text: /*
   * Copyright 2018-2020 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
   */
  
  /*
   * DES low level APIs are deprecated for public use, but still ok for internal
   * use.  We access the DES_set_odd_parity(3) function here.
   */
  #include "internal/deprecated.h"
  
  #include <stdlib.h>
  #include <stdarg.h>
  #include <string.h>
  
  #include <openssl/core_names.h>
  #include <openssl/des.h>
  #include <openssl/evp.h>
  #include <openssl/kdf.h>
  
  #include "internal/cryptlib.h"
  #include "crypto/evp.h"
  #include "internal/numbers.h"
  #include "prov/implementations.h"
  #include "prov/provider_ctx.h"
  #include "prov/provider_util.h"
  #include "prov/providercommon.h"
  #include "prov/providercommonerr.h"
  
  /* KRB5 KDF defined in RFC 3961, Section 5.1 */
  
  static OSSL_FUNC_kdf_newctx_fn krb5kdf_new;
  static OSSL_FUNC_kdf_freectx_fn krb5kdf_free;
  static OSSL_FUNC_kdf_reset_fn krb5kdf_reset;
  static OSSL_FUNC_kdf_derive_fn krb5kdf_derive;
  static OSSL_FUNC_kdf_settable_ctx_params_fn krb5kdf_settable_ctx_params;
  static OSSL_FUNC_kdf_set_ctx_params_fn krb5kdf_set_ctx_params;
  static OSSL_FUNC_kdf_gettable_ctx_params_fn krb5kdf_gettable_ctx_params;
  static OSSL_FUNC_kdf_get_ctx_params_fn krb5kdf_get_ctx_params;
  
  static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
                     const unsigned char *key, size_t key_len,
                     const unsigned char *constant, size_t constant_len,
                     unsigned char *okey, size_t okey_len);
  
  typedef struct {
      void *provctx;
      PROV_CIPHER cipher;
      unsigned char *key;
      size_t key_len;
      unsigned char *constant;
      size_t constant_len;
  } KRB5KDF_CTX;
  
  static void *krb5kdf_new(void *provctx)
  {
      KRB5KDF_CTX *ctx;
  
      if (!ossl_prov_is_running())
          return NULL;
  
      if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
          ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
      ctx->provctx = provctx;
      return ctx;
  }
  
  static void krb5kdf_free(void *vctx)
  {
      KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
  
      if (ctx != NULL) {
          krb5kdf_reset(ctx);
          OPENSSL_free(ctx);
      }
  }
  
  static void krb5kdf_reset(void *vctx)
  {
      KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
      void *provctx = ctx->provctx;
  
      ossl_prov_cipher_reset(&ctx->cipher);
      OPENSSL_clear_free(ctx->key, ctx->key_len);
      OPENSSL_clear_free(ctx->constant, ctx->constant_len);
      memset(ctx, 0, sizeof(*ctx));
      ctx->provctx = provctx;
  }
  
  static int krb5kdf_set_membuf(unsigned char **dst, size_t *dst_len,
                                const OSSL_PARAM *p)
  {
      OPENSSL_clear_free(*dst, *dst_len);
      *dst = NULL;
      return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
  }
  
  static int krb5kdf_derive(void *vctx, unsigned char *key,
                                size_t keylen)
  {
      KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
      const EVP_CIPHER *cipher;
      ENGINE *engine;
  
      if (!ossl_prov_is_running())
          return 0;
  
      cipher = ossl_prov_cipher_cipher(&ctx->cipher);
      if (cipher == NULL) {
          ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CIPHER);
          return 0;
      }
      if (ctx->key == NULL) {
          ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
          return 0;
      }
      if (ctx->constant == NULL) {
          ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CONSTANT);
          return 0;
      }
      engine = ossl_prov_cipher_engine(&ctx->cipher);
      return KRB5KDF(cipher, engine, ctx->key, ctx->key_len,
                     ctx->constant, ctx->constant_len,
                     key, keylen);
  }
  
  static int krb5kdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
  {
      const OSSL_PARAM *p;
      KRB5KDF_CTX *ctx = vctx;
      OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
  
      if (!ossl_prov_cipher_load_from_params(&ctx->cipher, params, provctx))
          return 0;
  
      if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
          if (!krb5kdf_set_membuf(&ctx->key, &ctx->key_len, p))
              return 0;
  
      if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CONSTANT))
          != NULL)
          if (!krb5kdf_set_membuf(&ctx->constant, &ctx->constant_len, p))
              return 0;
  
      return 1;
  }
  
  static const OSSL_PARAM *krb5kdf_settable_ctx_params(ossl_unused void *provctx)
  {
      static const OSSL_PARAM known_settable_ctx_params[] = {
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
          OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
          OSSL_PARAM_octet_string(OSSL_KDF_PARAM_CONSTANT, NULL, 0),
          OSSL_PARAM_END
      };
      return known_settable_ctx_params;
  }
  
