library/pk.c

/*
 *  Public Key abstraction layer
 *
 *  Copyright (C) 2006-2014, ARM Limited, All Rights Reserved
 *
 *  This file is part of mbed TLS (https://tls.mbed.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.
 *
 *  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.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#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"

#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

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
}

/*
 * Initialise a mbedtls_pk_context
 */
void mbedtls_pk_init( mbedtls_pk_context *ctx )
{
    if( ctx == NULL )
        return;

    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 || ctx->pk_info == NULL )
        return;

    ctx->pk_info->ctx_free_func( ctx->pk_ctx );

    mbedtls_zeroize( ctx, sizeof( mbedtls_pk_context ) );
}

/*
 * 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:
            return( &mbedtls_eckey_info );
        case MBEDTLS_PK_ECKEY_DH:
            return( &mbedtls_eckeydh_info );
#endif
#if defined(MBEDTLS_ECDSA_C)
        case MBEDTLS_PK_ECDSA:
            return( &mbedtls_ecdsa_info );
#endif
        /* 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 )
{
    if( ctx == NULL || info == NULL || 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;

    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;

    if( ctx == NULL || 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 )
{
    /* null or NONE context can't do anything */
    if( ctx == NULL || ctx->pk_info == NULL )
        return( 0 );

    return( ctx->pk_info->can_do( 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 )
{
    const mbedtls_md_info_t *md_info;

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

    if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
        return( -1 );

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

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

    if( ctx->pk_info->verify_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

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

/*
 * 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 )
{
    if( ctx == NULL || 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( 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
    }

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

    if( ctx->pk_info->sign_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

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

/*
 * 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 )
{
    if( ctx == NULL || ctx->pk_info == NULL )
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );

    if( ctx->pk_info->decrypt_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

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

    if( ctx->pk_info->encrypt_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

    return( ctx->pk_info->encrypt_func( 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 )
{
    if( pub == NULL || pub->pk_info == NULL ||
        prv == NULL || prv->pk_info == NULL ||
        prv->pk_info->check_pair_func == NULL )
    {
        return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
    }

    if( prv->pk_info->type == MBEDTLS_PK_RSA_ALT )
    {
        if( pub->pk_info->type != MBEDTLS_PK_RSA )
            return( MBEDTLS_ERR_PK_TYPE_MISMATCH );
    }
    else
    {
        if( pub->pk_info != prv->pk_info )
            return( MBEDTLS_ERR_PK_TYPE_MISMATCH );
    }

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

/*
 * Get key size in bits
 */
size_t mbedtls_pk_get_size( const mbedtls_pk_context *ctx )
{
    if( ctx == NULL || ctx->pk_info == NULL )
        return( 0 );

    return( ctx->pk_info->get_bitlen( ctx->pk_ctx ) );
}

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

    if( ctx->pk_info->debug_func == NULL )
        return( MBEDTLS_ERR_PK_TYPE_MISMATCH );

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

/*
 * 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( ctx->pk_info->name );
}

/*
 * 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( ctx->pk_info->type );
}

#endif /* MBEDTLS_PK_C */