dom_manipulation_task_source_with_canceller()
+        } else if let Some(worker_global) = self.global().downcast::<WorkerGlobalScope>() {
+            let task_source = worker_global.dom_manipulation_task_source();
+            let canceller = worker_global.task_canceller();
+            (task_source, canceller)
+        } else {
+            unreachable!("Couldn't downcast to Window or WorkerGlobalScope!");
+        }
+    }
+}
+
+impl SubtleCryptoMethods for SubtleCrypto {
+    /// <https://w3c.github.io/webcrypto/#SubtleCrypto-method-generateKey>
+    fn GenerateKey(
+        &self,
+        cx: JSContext,
+        algorithm: AlgorithmIdentifier,
+        extractable: bool,
+        key_usages: Vec<KeyUsage>,
+        comp: InRealm,
+    ) -> Rc<Promise> {
+        let normalized_algorithm = normalize_algorithm(cx, algorithm, "generateKey");
+        let promise = Promise::new_in_current_realm(comp);
+        if let Err(e) = normalized_algorithm {
+            promise.reject_error(e);
+            return promise;
+        }
+
+        let (task_source, canceller) = self.task_source_with_canceller();
+        let this = Trusted::new(self);
+        let trusted_promise = TrustedPromise::new(promise.clone());
+        let alg = normalized_algorithm.clone();
+        let _ = task_source.queue_with_canceller(
+            task!(generate_key: move || {
+                let subtle = this.root();
+                let promise = trusted_promise.root();
+                let key = match alg {
+                    Ok(NormalizedAlgorithm::AesKeyGenParams(key_gen_params)) => {
+                        subtle.generate_key_aes_cbc(key_usages, key_gen_params, extractable)
+                    },
+                    _ => Err(Error::NotSupported),
+                };
+                match key {
+                    Ok(key) => promise.resolve_native(&key),
+                    Err(e) => promise.reject_error(e),
+                }
+            }),
+            &canceller,
+        );
+
+        promise
+    }
+
+    /// <https://w3c.github.io/webcrypto/#SubtleCrypto-method-exportKey>
+    #[allow(unsafe_code)]
+    fn ExportKey(&self, format: KeyFormat, key: &CryptoKey, comp: InRealm) -> Rc<Promise> {
+        let promise = Promise::new_in_current_realm(comp);
+
+        let (task_source, canceller) = self.task_source_with_canceller();
+        let this = Trusted::new(self);
+        let trusted_key = Trusted::new(key);
+        let trusted_promise = TrustedPromise::new(promise.clone());
+        let _ = task_source.queue_with_canceller(
+            task!(export_key: move || {
+                let subtle = this.root();
+                let promise = trusted_promise.root();
+                let key = trusted_key.root();
+                let alg_name = key.algorithm();
+                if matches!(
+                    alg_name.as_str(), ALG_SHA1 | ALG_SHA256 | ALG_SHA384 | ALG_SHA512 | ALG_HKDF | ALG_PBKDF2
+                ) {
+                    promise.reject_error(Error::NotSupported);
+                    return;
+                }
+                if !key.Extractable() {
+                    promise.reject_error(Error::InvalidAccess);
+                    return;
+                }
+                let exported_key = match alg_name.as_str() {
+                    ALG_AES_CBC => subtle.export_key_aes_cbc(format, &*key),
+                    _ => Err(Error::NotSupported),
+                };
+                match exported_key {
+                    Ok(k) => {
+                        let cx = GlobalScope::get_cx();
+                        rooted!(in(*cx) let mut array_buffer_ptr = ptr::null_mut::<JSObject>());
+                        create_buffer_source::<ArrayBufferU8>(cx, &k, array_buffer_ptr.handle_mut())
+                            .expect("failed to create buffer source for exported key.");
+                        promise.resolve_native(&array_buffer_ptr.get())
+                    },
+                    Err(e) => promise.reject_error(e),
+                }
+            }),
+            &canceller,
+        );
+
+        promise
+    }
+}
+
+#[derive(Clone)]
+pub enum NormalizedAlgorithm {
+    #[allow(dead_code)]
+    Algorithm(SubtleAlgorithm),
+    AesKeyGenParams(SubtleAesKeyGenParams),
+}
+
+// These "subtle" structs are proxies for the codegen'd dicts which don't hold a DOMString
+// so they can be sent safely when running steps in parallel.
