library/pk.c

/*
 *  Public Key abstraction layer
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_PK_C)
#include "mbedtls/pk.h"
#include "mbedtls/pk_internal.h"

#include "mbedtls/platform_util.h"

#if defined(MBEDTLS_RSA_C)
#include "mbedtls/rsa.h"
#endif
#if defined(MBEDTLS_ECP_C)
#include "mbedtls/ecp.h"
#endif
#if defined(MBEDTLS_ECDSA_C)
#include "mbedtls/ecdsa.h"
#endif

#include <limits.h>
#include <stdint.h>

/* Parameter validation macros based on platform_util.h */
#define PK_VALIDATE_RET( cond )    \
    MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_PK_BAD_INPUT_DATA )
#define PK_VALIDATE( cond )        \
    MBEDTLS_INTERNAL_VALIDATE( cond )

/*
 * Access to members of the pk_info structure. These are meant to be replaced
 * by zero-runtime-cost accessors when a single PK type is hardcoded.
 *
 * For function members, don't make a getter, but a function that directly
 * calls the method, so that we can entirely get rid of function pointers
 * when hardcoding a single PK - some compilers optimize better that way.
 *
 * Not implemented for members that are only present in builds with
 * MBEDTLS_ECP_RESTARTABLE for now, as the main target for hardcoded is builds
 * with MBEDTLS_USE_TINYCRYPT, which don't have MBEDTLS_ECP_RESTARTABLE.
 */

MBEDTLS_ALWAYS_INLINE static inline mbedtls_pk_type_t pk_info_type(
    const mbedtls_pk_info_t *info )
{
    return( info->type );
}

MBEDTLS_ALWAYS_INLINE static inline const char * pk_info_name(
    const mbedtls_pk_info_t *info )
{
    return( info->name );
}

MBEDTLS_ALWAYS_INLINE static inline size_t pk_info_get_bitlen(
    const mbedtls_pk_info_t *info, const void *ctx )
{
    return( info->get_bitlen( ctx ) );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_can_do(
    const mbedtls_pk_info_t *info, mbedtls_pk_type_t type )
{
    return( info->can_do( type ) );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_verify_func(
    const mbedtls_pk_info_t *info, void *ctx, mbedtls_md_type_t md_alg,
    const unsigned char *hash, size_t hash_len,
    const unsigned char *sig, size_t sig_len )
{
    if( info->verify_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    return( info->verify_func( ctx, md_alg, hash, hash_len, sig, sig_len ) );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_sign_func(
    const mbedtls_pk_info_t *info, void *ctx, mbedtls_md_type_t md_alg,
    const unsigned char *hash, size_t hash_len,
    unsigned char *sig, size_t *sig_len,
    int (*f_rng)(void *, unsigned char *, size_t),
    void *p_rng )
{
    if( info->sign_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    return( info->sign_func( ctx, md_alg, hash, hash_len, sig, sig_len,
                             f_rng, p_rng ) );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_decrypt_func(
    const mbedtls_pk_info_t *info, void *ctx,
    const unsigned char *input, size_t ilen,
    unsigned char *output, size_t *olen, size_t osize,
    int (*f_rng)(void *, unsigned char *, size_t),
    void *p_rng )
{
    if( info->decrypt_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    return( info->decrypt_func( ctx, input, ilen, output, olen, osize,
                                f_rng, p_rng ) );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_encrypt_func(
    const mbedtls_pk_info_t *info, void *ctx,
    const unsigned char *input, size_t ilen,
    unsigned char *output, size_t *olen, size_t osize,
    int (*f_rng)(void *, unsigned char *, size_t),
    void *p_rng )
{
    if( info->encrypt_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    return( info->encrypt_func( ctx, input, ilen, output, olen, osize,
                                f_rng, p_rng ) );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_check_pair_func(
    const mbedtls_pk_info_t *info, const void *pub, const void *prv )
{
    if( info->check_pair_func == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    return( info->check_pair_func( pub, prv ) );
}

MBEDTLS_ALWAYS_INLINE static inline void *pk_info_ctx_alloc_func(
    const mbedtls_pk_info_t *info )
{
    return( info->ctx_alloc_func( ) );
}

