/*

 * Copyright 2022 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

 */

#include <string.h>

#include <openssl/core_names.h>

#include <openssl/kdf.h>

#include <openssl/params.h>

#include <openssl/err.h>

#include <openssl/proverr.h>

#include <openssl/hpke.h>

#include <openssl/sha.h>

#include <openssl/rand.h>

#include "crypto/ecx.h"

#include "internal/hpke_util.h"

#include "internal/packet.h"

#include "internal/nelem.h"

/*

 * Delimiter used in OSSL_HPKE_str2suite

 */

#define OSSL_HPKE_STR_DELIMCHAR ','

/*

 * table with identifier and synonym strings

 * right now, there are 4 synonyms for each - a name, a hex string

 * a hex string with a leading zero and a decimal string - more

 * could be added but that seems like enough

 */

typedef struct {

    uint16_t id;

    char *synonyms[4];

} synonymttab_t;

/* max length of string we'll try map to a suite */

#define OSSL_HPKE_MAX_SUITESTR 38

/* Define HPKE labels from RFC9180 in hex for EBCDIC compatibility */

/* ASCII: "HPKE-v1", in hex for EBCDIC compatibility */

static const char LABEL_HPKEV1[] = "\x48\x50\x4B\x45\x2D\x76\x31";

/*

 * Note that if additions are made to the set of IANA codepoints

 * and the tables below, corresponding additions should also be

 * made to the synonymtab tables a little further down so that

 * OSSL_HPKE_str2suite() continues to function correctly.

 *

 * The canonical place to check for IANA registered codepoints

 * is: https://www.iana.org/assignments/hpke/hpke.xhtml

 */

/*

 * @brief table of KEMs

 * See RFC9180 Section 7.1 "Table 2 KEM IDs"

 */

static const OSSL_HPKE_KEM_INFO hpke_kem_tab[] = {

#ifndef OPENSSL_NO_EC

    { OSSL_HPKE_KEM_ID_P256, "EC", OSSL_HPKE_KEMSTR_P256,

      LN_sha256, SHA256_DIGEST_LENGTH, 65, 65, 32, 0xFF },

    { OSSL_HPKE_KEM_ID_P384, "EC", OSSL_HPKE_KEMSTR_P384,

      LN_sha384, SHA384_DIGEST_LENGTH, 97, 97, 48, 0xFF },

    { OSSL_HPKE_KEM_ID_P521, "EC", OSSL_HPKE_KEMSTR_P521,

      LN_sha512, SHA512_DIGEST_LENGTH, 133, 133, 66, 0x01 },

    { OSSL_HPKE_KEM_ID_X25519, OSSL_HPKE_KEMSTR_X25519, NULL,

      LN_sha256, SHA256_DIGEST_LENGTH,

      X25519_KEYLEN, X25519_KEYLEN, X25519_KEYLEN, 0x00 },

    { OSSL_HPKE_KEM_ID_X448, OSSL_HPKE_KEMSTR_X448, NULL,

      LN_sha512, SHA512_DIGEST_LENGTH,

      X448_KEYLEN, X448_KEYLEN, X448_KEYLEN, 0x00 }

#else

    { OSSL_HPKE_KEM_ID_RESERVED, NULL, NULL, NULL, 0, 0, 0, 0, 0x00 }

#endif

};

/*

 * @brief table of AEADs

 * See RFC9180 Section 7.2 "Table 3 KDF IDs"

 */

static const OSSL_HPKE_AEAD_INFO hpke_aead_tab[] = {

    { OSSL_HPKE_AEAD_ID_AES_GCM_128, LN_aes_128_gcm, 16, 16,

      OSSL_HPKE_MAX_NONCELEN },

    { OSSL_HPKE_AEAD_ID_AES_GCM_256, LN_aes_256_gcm, 16, 32,

      OSSL_HPKE_MAX_NONCELEN },

#if !defined(OPENSSL_NO_CHACHA) && !defined(OPENSSL_NO_POLY1305)

    { OSSL_HPKE_AEAD_ID_CHACHA_POLY1305, LN_chacha20_poly1305, 16, 32,

      OSSL_HPKE_MAX_NONCELEN },

#endif

    { OSSL_HPKE_AEAD_ID_EXPORTONLY, NULL, 0, 0, 0 }

};

