/*

 * Copyright 2013-2025 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/*

 * Low level key APIs (DH etc) are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include "internal/cryptlib.h"

#include <openssl/asn1t.h>

#include <openssl/pem.h>

#include <openssl/x509v3.h>

#include <openssl/err.h>

#include <openssl/cms.h>

#include <openssl/aes.h>

#include "cms_local.h"

#include "crypto/asn1.h"

/* Key Agreement Recipient Info (KARI) routines */

int CMS_RecipientInfo_kari_get0_alg(CMS_RecipientInfo *ri,

                                    X509_ALGOR **palg,

                                    ASN1_OCTET_STRING **pukm)

{

    if (ri->type != CMS_RECIPINFO_AGREE) {

        ERR_raise(ERR_LIB_CMS, CMS_R_NOT_KEY_AGREEMENT);

        return 0;

    }

    if (palg)

        *palg = ri->d.kari->keyEncryptionAlgorithm;

    if (pukm)

        *pukm = ri->d.kari->ukm;

    return 1;

}

/* Retrieve recipient encrypted keys from a kari */

STACK_OF(CMS_RecipientEncryptedKey)

*CMS_RecipientInfo_kari_get0_reks(CMS_RecipientInfo *ri)

{

    if (ri->type != CMS_RECIPINFO_AGREE) {

        ERR_raise(ERR_LIB_CMS, CMS_R_NOT_KEY_AGREEMENT);

        return NULL;

    }

    return ri->d.kari->recipientEncryptedKeys;

}

int CMS_RecipientInfo_kari_get0_orig_id(CMS_RecipientInfo *ri,

                                        X509_ALGOR **pubalg,

                                        ASN1_BIT_STRING **pubkey,

                                        ASN1_OCTET_STRING **keyid,

                                        X509_NAME **issuer,

                                        ASN1_INTEGER **sno)

{

    CMS_OriginatorIdentifierOrKey *oik;

    if (ri->type != CMS_RECIPINFO_AGREE) {

        ERR_raise(ERR_LIB_CMS, CMS_R_NOT_KEY_AGREEMENT);

        return 0;

    }

    oik = ri->d.kari->originator;

    if (issuer)

        *issuer = NULL;

    if (sno)

        *sno = NULL;

    if (keyid)

        *keyid = NULL;

    if (pubalg)

        *pubalg = NULL;

    if (pubkey)

        *pubkey = NULL;

    if (oik->type == CMS_OIK_ISSUER_SERIAL) {

        if (issuer)

            *issuer = oik->d.issuerAndSerialNumber->issuer;

        if (sno)

            *sno = oik->d.issuerAndSerialNumber->serialNumber;

    } else if (oik->type == CMS_OIK_KEYIDENTIFIER) {

        if (keyid)

            *keyid = oik->d.subjectKeyIdentifier;

    } else if (oik->type == CMS_OIK_PUBKEY) {

        if (pubalg)

            *pubalg = oik->d.originatorKey->algorithm;

        if (pubkey)

            *pubkey = oik->d.originatorKey->publicKey;

    } else

        return 0;

    return 1;

}

int CMS_RecipientInfo_kari_orig_id_cmp(CMS_RecipientInfo *ri, X509 *cert)

{

    CMS_OriginatorIdentifierOrKey *oik;

    if (ri->type != CMS_RECIPINFO_AGREE) {

        ERR_raise(ERR_LIB_CMS, CMS_R_NOT_KEY_AGREEMENT);

        return -2;

    }

    oik = ri->d.kari->originator;

    if (oik->type == CMS_OIK_ISSUER_SERIAL)

        return ossl_cms_ias_cert_cmp(oik->d.issuerAndSerialNumber, cert);

    else if (oik->type == CMS_OIK_KEYIDENTIFIER)

        return ossl_cms_keyid_cert_cmp(oik->d.subjectKeyIdentifier, cert);

    return -1;

}

int CMS_RecipientEncryptedKey_get0_id(CMS_RecipientEncryptedKey *rek,

                                      ASN1_OCTET_STRING **keyid,

                                      ASN1_GENERALIZEDTIME **tm,

                                      CMS_OtherKeyAttribute **other,

                                      X509_NAME **issuer, ASN1_INTEGER **sno)