MBEDTLS_ALWAYS_INLINE static inline void pk_info_ctx_free_func(
    const mbedtls_pk_info_t *info, void *ctx )
{
    info->ctx_free_func( ctx );
}

MBEDTLS_ALWAYS_INLINE static inline int pk_info_debug_func(
    const mbedtls_pk_info_t *info,
    const void *ctx, mbedtls_pk_debug_item *items )
{
    if( info->debug_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    info->debug_func( ctx, items );
    return( 0 );
}

/*
 * Initialise a mbedtls_pk_context
 */
void mbedtls_pk_init( mbedtls_pk_context *ctx )
{
    PK_VALIDATE( ctx != NULL );

    ctx->pk_info = NULL;
    ctx->pk_ctx = NULL;
}

/*
 * Free (the components of) a mbedtls_pk_context
 */
void mbedtls_pk_free( mbedtls_pk_context *ctx )
{
    if( ctx == NULL )
        return;

    if ( ctx->pk_info != NULL )
        pk_info_ctx_free_func( ctx->pk_info, ctx->pk_ctx );

    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_pk_context ) );
}

#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
/*
 * Initialize a restart context
 */
void mbedtls_pk_restart_init( mbedtls_pk_restart_ctx *ctx )
{
    PK_VALIDATE( ctx != NULL );
    ctx->pk_info = NULL;
    ctx->rs_ctx = NULL;
}

/*
 * Free the components of a restart context
 */
void mbedtls_pk_restart_free( mbedtls_pk_restart_ctx *ctx )
{
    if( ctx == NULL || ctx->pk_info == NULL ||
        ctx->pk_info->rs_free_func == NULL )
    {
        return;
    }

    ctx->pk_info->rs_free_func( ctx->rs_ctx );

    ctx->pk_info = NULL;
    ctx->rs_ctx = NULL;
}
#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */

/*
 * Get pk_info structure from type
 */
const mbedtls_pk_info_t * mbedtls_pk_info_from_type( mbedtls_pk_type_t pk_type )
{
    switch( pk_type ) {
#if defined(MBEDTLS_RSA_C)
        case MBEDTLS_PK_RSA:
            return( &mbedtls_rsa_info );
#endif
#if defined(MBEDTLS_ECP_C)
        case MBEDTLS_PK_ECKEY_DH:
            return( &mbedtls_eckeydh_info );
#endif
#if defined(MBEDTLS_ECDSA_C)
        case MBEDTLS_PK_ECDSA:
            return( &mbedtls_ecdsa_info );
#endif
#if defined(MBEDTLS_USE_TINYCRYPT)
        case MBEDTLS_PK_ECKEY:
            return( &mbedtls_uecc_eckey_info );
#else /* MBEDTLS_USE_TINYCRYPT */
#if defined(MBEDTLS_ECP_C)
        case MBEDTLS_PK_ECKEY:
            return( &mbedtls_eckey_info );
#endif
#endif /* MBEDTLS_USE_TINYCRYPT */
        /* MBEDTLS_PK_RSA_ALT omitted on purpose */
        default:
            return( NULL );
    }
}

/*
 * Initialise context
 */
int mbedtls_pk_setup( mbedtls_pk_context *ctx, const mbedtls_pk_info_t *info )
{
    PK_VALIDATE_RET( ctx != NULL );
    if( info == NULL || ctx->pk_info != NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    if( ( ctx->pk_ctx = pk_info_ctx_alloc_func( info ) ) == NULL )
        return( MBEDTLS_ERR_PK_ALLOC_FAILED );

    ctx->pk_info = info;

    return( 0 );
}

#if defined(MBEDTLS_PK_RSA_ALT_SUPPORT)
/*
 * Initialize an RSA-alt context
 */
int mbedtls_pk_setup_rsa_alt( mbedtls_pk_context *ctx, void * key,
                         mbedtls_pk_rsa_alt_decrypt_func decrypt_func,
                         mbedtls_pk_rsa_alt_sign_func sign_func,
                         mbedtls_pk_rsa_alt_key_len_func key_len_func )
{
    mbedtls_rsa_alt_context *rsa_alt;
    const mbedtls_pk_info_t *info = &mbedtls_rsa_alt_info;

