Am 16.10.2016 um 05:22 schrieb Stephan Mueller <smueller@xxxxxxxxxx>:
> The previous description have been misleading and partially incorrect.
>
> Reported-by: Harsh Jain <harshjain.prof@xxxxxxxxx>
> Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
> ---
> crypto/algif_aead.c | 14 ++------------
> include/crypto/aead.h | 35 +++++++++++------------------------
> 2 files changed, 13 insertions(+), 36 deletions(-)
>
> diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
> index 80a0f1a..a0d8377 100644
> --- a/crypto/algif_aead.c
> +++ b/crypto/algif_aead.c
> @@ -551,18 +551,8 @@ static int aead_recvmsg_sync(struct socket *sock, struct msghdr *msg, int flags)
> lock_sock(sk);
>
> /*
> - * AEAD memory structure: For encryption, the tag is appended to the
> - * ciphertext which implies that the memory allocated for the ciphertext
> - * must be increased by the tag length. For decryption, the tag
> - * is expected to be concatenated to the ciphertext. The plaintext
> - * therefore has a memory size of the ciphertext minus the tag length.
> - *
> - * The memory structure for cipher operation has the following
> - * structure:
> - * AEAD encryption input: assoc data || plaintext
> - * AEAD encryption output: cipherntext || auth tag
> - * AEAD decryption input: assoc data || ciphertext || auth tag
> - * AEAD decryption output: plaintext
> + * Please see documentation of aead_request_set_crypt for the
> + * description of the AEAD memory structure expected from the caller.
> */
>
> if (ctx->more) {
> diff --git a/include/crypto/aead.h b/include/crypto/aead.h
> index 1bd3a2f..b7f3373 100644
> --- a/include/crypto/aead.h
> +++ b/include/crypto/aead.h
> @@ -483,30 +483,17 @@ static inline void aead_request_set_callback(struct aead_request *req,
> * destination is the ciphertext. For a decryption operation, the use is
> * reversed - the source is the ciphertext and the destination is the plaintext.
> *
> - * For both src/dst the layout is associated data, plain/cipher text,
> - * authentication tag.
> - *
> - * The content of the AD in the destination buffer after processing
> - * will either be untouched, or it will contain a copy of the AD
> - * from the source buffer. In order to ensure that it always has
> - * a copy of the AD, the user must copy the AD over either before
> - * or after processing. Of course this is not relevant if the user
> - * is doing in-place processing where src == dst.
> - *
> - * IMPORTANT NOTE AEAD requires an authentication tag (MAC). For decryption,
> - * the caller must concatenate the ciphertext followed by the
> - * authentication tag and provide the entire data stream to the
> - * decryption operation (i.e. the data length used for the
> - * initialization of the scatterlist and the data length for the
> - * decryption operation is identical). For encryption, however,
> - * the authentication tag is created while encrypting the data.
> - * The destination buffer must hold sufficient space for the
> - * ciphertext and the authentication tag while the encryption
> - * invocation must only point to the plaintext data size. The
> - * following code snippet illustrates the memory usage
> - * buffer = kmalloc(ptbuflen + (enc ? authsize : 0));
> - * sg_init_one(&sg, buffer, ptbuflen + (enc ? authsize : 0));
> - * aead_request_set_crypt(req, &sg, &sg, ptbuflen, iv);
> + * The memory structure for cipher operation has the following structure:
> + * AEAD encryption input: assoc data || plaintext
> + * AEAD encryption output: assoc data || cipherntext || auth tag
> + * AEAD decryption input: assoc data || ciphertext || auth tag
> + * AEAD decryption output: assoc data || plaintext
> + *
Hi Stephan,
as I wrote before in 3/7, you can use the reST markup in source
code comments. If you want a list markup, I recommend to write:
* The memory structure for cipher operation has the following structure:
*
* - AEAD encryption input: assoc data || plaintext
* - AEAD encryption output: assoc data || cipherntext || auth tag
* - AEAD decryption input: assoc data || ciphertext || auth tag
* - AEAD decryption output: assoc data || plaintext
*
And if you want a inline literal you can use the backquotes
* - AEAD decryption output: ``assoc data || plaintext``
reST is a simple ASCII markup, I can't advice excessive markup
in source code, but simple inline- or block-markups like lists
and code-blocks are sometimes helpful. For this, the the first
half of the reST primer is advisable:
http://www.sphinx-doc.org/en/stable/rest.html
These are only my 2cent in hope that helps ... there is no rule
to use any special markup ... use markup as you prefer ;-)
--Markus --
> + * Albeit the kernel requires the presence of the AAD buffer, however,
> + * the kernel does not fill the AAD buffer in the output case. If the
> + * caller wants to have that data buffer filled, the caller must either
> + * use an in-place cipher operation (i.e. same memory location for
> + * input/output memory location).
> */
> static inline void aead_request_set_crypt(struct aead_request *req,
> struct scatterlist *src,
> --
> 2.7.4
>
>
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