diff options
Diffstat (limited to 'crypto/lrw.c')
| -rw-r--r-- | crypto/lrw.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/crypto/lrw.c b/crypto/lrw.c new file mode 100644 index 00000000000..5d043158b90 --- /dev/null +++ b/crypto/lrw.c @@ -0,0 +1,301 @@ +/* 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 om 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> + +struct priv { + struct crypto_cipher *child; + /* optimizes multiplying a random (non incrementing, as at the + * start of a new sector) value with key2, we could also have + * used 4k optimization tables or no optimization at all. In the + * latter case we would have to store key2 here */ + struct gf128mul_64k *table; + /* stores: + * key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 }, + * key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 } + * key2*{ 0,0,...1,1,1,1,1 }, etc + * needed for optimized multiplication of incrementing values + * with key2 */ + be128 mulinc[128]; +}; + +static inline void setbit128_bbe(void *b, int bit) +{ + __set_bit(bit ^ 0x78, b); +} + +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, i; + be128 tmp = { 0 }; + int bsize = crypto_cipher_blocksize(child); + + crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); + crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + if ((err = crypto_cipher_setkey(child, key, keylen - bsize))) + return err; + crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & + CRYPTO_TFM_RES_MASK); + + if (ctx->table) + gf128mul_free_64k(ctx->table); + + /* initialize multiplication table for Key2 */ + ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize)); + 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; +} + +struct sinfo { + be128 t; + struct crypto_tfm *tfm; + void (*fn)(struct crypto_tfm *, u8 *, const u8 *); +}; + +static inline void inc(be128 *iv) +{ + if (!(iv->b = cpu_to_be64(be64_to_cpu(iv->b) + 1))) + iv->a = cpu_to_be64(be64_to_cpu(iv->a) + 1); +} + +static inline void 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 = crypto_cipher_blocksize(ctx->child); + 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); + + goto first; + + for (;;) { + do { + /* T <- I*Key2, using the optimization + * discussed in the specification */ + be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]); + inc(iv); + +first: + 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); +} + +static int init_tfm(struct crypto_tfm *tfm) +{ + 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; + + tfm = crypto_spawn_tfm(spawn); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + if (crypto_tfm_alg_blocksize(tfm) != 16) { + *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN; + return -EINVAL; + } + + ctx->child = crypto_cipher_cast(tfm); + return 0; +} + +static void exit_tfm(struct crypto_tfm *tfm) +{ + struct priv *ctx = crypto_tfm_ctx(tfm); + if (ctx->table) + gf128mul_free_64k(ctx->table); + crypto_free_cipher(ctx->child); +} + +static struct crypto_instance *alloc(void *param, unsigned int len) +{ + struct crypto_instance *inst; + struct crypto_alg *alg; + + alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER, + CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC); + if (IS_ERR(alg)) + return ERR_PTR(PTR_ERR(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"); |