diff options
Diffstat (limited to 'crypto/cmac.c')
| -rw-r--r-- | crypto/cmac.c | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/crypto/cmac.c b/crypto/cmac.c new file mode 100644 index 000000000..16301f528 --- /dev/null +++ b/crypto/cmac.c @@ -0,0 +1,321 @@ +/* + * CMAC: Cipher Block Mode for Authentication + * + * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi> + * + * Based on work by: + * Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com> + * Based on crypto/xcbc.c: + * Copyright © 2006 USAGI/WIDE Project, + * Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org> + * + * 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 <crypto/internal/hash.h> +#include <linux/err.h> +#include <linux/kernel.h> +#include <linux/module.h> + +/* + * +------------------------ + * | <parent tfm> + * +------------------------ + * | cmac_tfm_ctx + * +------------------------ + * | consts (block size * 2) + * +------------------------ + */ +struct cmac_tfm_ctx { + struct crypto_cipher *child; + u8 ctx[]; +}; + +/* + * +------------------------ + * | <shash desc> + * +------------------------ + * | cmac_desc_ctx + * +------------------------ + * | odds (block size) + * +------------------------ + * | prev (block size) + * +------------------------ + */ +struct cmac_desc_ctx { + unsigned int len; + u8 ctx[]; +}; + +static int crypto_cmac_digest_setkey(struct crypto_shash *parent, + const u8 *inkey, unsigned int keylen) +{ + unsigned long alignmask = crypto_shash_alignmask(parent); + struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent); + unsigned int bs = crypto_shash_blocksize(parent); + __be64 *consts = PTR_ALIGN((void *)ctx->ctx, + (alignmask | (__alignof__(__be64) - 1)) + 1); + u64 _const[2]; + int i, err = 0; + u8 msb_mask, gfmask; + + err = crypto_cipher_setkey(ctx->child, inkey, keylen); + if (err) + return err; + + /* encrypt the zero block */ + memset(consts, 0, bs); + crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts); + + switch (bs) { + case 16: + gfmask = 0x87; + _const[0] = be64_to_cpu(consts[1]); + _const[1] = be64_to_cpu(consts[0]); + + /* gf(2^128) multiply zero-ciphertext with u and u^2 */ + for (i = 0; i < 4; i += 2) { + msb_mask = ((s64)_const[1] >> 63) & gfmask; + _const[1] = (_const[1] << 1) | (_const[0] >> 63); + _const[0] = (_const[0] << 1) ^ msb_mask; + + consts[i + 0] = cpu_to_be64(_const[1]); + consts[i + 1] = cpu_to_be64(_const[0]); + } + + break; + case 8: + gfmask = 0x1B; + _const[0] = be64_to_cpu(consts[0]); + + /* gf(2^64) multiply zero-ciphertext with u and u^2 */ + for (i = 0; i < 2; i++) { + msb_mask = ((s64)_const[0] >> 63) & gfmask; + _const[0] = (_const[0] << 1) ^ msb_mask; + + consts[i] = cpu_to_be64(_const[0]); + } + + break; + } + + return 0; +} + +static int crypto_cmac_digest_init(struct shash_desc *pdesc) +{ + unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm); + struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); + int bs = crypto_shash_blocksize(pdesc->tfm); + u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs; + + ctx->len = 0; + memset(prev, 0, bs); + + return 0; +} + +static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p, + unsigned int len) +{ + struct crypto_shash *parent = pdesc->tfm; + unsigned long alignmask = crypto_shash_alignmask(parent); + struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent); + struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); + struct crypto_cipher *tfm = tctx->child; + int bs = crypto_shash_blocksize(parent); + u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1); + u8 *prev = odds + bs; + + /* checking the data can fill the block */ + if ((ctx->len + len) <= bs) { + memcpy(odds + ctx->len, p, len); + ctx->len += len; + return 0; + } + + /* filling odds with new data and encrypting it */ + memcpy(odds + ctx->len, p, bs - ctx->len); + len -= bs - ctx->len; + p += bs - ctx->len; + + crypto_xor(prev, odds, bs); + crypto_cipher_encrypt_one(tfm, prev, prev); + + /* clearing the