{

    CMS_KeyAgreeRecipientIdentifier *rid = rek->rid;

    if (rid->type == CMS_REK_ISSUER_SERIAL) {

        if (issuer)

            *issuer = rid->d.issuerAndSerialNumber->issuer;

        if (sno)

            *sno = rid->d.issuerAndSerialNumber->serialNumber;

        if (keyid)

            *keyid = NULL;

        if (tm)

            *tm = NULL;

        if (other)

            *other = NULL;

    } else if (rid->type == CMS_REK_KEYIDENTIFIER) {

        if (keyid)

            *keyid = rid->d.rKeyId->subjectKeyIdentifier;

        if (tm)

            *tm = rid->d.rKeyId->date;

        if (other)

            *other = rid->d.rKeyId->other;

        if (issuer)

            *issuer = NULL;

        if (sno)

            *sno = NULL;

    } else

        return 0;

    return 1;

}

int CMS_RecipientEncryptedKey_cert_cmp(CMS_RecipientEncryptedKey *rek,

                                       X509 *cert)

{

    CMS_KeyAgreeRecipientIdentifier *rid = rek->rid;

    if (rid->type == CMS_REK_ISSUER_SERIAL)

        return ossl_cms_ias_cert_cmp(rid->d.issuerAndSerialNumber, cert);

    else if (rid->type == CMS_REK_KEYIDENTIFIER)

        return ossl_cms_keyid_cert_cmp(rid->d.rKeyId->subjectKeyIdentifier,

                                       cert);

    else

        return -1;

}

int CMS_RecipientInfo_kari_set0_pkey_and_peer(CMS_RecipientInfo *ri,

                                              EVP_PKEY *pk, X509 *peer)

{

    EVP_PKEY_CTX *pctx;

    CMS_KeyAgreeRecipientInfo *kari = ri->d.kari;

    EVP_PKEY_CTX_free(kari->pctx);

    kari->pctx = NULL;

    if (pk == NULL)

        return 1;

    pctx = EVP_PKEY_CTX_new_from_pkey(ossl_cms_ctx_get0_libctx(kari->cms_ctx),

                                      pk,

                                      ossl_cms_ctx_get0_propq(kari->cms_ctx));

    if (pctx == NULL || EVP_PKEY_derive_init(pctx) <= 0)

        goto err;

    if (peer != NULL) {

        EVP_PKEY *pub_pkey = X509_get0_pubkey(peer);

        if (EVP_PKEY_derive_set_peer(pctx, pub_pkey) <= 0)

            goto err;

    }

    kari->pctx = pctx;

    return 1;

 err:

    EVP_PKEY_CTX_free(pctx);

    return 0;

}

int CMS_RecipientInfo_kari_set0_pkey(CMS_RecipientInfo *ri, EVP_PKEY *pk)

{

    return CMS_RecipientInfo_kari_set0_pkey_and_peer(ri, pk, NULL);

}

EVP_CIPHER_CTX *CMS_RecipientInfo_kari_get0_ctx(CMS_RecipientInfo *ri)

{

    if (ri->type == CMS_RECIPINFO_AGREE)

        return ri->d.kari->ctx;

    return NULL;

}

/*

 * Derive KEK and decrypt/encrypt with it to produce either the original CEK

 * or the encrypted CEK.

 */

static int cms_kek_cipher(unsigned char **pout, size_t *poutlen,

                          const unsigned char *in, size_t inlen,

                          CMS_KeyAgreeRecipientInfo *kari, int enc)

{

    /* Key encryption key */

    unsigned char kek[EVP_MAX_KEY_LENGTH];

    size_t keklen;

    int rv = 0;

    unsigned char *out = NULL;

    int outlen;

    keklen = EVP_CIPHER_CTX_get_key_length(kari->ctx);

    if (keklen > EVP_MAX_KEY_LENGTH)

        return 0;

    /* Derive KEK */

    if (EVP_PKEY_derive(kari->pctx, kek, &keklen) <= 0)

        goto err;