    PK_VALIDATE_RET( ctx != NULL );
    if( ctx->pk_info != NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    if( ( ctx->pk_ctx = info->ctx_alloc_func() ) == NULL )
        return( MBEDTLS_ERR_PK_ALLOC_FAILED );

    ctx->pk_info = info;

    rsa_alt = (mbedtls_rsa_alt_context *) ctx->pk_ctx;

    rsa_alt->key = key;
    rsa_alt->decrypt_func = decrypt_func;
    rsa_alt->sign_func = sign_func;
    rsa_alt->key_len_func = key_len_func;

    return( 0 );
}
#endif /* MBEDTLS_PK_RSA_ALT_SUPPORT */

/*
 * Tell if a PK can do the operations of the given type
 */
int mbedtls_pk_can_do( const mbedtls_pk_context *ctx, mbedtls_pk_type_t type )
{
    /* A context with null pk_info is not set up yet and can't do anything.
     * For backward compatibility, also accept NULL instead of a context
     * pointer. */
    if( ctx == NULL || ctx->pk_info == NULL )
        return( 0 );

    return( pk_info_can_do( ctx->pk_info, type ) );
}

/*
 * Helper for mbedtls_pk_sign and mbedtls_pk_verify
 */
static inline int pk_hashlen_helper( mbedtls_md_type_t md_alg, size_t *hash_len )
{
    mbedtls_md_handle_t md_info;

    if( *hash_len != 0 )
        return( 0 );

    if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) ==
        MBEDTLS_MD_INVALID_HANDLE )
    {
        return( -1 );
    }

    *hash_len = mbedtls_md_get_size( md_info );
    return( 0 );
}

#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
/*
 * Helper to set up a restart context if needed
 */
static int pk_restart_setup( mbedtls_pk_restart_ctx *ctx,
                             const mbedtls_pk_info_t *info )
{
    /* Don't do anything if already set up or invalid */
    if( ctx == NULL || ctx->pk_info != NULL )
        return( 0 );

    /* Should never happen when we're called */
    if( info->rs_alloc_func == NULL || info->rs_free_func == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    if( ( ctx->rs_ctx = info->rs_alloc_func() ) == NULL )
        return( MBEDTLS_ERR_PK_ALLOC_FAILED );

    ctx->pk_info = info;

    return( 0 );
}
#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */

/*
 * Verify a signature (restartable)
 */
int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
               mbedtls_md_type_t md_alg,
               const unsigned char *hash, size_t hash_len,
               const unsigned char *sig, size_t sig_len,
               mbedtls_pk_restart_ctx *rs_ctx )
{
    PK_VALIDATE_RET( ctx != NULL );
    PK_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && hash_len == 0 ) ||
                     hash != NULL );
    PK_VALIDATE_RET( sig != NULL );

    if( ctx->pk_info == NULL ||
        pk_hashlen_helper( md_alg, &hash_len ) != 0 )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
    /* optimization: use non-restartable version if restart disabled */
    if( rs_ctx != NULL &&
        mbedtls_ecp_restart_is_enabled() &&
        ctx->pk_info->verify_rs_func != NULL )
    {
        int ret;

        if( ( ret = pk_restart_setup( rs_ctx, ctx->pk_info ) ) != 0 )
            return( ret );

        ret = ctx->pk_info->verify_rs_func( ctx->pk_ctx,
                   md_alg, hash, hash_len, sig, sig_len, rs_ctx->rs_ctx );

        if( ret != MBEDTLS_ERR_ECP_IN_PROGRESS )
            mbedtls_pk_restart_free( rs_ctx );

        return( ret );
    }
#else /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
    (void) rs_ctx;
#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */

    return( pk_info_verify_func( ctx->pk_info, ctx->pk_ctx, md_alg, hash, hash_len,
                                       sig, sig_len ) );
}