+
+#[derive(Clone)]
+pub struct SubtleAlgorithm {
+    #[allow(dead_code)]
+    pub name: String,
+}
+
+impl From<DOMString> for SubtleAlgorithm {
+    fn from(name: DOMString) -> Self {
+        SubtleAlgorithm {
+            name: name.to_string(),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct SubtleAesKeyGenParams {
+    #[allow(dead_code)]
+    pub name: String,
+    pub length: u16,
+}
+
+impl From<AesKeyGenParams> for SubtleAesKeyGenParams {
+    fn from(params: AesKeyGenParams) -> Self {
+        SubtleAesKeyGenParams {
+            name: params.parent.name.to_string(),
+            length: params.length,
+        }
+    }
+}
+
+/// <https://w3c.github.io/webcrypto/#algorithm-normalization-normalize-an-algorithm>
+#[allow(unsafe_code)]
+fn normalize_algorithm(
+    cx: JSContext,
+    algorithm: AlgorithmIdentifier,
+    operation: &str,
+) -> Result<NormalizedAlgorithm, Error> {
+    match algorithm {
+        AlgorithmIdentifier::String(name) => Ok(NormalizedAlgorithm::Algorithm(name.into())),
+        AlgorithmIdentifier::Object(obj) => {
+            rooted!(in(*cx) let value = ObjectValue(unsafe { *obj.get_unsafe() }));
+            let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
+            else {
+                return Err(Error::Syntax);
+            };
+            match (algorithm.name.str().to_uppercase().as_str(), operation) {
+                (ALG_AES_CBC, "generateKey") => {
+                    let params_result =
+                        AesKeyGenParams::new(cx, value.handle()).map_err(|_| Error::Operation)?;
+                    let ConversionResult::Success(params) = params_result else {
+                        return Err(Error::Syntax);
+                    };
+                    Ok(NormalizedAlgorithm::AesKeyGenParams(params.into()))
+                },
+                _ => return Err(Error::NotSupported),
+            }
+        },
+    }
+}
+
+impl SubtleCrypto {
+    /// <https://w3c.github.io/webcrypto/#aes-cbc-operations>
+    fn generate_key_aes_cbc(
+        &self,
+        usages: Vec<KeyUsage>,
+        key_gen_params: SubtleAesKeyGenParams,
+        extractable: bool,
+    ) -> Result<DomRoot<CryptoKey>, Error> {
+        if !matches!(key_gen_params.length, 128 | 192 | 256) {
+            return Err(Error::Operation);
+        }
+
+        if usages.iter().any(|usage| {
+            !matches!(
+                usage,
+                KeyUsage::Encrypt | KeyUsage::Decrypt | KeyUsage::WrapKey | KeyUsage::UnwrapKey
+            )
+        }) || usages.is_empty()
+        {
+            return Err(Error::Syntax);
+        }
+
+        let mut rand = Vec::new();
+        rand.resize(key_gen_params.length as usize, 0);
+        self.rng.borrow_mut().fill_bytes(&mut rand);
+        let handle = match key_gen_params.length {
+            128 => Handle::Aes128(rand),
+            192 => Handle::Aes192(rand),
+            256 => Handle::Aes256(rand),
+            _ => return Err(Error::Operation),
+        };
+
+        Ok(CryptoKey::new(
+            &self.global(),
+            KeyType::Secret,
+            extractable,
+            KeyAlgorithm {
+                name: DOMString::from(ALG_AES_CBC),
+            },
+            usages,
+            handle,
+        ))
+    }
+
+    /// <https://w3c.github.io/webcrypto/#aes-cbc-operations>
+    fn export_key_aes_cbc(&self, format: KeyFormat, key: &CryptoKey) -> Result<Vec<u8>, Error> {
+        match format {
+            KeyFormat::Raw => match key.handle() {
+                Handle::Aes128(key) => Ok(key.as_slice().to_vec()),
+                Handle::Aes192(key) => Ok(key.as_slice().to_vec()),
+                Handle::Aes256(key) => Ok(key.as_slice().to_vec()),
+            },
+            KeyFormat::Jwk => {
+                // TODO: Support jwk
+                Err(Error::NotSupported)
+            },
+            _ => Err(Error::NotSupported),
+        }
+    }
+}
diff --git a/components/script/dom/webidls/Crypto.webidl b/components/script/dom/webidls/Crypto.webidl
index 84b14ff1d0c..0138e33a14f 100644
--- a/components/script/dom/webidls/Crypto.webidl
+++ b/components/script/dom/webidls/Crypto.webidl
@@ -17,7 +17,7 @@ WorkerGlobalScope includes GlobalCrypto;
 
 [Exposed=(Window,Worker)]
 interface Crypto {
-  //readonly attribute SubtleCrypto subtle;