  static int krb5kdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
  {
      KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
      const EVP_CIPHER *cipher;
      size_t len;
      OSSL_PARAM *p;
  
      cipher = ossl_prov_cipher_cipher(&ctx->cipher);
      if (cipher)
          len = EVP_CIPHER_key_length(cipher);
      else
          len = EVP_MAX_KEY_LENGTH;
  
      if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
          return OSSL_PARAM_set_size_t(p, len);
      return -2;
  }
  
  static const OSSL_PARAM *krb5kdf_gettable_ctx_params(ossl_unused void *provctx)
  {
      static const OSSL_PARAM known_gettable_ctx_params[] = {
          OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
          OSSL_PARAM_END
      };
      return known_gettable_ctx_params;
  }
  
  const OSSL_DISPATCH ossl_kdf_krb5kdf_functions[] = {
      { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))krb5kdf_new },
      { OSSL_FUNC_KDF_FREECTX, (void(*)(void))krb5kdf_free },
      { OSSL_FUNC_KDF_RESET, (void(*)(void))krb5kdf_reset },
      { OSSL_FUNC_KDF_DERIVE, (void(*)(void))krb5kdf_derive },
      { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
        (void(*)(void))krb5kdf_settable_ctx_params },
      { OSSL_FUNC_KDF_SET_CTX_PARAMS,
        (void(*)(void))krb5kdf_set_ctx_params },
      { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
        (void(*)(void))krb5kdf_gettable_ctx_params },
      { OSSL_FUNC_KDF_GET_CTX_PARAMS,
        (void(*)(void))krb5kdf_get_ctx_params },
      { 0, NULL }
  };
  
  #ifndef OPENSSL_NO_DES
  /*
   * DES3 is a special case, it requires a random-to-key function and its
   * input truncated to 21 bytes of the 24 produced by the cipher.
   * See RFC3961 6.3.1
   */
  static int fixup_des3_key(unsigned char *key)
  {
      unsigned char *cblock;
      int i, j;
  
      for (i = 2; i >= 0; i--) {
          cblock = &key[i * 8];
          memmove(cblock, &key[i * 7], 7);
          cblock[7] = 0;
          for (j = 0; j < 7; j++)
              cblock[7] |= (cblock[j] & 1) << (j + 1);
          DES_set_odd_parity((DES_cblock *)cblock);
      }
  
      /* fail if keys are such that triple des degrades to single des */
      if (CRYPTO_memcmp(&key[0], &key[8], 8) == 0 ||
          CRYPTO_memcmp(&key[8], &key[16], 8) == 0) {
          return 0;
      }
  
      return 1;
  }
  #endif
  
  /*
   * N-fold(K) where blocksize is N, and constant_len is K
   * Note: Here |= denotes concatenation
   *
   * L = lcm(N,K)
   * R = L/K
   *
   * for r: 1 -> R
   *   s |= constant rot 13*(r-1))
   *
   * block = 0
   * for k: 1 -> K
   *   block += s[N(k-1)..(N-1)k] (one's complement addition)
   *
   * Optimizing for space we compute:
   * for each l in L-1 -> 0:
   *   s[l] = (constant rot 13*(l/K))[l%k]
   *   block[l % N] += s[l] (with carry)
   * finally add carry if any
   */
  static void n_fold(unsigned char *block, unsigned int blocksize,
                     const unsigned char *constant, size_t constant_len)
  {
      unsigned int tmp, gcd, remainder, lcm, carry;
      int b, l;
  
      if (constant_len == blocksize) {
          memcpy(block, constant, constant_len);
          return;
      }
  
      /* Least Common Multiple of lengths: LCM(a,b)*/
      gcd = blocksize;
      remainder = constant_len;
      /* Calculate Great Common Divisor first GCD(a,b) */
      while (remainder != 0) {
          tmp = gcd % remainder;
          gcd = remainder;
          remainder = tmp;
      }
      /* resulting a is the GCD, LCM(a,b) = |a*b|/GCD(a,b) */
      lcm = blocksize * constant_len / gcd;
  
      /* now spread out the bits */
      memset(block, 0, blocksize);
  
      /* last to first to be able to bring carry forward */
      carry = 0;
      for (l = lcm - 1; l >= 0; l--) {
          unsigned int rotbits, rshift, rbyte;
  
          /* destination byte in block is l % N */
          b = l % blocksize;
          /* Our virtual s buffer is R = L/K long (K = constant_len) */
          /* So we rotate backwards from R-1 to 0 (none) rotations */
          rotbits = 13 * (l / constant_len);
          /* find the byte on s where rotbits falls onto */
          rbyte = l - (rotbits / 8);
          /* calculate how much shift on that byte */
          rshift = rotbits & 0x07;
          /* rbyte % constant_len gives us the unrotated byte in the
           * constant buffer, get also the previous byte then
           * appropriately shift them to get the rotated byte we need */
          tmp = (constant[(rbyte-1) % constant_len] << (8 - rshift)
                 | constant[rbyte % constant_len] >> rshift)
                & 0xff;
          /* add with carry to any value placed by previous passes */
          tmp += carry + block[b];
          block[b] = tmp & 0xff;
          /* save any carry that may be left */
          carry = tmp >> 8;
      }
  
