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Add Cookie::{encrypt,decrypt,sign,verify}(). #229

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Add Cookie::{encrypt,decrypt,sign,verify}(). #229

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103 changes: 96 additions & 7 deletions src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29,22 +29,29 @@
//!
//! * **`signed`**
//!
//! Enables _signed_ cookies via [`CookieJar::signed()`].
//! Enables _signed_ cookies via [`Cookie::sign()`], [`Cookie::verify()`], and
//! [`CookieJar::signed()`].
//!
//! When this feature is enabled, the [`CookieJar::signed()`] method,
//! [`SignedJar`] type, and [`Key`] type are available. The jar acts as "child
//! When this feature is enabled, the type [`Key`] and the methods
//! [`Cookie::sign()`] and [`Cookie::verify()`] are available, which can be
//! used to sign and verify cookies. Additionally, the type [`SignedJar`] and
//! the method [`CookieJar::signed()`] is available. The jar acts as "child
//! jar"; operations on the jar automatically sign and verify cookies as they
//! are added and retrieved from the parent jar.
//!
//! * **`private`**
//!
//! Enables _private_ (authenticated, encrypted) cookies via
//! [`Cookie::encrypt()`], [`Cookie::decrypt()`], and
//! [`CookieJar::private()`].
//!
//! When this feature is enabled, the [`CookieJar::private()`] method,
//! [`PrivateJar`] type, and [`Key`] type are available. The jar acts as "child
//! jar"; operations on the jar automatically encrypt and decrypt/authenticate
//! cookies as they are added and retrieved from the parent jar.
//! When this feature is enabled, the type [`Key`] and the methods
//! [`Cookie::encrypt()`] and [`Cookie::decrypt()`] are available, which can
//! be used to encrypt and decrypt/authenticate cookies. Additionally, the
//! type [`PrivateJar`] and the method [`CookieJar::private()`] is available.
//! The jar acts as "child jar"; operations on the jar automatically encrypt
//! and decrypt/authenticate cookies as they are added and retrieved from the
//! parent jar.
//!
//! * **`key-expansion`**
//!
Expand Down Expand Up @@ -1415,6 +1422,88 @@ assert_eq!(&c.stripped().encoded().to_string(), "key%3F=value");
pub fn stripped<'a>(&'a self) -> Display<'a, 'c> {
Display::new_stripped(self)
}

/// Encrypts and signs this cookie using authenticated encryption with the
/// provided key and returns the encrypted cookie.
///
/// # Example
///
/// ```rust
/// use cookie::{Cookie, Key};
///
/// let key = Key::generate();
/// let plain = Cookie::from(("name", "value"));
/// let encrypted = plain.encrypt(&key);
/// ```
#[cfg(feature = "private")]
#[cfg_attr(all(nightly, doc), doc(cfg(feature = "private")))]
pub fn encrypt(&self, key: &Key) -> Cookie<'static> {
let mut cookie = self.clone().into_owned();
secure::encrypt_cookie(&mut cookie, key.encryption());
cookie
}

/// Authenticates and decrypts this cookie with the provided key and returns
/// the plaintext version if decryption succeeds or `None` otherwise.
///
/// # Example
///
/// ```rust
/// use cookie::{Cookie, Key};
///
/// let key = Key::generate();
/// let plain = Cookie::from(("name", "value"));
/// let encrypted = plain.encrypt(&key);
///
/// let decrypted = encrypted.decrypt(&key).unwrap();
/// assert_eq!(decrypted.value(), "value");
/// ```
#[cfg(feature = "private")]
#[cfg_attr(all(nightly, doc), doc(cfg(feature = "private")))]
pub fn decrypt(&self, key: &Key) -> Option<Cookie<'static>> {
secure::decrypt_cookie(self, key.encryption())
}

/// Signs this cookie with the provided key and returns the signed cookie.
///
/// # Example
///
/// ```rust
/// use cookie::{Cookie, Key};
///
/// let key = Key::generate();
/// let plain = Cookie::from(("name", "value"));
/// let signed = plain.sign(&key);
/// ```
#[cfg(feature = "signed")]
#[cfg_attr(all(nightly, doc), doc(cfg(feature = "signed")))]
pub fn sign(&self, key: &Key) -> Cookie<'static> {
let mut cookie = self.clone().into_owned();
secure::sign_cookie(&mut cookie, key.signing());
cookie
}