+  [SecureContext] readonly attribute SubtleCrypto subtle;
   [Throws]
   ArrayBufferView getRandomValues(ArrayBufferView array);
 
diff --git a/components/script/dom/webidls/CryptoKey.webidl b/components/script/dom/webidls/CryptoKey.webidl
new file mode 100644
index 00000000000..1cad0097df2
--- /dev/null
+++ b/components/script/dom/webidls/CryptoKey.webidl
@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://w3c.github.io/webcrypto/#cryptokey-interface
+
+enum KeyType { "public", "private", "secret" };
+
+enum KeyUsage { "encrypt", "decrypt", "sign", "verify", "deriveKey", "deriveBits", "wrapKey", "unwrapKey" };
+
+[SecureContext, Exposed=(Window,Worker), Serializable, Pref="dom.crypto.subtle.enabled"]
+interface CryptoKey {
+  readonly attribute KeyType type;
+  readonly attribute boolean extractable;
+  readonly attribute object algorithm;
+  readonly attribute object usages;
+};
diff --git a/components/script/dom/webidls/SubtleCrypto.webidl b/components/script/dom/webidls/SubtleCrypto.webidl
new file mode 100644
index 00000000000..05e2df29ec3
--- /dev/null
+++ b/components/script/dom/webidls/SubtleCrypto.webidl
@@ -0,0 +1,87 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://w3c.github.io/webcrypto/#subtlecrypto-interface
+
+typedef (object or DOMString) AlgorithmIdentifier;
+
+typedef AlgorithmIdentifier HashAlgorithmIdentifier;
+
+dictionary Algorithm {
+  required DOMString name;
+};
+
+dictionary KeyAlgorithm {
+  required DOMString name;
+};
+
+enum KeyFormat { "raw", "spki", "pkcs8", "jwk" };
+
+[SecureContext,Exposed=(Window,Worker),Pref="dom.crypto.subtle.enabled"]
+interface SubtleCrypto {
+  // Promise<any> encrypt(AlgorithmIdentifier algorithm,
+  //                      CryptoKey key,
+  //                      BufferSource data);
+  // Promise<any> decrypt(AlgorithmIdentifier algorithm,
+  //                      CryptoKey key,
+  //                      BufferSource data);
+  // Promise<any> sign(AlgorithmIdentifier algorithm,
+  //                   CryptoKey key,
+  //                   BufferSource data);
+  // Promise<any> verify(AlgorithmIdentifier algorithm,
+  //                     CryptoKey key,
+  //                     BufferSource signature,
+  //                     BufferSource data);
+  // Promise<any> digest(AlgorithmIdentifier algorithm,
+  //                     BufferSource data);
+
+  Promise<any> generateKey(AlgorithmIdentifier algorithm,
+                          boolean extractable,
+                          sequence<KeyUsage> keyUsages );
+  // Promise<any> deriveKey(AlgorithmIdentifier algorithm,
+  //                        CryptoKey baseKey,
+  //                        AlgorithmIdentifier derivedKeyType,
+  //                        boolean extractable,
+  //                        sequence<KeyUsage> keyUsages );
+  // Promise<ArrayBuffer> deriveBits(AlgorithmIdentifier algorithm,
+  //                         CryptoKey baseKey,
+  //                         optional unsigned long? length = null);
+
+  // Promise<CryptoKey> importKey(KeyFormat format,
+  //                        (BufferSource or JsonWebKey) keyData,
+  //                        AlgorithmIdentifier algorithm,
+  //                        boolean extractable,
+  //                        sequence<KeyUsage> keyUsages );
+  Promise<any> exportKey(KeyFormat format, CryptoKey key);
+
+  // Promise<any> wrapKey(KeyFormat format,
+  //                      CryptoKey key,
+  //                      CryptoKey wrappingKey,
+  //                      AlgorithmIdentifier wrapAlgorithm);
+  // Promise<CryptoKey> unwrapKey(KeyFormat format,
+  //                        BufferSource wrappedKey,
+  //                        CryptoKey unwrappingKey,
+  //                        AlgorithmIdentifier unwrapAlgorithm,
+  //                        AlgorithmIdentifier unwrappedKeyAlgorithm,
+  //                        boolean extractable,
+  //                        sequence<KeyUsage> keyUsages );
+};
+
+// AES shared
+dictionary AesKeyAlgorithm : KeyAlgorithm {
+  required unsigned short length;
+};
+
+dictionary AesKeyGenParams : Algorithm {
+  required [EnforceRange] unsigned short length;
+};
+
+dictionary AesDerivedKeyParams : Algorithm {
+  required [EnforceRange] unsigned short length;
+};
+
+// AES_CBC
+dictionary AesCbcParams : Algorithm {
+  required BufferSource iv;
+};