linux/arch/x86/crypto/serpent_avx_glue.c
Kees Cook 5d26a105b5 crypto: prefix module autoloading with "crypto-"
This prefixes all crypto module loading with "crypto-" so we never run
the risk of exposing module auto-loading to userspace via a crypto API,
as demonstrated by Mathias Krause:

https://lkml.org/lkml/2013/3/4/70

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-11-24 22:43:57 +08:00

621 lines
17 KiB
C

/*
* Glue Code for AVX assembler versions of Serpent Cipher
*
* Copyright (C) 2012 Johannes Goetzfried
* <Johannes.Goetzfried@informatik.stud.uni-erlangen.de>
*
* Copyright © 2011-2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
*
* 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 program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*/
#include <linux/module.h>
#include <linux/hardirq.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/err.h>
#include <crypto/ablk_helper.h>
#include <crypto/algapi.h>
#include <crypto/serpent.h>
#include <crypto/cryptd.h>
#include <crypto/b128ops.h>
#include <crypto/ctr.h>
#include <crypto/lrw.h>
#include <crypto/xts.h>
#include <asm/xcr.h>
#include <asm/xsave.h>
#include <asm/crypto/serpent-avx.h>
#include <asm/crypto/glue_helper.h>
/* 8-way parallel cipher functions */
asmlinkage void serpent_ecb_enc_8way_avx(struct serpent_ctx *ctx, u8 *dst,
const u8 *src);
EXPORT_SYMBOL_GPL(serpent_ecb_enc_8way_avx);
asmlinkage void serpent_ecb_dec_8way_avx(struct serpent_ctx *ctx, u8 *dst,
const u8 *src);
EXPORT_SYMBOL_GPL(serpent_ecb_dec_8way_avx);
asmlinkage void serpent_cbc_dec_8way_avx(struct serpent_ctx *ctx, u8 *dst,
const u8 *src);
EXPORT_SYMBOL_GPL(serpent_cbc_dec_8way_avx);
asmlinkage void serpent_ctr_8way_avx(struct serpent_ctx *ctx, u8 *dst,
const u8 *src, le128 *iv);
EXPORT_SYMBOL_GPL(serpent_ctr_8way_avx);
asmlinkage void serpent_xts_enc_8way_avx(struct serpent_ctx *ctx, u8 *dst,
const u8 *src, le128 *iv);
EXPORT_SYMBOL_GPL(serpent_xts_enc_8way_avx);
asmlinkage void serpent_xts_dec_8way_avx(struct serpent_ctx *ctx, u8 *dst,
const u8 *src, le128 *iv);
EXPORT_SYMBOL_GPL(serpent_xts_dec_8way_avx);
void __serpent_crypt_ctr(void *ctx, u128 *dst, const u128 *src, le128 *iv)
{
be128 ctrblk;
le128_to_be128(&ctrblk, iv);
le128_inc(iv);
__serpent_encrypt(ctx, (u8 *)&ctrblk, (u8 *)&ctrblk);
u128_xor(dst, src, (u128 *)&ctrblk);
}
EXPORT_SYMBOL_GPL(__serpent_crypt_ctr);
void serpent_xts_enc(void *ctx, u128 *dst, const u128 *src, le128 *iv)
{
glue_xts_crypt_128bit_one(ctx, dst, src, iv,
GLUE_FUNC_CAST(__serpent_encrypt));
}
EXPORT_SYMBOL_GPL(serpent_xts_enc);
void serpent_xts_dec(void *ctx, u128 *dst, const u128 *src, le128 *iv)
{
glue_xts_crypt_128bit_one(ctx, dst, src, iv,
GLUE_FUNC_CAST(__serpent_decrypt));
}
EXPORT_SYMBOL_GPL(serpent_xts_dec);
static const struct common_glue_ctx serpent_enc = {
.num_funcs = 2,
.fpu_blocks_limit = SERPENT_PARALLEL_BLOCKS,
.funcs = { {
.num_blocks = SERPENT_PARALLEL_BLOCKS,
.fn_u = { .ecb = GLUE_FUNC_CAST(serpent_ecb_enc_8way_avx) }
}, {
.num_blocks = 1,
.fn_u = { .ecb = GLUE_FUNC_CAST(__serpent_encrypt) }
} }
};
static const struct common_glue_ctx serpent_ctr = {
.num_funcs = 2,
.fpu_blocks_limit = SERPENT_PARALLEL_BLOCKS,
.funcs = { {
.num_blocks = SERPENT_PARALLEL_BLOCKS,
.fn_u = { .ctr = GLUE_CTR_FUNC_CAST(serpent_ctr_8way_avx) }
}, {
.num_blocks = 1,
.fn_u = { .ctr = GLUE_CTR_FUNC_CAST(__serpent_crypt_ctr) }
} }
};
static const struct common_glue_ctx serpent_enc_xts = {
.num_funcs = 2,
.fpu_blocks_limit = SERPENT_PARALLEL_BLOCKS,
.funcs = { {
.num_blocks = SERPENT_PARALLEL_BLOCKS,
.fn_u = { .xts = GLUE_XTS_FUNC_CAST(serpent_xts_enc_8way_avx) }
}, {
.num_blocks = 1,
.fn_u = { .xts = GLUE_XTS_FUNC_CAST(serpent_xts_enc) }
} }
};
static const struct common_glue_ctx serpent_dec = {
