crypto/ablkcipher.c - linux/kernel/git/klassert/ipsec-next - Git at Google

 /*
  * Asynchronous block chaining cipher operations.
  *
  * This is the asynchronous version of blkcipher.c indicating completion
  * via a callback.
  *
  * 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.
  *
  */

 #include <crypto/internal/skcipher.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/rtnetlink.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/seq_file.h>

 #include "internal.h"

 static int setkey_unaligned(struct crypto_ablkcipher *tfm, const u8 *key,
 			    unsigned int keylen)
 {
 	struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
 	unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);
 	int ret;
 	u8 *buffer, *alignbuffer;
 	unsigned long absize;

 	absize = keylen + alignmask;
 	buffer = kmalloc(absize, GFP_ATOMIC);
 	if (!buffer)
 		return -ENOMEM;

 	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 	memcpy(alignbuffer, key, keylen);
 	ret = cipher->setkey(tfm, alignbuffer, keylen);
 	memset(alignbuffer, 0, keylen);
 	kfree(buffer);
 	return ret;
 }

 static int setkey(struct crypto_ablkcipher *tfm, const u8 *key,
 		  unsigned int keylen)
 {
 	struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
 	unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);

 	if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
 		crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
 		return -EINVAL;
 	}

 	if ((unsigned long)key & alignmask)
 		return setkey_unaligned(tfm, key, keylen);

 	return cipher->setkey(tfm, key, keylen);
 }

 static unsigned int crypto_ablkcipher_ctxsize(struct crypto_alg *alg, u32 type,
 					      u32 mask)
 {
 	return alg->cra_ctxsize;
 }

 int skcipher_null_givencrypt(struct skcipher_givcrypt_request *req)
 {
 	return crypto_ablkcipher_encrypt(&req->creq);
 }

 int skcipher_null_givdecrypt(struct skcipher_givcrypt_request *req)
 {
 	return crypto_ablkcipher_decrypt(&req->creq);
 }

 static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
 				      u32 mask)
 {
 	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
 	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

 	if (alg->ivsize > PAGE_SIZE / 8)
 		return -EINVAL;

 	crt->setkey = setkey;
 	crt->encrypt = alg->encrypt;
 	crt->decrypt = alg->decrypt;
 	if (!alg->ivsize) {
 		crt->givencrypt = skcipher_null_givencrypt;
 		crt->givdecrypt = skcipher_null_givdecrypt;
 	}
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;

 	return 0;
 }

 static void crypto_ablkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 	__attribute__ ((unused));
 static void crypto_ablkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 {
 	struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;

 	seq_printf(m, "type         : ablkcipher\n");
 	seq_printf(m, "async        : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
 					     "yes" : "no");
 	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
 	seq_printf(m, "min keysize  : %u\n", ablkcipher->min_keysize);
 	seq_printf(m, "max keysize  : %u\n", ablkcipher->max_keysize);
 	seq_printf(m, "ivsize       : %u\n", ablkcipher->ivsize);
 	seq_printf(m, "geniv        : %s\n", ablkcipher->geniv ?: "<default>");
 }

 const struct crypto_type crypto_ablkcipher_type = {
 	.ctxsize = crypto_ablkcipher_ctxsize,
 	.init = crypto_init_ablkcipher_ops,
 #ifdef CONFIG_PROC_FS
 	.show = crypto_ablkcipher_show,
 #endif
 };
 EXPORT_SYMBOL_GPL(crypto_ablkcipher_type);

 static int no_givdecrypt(struct skcipher_givcrypt_request *req)
 {
 	return -ENOSYS;
 }

 static int crypto_init_givcipher_ops(struct crypto_tfm *tfm, u32 type,
 				      u32 mask)
 {
 	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
 	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

 	if (alg->ivsize > PAGE_SIZE / 8)
 		return -EINVAL;

 	crt->setkey = tfm->__crt_alg->cra_flags & CRYPTO_ALG_GENIV ?
 		      alg->setkey : setkey;
 	crt->encrypt = alg->encrypt;
 	crt->decrypt = alg->decrypt;
 	crt->givencrypt = alg->givencrypt;
 	crt->givdecrypt = alg->givdecrypt ?: no_givdecrypt;
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;

