/* $OpenBSD: cms_pwri.c,v 1.27 2022/01/19 13:47:44 inoguchi Exp $ */
/*
 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 2009 The OpenSSL Project.  All rights reserved.
 *
 * 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 above 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 acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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.
 * ====================================================================
 */

#include <string.h>

#include "cryptlib.h"
#include <openssl/asn1t.h>
#include <openssl/pem.h>
#include <openssl/x509v3.h>
#include <openssl/err.h>
#include <openssl/cms.h>
#include <openssl/rand.h>
#include <openssl/aes.h>
#include "cms_lcl.h"
#include "asn1/asn1_locl.h"

int
CMS_RecipientInfo_set0_password(CMS_RecipientInfo *ri, unsigned char *pass,
    ssize_t passlen)
{
        CMS_PasswordRecipientInfo *pwri;

        if (ri->type != CMS_RECIPINFO_PASS) {
                CMSerror(CMS_R_NOT_PWRI);
                return 0;
        }

        pwri = ri->d.pwri;
        pwri->pass = pass;
        if (pass && passlen < 0)
                passlen = strlen((char *)pass);
        pwri->passlen = passlen;

        return 1;
}

CMS_RecipientInfo *
CMS_add0_recipient_password(CMS_ContentInfo *cms, int iter, int wrap_nid,
    int pbe_nid, unsigned char *pass, ssize_t passlen,
    const EVP_CIPHER *kekciph)
{
        CMS_RecipientInfo *ri = NULL;
        CMS_EnvelopedData *env;
        CMS_PasswordRecipientInfo *pwri;
        EVP_CIPHER_CTX *ctx = NULL;
        X509_ALGOR *encalg = NULL;
        unsigned char iv[EVP_MAX_IV_LENGTH];
        int ivlen;

        env = cms_get0_enveloped(cms);
        if (!env)
                return NULL;

        if (wrap_nid <= 0)
                wrap_nid = NID_id_alg_PWRI_KEK;

        if (pbe_nid <= 0)
                pbe_nid = NID_id_pbkdf2;

        /* Get from enveloped data */
        if (kekciph == NULL)
                kekciph = env->encryptedContentInfo->cipher;

        if (kekciph == NULL) {
                CMSerror(CMS_R_NO_CIPHER);
                return NULL;
        }
        if (wrap_nid != NID_id_alg_PWRI_KEK) {
                CMSerror(CMS_R_UNSUPPORTED_KEY_ENCRYPTION_ALGORITHM);
                return NULL;
        }

        /* Setup algorithm identifier for cipher */
        encalg = X509_ALGOR_new();
        if (encalg == NULL) {
                goto merr;
        }

        if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
                goto merr;

        if (EVP_EncryptInit_ex(ctx, kekciph, NULL, NULL, NULL) <= 0) {
                CMSerror(ERR_R_EVP_LIB);
                goto err;
        }

        ivlen = EVP_CIPHER_CTX_iv_length(ctx);

        if (ivlen > 0) {
                arc4random_buf(iv, ivlen);
                if (EVP_EncryptInit_ex(ctx, NULL, NULL, NULL, iv) <= 0) {
                        CMSerror(ERR_R_EVP_LIB);
                        goto err;
                }
                encalg->parameter = ASN1_TYPE_new();
                if (!encalg->parameter) {
                        CMSerror(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
                if (EVP_CIPHER_param_to_asn1(ctx, encalg->parameter) <= 0) {
                        CMSerror(CMS_R_CIPHER_PARAMETER_INITIALISATION_ERROR);
                        goto err;
                }
        }

        encalg->algorithm = OBJ_nid2obj(EVP_CIPHER_CTX_type(ctx));

        EVP_CIPHER_CTX_free(ctx);
        ctx = NULL;

        /* Initialize recipient info */
        ri = (CMS_RecipientInfo *)ASN1_item_new(&CMS_RecipientInfo_it);
        if (ri == NULL)
                goto merr;

        ri->d.pwri = (CMS_PasswordRecipientInfo *)ASN1_item_new(&CMS_PasswordRecipientInfo_it);
        if (ri->d.pwri == NULL)
                goto merr;
        ri->type = CMS_RECIPINFO_PASS;

        pwri = ri->d.pwri;
        /* Since this is overwritten, free up empty structure already there */
        X509_ALGOR_free(pwri->keyEncryptionAlgorithm);
        pwri->keyEncryptionAlgorithm = X509_ALGOR_new();
        if (pwri->keyEncryptionAlgorithm == NULL)
                goto merr;
        pwri->keyEncryptionAlgorithm->algorithm = OBJ_nid2obj(wrap_nid);
        pwri->keyEncryptionAlgorithm->parameter = ASN1_TYPE_new();
        if (pwri->keyEncryptionAlgorithm->parameter == NULL)
                goto merr;

        if (!ASN1_item_pack(encalg, &X509_ALGOR_it,
            &pwri->keyEncryptionAlgorithm->parameter->value.sequence))
                 goto merr;
        pwri->keyEncryptionAlgorithm->parameter->type = V_ASN1_SEQUENCE;