/// Verifies the signature of this cookie with the provided key and returns
/// the plaintext version if verification succeeds or `None` otherwise.
///
/// # Example
///
/// ```rust
/// use cookie::{Cookie, Key};
///
/// let key = Key::generate();
/// let plain = Cookie::from(("name", "value"));
/// let signed = plain.sign(&key);
///
/// let verified = signed.verify(&key).unwrap();
/// assert_eq!(verified.value(), "value");
/// ```
#[cfg(feature = "signed")]
#[cfg_attr(all(nightly, doc), doc(cfg(feature = "signed")))]
pub fn verify(&self, key: &Key) -> Option<Cookie<'static>> {
secure::verify_cookie(self, key.signing())
}

}

/// An iterator over cookie parse `Result`s: `Result<Cookie, ParseError>`.
Expand Down
126 changes: 66 additions & 60 deletions src/secure/private.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -37,56 +37,6 @@ impl<J> PrivateJar<J> {
PrivateJar { parent, key: key.encryption().try_into().expect("enc key len") }
}

/// Encrypts the cookie's value with authenticated encryption providing
/// confidentiality, integrity, and authenticity.
fn encrypt_cookie(&self, cookie: &mut Cookie) {
// Create a vec to hold the [nonce | cookie value | tag].
let cookie_val = cookie.value().as_bytes();
let mut data = vec![0; NONCE_LEN + cookie_val.len() + TAG_LEN];

// Split data into three: nonce, input/output, tag. Copy input.
let (nonce, in_out) = data.split_at_mut(NONCE_LEN);
let (in_out, tag) = in_out.split_at_mut(cookie_val.len());
in_out.copy_from_slice(cookie_val);

// Fill nonce piece with random data.
let mut rng = self::rand::thread_rng();
rng.try_fill_bytes(nonce).expect("couldn't random fill nonce");
let nonce = GenericArray::clone_from_slice(nonce);

// Perform the actual sealing operation, using the cookie's name as
// associated data to prevent value swapping.
let aad = cookie.name().as_bytes();
let aead = Aes256Gcm::new(GenericArray::from_slice(&self.key));
let aad_tag = aead.encrypt_in_place_detached(&nonce, aad, in_out)
.expect("encryption failure!");

// Copy the tag into the tag piece.
tag.copy_from_slice(&aad_tag);

// Base64 encode [nonce | encrypted value | tag].
cookie.set_value(base64::encode(&data));
}

/// Given a sealed value `str` and a key name `name`, where the nonce is
/// prepended to the original value and then both are Base64 encoded,
/// verifies and decrypts the sealed value and returns it. If there's a
/// problem, returns an `Err` with a string describing the issue.
fn unseal(&self, name: &str, value: &str) -> Result<String, &'static str> {
let data = base64::decode(value).map_err(|_| "bad base64 value")?;
if data.len() <= NONCE_LEN {
return Err("length of decoded data is <= NONCE_LEN");
}

let (nonce, cipher) = data.split_at(NONCE_LEN);
let payload = Payload { msg: cipher, aad: name.as_bytes() };

let aead = Aes256Gcm::new(GenericArray::from_slice(&self.key));
aead.decrypt(GenericArray::from_slice(nonce), payload)
.map_err(|_| "invalid key/nonce/value: bad seal")
.and_then(|s| String::from_utf8(s).map_err(|_| "bad unsealed utf8"))
}

/// Authenticates and decrypts `cookie`, returning the plaintext version if
/// decryption succeeds or `None` otherwise. Authenticatation and decryption
/// _always_ succeeds if `cookie` was generated by a `PrivateJar` with the
Expand All @@ -112,13 +62,8 @@ impl<J> PrivateJar<J> {
/// let plain = Cookie::new("plaintext", "hello");
/// assert!(jar.private(&key).decrypt(plain).is_none());
/// ```
pub fn decrypt(&self, mut cookie: Cookie<'static>) -> Option<Cookie<'static>> {
if let Ok(value) = self.unseal(cookie.name(), cookie.value()) {
cookie.set_value(value);
return Some(cookie);
}

None
pub fn decrypt(&self, cookie: Cookie<'static>) -> Option<Cookie<'static>> {
decrypt_cookie(&cookie, &self.key)
}
}

