I will look at matasano cryptography problems using rust, with rust to implement AES. I have this function to do basic encryption in ECB mode (basically taken almost verbatim from the rust-crypto storage example ):
pub fn aes_enc_ecb_128(key: &[u8], data: &[u8])
-> Result<Vec<u8>, symmetriccipher::SymmetricCipherError> {
let mut encryptor = aes::ecb_encryptor(
aes::KeySize::KeySize128,
key,
blockmodes::NoPadding);
let mut final_result = Vec::<u8>::new();
let mut read_buffer = buffer::RefReadBuffer::new(data);
let mut buffer = [0; 4096];
let mut write_buffer = buffer::RefWriteBuffer::new(&mut buffer);
loop {
let result = encryptor.encrypt(&mut read_buffer,
&mut write_buffer,
true);
final_result.extend(write_buffer
.take_read_buffer()
.take_remaining().iter().map(|&i| i));
match result {
Ok(BufferResult::BufferUnderflow) => break,
Ok(_) => {},
Err(e) => return Err(e)
}
}
Ok(final_result)
}
The above version compiles without problems and works as expected. However, to fit the rest of my error handling scheme, I would like to change the return type to Result<Vec<u8>,&'static str>. This is the function with this change:
pub fn aes_enc_ecb_128(key: &[u8], data: &[u8])
-> Result<Vec<u8>, &'static str> {
let mut encryptor = aes::ecb_encryptor(
aes::KeySize::KeySize128,
key,
blockmodes::NoPadding);
let mut final_result = Vec::<u8>::new();
let mut read_buffer = buffer::RefReadBuffer::new(data);
let mut buffer = [0; 4096];
let mut write_buffer = buffer::RefWriteBuffer::new(&mut buffer);
loop {
let result = encryptor.encrypt(&mut read_buffer,
&mut write_buffer,
true);
final_result.extend(write_buffer
.take_read_buffer()
.take_remaining().iter().map(|&i| i));
match result {
Ok(BufferResult::BufferUnderflow) => break,
Ok(_) => {},
Err(_) => return Err("Encryption failed")
}
}
Ok(final_result)
}
When I try to compile this version, I get the following error (paths removed for clarity):
error: source trait is private
let result = encryptor.encrypt(&mut read_buffer,
&mut write_buffer,
true);
error: source trait is private
let r = decryptor.decrypt(&mut read_buffer, &mut write_buffer, true);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The only way I was able to change this type is to wrap the original function in a conversion function as follows:
pub fn converted_enc(key: &[u8], data: &[u8])
-> Result<Vec<u8>, &'static str> {
match aes_enc_ecb_128(key,data) {
Ok(v) => Ok(v),
Err(_) => Err("Encryption failed")
}
}
, , API, ?
/:
rustc 1.2.0-nightly (0cc99f9cc 2015-05-17) (built 2015-05-18)
cargo 0.2.0-nightly (ac61996 2015-05-17) (built 2015-05-17)