        X509_ALGOR_free(encalg);
        encalg = NULL;

        /* Setup PBE algorithm */

        pwri->keyDerivationAlgorithm = PKCS5_pbkdf2_set(iter, NULL, 0, -1, -1);

        if (!pwri->keyDerivationAlgorithm)
                goto err;

        CMS_RecipientInfo_set0_password(ri, pass, passlen);
        pwri->version = 0;

        if (!sk_CMS_RecipientInfo_push(env->recipientInfos, ri))
                goto merr;

        return ri;

 merr:
        CMSerror(ERR_R_MALLOC_FAILURE);
 err:
        EVP_CIPHER_CTX_free(ctx);
        if (ri)
                ASN1_item_free((ASN1_VALUE *)ri, &CMS_RecipientInfo_it);
        X509_ALGOR_free(encalg);

        return NULL;
}

/*
 * This is an implementation of the key wrapping mechanism in RFC3211, at
 * some point this should go into EVP.
 */

static int
kek_unwrap_key(unsigned char *out, size_t *outlen, const unsigned char *in,
    size_t inlen, EVP_CIPHER_CTX *ctx)
{
        size_t blocklen = EVP_CIPHER_CTX_block_size(ctx);
        unsigned char *tmp;
        int outl, rv = 0;

        if (inlen < 2 * blocklen) {
                /* too small */
                return 0;
        }
        if (inlen % blocklen) {
                /* Invalid size */
                return 0;
        }
        if ((tmp = malloc(inlen)) == NULL) {
                CMSerror(ERR_R_MALLOC_FAILURE);
                return 0;
        }

        /* setup IV by decrypting last two blocks */
        if (!EVP_DecryptUpdate(ctx, tmp + inlen - 2 * blocklen, &outl,
            in + inlen - 2 * blocklen, blocklen * 2)
                /*
                 * Do a decrypt of last decrypted block to set IV to correct value
                 * output it to start of buffer so we don't corrupt decrypted block
                 * this works because buffer is at least two block lengths long.
                 */
                || !EVP_DecryptUpdate(ctx, tmp, &outl, tmp + inlen - blocklen, blocklen)
                /* Can now decrypt first n - 1 blocks */
                || !EVP_DecryptUpdate(ctx, tmp, &outl, in, inlen - blocklen)

                /* Reset IV to original value */
                || !EVP_DecryptInit_ex(ctx, NULL, NULL, NULL, NULL)
                /* Decrypt again */
                || !EVP_DecryptUpdate(ctx, tmp, &outl, tmp, inlen))
                goto err;
        /* Check check bytes */
        if (((tmp[1] ^ tmp[4]) & (tmp[2] ^ tmp[5]) & (tmp[3] ^ tmp[6])) != 0xff) {
                /* Check byte failure */
                goto err;
        }
        if (inlen < (size_t)(tmp[0] - 4)) {
                /* Invalid length value */
                goto err;
        }
        *outlen = (size_t)tmp[0];
        memcpy(out, tmp + 4, *outlen);
        rv = 1;

 err:
        freezero(tmp, inlen);

        return rv;
}

static int
kek_wrap_key(unsigned char *out, size_t *outlen, const unsigned char *in,
    size_t inlen, EVP_CIPHER_CTX *ctx)
{
        size_t blocklen = EVP_CIPHER_CTX_block_size(ctx);
        size_t olen;
        int dummy;

        /*
         * First decide length of output buffer: need header and round up to
         * multiple of block length.
         */
        olen = (inlen + 4 + blocklen - 1) / blocklen;
        olen *= blocklen;
        if (olen < 2 * blocklen) {
                /* Key too small */
                return 0;
        }
        if (inlen > 0xFF) {
                /* Key too large */
                return 0;
        }
        if (out) {
                /* Set header */
                out[0] = (unsigned char)inlen;
                out[1] = in[0] ^ 0xFF;
                out[2] = in[1] ^ 0xFF;
                out[3] = in[2] ^ 0xFF;
                memcpy(out + 4, in, inlen);
                /* Add random padding to end */
                if (olen > inlen + 4)
                        arc4random_buf(out + 4 + inlen, olen - 4 - inlen);
                /* Encrypt twice */
                if (!EVP_EncryptUpdate(ctx, out, &dummy, out, olen) ||
                    !EVP_EncryptUpdate(ctx, out, &dummy, out, olen))
                        return 0;
        }

