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//! Read/Write Wrapper for AES Encryption and Decryption during I/O Operations //! //! This crate provides an [`AesWriter`](struct.AesWriter.html), which can be used to wrap any //! existing [`Write`](https://doc.rust-lang.org/std/io/trait.Write.html) implementation with AES //! encryption, and [`AesReader`](struct.AesReader.html), which can wrap any existing //! [`Read`](https://doc.rust-lang.org/std/io/trait.Read.html) implemntation with AES decryption. //! If the inner reader provides a [`Seek`](https://doc.rust-lang.org/std/io/trait.Seek.html) //! implementation, AesReader will do so as well. //! See their struct-level documentation for more information. //! //! In fact this crate is not limited to AES. //! It can wrap any kind of [`BlockEncryptor`][be] i.e. [`BlockDecryptor`][bd] with CBC. //! //! [be]: https://docs.rs/rust-crypto/0.2.36/crypto/symmetriccipher/trait.BlockEncryptor.html //! [bd]: https://docs.rs/rust-crypto/0.2.36/crypto/symmetriccipher/trait.BlockEncryptor.html //! //! # Examples //! //! All examples use the following extern crates and imports: //! //! ```no_run //! extern crate crypto; //! extern crate rand; //! extern crate aesstream; //! //! use std::io::{Read, Write, Cursor}; //! use std::fs::File; //! use crypto::aessafe::{AesSafe128Encryptor, AesSafe128Decryptor}; //! use rand::{Rng, OsRng}; //! use aesstream::{AesWriter, AesReader}; //! # fn main() {} //! ``` //! //! You can use [`AesWriter`](struct.AesWriter.html) to wrap a file with encryption. //! //! ```no_run //! # extern crate crypto; //! # extern crate rand; //! # extern crate aesstream; //! # use std::io::{Write, Result}; //! # use std::fs::File; //! # use crypto::aessafe::AesSafe128Encryptor; //! # use rand::{Rng, OsRng}; //! # use aesstream::AesWriter; //! # fn encrypt() -> Result<()> { //! let key: [u8; 16] = OsRng::new()?.gen(); //! let file = File::create("...")?; //! let encryptor = AesSafe128Encryptor::new(&key); //! let mut writer = AesWriter::new(file, encryptor)?; //! writer.write_all("Hello World!".as_bytes())?; //! # Ok(()) //! # } //! # fn main() { let _ = encrypt(); } //! ``` //! //! And [`AesReader`](struct.AesReader.html) to decrypt it again. //! //! ```no_run //! # extern crate crypto; //! # extern crate rand; //! # extern crate aesstream; //! # use std::io::{Read, Result}; //! # use std::fs::File; //! # use crypto::aessafe::AesSafe128Decryptor; //! # use rand::{Rng, OsRng}; //! # use aesstream::AesReader; //! # fn decrypt() -> Result<()> { //! let key: [u8; 16] = OsRng::new()?.gen(); //! let file = File::open("...")?; //! let decryptor = AesSafe128Decryptor::new(&key); //! let mut reader = AesReader::new(file, decryptor)?; //! let mut decrypted = String::new(); //! reader.read_to_string(&mut decrypted)?; //! assert_eq!(decrypted, "Hello World!"); //! # Ok(()) //! # } //! # fn main() { let _ = decrypt(); } //! ``` //! //! They can be used to en- and decrypt in-memory as well. //! //! ``` //! # extern crate crypto; //! # extern crate rand; //! # extern crate aesstream; //! # use std::io::{Read, Write, Result, Cursor}; //! # use crypto::aessafe::{AesSafe128Encryptor, AesSafe128Decryptor}; //! # use rand::{Rng, OsRng}; //! # use aesstream::{AesWriter, AesReader}; //! # fn in_memory() -> Result<()> { //! let key: [u8; 16] = OsRng::new()?.gen(); //! let encryptor = AesSafe128Encryptor::new(&key); //! let mut encrypted = Vec::new(); //! { //! let mut writer = AesWriter::new(&mut encrypted, encryptor)?; //! writer.write_all("Hello World!".as_bytes())?; //! } //! let decryptor = AesSafe128Decryptor::new(&key); //! let mut reader = AesReader::new(Cursor::new(encrypted), decryptor)?; //! let mut decrypted = String::new(); //! reader.read_to_string(&mut decrypted)?; //! assert_eq!