/* LRW: as defined by Cyril Guyot in * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf * * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org> * * Based on ecb.c * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. */ /* This implementation is checked against the test vectors in the above * document and by a test vector provided by Ken Buchanan at * http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html * * The test vectors are included in the testing module tcrypt.[ch] */ #include <crypto/algapi.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/scatterlist.h> #include <linux/slab.h> #include <crypto/b128ops.h> #include <crypto/gf128mul.h> #include <crypto/lrw.h> struct priv { struct crypto_cipher *child; struct lrw_table_ctx table; }; static inline void setbit128_bbe(void *b, int bit) { __set_bit(bit ^ (0x80 - #ifdef __BIG_ENDIAN BITS_PER_LONG #else BITS_PER_BYTE #endif ), b); } int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak) { be128 tmp = { 0 }; int i; if (ctx->table) gf128mul_free_64k(ctx->table); /* initialize multiplication table for Key2 */ ctx->table = gf128mul_init_64k_bbe((be128 *)tweak); if (!ctx->table) return -ENOMEM; /* initialize optimization table */ for (i = 0; i < 128; i++) { setbit128_bbe(&tmp, i); ctx->mulinc[i] = tmp; gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table); } return 0; } EXPORT_SYMBOL_GPL(lrw_init_table); void lrw_free_table(struct lrw_table_ctx *ctx) { if (ctx->table) gf128mul_free_64k(ctx->table); } EXPORT_SYMBOL_GPL(lrw_free_table); static int setkey(struct crypto_tfm *parent, const u8 *key, unsigned int keylen) { struct priv *ctx = crypto_tfm_ctx(parent); struct crypto_cipher *child = ctx->child; int err, bsize = LRW_BLOCK_SIZE; const u8 *tweak = key + keylen - bsize; crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & CRYPTO_TFM_REQ_MASK); err = crypto_cipher_setkey(child, key, keylen - bsize); if (err) return err; crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & CRYPTO_TFM_RES_MASK); return lrw_init_table(&ctx->table, tweak); } struct sinfo { be128 t; struct crypto_tfm *tfm; void (*fn)(struct crypto_tfm *, u8 *, const u8 *); }; static inline void inc(be128 *iv) { be64_add_cpu(&iv->b, 1); if (!iv->b) be64_add_cpu(&iv->a, 1); } static inline void lrw_round(struct sinfo *s, void *dst, const void *src) { be128_xor(dst, &s->t, src); /* PP <- T xor P */ s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */ be128_xor(dst, dst, &s->t); /* C <- T xor CC */ } /* this returns the number of consequative 1 bits starting * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */ static inline int get_index128(be128 *block) { int x; __be32 *p = (__be32 *) block; for (p += 3, x = 0; x < 128; p--, x += 32) { u32 val = be32_to_cpup(p); if (!~val) continue; return x + ffz(val); } return x; } static int crypt(struct blkcipher_desc *d, struct blkcipher_walk *w, struct priv *ctx, void (*fn)(struct crypto_tfm *, u8 *, const u8 *)) { int err; unsigned int avail; const int bs = LRW_BLOCK_SIZE; struct sinfo s = { .tfm = crypto_cipher_tfm(ctx->child), .fn = fn }; be128 *iv; u8 *wsrc; u8 *wdst; err = blkcipher_walk_virt(d, w); if (!(avail = w->nbytes)) return err; wsrc = w->src.virt.addr; wdst = w->dst.virt.addr; /* calculate first value of T */ iv = (be128 *)w->iv; s.t = *iv; /* T <- I*Key2 */ gf128mul_64k_bbe(&s.t, ctx->table.table); goto first; for (;;) { do { /* T <- I*Key2, using the optimization * discussed in the specification */ be128_xor(&s.t, &s.t, &ctx->table.mulinc[get_index128(iv)]); inc(iv); first: lrw_round(&s, wdst, wsrc); wsrc += bs; wdst += bs; } while ((avail -= bs) >= bs); err = blkcipher_walk_done(d, w, avail); if (!