length */ + ctx->len = 0; + + /* encrypting the rest of data */ + while (len > bs) { + crypto_xor(prev, p, bs); + crypto_cipher_encrypt_one(tfm, prev, prev); + p += bs; + len -= bs; + } + + /* keeping the surplus of blocksize */ + if (len) { + memcpy(odds, p, len); + ctx->len = len; + } + + return 0; +} + +static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out) +{ + struct crypto_shash *parent = pdesc->tfm; + unsigned long alignmask = crypto_shash_alignmask(parent); + struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent); + struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); + struct crypto_cipher *tfm = tctx->child; + int bs = crypto_shash_blocksize(parent); + u8 *consts = PTR_ALIGN((void *)tctx->ctx, + (alignmask | (__alignof__(__be64) - 1)) + 1); + u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1); + u8 *prev = odds + bs; + unsigned int offset = 0; + + if (ctx->len != bs) { + unsigned int rlen; + u8 *p = odds + ctx->len; + + *p = 0x80; + p++; + + rlen = bs - ctx->len - 1; + if (rlen) + memset(p, 0, rlen); + + offset += bs; + } + + crypto_xor(prev, odds, bs); + crypto_xor(prev, consts + offset, bs); + + crypto_cipher_encrypt_one(tfm, out, prev); + + return 0; +} + +static int cmac_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 cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm); + + cipher = crypto_spawn_cipher(spawn); + if (IS_ERR(cipher)) + return PTR_ERR(cipher); + + ctx->child = cipher; + + return 0; +}; + +static void cmac_exit_tfm(struct crypto_tfm *tfm) +{ + struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm); + crypto_free_cipher(ctx->child); +} + +static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct shash_instance *inst; + struct crypto_alg *alg; + unsigned long alignmask; + int err; + + err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH); + if (err) + return err; + + alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, + CRYPTO_ALG_TYPE_MASK); + if (IS_ERR(alg)) + return PTR_ERR(alg); + + switch (alg->cra_blocksize) { + case 16: + case 8: + break; + default: + err = -EINVAL; + goto out_put_alg; + } + + inst = shash_alloc_instance("cmac", alg); + err = PTR_ERR(inst); + if (IS_ERR(inst)) + goto out_put_alg; + + err = crypto_init_spawn(shash_instance_ctx(inst), alg, + shash_crypto_instance(inst), + CRYPTO_ALG_TYPE_MASK); + if (err) + goto out_free_inst; + + alignmask = alg->cra_alignmask; + inst->alg.base.cra_alignmask = alignmask; + inst->alg.base.cra_priority = alg->cra_priority; + inst->alg.base.cra_blocksize = alg->cra_blocksize; + + inst->alg.digestsize = alg->cra_blocksize; + inst->alg.descsize = + ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment()) + + (alignmask & ~(crypto_tfm_ctx_alignment() - 1)) + + alg->cra_blocksize * 2; + + inst->alg.base.cra_ctxsize = + ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment()) + + ((alignmask | (__alignof__(__be64) - 1)) & + ~(crypto_tfm_ctx_alignment() - 1)) + + alg->cra_blocksize * 2; + + inst->alg.base.cra_init = cmac_init_tfm; + inst->alg.base.cra_exit = cmac_exit_tfm; + + inst->alg.init = crypto_cmac_digest_init; + inst->alg.update = crypto_cmac_digest_update; + inst->alg.final = crypto_cmac_digest_final; + inst->alg.setkey = crypto_cmac_digest_setkey; + + err = shash_register_instance(tmpl, inst); + if (err) { +out_free_inst: + shash_free_instance(shash_crypto_instance(inst)); + } + +out_put_alg: + crypto_mod_put(alg); + return err; +} + +static struct crypto_template crypto_cmac_tmpl = { + .name = "cmac", + .create = cmac_create, + .free = shash_free_instance, + .module = THIS_MODULE, +}; + +static int __init crypto_cmac_module_init(void) +{ + return crypto_register_template(&crypto_cmac_tmpl); +} + +static void __exit crypto_cmac_module_exit(void) +{ + crypto_unregister_template(&crypto_cmac_tmpl); +} + +module_init(crypto_cmac_module_init); +module_exit(crypto_cmac_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("CMAC keyed hash algorithm"); +MODULE_ALIAS_CRYPTO("cmac"); |