.num_funcs = 2,
.fpu_blocks_limit = SERPENT_PARALLEL_BLOCKS,
.funcs = { {
.num_blocks = SERPENT_PARALLEL_BLOCKS,
.fn_u = { .ecb = GLUE_FUNC_CAST(serpent_ecb_dec_8way_avx) }
}, {
.num_blocks = 1,
.fn_u = { .ecb = GLUE_FUNC_CAST(__serpent_decrypt) }
} }
};
static const struct common_glue_ctx serpent_dec_cbc = {
.num_funcs = 2,
.fpu_blocks_limit = SERPENT_PARALLEL_BLOCKS,
.funcs = { {
.num_blocks = SERPENT_PARALLEL_BLOCKS,
.fn_u = { .cbc = GLUE_CBC_FUNC_CAST(serpent_cbc_dec_8way_avx) }
}, {
.num_blocks = 1,
.fn_u = { .cbc = GLUE_CBC_FUNC_CAST(__serpent_decrypt) }
} }
};
static const struct common_glue_ctx serpent_dec_xts = {
.num_funcs = 2,
.fpu_blocks_limit = SERPENT_PARALLEL_BLOCKS,
.funcs = { {
.num_blocks = SERPENT_PARALLEL_BLOCKS,
.fn_u = { .xts = GLUE_XTS_FUNC_CAST(serpent_xts_dec_8way_avx) }
}, {
.num_blocks = 1,
.fn_u = { .xts = GLUE_XTS_FUNC_CAST(serpent_xts_dec) }
} }
};
static int ecb_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
return glue_ecb_crypt_128bit(&serpent_enc, desc, dst, src, nbytes);
}
static int ecb_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
return glue_ecb_crypt_128bit(&serpent_dec, desc, dst, src, nbytes);
}
static int cbc_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
return glue_cbc_encrypt_128bit(GLUE_FUNC_CAST(__serpent_encrypt), desc,
dst, src, nbytes);
}
static int cbc_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
return glue_cbc_decrypt_128bit(&serpent_dec_cbc, desc, dst, src,
nbytes);
}
static int ctr_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
return glue_ctr_crypt_128bit(&serpent_ctr, desc, dst, src, nbytes);
}
static inline bool serpent_fpu_begin(bool fpu_enabled, unsigned int nbytes)
{
return glue_fpu_begin(SERPENT_BLOCK_SIZE, SERPENT_PARALLEL_BLOCKS,
NULL, fpu_enabled, nbytes);
}
static inline void serpent_fpu_end(bool fpu_enabled)
{
glue_fpu_end(fpu_enabled);
}
struct crypt_priv {
struct serpent_ctx *ctx;
bool fpu_enabled;
};
static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = SERPENT_BLOCK_SIZE;
struct crypt_priv *ctx = priv;
int i;
ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
if (nbytes == bsize * SERPENT_PARALLEL_BLOCKS) {
serpent_ecb_enc_8way_avx(ctx->ctx, srcdst, srcdst);
return;
}
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
__serpent_encrypt(ctx->ctx, srcdst, srcdst);
}
static void decrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
const unsigned int bsize = SERPENT_BLOCK_SIZE;
struct crypt_priv *ctx = priv;
int i;
ctx->fpu_enabled = serpent_fpu_begin(ctx->fpu_enabled, nbytes);
if (nbytes == bsize * SERPENT_PARALLEL_BLOCKS) {
serpent_ecb_dec_8way_avx(ctx->ctx, srcdst, srcdst);
return;
}
for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
__serpent_decrypt(ctx->ctx, srcdst, srcdst);
}
int lrw_serpent_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
struct serpent_lrw_ctx *ctx = crypto_tfm_ctx(tfm);
int err;
err = __serpent_setkey(&ctx->serpent_ctx, key, keylen -
SERPENT_BLOCK_SIZE);
if (err)
return err;
return lrw_init_table(&ctx->lrw_table, key + keylen -
SERPENT_BLOCK_SIZE);
}
EXPORT_SYMBOL_GPL(lrw_serpent_setkey);
static int lrw_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct serpent_lrw_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
be128 buf[SERPENT_PARALLEL_BLOCKS];
struct crypt_priv crypt_ctx = {
.ctx = &ctx->serpent_ctx,
.fpu_enabled = false,
};
struct lrw_crypt_req req = {
.tbuf = buf,
.tbuflen = sizeof(buf),
.table_ctx = &ctx->lrw_table,
.crypt_ctx = &crypt_ctx,
.crypt_fn = encrypt_callback,
};
int ret;
desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
ret = lrw_crypt(desc, dst, src, nbytes, &req);
serpent_fpu_end(crypt_ctx.fpu_enabled);
return ret;
}
static int lrw_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct serpent_lrw_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
