linux-imx

// SPDX-License-Identifier: GPL-2.0-or-later

/* RSA asymmetric public-key algorithm [RFC3447]

 *

 * Copyright (c) 2015, Intel Corporation

 * Authors: Tadeusz Struk <tadeusz.struk@intel.com>

 */

​

#include <linux/module.h>

#include <linux/mpi.h>

#include <crypto/internal/rsa.h>

#include <crypto/internal/akcipher.h>

#include <crypto/akcipher.h>

#include <crypto/algapi.h>

​

struct rsa_mpi_key {

    MPI n;

    MPI e;

    MPI d;

};

​

/*

 * RSAEP function [RFC3447 sec 5.1.1]

 * c = m^e mod n;

 */

static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m)

{

    /* (1) Validate 0 <= m < n */

    if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)

        return -EINVAL;

​

    /* (2) c = m^e mod n */

    return mpi_powm(c, m, key->e, key->n);

}

​

/*

 * RSADP function [RFC3447 sec 5.1.2]

 * m = c^d mod n;

 */

static int _rsa_dec(const struct rsa_mpi_key *key, MPI m, MPI c)

{

    /* (1) Validate 0 <= c < n */

    if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)

        return -EINVAL;

​

    /* (2) m = c^d mod n */

    return mpi_powm(m, c, key->d, key->n);

}

​

static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)

{

    return akcipher_tfm_ctx(tfm);

}

​

static int rsa_enc(struct akcipher_request *req)

{

    struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);

    const struct rsa_mpi_key *pkey = rsa_get_key(tfm);

    MPI m, c = mpi_alloc(0);

    int ret = 0;

    int sign;

​

    if (!c)

        return -ENOMEM;

​

    if (unlikely(!pkey->n || !pkey->e)) {

        ret = -EINVAL;

        goto err_free_c;

    }

​

    ret = -ENOMEM;

    m = mpi_read_raw_from_sgl(req->src, req->src_len);

    if (!m)

        goto err_free_c;

​

    ret = _rsa_enc(pkey, c, m);

    if (ret)

        goto err_free_m;

​

    ret = mpi_write_to_sgl(c, req->dst, req->dst_len, &sign);

    if (ret)

        goto err_free_m;

​

    if (sign < 0)

        ret = -EBADMSG;

​

err_free_m:

    mpi_free(m);

err_free_c:

    mpi_free(c);

    return ret;

}

​