 	return 0;
 }

 static void crypto_givcipher_show(struct seq_file *m, struct crypto_alg *alg)
 	__attribute__ ((unused));
 static void crypto_givcipher_show(struct seq_file *m, struct crypto_alg *alg)
 {
 	struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;

 	seq_printf(m, "type         : givcipher\n");
 	seq_printf(m, "async        : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
 					     "yes" : "no");
 	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
 	seq_printf(m, "min keysize  : %u\n", ablkcipher->min_keysize);
 	seq_printf(m, "max keysize  : %u\n", ablkcipher->max_keysize);
 	seq_printf(m, "ivsize       : %u\n", ablkcipher->ivsize);
 	seq_printf(m, "geniv        : %s\n", ablkcipher->geniv ?: "<built-in>");
 }

 const struct crypto_type crypto_givcipher_type = {
 	.ctxsize = crypto_ablkcipher_ctxsize,
 	.init = crypto_init_givcipher_ops,
 #ifdef CONFIG_PROC_FS
 	.show = crypto_givcipher_show,
 #endif
 };
 EXPORT_SYMBOL_GPL(crypto_givcipher_type);

 const char *crypto_default_geniv(const struct crypto_alg *alg)
 {
 	return alg->cra_flags & CRYPTO_ALG_ASYNC ? "eseqiv" : "chainiv";
 }

 static int crypto_givcipher_default(struct crypto_alg *alg, u32 type, u32 mask)
 {
 	struct rtattr *tb[3];
 	struct {
 		struct rtattr attr;
 		struct crypto_attr_type data;
 	} ptype;
 	struct {
 		struct rtattr attr;
 		struct crypto_attr_alg data;
 	} palg;
 	struct crypto_template *tmpl;
 	struct crypto_instance *inst;
 	struct crypto_alg *larval;
 	const char *geniv;
 	int err;

 	larval = crypto_larval_lookup(alg->cra_driver_name,
 				      CRYPTO_ALG_TYPE_GIVCIPHER,
 				      CRYPTO_ALG_TYPE_MASK);
 	err = PTR_ERR(larval);
 	if (IS_ERR(larval))
 		goto out;

 	err = -EAGAIN;
 	if (!crypto_is_larval(larval))
 		goto drop_larval;

 	ptype.attr.rta_len = sizeof(ptype);
 	ptype.attr.rta_type = CRYPTOA_TYPE;
 	ptype.data.type = type | CRYPTO_ALG_GENIV;
 	/* GENIV tells the template that we're making a default geniv. */
 	ptype.data.mask = mask | CRYPTO_ALG_GENIV;
 	tb[0] = &ptype.attr;

 	palg.attr.rta_len = sizeof(palg);
 	palg.attr.rta_type = CRYPTOA_ALG;
 	/* Must use the exact name to locate ourselves. */
 	memcpy(palg.data.name, alg->cra_driver_name, CRYPTO_MAX_ALG_NAME);
 	tb[1] = &palg.attr;

 	tb[2] = NULL;

 	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
 	    CRYPTO_ALG_TYPE_BLKCIPHER)
 		geniv = alg->cra_blkcipher.geniv;
 	else
 		geniv = alg->cra_ablkcipher.geniv;

 	if (!geniv)
 		geniv = crypto_default_geniv(alg);

 	tmpl = crypto_lookup_template(geniv);
 	err = -ENOENT;
 	if (!tmpl)
 		goto kill_larval;

 	inst = tmpl->alloc(tb);
 	err = PTR_ERR(inst);
 	if (IS_ERR(inst))
 		goto put_tmpl;

 	if ((err = crypto_register_instance(tmpl, inst))) {
 		tmpl->free(inst);
 		goto put_tmpl;
 	}