be128 buf[SERPENT_PARALLEL_BLOCKS];
struct crypt_priv crypt_ctx = {
.ctx = &ctx->serpent_ctx,
.fpu_enabled = false,
};
struct lrw_crypt_req req = {
.tbuf = buf,
.tbuflen = sizeof(buf),
.table_ctx = &ctx->lrw_table,
.crypt_ctx = &crypt_ctx,
.crypt_fn = decrypt_callback,
};
int ret;
desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
ret = lrw_crypt(desc, dst, src, nbytes, &req);
serpent_fpu_end(crypt_ctx.fpu_enabled);
return ret;
}
void lrw_serpent_exit_tfm(struct crypto_tfm *tfm)
{
struct serpent_lrw_ctx *ctx = crypto_tfm_ctx(tfm);
lrw_free_table(&ctx->lrw_table);
}
EXPORT_SYMBOL_GPL(lrw_serpent_exit_tfm);
int xts_serpent_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
struct serpent_xts_ctx *ctx = crypto_tfm_ctx(tfm);
u32 *flags = &tfm->crt_flags;
int err;
/* key consists of keys of equal size concatenated, therefore
* the length must be even
*/
if (keylen % 2) {
*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
/* first half of xts-key is for crypt */
err = __serpent_setkey(&ctx->crypt_ctx, key, keylen / 2);
if (err)
return err;
/* second half of xts-key is for tweak */
return __serpent_setkey(&ctx->tweak_ctx, key + keylen / 2, keylen / 2);
}
EXPORT_SYMBOL_GPL(xts_serpent_setkey);
static int xts_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct serpent_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
return glue_xts_crypt_128bit(&serpent_enc_xts, desc, dst, src, nbytes,
XTS_TWEAK_CAST(__serpent_encrypt),
&ctx->tweak_ctx, &ctx->crypt_ctx);
}
static int xts_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct serpent_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
return glue_xts_crypt_128bit(&serpent_dec_xts, desc, dst, src, nbytes,
XTS_TWEAK_CAST(__serpent_encrypt),
&ctx->tweak_ctx, &ctx->crypt_ctx);
}
static struct crypto_alg serpent_algs[10] = { {
.cra_name = "__ecb-serpent-avx",
.cra_driver_name = "__driver-ecb-serpent-avx",
.cra_priority = 0,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct serpent_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_blkcipher_type,
.cra_module = THIS_MODULE,
.cra_u = {
.blkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE,
.setkey = serpent_setkey,
.encrypt = ecb_encrypt,
.decrypt = ecb_decrypt,
},
},
}, {
.cra_name = "__cbc-serpent-avx",
.cra_driver_name = "__driver-cbc-serpent-avx",
.cra_priority = 0,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct serpent_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_blkcipher_type,
.cra_module = THIS_MODULE,
.cra_u = {
.blkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE,
.setkey = serpent_setkey,
.encrypt = cbc_encrypt,
.decrypt = cbc_decrypt,
},
},
}, {
.cra_name = "__ctr-serpent-avx",
.cra_driver_name = "__driver-ctr-serpent-avx",
.cra_priority = 0,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct serpent_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_blkcipher_type,
.cra_module = THIS_MODULE,
.cra_u = {
.blkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = serpent_setkey,
.encrypt = ctr_crypt,
.decrypt = ctr_crypt,
},
},
}, {
.cra_name = "__lrw-serpent-avx",
.cra_driver_name = "__driver-lrw-serpent-avx",
.cra_priority = 0,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct serpent_lrw_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_blkcipher_type,
.cra_module = THIS_MODULE,
.cra_exit = lrw_serpent_exit_tfm,
.cra_u = {
.blkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE +
SERPENT_BLOCK_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE +
SERPENT_BLOCK_SIZE,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = lrw_serpent_setkey,
.encrypt = lrw_encrypt,
.decrypt = lrw_decrypt,
},
},
}, {
.cra_name = "__xts-serpent-avx",
