diff options
| -rw-r--r-- | crypto/xts.c | 75 | ||||
| -rw-r--r-- | include/crypto/xts.h | 27 |
2 files changed, 100 insertions, 2 deletions
diff --git a/crypto/xts.c b/crypto/xts.c index 96f3f88..ca1608f 100644 --- a/crypto/xts.c +++ b/crypto/xts.c @@ -21,11 +21,10 @@ #include <linux/scatterlist.h> #include <linux/slab.h> +#include <crypto/xts.h> #include <crypto/b128ops.h> #include <crypto/gf128mul.h> -#define XTS_BLOCK_SIZE 16 - struct priv { struct crypto_cipher *child; struct crypto_cipher *tweak; @@ -167,6 +166,78 @@ static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst, crypto_cipher_alg(ctx->child)->cia_decrypt); } +int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst, + struct scatterlist *ssrc, unsigned int nbytes, + struct xts_crypt_req *req) +{ + const unsigned int bsize = XTS_BLOCK_SIZE; + const unsigned int max_blks = req->tbuflen / bsize; + struct blkcipher_walk walk; + unsigned int nblocks; + be128 *src, *dst, *t; + be128 *t_buf = req->tbuf; + int err, i; + + BUG_ON(max_blks < 1); + + blkcipher_walk_init(&walk, sdst, ssrc, nbytes); + + err = blkcipher_walk_virt(desc, &walk); + nbytes = walk.nbytes; + if (!nbytes) + return err; + + nblocks = min(nbytes / bsize, max_blks); + src = (be128 *)walk.src.virt.addr; + dst = (be128 *)walk.dst.virt.addr; + + /* calculate first value of T */ + req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv); + + i = 0; + goto first; + + for (;;) { + do { + for (i = 0; i < nblocks; i++) { + gf128mul_x_ble(&t_buf[i], t); +first: + t = &t_buf[i]; + + /* PP <- T xor P */ + be128_xor(dst + i, t, src + i); + } + + /* CC <- E(Key2,PP) */ + req->crypt_fn(req->crypt_ctx, (u8 *)dst, + nblocks * bsize); + + /* C <- T xor CC */ + for (i = 0; i < nblocks; i++) + be128_xor(dst + i, dst + i, &t_buf[i]); + + src += nblocks; + dst += nblocks; + nbytes -= nblocks * bsize; + nblocks = min(nbytes / bsize, max_blks); + } while (nblocks > 0); + + *(be128 *)walk.iv = *t; + + err = blkcipher_walk_done(desc, &walk, nbytes); + nbytes = walk.nbytes; + if (!nbytes) + break; + + nblocks = min(nbytes / bsize, max_blks); + src = (be128 *)walk.src.virt.addr; + dst = (be128 *)walk.dst.virt.addr; + } + + return err; +} +EXPORT_SYMBOL_GPL(xts_crypt); + static int init_tfm(struct crypto_tfm *tfm) { struct crypto_cipher *cipher; diff --git a/include/crypto/xts.h b/include/crypto/xts.h new file mode 100644 index 0000000..72c09eb --- /dev/null +++ b/include/crypto/xts.h @@ -0,0 +1,27 @@ +#ifndef _CRYPTO_XTS_H +#define _CRYPTO_XTS_H + +#include <crypto/b128ops.h> + +struct scatterlist; +struct blkcipher_desc; + +#define XTS_BLOCK_SIZE 16 + +struct xts_crypt_req { + be128 *tbuf; + unsigned int tbuflen; + + void *tweak_ctx; + void (*tweak_fn)(void *ctx, u8* dst, const u8* src); + void *crypt_ctx; + void (*crypt_fn)(void *ctx, u8 *blks, unsigned int nbytes); +}; + +#define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x)) + +int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *dst, + struct scatterlist *src, unsigned int nbytes, + struct xts_crypt_req *req); + +#endif /* _CRYPTO_XTS_H */ |