/*
 * Verify a signature
 */
int mbedtls_pk_verify( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
               const unsigned char *hash, size_t hash_len,
               const unsigned char *sig, size_t sig_len )
{
    return( mbedtls_pk_verify_restartable( ctx, md_alg, hash, hash_len,
                                           sig, sig_len, NULL ) );
}

/*
 * Verify a signature with options
 */
int mbedtls_pk_verify_ext( mbedtls_pk_type_t type, const void *options,
                   mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
                   const unsigned char *hash, size_t hash_len,
                   const unsigned char *sig, size_t sig_len )
{
    PK_VALIDATE_RET( ctx != NULL );
    PK_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && hash_len == 0 ) ||
                     hash != NULL );
    PK_VALIDATE_RET( sig != NULL );

    if( ctx->pk_info == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    if( ! mbedtls_pk_can_do( ctx, type ) )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    if( type == MBEDTLS_PK_RSASSA_PSS )
    {
#if defined(MBEDTLS_RSA_C) && defined(MBEDTLS_PKCS1_V21)
        int ret;
        const mbedtls_pk_rsassa_pss_options *pss_opts;

#if SIZE_MAX > UINT_MAX
        if( md_alg == MBEDTLS_MD_NONE && UINT_MAX < hash_len )
            return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
#endif /* SIZE_MAX > UINT_MAX */

        if( options == NULL )
            return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

        pss_opts = (const mbedtls_pk_rsassa_pss_options *) options;

        if( sig_len < mbedtls_pk_get_len( ctx ) )
            return( MBEDTLS_ERR_RSA_VERIFY_FAILED );

        ret = mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_pk_rsa( *ctx ),
                NULL, NULL, MBEDTLS_RSA_PUBLIC,
                md_alg, (unsigned int) hash_len, hash,
                pss_opts->mgf1_hash_id,
                pss_opts->expected_salt_len,
                sig );
        if( ret != 0 )
            return( ret );

        if( sig_len > mbedtls_pk_get_len( ctx ) )
            return( MBEDTLS_ERR_PK_SIG_LEN_MISMATCH );

        return( 0 );
#else
        return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
#endif /* MBEDTLS_RSA_C && MBEDTLS_PKCS1_V21 */
    }

    /* General case: no options */
    if( options != NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    return( mbedtls_pk_verify( ctx, md_alg, hash, hash_len, sig, sig_len ) );
}

/*
 * Make a signature (restartable)
 */
int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
             mbedtls_md_type_t md_alg,
             const unsigned char *hash, size_t hash_len,
             unsigned char *sig, size_t *sig_len,
             int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
             mbedtls_pk_restart_ctx *rs_ctx )
{
    PK_VALIDATE_RET( ctx != NULL );
    PK_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && hash_len == 0 ) ||
                     hash != NULL );
    PK_VALIDATE_RET( sig != NULL );

    if( ctx->pk_info == NULL ||
        pk_hashlen_helper( md_alg, &hash_len ) != 0 )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
    /* optimization: use non-restartable version if restart disabled */
    if( rs_ctx != NULL &&
        mbedtls_ecp_restart_is_enabled() &&
        ctx->pk_info->sign_rs_func != NULL )
    {
        int ret;

        if( ( ret = pk_restart_setup( rs_ctx, ctx->pk_info ) ) != 0 )
            return( ret );

        ret = ctx->pk_info->sign_rs_func( ctx->pk_ctx, md_alg,
                hash, hash_len, sig, sig_len, f_rng, p_rng, rs_ctx->rs_ctx );

        if( ret != MBEDTLS_ERR_ECP_IN_PROGRESS )
            mbedtls_pk_restart_free( rs_ctx );

        return( ret );
    }
#else /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
    (void) rs_ctx;
#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */

    return( pk_info_sign_func( ctx->pk_info, ctx->pk_ctx, md_alg, hash, hash_len,
                                     sig, sig_len, f_rng, p_rng ) );
}