.cra_driver_name = "__driver-xts-serpent-avx",
.cra_priority = 0,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct serpent_xts_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_blkcipher_type,
.cra_module = THIS_MODULE,
.cra_u = {
.blkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE * 2,
.max_keysize = SERPENT_MAX_KEY_SIZE * 2,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = xts_serpent_setkey,
.encrypt = xts_encrypt,
.decrypt = xts_decrypt,
},
},
}, {
.cra_name = "ecb(serpent)",
.cra_driver_name = "ecb-serpent-avx",
.cra_priority = 500,
.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct async_helper_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_ablkcipher_type,
.cra_module = THIS_MODULE,
.cra_init = ablk_init,
.cra_exit = ablk_exit,
.cra_u = {
.ablkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE,
.setkey = ablk_set_key,
.encrypt = ablk_encrypt,
.decrypt = ablk_decrypt,
},
},
}, {
.cra_name = "cbc(serpent)",
.cra_driver_name = "cbc-serpent-avx",
.cra_priority = 500,
.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct async_helper_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_ablkcipher_type,
.cra_module = THIS_MODULE,
.cra_init = ablk_init,
.cra_exit = ablk_exit,
.cra_u = {
.ablkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = ablk_set_key,
.encrypt = __ablk_encrypt,
.decrypt = ablk_decrypt,
},
},
}, {
.cra_name = "ctr(serpent)",
.cra_driver_name = "ctr-serpent-avx",
.cra_priority = 500,
.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct async_helper_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_ablkcipher_type,
.cra_module = THIS_MODULE,
.cra_init = ablk_init,
.cra_exit = ablk_exit,
.cra_u = {
.ablkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = ablk_set_key,
.encrypt = ablk_encrypt,
.decrypt = ablk_encrypt,
.geniv = "chainiv",
},
},
}, {
.cra_name = "lrw(serpent)",
.cra_driver_name = "lrw-serpent-avx",
.cra_priority = 500,
.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct async_helper_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_ablkcipher_type,
.cra_module = THIS_MODULE,
.cra_init = ablk_init,
.cra_exit = ablk_exit,
.cra_u = {
.ablkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE +
SERPENT_BLOCK_SIZE,
.max_keysize = SERPENT_MAX_KEY_SIZE +
SERPENT_BLOCK_SIZE,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = ablk_set_key,
.encrypt = ablk_encrypt,
.decrypt = ablk_decrypt,
},
},
}, {
.cra_name = "xts(serpent)",
.cra_driver_name = "xts-serpent-avx",
.cra_priority = 500,
.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
.cra_blocksize = SERPENT_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct async_helper_ctx),
.cra_alignmask = 0,
.cra_type = &crypto_ablkcipher_type,
.cra_module = THIS_MODULE,
.cra_init = ablk_init,
.cra_exit = ablk_exit,
.cra_u = {
.ablkcipher = {
.min_keysize = SERPENT_MIN_KEY_SIZE * 2,
.max_keysize = SERPENT_MAX_KEY_SIZE * 2,
.ivsize = SERPENT_BLOCK_SIZE,
.setkey = ablk_set_key,
.encrypt = ablk_encrypt,
.decrypt = ablk_decrypt,
},
},
} };
static int __init serpent_init(void)
{
u64 xcr0;
if (!cpu_has_avx || !cpu_has_osxsave) {
printk(KERN_INFO "AVX instructions are not detected.\n");
return -ENODEV;
}
xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
if ((xcr0 & (XSTATE_SSE | XSTATE_YMM)) != (XSTATE_SSE | XSTATE_YMM)) {
printk(KERN_INFO "AVX detected but unusable.\n");
return -ENODEV;
}
return crypto_register_algs(serpent_algs, ARRAY_SIZE(serpent_algs));
}
static void __exit serpent_exit(void)
{
crypto_unregister_algs(serpent_algs, ARRAY_SIZE(serpent_algs));
}
module_init(serpent_init);
module_exit(serpent_exit);
MODULE_DESCRIPTION("Serpent Cipher Algorithm, AVX optimized");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("serpent");