/*

 * @brief table of KDFs

 * See RFC9180 Section 7.3 "Table 5 AEAD IDs"

 */

static const OSSL_HPKE_KDF_INFO hpke_kdf_tab[] = {

    { OSSL_HPKE_KDF_ID_HKDF_SHA256, LN_sha256, SHA256_DIGEST_LENGTH },

    { OSSL_HPKE_KDF_ID_HKDF_SHA384, LN_sha384, SHA384_DIGEST_LENGTH },

    { OSSL_HPKE_KDF_ID_HKDF_SHA512, LN_sha512, SHA512_DIGEST_LENGTH }

};

/**

 * Synonym tables for KEMs, KDFs and AEADs: idea is to allow

 * mapping strings to suites with a little flexibility in terms

 * of allowing a name or a couple of forms of number (for

 * the IANA codepoint). If new IANA codepoints are allocated

 * then these tables should be updated at the same time as the

 * others above.

 *

 * The function to use these is ossl_hpke_str2suite() further down

 * this file and shouln't need modification so long as the table

 * sizes (i.e. allow exactly 4 synonyms) don't change.

 */

static const synonymttab_t kemstrtab[] = {

    {OSSL_HPKE_KEM_ID_P256,

     {OSSL_HPKE_KEMSTR_P256, "0x10", "0x10", "16" }},

    {OSSL_HPKE_KEM_ID_P384,

     {OSSL_HPKE_KEMSTR_P384, "0x11", "0x11", "17" }},

    {OSSL_HPKE_KEM_ID_P521,

     {OSSL_HPKE_KEMSTR_P521, "0x12", "0x12", "18" }},

    {OSSL_HPKE_KEM_ID_X25519,

     {OSSL_HPKE_KEMSTR_X25519, "0x20", "0x20", "32" }},

    {OSSL_HPKE_KEM_ID_X448,

     {OSSL_HPKE_KEMSTR_X448, "0x21", "0x21", "33" }}

};

static const synonymttab_t kdfstrtab[] = {

    {OSSL_HPKE_KDF_ID_HKDF_SHA256,

     {OSSL_HPKE_KDFSTR_256, "0x1", "0x01", "1"}},

    {OSSL_HPKE_KDF_ID_HKDF_SHA384,

     {OSSL_HPKE_KDFSTR_384, "0x2", "0x02", "2"}},

    {OSSL_HPKE_KDF_ID_HKDF_SHA512,

     {OSSL_HPKE_KDFSTR_512, "0x3", "0x03", "3"}}

};

static const synonymttab_t aeadstrtab[] = {

    {OSSL_HPKE_AEAD_ID_AES_GCM_128,

     {OSSL_HPKE_AEADSTR_AES128GCM, "0x1", "0x01", "1"}},

    {OSSL_HPKE_AEAD_ID_AES_GCM_256,

     {OSSL_HPKE_AEADSTR_AES256GCM, "0x2", "0x02", "2"}},

    {OSSL_HPKE_AEAD_ID_CHACHA_POLY1305,

     {OSSL_HPKE_AEADSTR_CP, "0x3", "0x03", "3"}},

    {OSSL_HPKE_AEAD_ID_EXPORTONLY,

     {OSSL_HPKE_AEADSTR_EXP, "ff", "0xff", "255"}}

};

/* Return an object containing KEM constants associated with a EC curve name */

const OSSL_HPKE_KEM_INFO *ossl_HPKE_KEM_INFO_find_curve(const char *curve)

{

    int i, sz = OSSL_NELEM(hpke_kem_tab);

    for (i = 0; i < sz; ++i) {

        const char *group = hpke_kem_tab[i].groupname;

        if (group == NULL)

            group = hpke_kem_tab[i].keytype;

        if (OPENSSL_strcasecmp(curve, group) == 0)

            return &hpke_kem_tab[i];

    }

    ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CURVE);

    return NULL;

}

const OSSL_HPKE_KEM_INFO *ossl_HPKE_KEM_INFO_find_id(uint16_t kemid)

{

    int i, sz = OSSL_NELEM(hpke_kem_tab);

    /*

     * this check can happen if we're in a no-ec build and there are no

     * KEMS available

     */

    if (kemid == OSSL_HPKE_KEM_ID_RESERVED) {

        ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CURVE);

        return NULL;

    }

    for (i = 0; i != sz; ++i) {

        if (hpke_kem_tab[i].kem_id == kemid)

            return &hpke_kem_tab[i];