/*
 * Make a signature
 */
int mbedtls_pk_sign( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
             const unsigned char *hash, size_t hash_len,
             unsigned char *sig, size_t *sig_len,
             int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
    return( mbedtls_pk_sign_restartable( ctx, md_alg, hash, hash_len,
                                         sig, sig_len, f_rng, p_rng, NULL ) );
}

/*
 * Decrypt message
 */
int mbedtls_pk_decrypt( mbedtls_pk_context *ctx,
                const unsigned char *input, size_t ilen,
                unsigned char *output, size_t *olen, size_t osize,
                int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
    PK_VALIDATE_RET( ctx != NULL );
    PK_VALIDATE_RET( input != NULL || ilen == 0 );
    PK_VALIDATE_RET( output != NULL || osize == 0 );
    PK_VALIDATE_RET( olen != NULL );

    if( ctx->pk_info == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    return( pk_info_decrypt_func( ctx->pk_info, ctx->pk_ctx, input, ilen,
                output, olen, osize, f_rng, p_rng ) );
}

/*
 * Encrypt message
 */
int mbedtls_pk_encrypt( mbedtls_pk_context *ctx,
                const unsigned char *input, size_t ilen,
                unsigned char *output, size_t *olen, size_t osize,
                int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
    PK_VALIDATE_RET( ctx != NULL );
    PK_VALIDATE_RET( input != NULL || ilen == 0 );
    PK_VALIDATE_RET( output != NULL || osize == 0 );
    PK_VALIDATE_RET( olen != NULL );

    if( ctx->pk_info == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    return( pk_info_encrypt_func( ctx->pk_info, ctx->pk_ctx, input, ilen,
                output, olen, osize, f_rng, p_rng ) );
}

/*
 * Check public-private key pair
 */
int mbedtls_pk_check_pair( const mbedtls_pk_context *pub, const mbedtls_pk_context *prv )
{
    PK_VALIDATE_RET( pub != NULL );
    PK_VALIDATE_RET( prv != NULL );

    if( pub->pk_info == NULL || prv->pk_info == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

#if defined(MBEDTLS_PK_RSA_ALT_SUPPORT)
    if( pk_info_type( prv->pk_info ) == MBEDTLS_PK_RSA_ALT )
    {
        if( pk_info_type( pub->pk_info ) != MBEDTLS_PK_RSA )
            return( MBEDTLS_ERR_PK_TYPE_MISMATCH );
    }
    else
#endif /* MBEDTLS_PK_RSA_ALT_SUPPORT */
    {
        if( pub->pk_info != prv->pk_info )
            return( MBEDTLS_ERR_PK_TYPE_MISMATCH );
    }

    return( pk_info_check_pair_func( prv->pk_info, pub->pk_ctx, prv->pk_ctx ) );
}

/*
 * Get key size in bits
 */
size_t mbedtls_pk_get_bitlen( const mbedtls_pk_context *ctx )
{
    /* For backward compatibility, accept NULL or a context that
     * isn't set up yet, and return a fake value that should be safe. */
    if( ctx == NULL || ctx->pk_info == NULL )
        return( 0 );

    return( pk_info_get_bitlen( ctx->pk_info, ctx->pk_ctx ) );
}

/*
 * Export debug information
 */
int mbedtls_pk_debug( const mbedtls_pk_context *ctx, mbedtls_pk_debug_item *items )
{
    PK_VALIDATE_RET( ctx != NULL );
    if( ctx->pk_info == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    return( pk_info_debug_func( ctx->pk_info, ctx->pk_ctx, items ) );
}

/*
 * Access the PK type name
 */
const char *mbedtls_pk_get_name( const mbedtls_pk_context *ctx )
{
    if( ctx == NULL || ctx->pk_info == NULL )
        return( "invalid PK" );

    return( pk_info_name( ctx->pk_info ) );
}

/*
 * Access the PK type
 */
mbedtls_pk_type_t mbedtls_pk_get_type( const mbedtls_pk_context *ctx )
{
    if( ctx == NULL || ctx->pk_info == NULL )
        return( MBEDTLS_PK_NONE );

    return( pk_info_type( ctx->pk_info ) );
}

#endif /* MBEDTLS_PK_C */