 	/* Redo the lookup to use the instance we just registered. */
 	err = -EAGAIN;

 put_tmpl:
 	crypto_tmpl_put(tmpl);
 kill_larval:
 	crypto_larval_kill(larval);
 drop_larval:
 	crypto_mod_put(larval);
 out:
 	crypto_mod_put(alg);
 	return err;
 }

 static struct crypto_alg *crypto_lookup_skcipher(const char *name, u32 type,
 						 u32 mask)
 {
 	struct crypto_alg *alg;

 	alg = crypto_alg_mod_lookup(name, type, mask);
 	if (IS_ERR(alg))
 		return alg;

 	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
 	    CRYPTO_ALG_TYPE_GIVCIPHER)
 		return alg;

 	if (!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
 	      CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
 					  alg->cra_ablkcipher.ivsize))
 		return alg;

 	return ERR_PTR(crypto_givcipher_default(alg, type, mask));
 }

 int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
 			 u32 type, u32 mask)
 {
 	struct crypto_alg *alg;
 	int err;

 	type = crypto_skcipher_type(type);
 	mask = crypto_skcipher_mask(mask);

 	alg = crypto_lookup_skcipher(name, type, mask);
 	if (IS_ERR(alg))
 		return PTR_ERR(alg);

 	err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
 	crypto_mod_put(alg);
 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

 struct crypto_ablkcipher *crypto_alloc_ablkcipher(const char *alg_name,
 						  u32 type, u32 mask)
 {
 	struct crypto_tfm *tfm;
 	int err;

 	type = crypto_skcipher_type(type);
 	mask = crypto_skcipher_mask(mask);

 	for (;;) {
 		struct crypto_alg *alg;

 		alg = crypto_lookup_skcipher(alg_name, type, mask);
 		if (IS_ERR(alg)) {
 			err = PTR_ERR(alg);
 			goto err;
 		}

 		tfm = __crypto_alloc_tfm(alg, type, mask);
 		if (!IS_ERR(tfm))
 			return __crypto_ablkcipher_cast(tfm);

 		crypto_mod_put(alg);
 		err = PTR_ERR(tfm);

 err:
 		if (err != -EAGAIN)
 			break;
 		if (signal_pending(current)) {
 			err = -EINTR;
 			break;
 		}
 	}

 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(crypto_alloc_ablkcipher);
	/*
	* Asynchronous block chaining cipher operations.
	*
	* This is the asynchronous version of blkcipher.c indicating completion
	* via a callback.
	*
	* 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.
	*
	*/

	#include <crypto/internal/skcipher.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/rtnetlink.h>
	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <linux/seq_file.h>

	#include "internal.h"

	static int setkey_unaligned(struct crypto_ablkcipher tfm, const u8 key,
	unsigned int keylen)
	{
	struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
	unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);
	int ret;
	u8 buffer, alignbuffer;
	unsigned long absize;

	absize = keylen + alignmask;
	buffer = kmalloc(absize, GFP_ATOMIC);
	if (!buffer)
	return -ENOMEM;

	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
	memcpy(alignbuffer, key, keylen);
	ret = cipher->setkey(tfm, alignbuffer, keylen);
	memset(alignbuffer, 0, keylen);
	kfree(buffer);
	return ret;
	}

	static int setkey(struct crypto_ablkcipher tfm, const u8 key,
	unsigned int keylen)
	{
	struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
	unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);

	if (keylen < cipher->min_keysize \|\| keylen > cipher->max_keysize) {
	crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
	return -EINVAL;
	}

	if ((unsigned long)key & alignmask)
	return setkey_unaligned(tfm, key, keylen);

	return cipher->setkey(tfm, key, keylen);
	}

	static unsigned int crypto_ablkcipher_ctxsize(struct crypto_alg *alg, u32 type,
	u32 mask)
	{
	return alg->cra_ctxsize;
	}

	int skcipher_null_givencrypt(struct skcipher_givcrypt_request *req)
	{
	return crypto_ablkcipher_encrypt(&req->creq);
	}

	int skcipher_null_givdecrypt(struct skcipher_givcrypt_request *req)
	{
	return crypto_ablkcipher_decrypt(&req->creq);
	}

	static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
	u32 mask)
	{
	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

	if (alg->ivsize > PAGE_SIZE / 8)
	return -EINVAL;

