age: Add streamlined APIs for encryption and decryption

Closes #333.

age/CHANGELOG.md

@@ -10,6 +10,11 @@ to 1.0.0 are beta releases.
 
 ## [Unreleased]
 ### Added
+- New streamlined APIs for use with a single recipient or identity and a small
+  amount of data (that can fit entirely in memory):
+  - `age::encrypt`
+  - `age::encrypt_and_armor`
+  - `age::decrypt`
 - `age::Decryptor::{decrypt, decrypt_async, is_scrypt}`
 - `age::IdentityFile::to_recipients`
 - `age::IdentityFile::with_callbacks`

age/src/lib.rs

@@ -27,7 +27,76 @@
 //!
 //! # Examples
 //!
-//! ## Recipient-based encryption
+//! ## Streamlined APIs
+//!
+//! These are useful when you only need to encrypt to a single recipient, and the data is
+//! small enough to fit in memory.
+//!
+//! ### Recipient-based encryption
+//!
+//! ```
+//! # fn run_main() -> Result<(), ()> {
+//! let key = age::x25519::Identity::generate();
+//! let pubkey = key.to_public();
+//!
+//! let plaintext = b"Hello world!";
+//!
+//! # fn encrypt(pubkey: age::x25519::Recipient, plaintext: &[u8]) -> Result<Vec<u8>, age::EncryptError> {
+//! let encrypted = age::encrypt(&pubkey, plaintext)?;
+//! # Ok(encrypted)
+//! # }
+//! # fn decrypt(key: age::x25519::Identity, encrypted: Vec<u8>) -> Result<Vec<u8>, age::DecryptError> {
+//! let decrypted = age::decrypt(&key, &encrypted)?;
+//! # Ok(decrypted)
+//! # }
+//! # let decrypted = decrypt(
+//! #     key,
+//! #     encrypt(pubkey, &plaintext[..]).map_err(|_| ())?
+//! # ).map_err(|_| ())?;
+//!
+//! assert_eq!(decrypted, plaintext);
+//! # Ok(())
+//! # }
+//! # run_main().unwrap();
+//! ```
+//!
+//! ## Passphrase-based encryption
+//!
+//! ```
+//! use age::secrecy::Secret;
+//!
+//! # fn run_main() -> Result<(), ()> {
+//! let passphrase = Secret::new("this is not a good passphrase".to_owned());
+//! let recipient = age::scrypt::Recipient::new(passphrase.clone());
+//! let identity = age::scrypt::Identity::new(passphrase);
+//!
+//! let plaintext = b"Hello world!";
+//!
+//! # fn encrypt(recipient: age::scrypt::Recipient, plaintext: &[u8]) -> Result<Vec<u8>, age::EncryptError> {
+//! let encrypted = age::encrypt(&recipient, plaintext)?;
+//! # Ok(encrypted)
+//! # }
+//! # fn decrypt(identity: age::scrypt::Identity, encrypted: Vec<u8>) -> Result<Vec<u8>, age::DecryptError> {
+//! let decrypted = age::decrypt(&identity, &encrypted)?;
+//! # Ok(decrypted)
+//! # }
+//! # let decrypted = decrypt(
+//! #     identity,
+//! #     encrypt(recipient, &plaintext[..]).map_err(|_| ())?
+//! # ).map_err(|_| ())?;
+//!
+//! assert_eq!(decrypted, plaintext);
+//! # Ok(())
+//! # }
+//! # run_main().unwrap();
+//! ```
+//!
+//! ## Full APIs
+//!
+//! The full APIs support encrypting to multiple recipients, streaming the data, and have
+//! async I/O options.
+//!
+//! ### Recipient-based encryption
 //!
 //! ```
 //! use std::io::{Read, Write};
@@ -164,6 +233,16 @@ pub mod cli_common;
 mod i18n;
 pub use i18n::localizer;
 
+//
+// Simple interface
+//
+
+mod simple;
+pub use simple::{decrypt, encrypt};
+
+#[cfg(feature = "armor")]
+pub use simple::encrypt_and_armor;
+
 //
 // Identity types
 //
@@ -180,6 +259,10 @@ pub mod plugin;
 #[cfg_attr(docsrs, doc(cfg(feature = "ssh")))]
 pub mod ssh;
 
+//
+// Core traits
+//
+
 use age_core::{
     format::{FileKey, Stanza},
     secrecy::SecretString,
@@ -342,6 +425,10 @@ impl Callbacks for NoCallbacks {
     }
 }
 
