From db131ef9084110d9e82549c0a627e157e8bb99d7 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 21 Sep 2006 11:44:08 +1000 Subject: [CRYPTO] cipher: Added block ciphers for CBC/ECB This patch adds two block cipher algorithms, CBC and ECB. These are implemented as templates on top of existing single-block cipher algorithms. They invoke the single-block cipher through the new encrypt_one/decrypt_one interface. This also optimises the in-place encryption and decryption to remove the cost of an IV copy each round. Signed-off-by: Herbert Xu --- crypto/cbc.c | 344 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 344 insertions(+) create mode 100644 crypto/cbc.c (limited to 'crypto/cbc.c') diff --git a/crypto/cbc.c b/crypto/cbc.c new file mode 100644 index 00000000000..f5542b4db38 --- /dev/null +++ b/crypto/cbc.c @@ -0,0 +1,344 @@ +/* + * CBC: Cipher Block Chaining mode + * + * Copyright (c) 2006 Herbert Xu + * + * 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. + * + */ + +#include +#include +#include +#include +#include +#include +#include + +struct crypto_cbc_ctx { + struct crypto_cipher *child; + void (*xor)(u8 *dst, const u8 *src, unsigned int bs); +}; + +static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key, + unsigned int keylen) +{ + struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent); + struct crypto_cipher *child = ctx->child; + int err; + + 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); + crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & + CRYPTO_TFM_RES_MASK); + return err; +} + +static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm, + void (*xor)(u8 *, const u8 *, + unsigned int)) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + u8 *iv = walk->iv; + + do { + xor(iv, src, bsize); + fn(crypto_cipher_tfm(tfm), dst, iv); + memcpy(iv, dst, bsize); + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm, + void (*xor)(u8 *, const u8 *, + unsigned int)) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *iv = walk->iv; + + do { + xor(src, iv, bsize); + fn(crypto_cipher_tfm(tfm), src, src); + iv = src; + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(walk->iv, iv, bsize); + + return nbytes; +} + +static int crypto_cbc_encrypt(struct blkcipher_desc *desc, + struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes) +{ + struct blkcipher_walk walk; + struct crypto_blkcipher *tfm = desc->tfm; + struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_cipher *child = ctx->child; + void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor; + int err; + + blkcipher_walk_init(&walk, dst, src, nbytes); + err = blkcipher_walk_virt(desc, &walk); + + while ((nbytes = walk.nbytes)) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child, + xor); + else + nbytes = crypto_cbc_encrypt_segment(desc, &walk, child, + xor); + err = blkcipher_walk_done(desc, &walk, nbytes); + } + + return err; +} + +static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm, + void (*xor)(u8 *, const u8 *, + unsigned int)) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_decrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + u8 *iv = walk->iv; + + do { + fn(crypto_cipher_tfm(tfm), dst, src); + xor(dst, iv, bsize); + iv = src; + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(walk->iv, iv, bsize); + + return nbytes; +} + +static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm, + void (*xor)(u8 *, const u8 *, + unsigned int)) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_decrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned long alignmask = crypto_cipher_alignmask(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 stack[bsize + alignmask]; + u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1); + + memcpy(first_iv, walk->iv, bsize); + + /* Start of the last block. */ + src += nbytes - nbytes % bsize - bsize; + memcpy(walk->iv, src, bsize); + + for (;;) { + fn(crypto_cipher_tfm(tfm), src, src); + if ((nbytes -= bsize) < bsize) + break; + xor(src, src - bsize, bsize); + src -= bsize; + } + + xor(src, first_iv, bsize); + + return nbytes; +} + +static int crypto_cbc_decrypt(struct blkcipher_desc *desc, + struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes) +{ + struct blkcipher_walk walk; + struct crypto_blkcipher *tfm = desc->tfm; + struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_cipher *child = ctx->child; + void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor; + int err; + + blkcipher_walk_init(&walk, dst, src, nbytes); + err = blkcipher_walk_virt(desc, &walk); + + while ((nbytes = walk.nbytes)) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child, + xor); + else + nbytes = crypto_cbc_decrypt_segment(desc, &walk, child, + xor); + err = blkcipher_walk_done(desc, &walk, nbytes); + } + + return err; +} + +static void xor_byte(u8 *a, const u8 *b, unsigned int bs) +{ + do { + *a++ ^= *b++; + } while (--bs); +} + +static void xor_quad(u8 *dst, const u8 *src, unsigned int bs) +{ + u32 *a = (u32 *)dst; + u32 *b = (u32 *)src; + + do { + *a++ ^= *b++; + } while ((bs -= 4)); +} + +static void xor_64(u8 *a, const u8 *b, unsigned int bs) +{ + ((u32 *)a)[0] ^= ((u32 *)b)[0]; + ((u32 *)a)[1] ^= ((u32 *)b)[1]; +} + +static void xor_128(u8 *a, const u8 *b, unsigned int bs) +{ + ((u32 *)a)[0] ^= ((u32 *)b)[0]; + ((u32 *)a)[1] ^= ((u32 *)b)[1]; + ((u32 *)a)[2] ^= ((u32 *)b)[2]; + ((u32 *)a)[3] ^= ((u32 *)b)[3]; +} + +static int crypto_cbc_init_tfm(struct crypto_tfm *tfm) +{ + struct crypto_instance *inst = (void *)tfm->__crt_alg; + struct crypto_spawn *spawn = crypto_instance_ctx(inst); + struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm); + + switch (crypto_tfm_alg_blocksize(tfm)) { + case 8: + ctx->xor = xor_64; + break; + + case 16: + ctx->xor = xor_128; + break; + + default: + if (crypto_tfm_alg_blocksize(tfm) % 4) + ctx->xor = xor_byte; + else + ctx->xor = xor_quad; + } + + tfm = crypto_spawn_tfm(spawn); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + ctx->child = crypto_cipher_cast(tfm); + return 0; +} + +static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm) +{ + struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm); + crypto_free_cipher(ctx->child); +} + +static struct crypto_instance *crypto_cbc_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("cbc", 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; + 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; + inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; + + inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx); + + inst->alg.cra_init = crypto_cbc_init_tfm; + inst->alg.cra_exit = crypto_cbc_exit_tfm; + + inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey; + inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt; + inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt; + +out_put_alg: + crypto_mod_put(alg); + return inst; +} + +static void crypto_cbc_free(struct crypto_instance *inst) +{ + crypto_drop_spawn(crypto_instance_ctx(inst)); + kfree(inst); +} + +static struct crypto_template crypto_cbc_tmpl = { + .name = "cbc", + .alloc = crypto_cbc_alloc, + .free = crypto_cbc_free, + .module = THIS_MODULE, +}; + +static int __init crypto_cbc_module_init(void) +{ + return crypto_register_template(&crypto_cbc_tmpl); +} + +static void __exit crypto_cbc_module_exit(void) +{ + crypto_unregister_template(&crypto_cbc_tmpl); +} + +module_init(crypto_cbc_module_init); +module_exit(crypto_cbc_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("CBC block cipher algorithm"); -- cgit v1.2.3