	crt->setkey = setkey;
	crt->encrypt = alg->encrypt;
	crt->decrypt = alg->decrypt;
	if (!alg->ivsize) {
	crt->givencrypt = skcipher_null_givencrypt;
	crt->givdecrypt = skcipher_null_givdecrypt;
	}
	crt->base = __crypto_ablkcipher_cast(tfm);
	crt->ivsize = alg->ivsize;

	return 0;
	}

	static void crypto_ablkcipher_show(struct seq_file m, struct crypto_alg alg)
	__attribute__ ((unused));
	static void crypto_ablkcipher_show(struct seq_file m, struct crypto_alg alg)
	{
	struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;

	seq_printf(m, "type : ablkcipher\n");
	seq_printf(m, "async : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
	"yes" : "no");
	seq_printf(m, "blocksize : %u\n", alg->cra_blocksize);
	seq_printf(m, "min keysize : %u\n", ablkcipher->min_keysize);
	seq_printf(m, "max keysize : %u\n", ablkcipher->max_keysize);
	seq_printf(m, "ivsize : %u\n", ablkcipher->ivsize);
	seq_printf(m, "geniv : %s\n", ablkcipher->geniv ?: "<default>");
	}

	const struct crypto_type crypto_ablkcipher_type = {
	.ctxsize = crypto_ablkcipher_ctxsize,
	.init = crypto_init_ablkcipher_ops,
	#ifdef CONFIG_PROC_FS
	.show = crypto_ablkcipher_show,
	#endif
	};
	EXPORT_SYMBOL_GPL(crypto_ablkcipher_type);

	static int no_givdecrypt(struct skcipher_givcrypt_request *req)
	{
	return -ENOSYS;
	}

	static int crypto_init_givcipher_ops(struct crypto_tfm *tfm, u32 type,
	u32 mask)
	{
	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

	if (alg->ivsize > PAGE_SIZE / 8)
	return -EINVAL;

	crt->setkey = tfm->__crt_alg->cra_flags & CRYPTO_ALG_GENIV ?
	alg->setkey : setkey;
	crt->encrypt = alg->encrypt;
	crt->decrypt = alg->decrypt;
	crt->givencrypt = alg->givencrypt;
	crt->givdecrypt = alg->givdecrypt ?: no_givdecrypt;
	crt->base = __crypto_ablkcipher_cast(tfm);
	crt->ivsize = alg->ivsize;

	return 0;
	}

	static void crypto_givcipher_show(struct seq_file m, struct crypto_alg alg)
	__attribute__ ((unused));
	static void crypto_givcipher_show(struct seq_file m, struct crypto_alg alg)
	{
	struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;

	seq_printf(m, "type : givcipher\n");
	seq_printf(m, "async : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
	"yes" : "no");
	seq_printf(m, "blocksize : %u\n", alg->cra_blocksize);
	seq_printf(m, "min keysize : %u\n", ablkcipher->min_keysize);
	seq_printf(m, "max keysize : %u\n", ablkcipher->max_keysize);
	seq_printf(m, "ivsize : %u\n", ablkcipher->ivsize);
	seq_printf(m, "geniv : %s\n", ablkcipher->geniv ?: "<built-in>");
	}

	const struct crypto_type crypto_givcipher_type = {
	.ctxsize = crypto_ablkcipher_ctxsize,
	.init = crypto_init_givcipher_ops,
	#ifdef CONFIG_PROC_FS
	.show = crypto_givcipher_show,
	#endif
	};
	EXPORT_SYMBOL_GPL(crypto_givcipher_type);

	const char crypto_default_geniv(const struct crypto_alg alg)
	{
	return alg->cra_flags & CRYPTO_ALG_ASYNC ? "eseqiv" : "chainiv";
	}

	static int crypto_givcipher_default(struct crypto_alg *alg, u32 type, u32 mask)
	{
	struct rtattr *tb[3];
	struct {
	struct rtattr attr;
	struct crypto_attr_type data;
	} ptype;
	struct {
	struct rtattr attr;
	struct crypto_attr_alg data;
	} palg;
	struct crypto_template *tmpl;
	struct crypto_instance *inst;
	struct crypto_alg *larval;
	const char *geniv;
	int err;

