This patch adds the AEAD support for AF_ALG. The implementation is based on algif_skcipher, but contains heavy modifications to streamline the interface for AEAD uses. To use AEAD, the user space consumer has to use the salg_type named "aead". The AEAD implementation includes some 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 explaining when and how that operation is performed. A fully working example using all aspects of AEAD is provided at http://www.chronox.de/libkcapi.html Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>