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2008-01-11[CRYPTO] seqiv: Add Sequence Number IV GeneratorHerbert Xu
This generator generates an IV based on a sequence number by xoring it with a salt. This algorithm is mainly useful for CTR and similar modes. This patch also sets it as the default IV generator for ctr. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-01-11[CRYPTO] ctr: Refactor into ctr and rfc3686Herbert Xu
As discussed previously, this patch moves the basic CTR functionality into a chainable algorithm called ctr. The IPsec-specific variant of it is now placed on top with the name rfc3686. So ctr(aes) gives a chainable cipher with IV size 16 while the IPsec variant will be called rfc3686(ctr(aes)). This patch also adjusts gcm accordingly. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-01-11[CRYPTO] ctr: Fix multi-page processingHerbert Xu
When the data spans across a page boundary, CTR may incorrectly process a partial block in the middle because the blkcipher walking code may supply partial blocks in the middle as long as the total length of the supplied data is more than a block. CTR is supposed to return any unused partial block in that case to the walker. This patch fixes this by doing exactly that, returning partial blocks to the walker unless we received less than a block-worth of data to start with. This also allows us to optimise the bulk of the processing since we no longer have to worry about partial blocks until the very end. Thanks to Tan Swee Heng for fixes and actually testing this :) Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-01-11[CRYPTO] ctr: Use crypto_inc and crypto_xorHerbert Xu
This patch replaces the custom inc/xor in CTR with the generic functions. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-01-11[CRYPTO] ctr: Add countersizeJoy Latten
This patch adds countersize to CTR mode. The template is now ctr(algo,noncesize,ivsize,countersize). For example, ctr(aes,4,8,4) indicates the counterblock will be composed of a salt/nonce that is 4 bytes, an iv that is 8 bytes and the counter is 4 bytes. When noncesize + ivsize < blocksize, CTR initializes the last block - ivsize - noncesize portion of the block to zero. Otherwise the counter block is composed of the IV (and nonce if necessary). If noncesize + ivsize == blocksize, then this indicates that user is passing in entire counterblock. Thus countersize indicates the amount of bytes in counterblock to use as the counter for incrementing. CTR will increment counter portion by 1, and begin encryption with that value. Note that CTR assumes the counter portion of the block that will be incremented is stored in big endian. Signed-off-by: Joy Latten <latten@austin.ibm.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-01-11[CRYPTO] ctr: Add CTR (Counter) block cipher modeJoy Latten
This patch implements CTR mode for IPsec. It is based off of RFC 3686. Please note: 1. CTR turns a block cipher into a stream cipher. Encryption is done in blocks, however the last block may be a partial block. A "counter block" is encrypted, creating a keystream that is xor'ed with the plaintext. The counter portion of the counter block is incremented after each block of plaintext is encrypted. Decryption is performed in same manner. 2. The CTR counterblock is composed of, nonce + IV + counter The size of the counterblock is equivalent to the blocksize of the cipher. sizeof(nonce) + sizeof(IV) + sizeof(counter) = blocksize The CTR template requires the name of the cipher algorithm, the sizeof the nonce, and the sizeof the iv. ctr(cipher,sizeof_nonce,sizeof_iv) So for example, ctr(aes,4,8) specifies the counterblock will be composed of 4 bytes from a nonce, 8 bytes from the iv, and 4 bytes for counter since aes has a blocksize of 16 bytes. 3. The counter portion of the counter block is stored in big endian for conformance to rfc 3686. Signed-off-by: Joy Latten <latten@austin.ibm.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>