    /* Set KEK in context */

    if (!EVP_CipherInit_ex(kari->ctx, NULL, NULL, kek, NULL, enc))

        goto err;

    /* obtain output length of ciphered key */

    if (!EVP_CipherUpdate(kari->ctx, NULL, &outlen, in, inlen))

        goto err;

    out = OPENSSL_malloc(outlen);

    if (out == NULL)

        goto err;

    if (!EVP_CipherUpdate(kari->ctx, out, &outlen, in, inlen))

        goto err;

    *pout = out;

    *poutlen = (size_t)outlen;

    rv = 1;

 err:

    OPENSSL_cleanse(kek, keklen);

    if (!rv)

        OPENSSL_free(out);

    EVP_CIPHER_CTX_reset(kari->ctx);

    /* FIXME: WHY IS kari->pctx freed here?  /RL */

    EVP_PKEY_CTX_free(kari->pctx);

    kari->pctx = NULL;

    return rv;

}

int CMS_RecipientInfo_kari_decrypt(CMS_ContentInfo *cms,

                                   CMS_RecipientInfo *ri,

                                   CMS_RecipientEncryptedKey *rek)

{

    int rv = 0;

    unsigned char *enckey = NULL, *cek = NULL;

    size_t enckeylen;

    size_t ceklen;

    CMS_EncryptedContentInfo *ec;

    enckeylen = rek->encryptedKey->length;

    enckey = rek->encryptedKey->data;

    /* Setup all parameters to derive KEK */

    if (!ossl_cms_env_asn1_ctrl(ri, 1))

        goto err;

    /* Attempt to decrypt CEK */

    if (!cms_kek_cipher(&cek, &ceklen, enckey, enckeylen, ri->d.kari, 0))

        goto err;

    ec = ossl_cms_get0_env_enc_content(cms);

    OPENSSL_clear_free(ec->key, ec->keylen);

    ec->key = cek;

    ec->keylen = ceklen;

    cek = NULL;

    rv = 1;

 err:

    OPENSSL_free(cek);

    return rv;

}

/* Create ephemeral key and initialise context based on it */

static int cms_kari_create_ephemeral_key(CMS_KeyAgreeRecipientInfo *kari,

                                         EVP_PKEY *pk)

{

    EVP_PKEY_CTX *pctx = NULL;

    EVP_PKEY *ekey = NULL;

    int rv = 0;

    const CMS_CTX *ctx = kari->cms_ctx;

    OSSL_LIB_CTX *libctx = ossl_cms_ctx_get0_libctx(ctx);

    const char *propq = ossl_cms_ctx_get0_propq(ctx);

    pctx = EVP_PKEY_CTX_new_from_pkey(libctx, pk, propq);

    if (pctx == NULL)

        goto err;

    if (EVP_PKEY_keygen_init(pctx) <= 0)

        goto err;

    if (EVP_PKEY_keygen(pctx, &ekey) <= 0)

        goto err;

    EVP_PKEY_CTX_free(pctx);

    pctx = EVP_PKEY_CTX_new_from_pkey(libctx, ekey, propq);

    if (pctx == NULL)

        goto err;

    if (EVP_PKEY_derive_init(pctx) <= 0)

        goto err;

    kari->pctx = pctx;

    rv = 1;

 err:

    if (!rv)

        EVP_PKEY_CTX_free(pctx);

    EVP_PKEY_free(ekey);

    return rv;

}

/* Set originator private key and initialise context based on it */

static int cms_kari_set_originator_private_key(CMS_KeyAgreeRecipientInfo *kari,

                                               EVP_PKEY *originatorPrivKey )

{

    EVP_PKEY_CTX *pctx = NULL;

    int rv = 0;

    const CMS_CTX *ctx = kari->cms_ctx;

    pctx = EVP_PKEY_CTX_new_from_pkey(ossl_cms_ctx_get0_libctx(ctx),

                                      originatorPrivKey,

                                      ossl_cms_ctx_get0_propq(ctx));

    if (pctx == NULL)

        goto err;

    if (EVP_PKEY_derive_init(pctx) <= 0)

         goto err;

    kari->pctx = pctx;

    rv = 1;

 err:

    if (rv == 0)