Expand All @@ -143,7 +88,7 @@ impl<J: Borrow<CookieJar>> PrivateJar<J> {
/// assert_eq!(private_jar.get("name").unwrap().value(), "value");
/// ```
pub fn get(&self, name: &str) -> Option<Cookie<'static>> {
self.parent.borrow().get(name).and_then(|c| self.decrypt(c.clone()))
self.parent.borrow().get(name).and_then(|c| decrypt_cookie(c, &self.key))
}
}

Expand All @@ -166,7 +111,7 @@ impl<J: BorrowMut<CookieJar>> PrivateJar<J> {
/// ```
pub fn add<C: Into<Cookie<'static>>>(&mut self, cookie: C) {
let mut cookie = cookie.into();
self.encrypt_cookie(&mut cookie);
encrypt_cookie(&mut cookie, &self.key);
self.parent.borrow_mut().add(cookie);
}

Expand Down Expand Up @@ -194,7 +139,7 @@ impl<J: BorrowMut<CookieJar>> PrivateJar<J> {
/// ```
pub fn add_original<C: Into<Cookie<'static>>>(&mut self, cookie: C) {
let mut cookie = cookie.into();
self.encrypt_cookie(&mut cookie);
encrypt_cookie(&mut cookie, &self.key);
self.parent.borrow_mut().add_original(cookie);
}

Expand Down Expand Up @@ -226,6 +171,67 @@ impl<J: BorrowMut<CookieJar>> PrivateJar<J> {
}
}

/// Encrypts `cookie` in-place using authenticated encryption with the provided
/// key `key`.
pub(crate) fn encrypt_cookie(cookie: &mut Cookie<'static>, key: &[u8]) {
// Create a vec to hold the [nonce | cookie value | tag].
let cookie_val = cookie.value().as_bytes();
let mut data = vec![0; NONCE_LEN + cookie_val.len() + TAG_LEN];

// Split data into three: nonce, input/output, tag. Copy input.
let (nonce, in_out) = data.split_at_mut(NONCE_LEN);
let (in_out, tag) = in_out.split_at_mut(cookie_val.len());
in_out.copy_from_slice(cookie_val);

// Fill nonce piece with random data.
let mut rng = rand::thread_rng();
rng.try_fill_bytes(nonce).expect("couldn't random fill nonce");
let nonce = GenericArray::clone_from_slice(nonce);

// Perform the actual sealing operation, using the cookie's name as
// associated data to prevent value swapping.
let aad = cookie.name().as_bytes();
let aead = Aes256Gcm::new(GenericArray::from_slice(key));
let aad_tag = aead.encrypt_in_place_detached(&nonce, aad, in_out)
.expect("encryption failure!");

// Copy the tag into the tag piece.
tag.copy_from_slice(&aad_tag);

// Base64 encode [nonce | encrypted value | tag].
let new_value = base64::encode(&data);

// Return encrypted cookie.
cookie.set_value(new_value);
}

/// Authenticates and decrypts `cookie` using the provided key `key` and returns
/// the plaintext version if decryption succeeds, otherwise `None`.
pub(crate) fn decrypt_cookie<'a>(cookie: &Cookie<'a>, key: &[u8]) -> Option<Cookie<'static>> {
if let Ok(value) = decrypt_cookie_impl(cookie, key) {
let mut cookie = cookie.clone().into_owned();
cookie.set_value(value);
return Some(cookie);
}

None
}

fn decrypt_cookie_impl<'a>(cookie: &Cookie<'a>, key: &[u8]) -> Result<String, &'static str> {
let data = base64::decode(cookie.value()).map_err(|_| "bad base64 value")?;
if data.len() <= NONCE_LEN {
return Err("length of decoded data is <= NONCE_LEN");
}

let (nonce, cipher) = data.split_at(NONCE_LEN);
let payload = Payload { msg: cipher, aad: cookie.name().as_bytes() };

let aead = Aes256Gcm::new(GenericArray::from_slice(key));
aead.decrypt(GenericArray::from_slice(nonce), payload)
.map_err(|_| "invalid key/nonce/value: bad seal")
.and_then(|s| String::from_utf8(s).map_err(|_| "bad unsealed utf8"))
}

#[cfg(test)]
mod test {
use crate::{CookieJar, Cookie, Key};
Expand Down
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