    }

    ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CURVE);

    return NULL;

}

const OSSL_HPKE_KEM_INFO *ossl_HPKE_KEM_INFO_find_random(OSSL_LIB_CTX *ctx)

{

    unsigned char rval = 0;

    int sz = OSSL_NELEM(hpke_kem_tab);

    if (RAND_bytes_ex(ctx, &rval, sizeof(rval), 0) <= 0)

        return NULL;

    return &hpke_kem_tab[rval % sz];

}

const OSSL_HPKE_KDF_INFO *ossl_HPKE_KDF_INFO_find_id(uint16_t kdfid)

{

    int i, sz = OSSL_NELEM(hpke_kdf_tab);

    for (i = 0; i != sz; ++i) {

        if (hpke_kdf_tab[i].kdf_id == kdfid)

            return &hpke_kdf_tab[i];

    }

    ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KDF);

    return NULL;

}

const OSSL_HPKE_KDF_INFO *ossl_HPKE_KDF_INFO_find_random(OSSL_LIB_CTX *ctx)

{

    unsigned char rval = 0;

    int sz = OSSL_NELEM(hpke_kdf_tab);

    if (RAND_bytes_ex(ctx, &rval, sizeof(rval), 0) <= 0)

        return NULL;

    return &hpke_kdf_tab[rval % sz];

}

const OSSL_HPKE_AEAD_INFO *ossl_HPKE_AEAD_INFO_find_id(uint16_t aeadid)

{

    int i, sz = OSSL_NELEM(hpke_aead_tab);

    for (i = 0; i != sz; ++i) {

        if (hpke_aead_tab[i].aead_id == aeadid)

            return &hpke_aead_tab[i];

    }

    ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_AEAD);

    return NULL;

}

const OSSL_HPKE_AEAD_INFO *ossl_HPKE_AEAD_INFO_find_random(OSSL_LIB_CTX *ctx)

{

    unsigned char rval = 0;

    /* the minus 1 below is so we don't pick the EXPORTONLY codepoint */

    int sz = OSSL_NELEM(hpke_aead_tab) - 1;

    if (RAND_bytes_ex(ctx, &rval, sizeof(rval), 0) <= 0)

        return NULL;

    return &hpke_aead_tab[rval % sz];

}

static int kdf_derive(EVP_KDF_CTX *kctx,

                      unsigned char *out, size_t outlen, int mode,

                      const unsigned char *salt, size_t saltlen,

                      const unsigned char *ikm, size_t ikmlen,

                      const unsigned char *info, size_t infolen)

{

    int ret;

    OSSL_PARAM params[5], *p = params;

    *p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_MODE, &mode);

    if (salt != NULL)

        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,

                                                 (char *)salt, saltlen);

    if (ikm != NULL)

        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,

                                                 (char *)ikm, ikmlen);

    if (info != NULL)

        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,

                                                 (char *)info, infolen);

    *p = OSSL_PARAM_construct_end();

    ret = EVP_KDF_derive(kctx, out, outlen, params) > 0;

    if (!ret)

        ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_DURING_DERIVATION);

    return ret;

}

int ossl_hpke_kdf_extract(EVP_KDF_CTX *kctx,

                          unsigned char *prk, size_t prklen,

                          const unsigned char *salt, size_t saltlen,

                          const unsigned char *ikm, size_t ikmlen)

{

    return kdf_derive(kctx, prk, prklen, EVP_KDF_HKDF_MODE_EXTRACT_ONLY,

                      salt, saltlen, ikm, ikmlen, NULL, 0);

}

/* Common code to perform a HKDF expand */

int ossl_hpke_kdf_expand(EVP_KDF_CTX *kctx,

                         unsigned char *okm, size_t okmlen,

                         const unsigned char *prk, size_t prklen,

                         const unsigned char *info, size_t infolen)

{

    return kdf_derive(kctx, okm, okmlen, EVP_KDF_HKDF_MODE_EXPAND_ONLY,

                      NULL, 0, prk, prklen, info, infolen);

}

/*

 * See RFC 9180 Section 4 LabelExtract()

 */

int ossl_hpke_labeled_extract(EVP_KDF_CTX *kctx,

                              unsigned char *prk, size_t prklen,

                              const unsigned char *salt, size_t saltlen,

                              const char *protocol_label,

                              const unsigned char *suiteid, size_t suiteidlen,

                              const char *label,

                              const unsigned char *ikm, size_t ikmlen)