        EVP_PKEY_CTX_free(pctx);

    return rv;

}

/* Initialise a kari based on passed certificate and key */

int ossl_cms_RecipientInfo_kari_init(CMS_RecipientInfo *ri,  X509 *recip,

                                     EVP_PKEY *recipPubKey, X509 *originator,

                                     EVP_PKEY *originatorPrivKey,

                                     unsigned int flags, const CMS_CTX *ctx)

{

    CMS_KeyAgreeRecipientInfo *kari;

    CMS_RecipientEncryptedKey *rek = NULL;

    ri->d.kari = M_ASN1_new_of(CMS_KeyAgreeRecipientInfo);

    if (ri->d.kari == NULL)

        return 0;

    ri->type = CMS_RECIPINFO_AGREE;

    kari = ri->d.kari;

    kari->version = 3;

    kari->cms_ctx = ctx;

    rek = M_ASN1_new_of(CMS_RecipientEncryptedKey);

    if (rek == NULL)

        return 0;

    if (!sk_CMS_RecipientEncryptedKey_push(kari->recipientEncryptedKeys, rek)) {

        M_ASN1_free_of(rek, CMS_RecipientEncryptedKey);

        return 0;

    }

    if (flags & CMS_USE_KEYID) {

        rek->rid->type = CMS_REK_KEYIDENTIFIER;

        rek->rid->d.rKeyId = M_ASN1_new_of(CMS_RecipientKeyIdentifier);

        if (rek->rid->d.rKeyId == NULL)

            return 0;

        if (!ossl_cms_set1_keyid(&rek->rid->d.rKeyId->subjectKeyIdentifier, recip))

            return 0;

    } else {

        rek->rid->type = CMS_REK_ISSUER_SERIAL;

        if (!ossl_cms_set1_ias(&rek->rid->d.issuerAndSerialNumber, recip))

            return 0;

    }

    if (originatorPrivKey == NULL && originator == NULL) {

        /* Create ephemeral key */

        if (!cms_kari_create_ephemeral_key(kari, recipPubKey))

            return 0;

    } else {

        /* Use originator key */

        CMS_OriginatorIdentifierOrKey *oik = ri->d.kari->originator;

        if (originatorPrivKey == NULL || originator == NULL)

            return 0;

        if (flags & CMS_USE_ORIGINATOR_KEYID) {

             oik->type = CMS_OIK_KEYIDENTIFIER;

             oik->d.subjectKeyIdentifier = ASN1_OCTET_STRING_new();

             if (oik->d.subjectKeyIdentifier == NULL)

                  return 0;

             if (!ossl_cms_set1_keyid(&oik->d.subjectKeyIdentifier, originator))

                  return 0;

        } else {

             oik->type = CMS_REK_ISSUER_SERIAL;

             if (!ossl_cms_set1_ias(&oik->d.issuerAndSerialNumber, originator))

                  return 0;

        }

        if (!cms_kari_set_originator_private_key(kari, originatorPrivKey))

            return 0;

    }

    EVP_PKEY_up_ref(recipPubKey);

    rek->pkey = recipPubKey;

    return 1;

}

static int cms_wrap_init(CMS_KeyAgreeRecipientInfo *kari,

                         const EVP_CIPHER *cipher)

{

    const CMS_CTX *cms_ctx = kari->cms_ctx;

    EVP_CIPHER_CTX *ctx = kari->ctx;

    const EVP_CIPHER *kekcipher;

    EVP_CIPHER *fetched_kekcipher;

    const char *kekcipher_name;

    int keylen;

    int ret;

    /* If a suitable wrap algorithm is already set nothing to do */

    kekcipher = EVP_CIPHER_CTX_get0_cipher(ctx);

    if (kekcipher != NULL) {

        if (EVP_CIPHER_CTX_get_mode(ctx) != EVP_CIPH_WRAP_MODE)

            return 0;

        return 1;

