/* $OpenBSD: cms_pwri.c,v 1.31 2024/01/14 18:40:24 tb 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 <sys/types.h>

#include <stdlib.h>
#include <string.h>

#include <openssl/asn1.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/cms.h>
#include <openssl/objects.h>
#include <openssl/x509.h>

#include "cms_local.h"
#include "evp_local.h"
#include "x509_local.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;
}
LCRYPTO_ALIAS(CMS_RecipientInfo_set0_password);

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;
}
LCRYPTO_ALIAS(CMS_add0_recipient_password);

/*
 * 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;
}