{

    int ret = 0;

    size_t label_hpkev1len = 0;

    size_t protocol_labellen = 0;

    size_t labellen = 0;

    size_t labeled_ikmlen = 0;

    unsigned char *labeled_ikm = NULL;

    WPACKET pkt;

    label_hpkev1len = strlen(LABEL_HPKEV1);

    protocol_labellen = strlen(protocol_label);

    labellen = strlen(label);

    labeled_ikmlen = label_hpkev1len + protocol_labellen

        + suiteidlen + labellen + ikmlen;

    labeled_ikm = OPENSSL_malloc(labeled_ikmlen);

    if (labeled_ikm == NULL)

        return 0;

    /* labeled_ikm = concat("HPKE-v1", suiteid, label, ikm) */

    if (!WPACKET_init_static_len(&pkt, labeled_ikm, labeled_ikmlen, 0)

            || !WPACKET_memcpy(&pkt, LABEL_HPKEV1, label_hpkev1len)

            || !WPACKET_memcpy(&pkt, protocol_label, protocol_labellen)

            || !WPACKET_memcpy(&pkt, suiteid, suiteidlen)

            || !WPACKET_memcpy(&pkt, label, labellen)

            || !WPACKET_memcpy(&pkt, ikm, ikmlen)

            || !WPACKET_get_total_written(&pkt, &labeled_ikmlen)

            || !WPACKET_finish(&pkt)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);

        goto end;

    }

    ret = ossl_hpke_kdf_extract(kctx, prk, prklen, salt, saltlen,

                                labeled_ikm, labeled_ikmlen);

end:

    WPACKET_cleanup(&pkt);

    OPENSSL_cleanse(labeled_ikm, labeled_ikmlen);

    OPENSSL_free(labeled_ikm);

    return ret;

}

/*

 * See RFC 9180 Section 4 LabelExpand()

 */

int ossl_hpke_labeled_expand(EVP_KDF_CTX *kctx,

                             unsigned char *okm, size_t okmlen,

                             const unsigned char *prk, size_t prklen,

                             const char *protocol_label,

                             const unsigned char *suiteid, size_t suiteidlen,

                             const char *label,

                             const unsigned char *info, size_t infolen)

{

    int ret = 0;

    size_t label_hpkev1len = 0;

    size_t protocol_labellen = 0;

    size_t labellen = 0;

    size_t labeled_infolen = 0;

    unsigned char *labeled_info = NULL;

    WPACKET pkt;

    label_hpkev1len = strlen(LABEL_HPKEV1);

    protocol_labellen = strlen(protocol_label);

    labellen = strlen(label);

    labeled_infolen = 2 + okmlen + prklen + label_hpkev1len

        + protocol_labellen + suiteidlen + labellen + infolen;

    labeled_info = OPENSSL_malloc(labeled_infolen);

    if (labeled_info == NULL)

        return 0;

    /* labeled_info = concat(okmlen, "HPKE-v1", suiteid, label, info) */

    if (!WPACKET_init_static_len(&pkt, labeled_info, labeled_infolen, 0)

            || !WPACKET_put_bytes_u16(&pkt, okmlen)

            || !WPACKET_memcpy(&pkt, LABEL_HPKEV1, label_hpkev1len)

            || !WPACKET_memcpy(&pkt, protocol_label, protocol_labellen)

            || !WPACKET_memcpy(&pkt, suiteid, suiteidlen)

            || !WPACKET_memcpy(&pkt, label, labellen)

            || !WPACKET_memcpy(&pkt, info, infolen)

            || !WPACKET_get_total_written(&pkt, &labeled_infolen)

            || !WPACKET_finish(&pkt)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);

        goto end;

    }

    ret = ossl_hpke_kdf_expand(kctx, okm, okmlen,

                               prk, prklen, labeled_info, labeled_infolen);

end:

    WPACKET_cleanup(&pkt);

    OPENSSL_free(labeled_info);

    return ret;

}

/* Common code to create a HKDF ctx */

EVP_KDF_CTX *ossl_kdf_ctx_create(const char *kdfname, const char *mdname,

                                 OSSL_LIB_CTX *libctx, const char *propq)

{

    EVP_KDF *kdf;