        *outlen = olen;

        return 1;
}

/* Encrypt/Decrypt content key in PWRI recipient info */

int
cms_RecipientInfo_pwri_crypt(CMS_ContentInfo *cms, CMS_RecipientInfo *ri,
    int en_de)
{
        CMS_EncryptedContentInfo *ec;
        CMS_PasswordRecipientInfo *pwri;
        int r = 0;
        X509_ALGOR *algtmp, *kekalg = NULL;
        EVP_CIPHER_CTX *kekctx = NULL;
        const EVP_CIPHER *kekcipher;
        unsigned char *key = NULL;
        size_t keylen;

        ec = cms->d.envelopedData->encryptedContentInfo;

        pwri = ri->d.pwri;

        if (!pwri->pass) {
                CMSerror(CMS_R_NO_PASSWORD);
                return 0;
        }
        algtmp = pwri->keyEncryptionAlgorithm;

        if (!algtmp || OBJ_obj2nid(algtmp->algorithm) != NID_id_alg_PWRI_KEK) {
                CMSerror(CMS_R_UNSUPPORTED_KEY_ENCRYPTION_ALGORITHM);
                return 0;
        }

        if (algtmp->parameter != NULL &&
            algtmp->parameter->type == V_ASN1_SEQUENCE &&
            algtmp->parameter->value.sequence != NULL)
                kekalg = ASN1_item_unpack(algtmp->parameter->value.sequence,
                    &X509_ALGOR_it);

        if (kekalg == NULL) {
                CMSerror(CMS_R_INVALID_KEY_ENCRYPTION_PARAMETER);
                return 0;
        }

        kekcipher = EVP_get_cipherbyobj(kekalg->algorithm);
        if (!kekcipher) {
                CMSerror(CMS_R_UNKNOWN_CIPHER);
                return 0;
        }

        kekctx = EVP_CIPHER_CTX_new();
        if (kekctx == NULL) {
                CMSerror(ERR_R_MALLOC_FAILURE);
                return 0;
        }
        /* Fixup cipher based on AlgorithmIdentifier to set IV etc */
        if (!EVP_CipherInit_ex(kekctx, kekcipher, NULL, NULL, NULL, en_de))
                goto err;
        EVP_CIPHER_CTX_set_padding(kekctx, 0);
        if (EVP_CIPHER_asn1_to_param(kekctx, kekalg->parameter) <= 0) {
                CMSerror(CMS_R_CIPHER_PARAMETER_INITIALISATION_ERROR);
                goto err;
        }

        algtmp = pwri->keyDerivationAlgorithm;

        /* Finish password based key derivation to setup key in "ctx" */

        if (EVP_PBE_CipherInit(algtmp->algorithm, (char *)pwri->pass,
            pwri->passlen, algtmp->parameter, kekctx, en_de) < 0) {
                CMSerror(ERR_R_EVP_LIB);
                goto err;
        }

        /* Finally wrap/unwrap the key */

        if (en_de) {
                if (!kek_wrap_key(NULL, &keylen, ec->key, ec->keylen, kekctx))
                        goto err;

                key = malloc(keylen);
                if (key == NULL)
                        goto err;

                if (!kek_wrap_key(key, &keylen, ec->key, ec->keylen, kekctx))
                        goto err;
                pwri->encryptedKey->data = key;
                pwri->encryptedKey->length = keylen;
        } else {
                key = malloc(pwri->encryptedKey->length);
                if (key == NULL) {
                        CMSerror(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
                if (!kek_unwrap_key(key, &keylen, pwri->encryptedKey->data,
                    pwri->encryptedKey->length, kekctx)) {
                        CMSerror(CMS_R_UNWRAP_FAILURE);
                        goto err;
                }

                freezero(ec->key, ec->keylen);
                ec->key = key;
                ec->keylen = keylen;
        }

        r = 1;

 err:
        EVP_CIPHER_CTX_free(kekctx);
        if (!r)
                free(key);
        X509_ALGOR_free(kekalg);

        return r;
}