      /* if any carry is left at the end, add it through the number */
      for (b = blocksize - 1; b >= 0 && carry != 0; b--) {
          carry += block[b];
          block[b] = carry & 0xff;
          carry >>= 8;
      }
  }
  
  static int cipher_init(EVP_CIPHER_CTX *ctx,
                         const EVP_CIPHER *cipher, ENGINE *engine,
                         const unsigned char *key, size_t key_len)
  {
      int klen, ret;
  
      ret = EVP_EncryptInit_ex(ctx, cipher, engine, key, NULL);
      if (!ret)
          goto out;
      /* set the key len for the odd variable key len cipher */
      klen = EVP_CIPHER_CTX_key_length(ctx);
      if (key_len != (size_t)klen) {
          ret = EVP_CIPHER_CTX_set_key_length(ctx, key_len);
          if (!ret)
              goto out;
      }
      /* we never want padding, either the length requested is a multiple of
       * the cipher block size or we are passed a cipher that can cope with
       * partial blocks via techniques like cipher text stealing */
      ret = EVP_CIPHER_CTX_set_padding(ctx, 0);
      if (!ret)
          goto out;
  
  out:
      return ret;
  }
  
  static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
                     const unsigned char *key, size_t key_len,
                     const unsigned char *constant, size_t constant_len,
                     unsigned char *okey, size_t okey_len)
  {
      EVP_CIPHER_CTX *ctx = NULL;
      unsigned char block[EVP_MAX_BLOCK_LENGTH * 2];
      unsigned char *plainblock, *cipherblock;
      size_t blocksize;
      size_t cipherlen;
      size_t osize;
  #ifndef OPENSSL_NO_DES
      int des3_no_fixup = 0;
  #endif
      int ret;
  
      if (key_len != okey_len) {
  #ifndef OPENSSL_NO_DES
          /* special case for 3des, where the caller may be requesting
           * the random raw key, instead of the fixed up key  */
          if (EVP_CIPHER_nid(cipher) == NID_des_ede3_cbc &&
              key_len == 24 && okey_len == 21) {
                  des3_no_fixup = 1;
          } else {
  #endif
              ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
              return 0;
  #ifndef OPENSSL_NO_DES
          }
  #endif
      }
  
      ctx = EVP_CIPHER_CTX_new();
      if (ctx == NULL)
          return 0;
  
      ret = cipher_init(ctx, cipher, engine, key, key_len);
      if (!ret)
          goto out;
  
      /* Initialize input block */
      blocksize = EVP_CIPHER_CTX_block_size(ctx);
  
      if (constant_len > blocksize) {
          ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CONSTANT_LENGTH);
          ret = 0;
          goto out;
      }
  
      n_fold(block, blocksize, constant, constant_len);
      plainblock = block;
      cipherblock = block + EVP_MAX_BLOCK_LENGTH;
  
      for (osize = 0; osize < okey_len; osize += cipherlen) {
          int olen;
  
          ret = EVP_EncryptUpdate(ctx, cipherblock, &olen,
                                  plainblock, blocksize);
          if (!ret)
              goto out;
          cipherlen = olen;
          ret = EVP_EncryptFinal_ex(ctx, cipherblock, &olen);
          if (!ret)
              goto out;
          if (olen != 0) {
              ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_FINAL_BLOCK_LENGTH);
              ret = 0;
              goto out;
          }
  
          /* write cipherblock out */
          if (cipherlen > okey_len - osize)
              cipherlen = okey_len - osize;
          memcpy(okey + osize, cipherblock, cipherlen);
  
          if (okey_len > osize + cipherlen) {
              /* we need to reinitialize cipher context per spec */
              ret = EVP_CIPHER_CTX_reset(ctx);
              if (!ret)
                  goto out;
              ret = cipher_init(ctx, cipher, engine, key, key_len);
              if (!ret)
                  goto out;
  
              /* also swap block offsets so last ciphertext becomes new
               * plaintext */
              plainblock = cipherblock;
              if (cipherblock == block) {
                  cipherblock += EVP_MAX_BLOCK_LENGTH;
              } else {
                  cipherblock = block;
              }
          }
      }
  
  #ifndef OPENSSL_NO_DES
      if (EVP_CIPHER_nid(cipher) == NID_des_ede3_cbc && !des3_no_fixup) {
          ret = fixup_des3_key(okey);
          if (!ret) {
              ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GENERATE_KEY);
              goto out;
          }
      }
  #endif
  
      ret = 1;
  
  out:
      EVP_CIPHER_CTX_free(ctx);
      OPENSSL_cleanse(block, EVP_MAX_BLOCK_LENGTH * 2);
      return ret;
  }
  
  