    }

    if (cipher == NULL)

        return 0;

    keylen = EVP_CIPHER_get_key_length(cipher);

    if ((EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_GET_WRAP_CIPHER) != 0) {

        ret = EVP_CIPHER_meth_get_ctrl(cipher)(NULL, EVP_CTRL_GET_WRAP_CIPHER,

                                               0, &kekcipher);

        if (ret <= 0)

             return 0;

        if (kekcipher != NULL) {

             if (EVP_CIPHER_get_mode(kekcipher) != EVP_CIPH_WRAP_MODE)

                 return 0;

             kekcipher_name = EVP_CIPHER_get0_name(kekcipher);

             goto enc;

        }

    }

    /*

     * Pick a cipher based on content encryption cipher. If it is DES3 use

     * DES3 wrap otherwise use AES wrap similar to key size.

     */

#ifndef OPENSSL_NO_DES

    if (EVP_CIPHER_get_type(cipher) == NID_des_ede3_cbc)

        kekcipher_name = SN_id_smime_alg_CMS3DESwrap;

    else

#endif

    if (keylen <= 16)

        kekcipher_name = SN_id_aes128_wrap;

    else if (keylen <= 24)

        kekcipher_name = SN_id_aes192_wrap;

    else

        kekcipher_name = SN_id_aes256_wrap;

enc:

    fetched_kekcipher = EVP_CIPHER_fetch(ossl_cms_ctx_get0_libctx(cms_ctx),

                                         kekcipher_name,

                                         ossl_cms_ctx_get0_propq(cms_ctx));

    if (fetched_kekcipher == NULL)

        return 0;

    ret = EVP_EncryptInit_ex(ctx, fetched_kekcipher, NULL, NULL, NULL);

    EVP_CIPHER_free(fetched_kekcipher);

    return ret;

}

/* Encrypt content key in key agreement recipient info */

int ossl_cms_RecipientInfo_kari_encrypt(const CMS_ContentInfo *cms,

                                        CMS_RecipientInfo *ri)

{

    CMS_KeyAgreeRecipientInfo *kari;

    CMS_EncryptedContentInfo *ec;

    CMS_RecipientEncryptedKey *rek;

    STACK_OF(CMS_RecipientEncryptedKey) *reks;

    int i;

    if (ri->type != CMS_RECIPINFO_AGREE) {

        ERR_raise(ERR_LIB_CMS, CMS_R_NOT_KEY_AGREEMENT);

        return 0;

    }

    kari = ri->d.kari;

    reks = kari->recipientEncryptedKeys;

    ec = ossl_cms_get0_env_enc_content(cms);

    /* Initialise wrap algorithm parameters */

    if (!cms_wrap_init(kari, ec->cipher))

        return 0;

    /*

     * If no originator key set up initialise for ephemeral key the public key

     * ASN1 structure will set the actual public key value.

     */

    if (kari->originator->type == -1) {

        CMS_OriginatorIdentifierOrKey *oik = kari->originator;

        oik->type = CMS_OIK_PUBKEY;

        oik->d.originatorKey = M_ASN1_new_of(CMS_OriginatorPublicKey);

        if (!oik->d.originatorKey)

            return 0;

    } else {

        /*

         * Currently it is not possible to get public key as it is not stored

         * during kari initialization.

         */

        ERR_raise(ERR_LIB_CMS, CMS_R_ERROR_UNSUPPORTED_STATIC_KEY_AGREEMENT);

        return 0;

    }

    /* Initialise KDF algorithm */

    if (!ossl_cms_env_asn1_ctrl(ri, 0))

        return 0;

    /* For each rek, derive KEK, encrypt CEK */

    for (i = 0; i < sk_CMS_RecipientEncryptedKey_num(reks); i++) {

        unsigned char *enckey;

        size_t enckeylen;

        rek = sk_CMS_RecipientEncryptedKey_value(reks, i);

        if (EVP_PKEY_derive_set_peer(kari->pctx, rek->pkey) <= 0)

            return 0;

        if (!cms_kek_cipher(&enckey, &enckeylen, ec->key, ec->keylen,

                            kari, 1))

            return 0;

        ASN1_STRING_set0(rek->encryptedKey, enckey, enckeylen);

    }

    return 1;

}