(avail = w->nbytes)) break; wsrc = w->src.virt.addr; wdst = w->dst.virt.addr; } return err; } static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst, struct scatterlist *src, unsigned int nbytes) { struct priv *ctx = crypto_blkcipher_ctx(desc->tfm); struct blkcipher_walk w; blkcipher_walk_init(&w, dst, src, nbytes); return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->child)->cia_encrypt); } static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst, struct scatterlist *src, unsigned int nbytes) { struct priv *ctx = crypto_blkcipher_ctx(desc->tfm); struct blkcipher_walk w; blkcipher_walk_init(&w, dst, src, nbytes); return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->child)->cia_decrypt); } int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst, struct scatterlist *ssrc, unsigned int nbytes, struct lrw_crypt_req *req) { const unsigned int bsize = LRW_BLOCK_SIZE; const unsigned int max_blks = req->tbuflen / bsize; struct lrw_table_ctx *ctx = req->table_ctx; struct blkcipher_walk walk; unsigned int nblocks; be128 *iv, *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(walk.nbytes / bsize, max_blks); src = (be128 *)walk.src.virt.addr; dst = (be128 *)walk.dst.virt.addr; /* calculate first value of T */ iv = (be128 *)walk.iv; t_buf[0] = *iv; /* T <- I*Key2 */ gf128mul_64k_bbe(&t_buf[0], ctx->table); i = 0; goto first; for (;;) { do { for (i = 0; i < nblocks; i++) { /* T <- I*Key2, using the optimization * discussed in the specification */ be128_xor(&t_buf[i], t, &ctx->mulinc[get_index128(iv)]); inc(iv); 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); 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(lrw_crypt); static int init_tfm(struct crypto_tfm *tfm) { struct crypto_cipher *cipher; struct crypto_instance *inst = (void *)tfm->__crt_alg; struct crypto_spawn *spawn = crypto_instance_ctx(inst); struct priv *ctx = crypto_tfm_ctx(tfm); u32 *flags = &tfm->crt_flags; cipher = crypto_spawn_cipher(spawn); if (IS_ERR(cipher)) return PTR_ERR(cipher); if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) { *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN; crypto_free_cipher(cipher); return -EINVAL; } ctx->child = cipher; return 0; } static void exit_tfm(struct crypto_tfm *tfm) { struct priv *ctx = crypto_tfm_ctx(tfm); lrw_free_table(&ctx->table); crypto_free_cipher(ctx->child); } static struct crypto_instance *alloc(struct rtattr **tb) { struct crypto_instance *inst; struct crypto_alg *alg; int err; err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); if (err) return ERR_PTR(err); alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, CRYPTO_ALG_TYPE_MASK); if (IS_ERR(alg)) return ERR_CAST(alg); inst = crypto_alloc_instance("lrw", alg); if (IS_ERR(inst)) goto out_put_alg; inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; inst->alg.cra_priority = alg->cra_priority; inst->alg.cra_blocksize = alg->cra_blocksize; if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7; else inst->alg.cra_alignmask = alg->cra_alignmask; inst->alg.cra_type = &crypto_blkcipher_type; if (!(alg->cra_blocksize % 4)) inst->alg.cra_alignmask |= 3; inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize + alg->cra_blocksize; inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize + alg->cra_blocksize; inst->alg.cra_ctxsize = sizeof(struct priv); inst->alg.cra_init = init_tfm; inst->alg.cra_exit = exit_tfm; inst->alg.cra_blkcipher.setkey = setkey; inst->alg.cra_blkcipher.encrypt = encrypt; inst->alg.cra_blkcipher.decrypt = decrypt; out_put_alg: crypto_mod_put(alg); return inst; } static void free(struct crypto_instance *inst) { crypto_drop_spawn(crypto_instance_ctx(inst)); kfree(inst); } static struct crypto_template crypto_tmpl = { .name = "lrw", .alloc = alloc, .free = free, .module = THIS_MODULE, }; static int __init crypto_module_init(void) { return crypto_register_template(&crypto_tmpl); } static void __exit crypto_module_exit(void) { crypto_unregister_template(&crypto_tmpl); } module_init(crypto_module_init); module_exit(crypto_module_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("LRW block cipher mode"); MODULE_ALIAS_CRYPTO("lrw");