(decrypted, "Hello World!"); //! # Ok(()) //! # } //! # fn main() { let _ = in_memory(); } //! ``` extern crate crypto; extern crate rand; #[cfg(test)] mod tests; use std::io::{Read, Write, Seek, SeekFrom, Result, Error, ErrorKind}; use crypto::symmetriccipher::{BlockDecryptor, BlockEncryptor, Encryptor, Decryptor}; use crypto::blockmodes::{PkcsPadding, CbcEncryptor, CbcDecryptor, EncPadding, DecPadding}; use crypto::buffer::{RefReadBuffer, RefWriteBuffer, BufferResult, WriteBuffer, ReadBuffer}; use rand::{OsRng, Rng}; const BUFFER_SIZE: usize = 8192; /// Wraps a [`Write`](https://doc.rust-lang.org/std/io/trait.Write.html) implementation with CBC /// based on given [`BlockEncryptor`][be] /// /// [be]: https://docs.rs/rust-crypto/0.2.36/crypto/symmetriccipher/trait.BlockEncryptor.html /// /// # Examples /// /// Write encrypted to a file. /// /// ```no_run /// # extern crate crypto; /// # extern crate rand; /// # extern crate aesstream; /// # use std::io::{Write, Result}; /// # use std::fs::File; /// # use crypto::aessafe::AesSafe128Encryptor; /// # use rand::{OsRng, Rng}; /// # use aesstream::AesWriter; /// # fn foo() -> Result<()> { /// let key: [u8; 16] = OsRng::new()?.gen(); /// let file = File::create("...")?; /// let encryptor = AesSafe128Encryptor::new(&key); /// let mut writer = AesWriter::new(file, encryptor)?; /// writer.write_all("Hello World!".as_bytes())?; /// # Ok(()) /// # } /// # fn main() { let _ = foo(); } /// ``` /// /// Encrypt in-memory. /// /// ``` /// # extern crate crypto; /// # extern crate rand; /// # extern crate aesstream; /// # use std::io::{Write, Result, Cursor}; /// # use crypto::aessafe::AesSafe128Encryptor; /// # use rand::{OsRng, Rng}; /// # use aesstream::AesWriter; /// # fn foo() -> Result<()> { /// let key: [u8; 16] = OsRng::new()?.gen(); /// let encryptor = AesSafe128Encryptor::new(&key); /// let mut encrypted = Vec::new(); /// { /// let mut writer = AesWriter::new(&mut encrypted, encryptor)?; /// writer.write_all("Hello World!".as_bytes())?; /// } /// # Ok(()) /// # } /// # fn main() { let _ = foo(); } /// ``` pub struct AesWriter<E: BlockEncryptor, W: Write> { /// Writer to write encrypted data to writer: Option<W>, /// Encryptor to encrypt data with enc: CbcEncryptor<E, EncPadding<PkcsPadding>>, /// Indicates weather the encryptor has done its final operation (inserting padding) closed: bool, } impl<E: BlockEncryptor, W: Write> AesWriter<E, W> { /// Creates a new AesWriter with a random IV. /// /// The IV will be written as first block of the file. /// /// # Parameters /// /// * **writer**: Writer to write encrypted data into /// * **enc**: [`BlockEncryptor`][be] to use for encyrption /// /// # Examples /// /// ```no_run /// # extern crate crypto; /// # extern crate rand; /// # extern crate aesstream; /// # use crypto::aessafe::AesSafe128Encryptor; /// # use rand::{OsRng, Rng}; /// # use std::io::Result; /// # use std::fs::File; /// # use aesstream::AesWriter; /// # fn foo() -> Result<()> { /// let key: [u8; 16] = OsRng::new()?.gen(); /// let encryptor = AesSafe128Encryptor::new(&key); /// let file = File::create("...")