如何更改此功能的返回类型？

Question

我正在通过使用rust的matasano加密挑战 ，以及用于AES实现的rust-crypto。 我有这个功能来进行基本的ECB模式加密（基本上从rust-crypto存储库的例子中逐字逐句）：

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)
}

上面的版本编译没有问题，并按预期工作。 但是，为了使其适合我的错误处理方案的其余部分，我想将返回类型更改为Result<Vec<u8>,&'static str> 。 这是应用该更改的功能：

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)
}

当我尝试编译此版本时，我收到以下错误（为清晰起见，删除了路径）：

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);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

我能够改变这种类型的唯一方法是将原始函数包装在这样的转换函数中：

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")
   } 
}

为了使返回值适合我的其余API，我应该做什么而不是上面的内容，为什么更直接的方法失败？

我使用以下版本的锈/货：

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)

Answer 1

我想你遇到过编译器的错误。 你的代码应该编译

你可以use crypto::symmetriccipher::Encryptor; 作为一种解决方法：

pub fn aes_enc_ecb_128(key: &[u8], data: &[u8]) 
                       -> Result<Vec<u8>, &'static str> {
    use crypto::symmetriccipher::Encryptor;
    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)
}