On Fri, Nov 21, 2014 at 06:32:16AM +0100, Stephan Mueller wrote: > This patch adds the AEAD support for AF_ALG. > > The AEAD implementation uses the entire memory handling and > infrastructure of the existing skcipher implementation. > > To use AEAD, the user space consumer has to use the salg_type named > "aead". The AEAD extension only uses the bind callback as the key > differentiator. The previously added functions that select whether to > use AEAD or ablkcipher crypto API functions depend on the TFM type > allocated during the bind() call. > > The addition of AEAD brings a bit of overhead to calculate the size of > the ciphertext, because the AEAD implementation of the kernel crypto API > makes implied assumption on the location of the authentication tag. When > performing an encryption, the tag will be added to the created > ciphertext (note, the tag is placed adjacent to the ciphertext). For > decryption, the caller must hand in the ciphertext with the tag appended > to the ciphertext. Therefore, the selection of the used memory > needs to add/subtract the tag size from the source/destination buffers > depending on the encryption type. The code is provided with comments > explainint when and how that operation is performed. > > Note: The AF_ALG interface does not support zero length input data. > Such zero length input data may be used if one wants to access the hash > implementation of an AEAD directly (e.g. the GHASH of GCM or CMAC for > CCM). However, this is a use case that is not of interest. GHASH or > CMAC is directly available via the hash AF_ALG interface and we > therefore do not need to take precautions for this use case. > > A fully working example using all aspects of AEAD is provided at > http://www.chronox.de/libkcapi.html > > Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx> I appreciate the effort to share code, but shoe-horning AEAD into algif_skcipher is just too ugly. How about let's just start with a separate algif_aead and then add helpers to merge common code as applicable? Thanks, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