?; /// let mut writer = AesWriter::new(file, encryptor)?; /// # Ok(()) /// # } /// # fn main() { let _ = foo(); } /// ``` /// /// [be]: https://docs.rs/rust-crypto/0.2.36/crypto/symmetriccipher/trait.BlockEncryptor.html pub fn new(mut writer: W, enc: E) -> Result<AesWriter<E, W>> { let mut iv = vec![0u8; enc.block_size()]; OsRng::new()?.fill_bytes(&mut iv); writer.write_all(&iv)?; Ok(AesWriter { writer: Some(writer), enc: CbcEncryptor::new(enc, PkcsPadding, iv), closed: false, }) } /// Encrypts passed buffer and writes all resulting encrypted blocks to the underlying writer /// /// # Parameters /// /// * **buf**: Plaintext to encrypt and write /// * **eof**: If the provided buf is the last one to come and therefore encryption should be /// finished and padding added. fn encrypt_write(&mut self, buf: &[u8], eof: bool) -> Result<usize> { let mut read_buf = RefReadBuffer::new(buf); let mut out = [0u8; BUFFER_SIZE]; let mut write_buf = RefWriteBuffer::new(&mut out); loop { let res = self.enc.encrypt(&mut read_buf, &mut write_buf, eof) .map_err(|e| Error::new(ErrorKind::Other, format!("encryption error: {:?}", e)))?; let mut enc = write_buf.take_read_buffer(); let enc = enc.take_remaining(); self.writer.as_mut().unwrap().write_all(enc)?; match res { BufferResult::BufferUnderflow => break, BufferResult::BufferOverflow if eof => panic!("read_buf underflow during encryption with eof"), BufferResult::BufferOverflow => {}, } } // CbcEncryptor has its own internal buffer and always consumes all input assert_eq!(read_buf.remaining(), 0); Ok(buf.len()) } } impl<E: BlockEncryptor, W: Write> Write for AesWriter<E, W> { /// Encrypts the passed buffer and writes the result to the underlying writer. /// /// Due to the blocksize of CBC not all data will be written instantaneously. /// For example if 17 bytes are passed, the first 16 will be encrypted as one block and written /// the underlying writer, but the last byte won't be encrypted and written yet. /// /// If [`flush`](#method.flush) has been called, this method will always return an error. fn write(&mut self, buf: &[u8]) -> Result<usize> { if self.closed { return Err(Error::new(ErrorKind::Other, "AesWriter is closed")); } let written = self.encrypt_write(buf, false)?; Ok(written) } /// Flush this output stream, ensuring that all intermediately buffered contents reach their destination. /// [Read more](https://doc.rust-lang.org/nightly/std/io/trait.Write.html#tymethod.flush) /// /// **Warning**: When this method is called, the encryption will finish and insert final padding. /// After calling `flush`, this writer cannot be written to anymore and will always return an /// error. fn flush(&mut self) -> Result<()> { if self.closed { return Ok(()); } self.encrypt_write(&[], true)?; self.closed = true; self.writer.as_mut().unwrap().flush() } } impl<E: BlockEncryptor, W: Write> Drop for AesWriter<E, W> { /// Drops this AesWriter trying to finish encryption and to write everything to the underlying writer. fn drop(&mut self) { if self.writer.is_some() { if !std::thread::panicking() { self.flush().unwrap(); } else { let _ = self.flush(); } } } } /// Wraps a [`Read`](https://doc.rust-lang.org/std/io/trait.Read.html) implementation with CBC /// based on given [`BlockDecryptor`][bd] /// /// [bd]: https://docs.rs/rust-crypto/0.2.36/crypto/symmetriccipher/trait.BlockDecryptor.html /// /// # Examples /// /// Read encrypted file. /// /// ```no_run /// # extern crate crypto; /// # extern crate rand; /// # extern crate aesstream; /// # use std::io::{Read, Result}; /// # use std::fs::File; /// # use crypto::aessafe::AesSafe128Decryptor; /// # use rand::{OsRng, Rng}; /// # use aesstream::AesReader; /// # fn foo() -> Result<()> { /// let key: [u8; 16] = OsRng::new()?.gen(); /// let file = File::open("...")