/* crypto/rsa/rsa_sign.c */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 *

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

#include <stdio.h>

#include "cryptlib.h"

#include <openssl/bn.h>

#include <openssl/rsa.h>

#include <openssl/objects.h>

#include <openssl/x509.h>

#include "rsa_locl.h"

/* Size of an SSL signature: MD5+SHA1 */

#define SSL_SIG_LENGTH  36

int RSA_sign(int type, const unsigned char *m, unsigned int m_len,

             unsigned char *sigret, unsigned int *siglen, RSA *rsa)

{

    X509_SIG sig;

    ASN1_TYPE parameter;

    int i, j, ret = 1;

    unsigned char *p, *tmps = NULL;

    const unsigned char *s = NULL;

    X509_ALGOR algor;

    ASN1_OCTET_STRING digest;

#ifdef OPENSSL_FIPS

    if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)

        && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {

        RSAerr(RSA_F_RSA_SIGN, RSA_R_NON_FIPS_RSA_METHOD);

        return 0;

    }

#endif

    if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_sign) {

        return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);

    }

    /* Special case: SSL signature, just check the length */

    if (type == NID_md5_sha1) {

        if (m_len != SSL_SIG_LENGTH) {

            RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);

            return (0);

        }

        i = SSL_SIG_LENGTH;

        s = m;

    } else {

        sig.algor = &algor;

        sig.algor->algorithm = OBJ_nid2obj(type);

        if (sig.algor->algorithm == NULL) {

            RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);

            return (0);

        }

        if (sig.algor->algorithm->length == 0) {

            RSAerr(RSA_F_RSA_SIGN,

                   RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);

            return (0);

        }

        parameter.type = V_ASN1_NULL;

        parameter.value.ptr = NULL;

        sig.algor->parameter = &parameter;

        sig.digest = &digest;

        sig.digest->data = (unsigned char *)m; /* TMP UGLY CAST */

        sig.digest->length = m_len;

        i = i2d_X509_SIG(&sig, NULL);

    }

    j = RSA_size(rsa);

    if (i > (j - RSA_PKCS1_PADDING_SIZE)) {

        RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);

        return (0);

    }

    if (type != NID_md5_sha1) {

        tmps = (unsigned char *)OPENSSL_malloc((unsigned int)j + 1);

        if (tmps == NULL) {

            RSAerr(RSA_F_RSA_SIGN, ERR_R_MALLOC_FAILURE);

            return (0);

        }

        p = tmps;

        i2d_X509_SIG(&sig, &p);

        s = tmps;

    }

    i = RSA_private_encrypt(i, s, sigret, rsa, RSA_PKCS1_PADDING);

    if (i <= 0)

        ret = 0;

    else

        *siglen = i;

    if (type != NID_md5_sha1) {

        OPENSSL_cleanse(tmps, (unsigned int)j + 1);

        OPENSSL_free(tmps);

    }

    return (ret);

}

/*

 * Check DigestInfo structure does not contain extraneous data by reencoding

 * using DER and checking encoding against original.

 */

static int rsa_check_digestinfo(X509_SIG *sig, const unsigned char *dinfo,

                                int dinfolen)

{

    unsigned char *der = NULL;

    int derlen;

    int ret = 0;

    derlen = i2d_X509_SIG(sig, &der);

    if (derlen <= 0)

        return 0;

    if (derlen == dinfolen && !memcmp(dinfo, der, derlen))

        ret = 1;

    OPENSSL_cleanse(der, derlen);

    OPENSSL_free(der);

    return ret;

}

int int_rsa_verify(int dtype, const unsigned char *m,

                   unsigned int m_len,

                   unsigned char *rm, size_t *prm_len,

                   const unsigned char *sigbuf, size_t siglen, RSA *rsa)

{

    int i, ret = 0, sigtype;

    unsigned char *s;

    X509_SIG *sig = NULL;

#ifdef OPENSSL_FIPS

    if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)

        && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {

        RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_NON_FIPS_RSA_METHOD);

        return 0;

    }

#endif

    if (siglen != (unsigned int)RSA_size(rsa)) {

        RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH);

        return (0);

    }

    if ((dtype == NID_md5_sha1) && rm) {

        i = RSA_public_decrypt((int)siglen,

                               sigbuf, rm, rsa, RSA_PKCS1_PADDING);

        if (i <= 0)

            return 0;

        *prm_len = i;

        return 1;

    }

    s = (unsigned char *)OPENSSL_malloc((unsigned int)siglen);

    if (s == NULL) {

        RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE);

        goto err;

    }

    if ((dtype == NID_md5_sha1) && (m_len != SSL_SIG_LENGTH)) {

        RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);

        goto err;

    }

    i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING);

    if (i <= 0)

        goto err;

    /*

     * Oddball MDC2 case: signature can be OCTET STRING. check for correct

     * tag and length octets.

     */

    if (dtype == NID_mdc2 && i == 18 && s[0] == 0x04 && s[1] == 0x10) {

        if (rm) {

            memcpy(rm, s + 2, 16);

            *prm_len = 16;

            ret = 1;

        } else if (memcmp(m, s + 2, 16)) {

            RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);

        } else {

            ret = 1;

        }

    } else if (dtype == NID_md5_sha1) {

        /* Special case: SSL signature */

        if ((i != SSL_SIG_LENGTH) || memcmp(s, m, SSL_SIG_LENGTH))

            RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);

        else

            ret = 1;

    } else {

        const unsigned char *p = s;

        sig = d2i_X509_SIG(NULL, &p, (long)i);

        if (sig == NULL)

            goto err;

        /* Excess data can be used to create forgeries */

        if (p != s + i || !rsa_check_digestinfo(sig, s, i)) {

            RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);

            goto err;

        }

        /*

         * Parameters to the signature algorithm can also be used to create

         * forgeries

         */

        if (sig->algor->parameter

            && ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) {

            RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);

            goto err;

        }

        sigtype = OBJ_obj2nid(sig->algor->algorithm);

#ifdef RSA_DEBUG

        /* put a backward compatibility flag in EAY */

        fprintf(stderr, "in(%s) expect(%s)\n", OBJ_nid2ln(sigtype),

                OBJ_nid2ln(dtype));

#endif

        if (sigtype != dtype) {

            RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_ALGORITHM_MISMATCH);

            goto err;

        }

        if (rm) {

            const EVP_MD *md;

            md = EVP_get_digestbynid(dtype);

            if (md && (EVP_MD_size(md) != sig->digest->length))

                RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH);

            else {

                memcpy(rm, sig->digest->data, sig->digest->length);

                *prm_len = sig->digest->length;

                ret = 1;

            }

        } else if (((unsigned int)sig->digest->length != m_len) ||

                   (memcmp(m, sig->digest->data, m_len) != 0)) {

            RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);

        } else

            ret = 1;

    }

 err:

    if (sig != NULL)

        X509_SIG_free(sig);

    if (s != NULL) {

        OPENSSL_cleanse(s, (unsigned int)siglen);

        OPENSSL_free(s);

    }

    return (ret);

}

int RSA_verify(int dtype, const unsigned char *m, unsigned int m_len,

               const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)

{

    if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify) {

        return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen, rsa);

    }

    return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa);

}