	larval = crypto_larval_lookup(alg->cra_driver_name,
	CRYPTO_ALG_TYPE_GIVCIPHER,
	CRYPTO_ALG_TYPE_MASK);
	err = PTR_ERR(larval);
	if (IS_ERR(larval))
	goto out;

	err = -EAGAIN;
	if (!crypto_is_larval(larval))
	goto drop_larval;

	ptype.attr.rta_len = sizeof(ptype);
	ptype.attr.rta_type = CRYPTOA_TYPE;
	ptype.data.type = type \| CRYPTO_ALG_GENIV;
	/* GENIV tells the template that we're making a default geniv. */
	ptype.data.mask = mask \| CRYPTO_ALG_GENIV;
	tb[0] = &ptype.attr;

	palg.attr.rta_len = sizeof(palg);
	palg.attr.rta_type = CRYPTOA_ALG;
	/* Must use the exact name to locate ourselves. */
	memcpy(palg.data.name, alg->cra_driver_name, CRYPTO_MAX_ALG_NAME);
	tb[1] = &palg.attr;

	tb[2] = NULL;

	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
	CRYPTO_ALG_TYPE_BLKCIPHER)
	geniv = alg->cra_blkcipher.geniv;
	else
	geniv = alg->cra_ablkcipher.geniv;

	if (!geniv)
	geniv = crypto_default_geniv(alg);

	tmpl = crypto_lookup_template(geniv);
	err = -ENOENT;
	if (!tmpl)
	goto kill_larval;

	inst = tmpl->alloc(tb);
	err = PTR_ERR(inst);
	if (IS_ERR(inst))
	goto put_tmpl;

	if ((err = crypto_register_instance(tmpl, inst))) {
	tmpl->free(inst);
	goto put_tmpl;
	}

	/* Redo the lookup to use the instance we just registered. */
	err = -EAGAIN;

	put_tmpl:
	crypto_tmpl_put(tmpl);
	kill_larval:
	crypto_larval_kill(larval);
	drop_larval:
	crypto_mod_put(larval);
	out:
	crypto_mod_put(alg);
	return err;
	}

	static struct crypto_alg crypto_lookup_skcipher(const char name, u32 type,
	u32 mask)
	{
	struct crypto_alg *alg;

	alg = crypto_alg_mod_lookup(name, type, mask);
	if (IS_ERR(alg))
	return alg;

	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
	CRYPTO_ALG_TYPE_GIVCIPHER)
	return alg;

	if (!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
	CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
	alg->cra_ablkcipher.ivsize))
	return alg;

	return ERR_PTR(crypto_givcipher_default(alg, type, mask));
	}

	int crypto_grab_skcipher(struct crypto_skcipher_spawn spawn, const char name,
	u32 type, u32 mask)
	{
	struct crypto_alg *alg;
	int err;

	type = crypto_skcipher_type(type);
	mask = crypto_skcipher_mask(mask);

	alg = crypto_lookup_skcipher(name, type, mask);
	if (IS_ERR(alg))
	return PTR_ERR(alg);

	err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
	crypto_mod_put(alg);
	return err;
	}
	EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

	struct crypto_ablkcipher crypto_alloc_ablkcipher(const char alg_name,
	u32 type, u32 mask)
	{
	struct crypto_tfm *tfm;
	int err;

	type = crypto_skcipher_type(type);
	mask = crypto_skcipher_mask(mask);

	for (;;) {
	struct crypto_alg *alg;

	alg = crypto_lookup_skcipher(alg_name, type, mask);
	if (IS_ERR(alg)) {
	err = PTR_ERR(alg);
	goto err;
	}

	tfm = __crypto_alloc_tfm(alg, type, mask);
	if (!IS_ERR(tfm))
	return __crypto_ablkcipher_cast(tfm);

	crypto_mod_put(alg);
	err = PTR_ERR(tfm);

	err:
	if (err != -EAGAIN)
	break;
	if (signal_pending(current)) {
	err = -EINTR;
	break;
	}
	}

	return ERR_PTR(err);
	}
	EXPORT_SYMBOL_GPL(crypto_alloc_ablkcipher);