?; /// let decryptor = AesSafe128Decryptor::new(&key); /// let mut reader = AesReader::new(file, decryptor)?; /// let mut decrypted = Vec::new(); /// reader.read_to_end(&mut decrypted)?; /// # Ok(()) /// # } /// # fn main() { let _ = foo(); } /// ``` /// /// Decrypt in-memory. /// /// ``` /// # extern crate crypto; /// # extern crate rand; /// # extern crate aesstream; /// # use std::io::{Read, Result, Cursor}; /// # use std::fs::File; /// # use crypto::aessafe::AesSafe128Decryptor; /// # use rand::{OsRng, Rng}; /// # use aesstream::AesReader; /// # fn foo() -> Result<()> { /// let encrypted = vec![]; /// let key: [u8; 16] = OsRng::new()?.gen(); /// let decryptor = AesSafe128Decryptor::new(&key); /// let mut reader = AesReader::new(Cursor::new(encrypted), decryptor)?; /// let mut decrypted = Vec::new(); /// reader.read_to_end(&mut decrypted)?; /// # Ok(()) /// # } /// # fn main() { let _ = foo(); } /// ``` pub struct AesReader<D: BlockDecryptor, R: Read> { /// Reader to read encrypted data from reader: R, /// Decryptor to decrypt data with dec: CbcDecryptor<D, DecPadding<PkcsPadding>>, /// Block size of BlockDecryptor, needed when seeking to correctly seek to the nearest block block_size: usize, /// Buffer used to store blob needed to find out if we reached eof buffer: Vec<u8>, /// Indicates wheather eof of the underlying buffer was reached eof: bool, } impl<D: BlockDecryptor, R: Read> AesReader<D, R> { /// Creates a new AesReader. /// /// Assumes that the first block of given reader is the IV. /// /// # Parameters /// /// * **reader**: Reader to read encrypted data from /// * **dec**: [`BlockDecryptor`][bd] to use for decyrption /// /// # Examples /// /// ```no_run /// # extern crate crypto; /// # extern crate rand; /// # extern crate aesstream; /// # use crypto::aessafe::AesSafe128Decryptor; /// # use rand::{OsRng, Rng}; /// # use std::io::Result; /// # use std::fs::File; /// # use aesstream::AesReader; /// # fn foo() -> Result<()> { /// let key: [u8; 16] = OsRng::new()?.gen(); /// let decryptor = AesSafe128Decryptor::new(&key); /// let file = File::open("...")?; /// let mut reader = AesReader::new(file, decryptor)?; /// # Ok(()) /// # } /// # fn main() { let _ = foo(); } /// ``` /// /// [bd]: https://docs.rs/rust-crypto/0.2.36/crypto/symmetriccipher/trait.BlockDecryptor.html pub fn new(mut reader: R, dec: D) -> Result<AesReader<D, R>> { let mut iv = vec![0u8; dec.block_size()]; reader.read_exact(&mut iv)?; Ok(AesReader { reader: reader, block_size: dec.block_size(), dec: CbcDecryptor::new(dec, PkcsPadding, iv), buffer: Vec::new(), eof: false, }) } /// Reads at max BUFFER_SIZE bytes, handles potential eof and returns the buffer as Vec<u8> fn fill_buf(&mut self) -> Result<Vec<u8>> { let mut eof_buffer = vec![0u8; BUFFER_SIZE]; let read = self.reader.read(&mut eof_buffer)?; self.eof = read == 0; eof_buffer.truncate(read); Ok(eof_buffer) } /// Reads and decrypts data from the underlying stream and writes it into the passed buffer. /// /// The CbcDecryptor has an internal output buffer, but not an input buffer. /// Therefore, we need to take care of letfover input. /// Additionally, we need to handle eof correctly, as CbcDecryptor needs to correctly interpret /// padding. /// Thus, we need to read 2 buffers. The first one is read as input for decryption and the second /// one to determine if eof is reached. /// The next time this function is called, the second buffer is passed as input into decryption /// and the first buffer is filled to find out if we reached eof. /// /// # Parameters /// /// * **buf**: Buffer to write decrypted data into. fn read_decrypt(&mut self, buf: &mut [u8]) -> Result<usize> { // if this is the first iteration, fill internal buffer if self.buffer.is_empty() && !self.eof { self.buffer = self.fill_buf()?; } let buf_len = buf.len(); let mut write_buf = RefWriteBuffer::new(buf); let res; let remaining; { let mut read_buf = RefReadBuffer::new(&self.buffer); // test if CbcDecryptor still has enough decrypted data or we have enough buffered res = self.dec.decrypt(&mut read_buf, &mut write_buf, self.eof) .map_err(|e| Error::new(ErrorKind::Other, format!("decryption error: {:?}", e)))?; remaining = read_buf.remaining(); } // keep remaining bytes let len = self.buffer.len(); self.buffer.drain(..(len - remaining)); // if we were able to decrypt, return early match res { BufferResult::BufferOverflow => return Ok(buf_len), BufferResult::BufferUnderflow if self.eof => return Ok(write_buf.position()), _ => {} } // else read new buffer let mut dec_len = 0; // We must return something, if we have something. // If the reader doesn't return enough so that we can decrypt a block, we need to continue // reading until we have enough data to return one decrypted block, or until we reach eof. // If we reach eof, we will be able to decrypt the final block because of padding. while dec_len == 0 && !self.eof { let eof_buffer = self.fill_buf()?; let remaining; { let mut read_buf = RefReadBuffer::new(&self.buffer); self.dec.decrypt(&mut read_buf, &mut write_buf, self.eof) .map_err(|e| Error::new(ErrorKind::Other, format!("decryption error: {:?}", e)))?; let mut dec = write_buf.take_read_buffer(); let dec = dec.take_remaining(); dec_len = dec.len(); remaining = read_buf.remaining(); } // keep remaining bytes let len = self.buffer.len(); self.buffer.drain(..(len - remaining)); // append newly read bytes self.buffer.extend(eof_buffer); } Ok(dec_len) } } impl<D: BlockDecryptor, R: Read + Seek> AesReader<D, R> { /// Seeks to *offset* from the start of the file fn seek_from_start(&mut self, offset: u64) -> Result<u64> { let block_num = offset / self.block_size as u64; let block_offset = offset % self.block_size as u64; // reset CbcDecryptor self.reader.seek(SeekFrom::Start((block_num - 1) * self.block_size as u64))?; let mut iv = vec![0u8; self.block_size]; self.reader.read_exact(&mut iv)?; self.dec.reset(&iv); self.buffer = Vec::new(); self.eof = false; let mut skip = vec![0u8; block_offset as usize]; self.read_exact(&mut skip)?; // subtract IV Ok(offset - 16) } } impl<D: BlockDecryptor, R: Read> Read for AesReader<D, R> { /// Reads encrypted data from the underlying reader, decrypts it and writes the result into the /// passed buffer. fn read(&mut self, buf: &mut [u8]) -> Result<usize> { let read = self.read_decrypt(buf)?; Ok(read) } } impl<D: BlockDecryptor, R: Read + Seek> Seek for AesReader<D, R> { /// Seek to an offset, in bytes, in a stream. /// [Read more](https://doc.rust-lang.org/nightly/std/io/trait.Seek.html#tymethod.seek) /// /// When seeking, this reader takes care of reinitializing the CbcDecryptor with the correct IV. /// The passed position does *not* need to be aligned to the blocksize. fn seek(&mut self, pos: SeekFrom) -> Result<u64> { match pos { SeekFrom::Start(offset) => { // +16 because first block is the iv self.seek_from_start(offset + 16) }, SeekFrom::End(_) | SeekFrom::Current(_) => { let pos = self.reader.seek(pos)?; self.seek_from_start(pos) }, } } }