+//
+// Fuzzing APIs
+//
+
 /// Helper for fuzzing the Header parser and serializer.
 #[cfg(fuzzing)]
 pub fn fuzz_header(data: &[u8]) {

age/src/simple.rs

@@ -0,0 +1,106 @@
+use std::io::{Read, Write};
+use std::iter;
+
+use crate::{
+    error::{DecryptError, EncryptError},
+    Decryptor, Encryptor, Identity, Recipient,
+};
+
+#[cfg(feature = "armor")]
+use crate::armor::{ArmoredReader, ArmoredWriter, Format};
+
+/// Encrypts the given plaintext to the given recipient.
+///
+/// To encrypt to more than one recipient, use [`Encryptor::with_recipients`].
+///
+/// This function returns binary ciphertext. To obtain an ASCII-armored text string, use
+/// [`encrypt_and_armor`].
+pub fn encrypt(recipient: &impl Recipient, plaintext: &[u8]) -> Result<Vec<u8>, EncryptError> {
+    let encryptor =
+        Encryptor::with_recipients(iter::once(recipient as _)).expect("we provided a recipient");
+
+    let mut ciphertext = Vec::with_capacity(plaintext.len());
+    let mut writer = encryptor.wrap_output(&mut ciphertext)?;
+    writer.write_all(plaintext)?;
+    writer.finish()?;
+
+    Ok(ciphertext)
+}
+
+/// Encrypts the given plaintext to the given recipient, and wraps the ciphertext in ASCII
+/// armor.
+///
+/// To encrypt to more than one recipient, use [`Encryptor::with_recipients`] along with
+/// [`ArmoredWriter`].
+#[cfg(feature = "armor")]
+pub fn encrypt_and_armor(
+    recipient: &impl Recipient,
+    plaintext: &[u8],
+) -> Result<String, EncryptError> {
+    let encryptor =
+        Encryptor::with_recipients(iter::once(recipient as _)).expect("we provided a recipient");
+
+    let mut ciphertext = Vec::with_capacity(plaintext.len());
+    let mut writer = encryptor.wrap_output(ArmoredWriter::wrap_output(
+        &mut ciphertext,
+        Format::AsciiArmor,
+    )?)?;
+    writer.write_all(plaintext)?;
+    writer.finish()?.finish()?;
+
+    Ok(String::from_utf8(ciphertext).expect("is armored"))
+}
+
+/// Decrypts the given ciphertext with the given identity.
+///
+/// If the `armor` feature flag is enabled, this will also handle armored age ciphertexts.
+///
+/// To attempt decryption with more than one identity, use [`Decryptor`] (as well as
+/// [`ArmoredReader`] if the `armor` feature flag is enabled).
+pub fn decrypt(identity: &impl Identity, ciphertext: &[u8]) -> Result<Vec<u8>, DecryptError> {
+    #[cfg(feature = "armor")]
+    let decryptor = Decryptor::new_buffered(ArmoredReader::new(ciphertext))?;
+
+    #[cfg(not(feature = "armor"))]
+    let decryptor = Decryptor::new_buffered(ciphertext)?;
+
+    let mut plaintext = vec![];
+    let mut reader = decryptor.decrypt(iter::once(identity as _))?;
+    reader.read_to_end(&mut plaintext)?;
+
+    Ok(plaintext)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{decrypt, encrypt};
+    use crate::x25519;
+
+    #[cfg(feature = "armor")]
+    use super::encrypt_and_armor;
+
+    #[test]
+    fn x25519_round_trip() {
+        let sk: x25519::Identity = crate::x25519::tests::TEST_SK.parse().unwrap();
+        let pk: x25519::Recipient = crate::x25519::tests::TEST_PK.parse().unwrap();
+        let test_msg = b"This is a test message. For testing.";
+
+        let encrypted = encrypt(&pk, test_msg).unwrap();
+        let decrypted = decrypt(&sk, &encrypted).unwrap();
+        assert_eq!(&decrypted[..], &test_msg[..]);
+    }
+
+    #[cfg(feature = "armor")]
+    #[test]
+    fn x25519_round_trip_armor() {
+        let sk: x25519::Identity = crate::x25519::tests::TEST_SK.parse().unwrap();
+        let pk: x25519::Recipient = crate::x25519::tests::TEST_PK.parse().unwrap();
+        let test_msg = b"This is a test message. For testing.";
+
+        let encrypted = encrypt_and_armor(&pk, test_msg).unwrap();
+        assert!(encrypted.starts_with("-----BEGIN AGE ENCRYPTED FILE-----"));
+
+        let decrypted = decrypt(&sk, encrypted.as_bytes()).unwrap();
+        assert_eq!(&decrypted[..], &test_msg[..]);
+    }
+}