    EVP_KDF_CTX *kctx = NULL;

    kdf = EVP_KDF_fetch(libctx, kdfname, propq);

    if (kdf == NULL) {

        ERR_raise(ERR_LIB_CRYPTO, ERR_R_FETCH_FAILED);

        return NULL;

    }

    kctx = EVP_KDF_CTX_new(kdf);

    EVP_KDF_free(kdf);

    if (kctx != NULL && mdname != NULL) {

        OSSL_PARAM params[3], *p = params;

        if (mdname != NULL)

            *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,

                                                    (char *)mdname, 0);

        if (propq != NULL)

            *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_PROPERTIES,

                                                    (char *)propq, 0);

        *p = OSSL_PARAM_construct_end();

        if (EVP_KDF_CTX_set_params(kctx, params) <= 0) {

            EVP_KDF_CTX_free(kctx);

            return NULL;

        }

    }

    return kctx;

}

/*

 * @brief look for a label into the synonym tables, and return its id

 * @param st is the string value

 * @param synp is the synonyms labels array

 * @param arrsize is the previous array size

 * @return 0 when not found, else the matching item id.

 */

static uint16_t synonyms_name2id(const char *st, const synonymttab_t *synp,

                                 size_t arrsize)

{

    size_t i, j;

    for (i = 0; i < arrsize; ++i) {

        for (j = 0; j < OSSL_NELEM(synp[i].synonyms); ++j) {

            if (OPENSSL_strcasecmp(st, synp[i].synonyms[j]) == 0)

                return synp[i].id;

        }

    }

    return 0;

}

/*

 * @brief map a string to a HPKE suite based on synonym tables

 * @param str is the string value

 * @param suite is the resulting suite

 * @return 1 for success, otherwise failure

 */

int ossl_hpke_str2suite(const char *suitestr, OSSL_HPKE_SUITE *suite)

{

    uint16_t kem = 0, kdf = 0, aead = 0;

    char *st = NULL, *instrcp = NULL;

    size_t inplen;

    int labels = 0, result = 0;

    int delim_count = 0;

    if (suitestr == NULL || suitestr[0] == 0x00 || suite == NULL) {

        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    inplen = OPENSSL_strnlen(suitestr, OSSL_HPKE_MAX_SUITESTR);

    if (inplen >= OSSL_HPKE_MAX_SUITESTR) {

        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_INVALID_ARGUMENT);

        return 0;

    }

    /*

     * we don't want a delimiter at the end of the string;

     * strtok_r/s() doesn't care about that, so we should

     */

    if (suitestr[inplen - 1] == OSSL_HPKE_STR_DELIMCHAR)

        return 0;

    /* We want exactly two delimiters in the input string */

    for (st = (char *)suitestr; *st != '\0'; st++) {

        if (*st == OSSL_HPKE_STR_DELIMCHAR)

            delim_count++;

    }

    if (delim_count != 2)

        return 0;

    /* Duplicate `suitestr` to allow its parsing  */

    instrcp = OPENSSL_memdup(suitestr, inplen + 1);

    if (instrcp == NULL)

        goto fail;

    /* See if it contains a mix of our strings and numbers */

    st = instrcp;

    while (st != NULL && labels < 3) {

        char *cp = strchr(st, OSSL_HPKE_STR_DELIMCHAR);

        /* add a NUL like strtok would if we're not at the end */

        if (cp != NULL)

            *cp = '\0';

        /* check if string is known or number and if so handle appropriately */

        if (labels == 0

            && (kem = synonyms_name2id(st, kemstrtab,

                                       OSSL_NELEM(kemstrtab))) == 0)

            goto fail;

        else if (labels == 1

                 && (kdf = synonyms_name2id(st, kdfstrtab,

                                            OSSL_NELEM(kdfstrtab))) == 0)

            goto fail;

        else if (labels == 2

                 && (aead = synonyms_name2id(st, aeadstrtab,

                                             OSSL_NELEM(aeadstrtab))) == 0)

            goto fail;

        if (cp == NULL)

            st = NULL;

        else

            st = cp + 1;

        ++labels;

    }

    if (st != NULL || labels != 3)

        goto fail;

    suite->kem_id = kem;

    suite->kdf_id = kdf;

    suite->aead_id = aead;

    result = 1;

fail:

    OPENSSL_free(instrcp);

    return result;

}