// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef OPENSSL_HEADER_CIPHER_H
#define OPENSSL_HEADER_CIPHER_H

#include <openssl/base.h>  // IWYU pragma: export

#if defined(__cplusplus)
extern "C" {
#endif


// Ciphers.


// Cipher primitives.
//
// The following functions return `EVP_CIPHER` objects that implement the named
// cipher algorithm.

OPENSSL_EXPORT const EVP_CIPHER *EVP_rc4(void);

OPENSSL_EXPORT const EVP_CIPHER *EVP_des_cbc(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_des_ecb(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_des_ede(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_des_ede3(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_des_ede_cbc(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_des_ede3_cbc(void);

OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_ecb(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_cbc(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_ctr(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_ofb(void);

OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_ecb(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_cbc(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_ctr(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_ofb(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_xts(void);

// EVP_enc_null returns a 'cipher' that passes plaintext through as
// ciphertext.
OPENSSL_EXPORT const EVP_CIPHER *EVP_enc_null(void);

// EVP_rc2_cbc returns a cipher that implements 128-bit RC2 in CBC mode.
OPENSSL_EXPORT const EVP_CIPHER *EVP_rc2_cbc(void);

// EVP_rc2_40_cbc returns a cipher that implements 40-bit RC2 in CBC mode. This
// is obviously very, very weak and is included only in order to read PKCS#12
// files, which often encrypt the certificate chain using this cipher. It is
// deliberately not exported.
const EVP_CIPHER *EVP_rc2_40_cbc(void);

// EVP_get_cipherbynid returns the cipher corresponding to the given NID, or
// NULL if no such cipher is known. Note using this function links almost every
// cipher implemented by BoringSSL into the binary, whether the caller uses them
// or not. Size-conscious callers, such as client software, should not use this
// function.
OPENSSL_EXPORT const EVP_CIPHER *EVP_get_cipherbynid(int nid);


// Cipher context allocation.
//
// An `EVP_CIPHER_CTX` represents the state of an encryption or decryption in
// progress.

// EVP_CIPHER_CTX_init sets an uninitialized `EVP_CIPHER_CTX` to the zero state.
// This is the same as setting the structure to zero.
//
// This function is used for initializing uninitialized memory in an
// `EVP_CIPHER_CTX`, e.g. if it is declared as a local variable on the stack.
// This function should not be used on objects that have already been
// initialized.
OPENSSL_EXPORT void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_new returns a newly-allocated `EVP_CIPHER_CTX` in the zero
// state, or NULL on allocation failure. The caller must use
// `EVP_CIPHER_CTX_free` to release the resulting object.
OPENSSL_EXPORT EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);

// EVP_CIPHER_CTX_cleanup frees any memory referenced by `ctx`. It returns
// one.
OPENSSL_EXPORT int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_free calls `EVP_CIPHER_CTX_cleanup` on `ctx` and then frees
// `ctx` itself.
OPENSSL_EXPORT void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_copy sets `out` to be a duplicate of the current state of
// `in`. The `out` argument must have been previously initialised, e.g. with
// `EVP_CIPHER_CTX_init` or `EVP_CIPHER_CTX_new`.
OPENSSL_EXPORT int EVP_CIPHER_CTX_copy(EVP_CIPHER_CTX *out,
                                       const EVP_CIPHER_CTX *in);

// EVP_CIPHER_CTX_reset calls `EVP_CIPHER_CTX_cleanup` followed by
// `EVP_CIPHER_CTX_init` and returns one.
OPENSSL_EXPORT int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);


// Cipher context configuration.

// EVP_CipherInit_ex configures `ctx` for a fresh encryption (or decryption, if
// `enc` is zero) operation using `cipher`. The memory in `ctx` must already
// have been initialized, e.g. with `EVP_CIPHER_CTX_init` or
// `EVP_CIPHER_CTX_new`. If non-NULL, `key` and `iv` will be used as the key and
// IV, respectively. These must point to `EVP_CIPHER_key_length` and
// `EVP_CIPHER_iv_length` bytes, respectively. It returns one on success and
// zero on error.
//
// This function may be called multiple times on a single `EVP_CIPHER_CTX`,
// either to reset an existing object, or to configure a single operation in
// multiple steps. In such cases:
//
// - `cipher` may be NULL to reuse the previous cipher state. A non-NULL
//   `cipher` will reset all cipher state, including the key and IV, even if
//   configuring the same `EVP_CIPHER` as before.
//
// - `key` and `iv` may be NULL to either reuse the previous value, or leave
//   them unconfigured.
//
// - `enc` may be -1 to reuse the previous value. In ciphers that use a
//   different key schedule between encryption and decryption (e.g. CBC and ECB
//   modes), callers must configure `key` and `enc` together.
//
// Some example multi-step configuration patterns:
//
// - If setting a variable-length key with `EVP_CIPHER_CTX_set_key_length`,
//   first configure only `cipher`, then use `EVP_CIPHER_CTX_set_key_length`,
//   and finally configure `key`, leaving `cipher` NULL.
//
// - If setting a variable-length IV with `EVP_CTRL_AEAD_SET_IVLEN`, first
//   configure `cipher` and `key`, then use `EVP_CTRL_AEAD_SET_IVLEN`, and
//   finally configure `iv`, leaving other parameters NULL.
//
// - If retaining a long-lived context to reuse the key schedule across
//   operations, first configure only `cipher` and `key` on the long-lived
//   context, then copy the key schedule to a per-operation context with
//   `EVP_CIPHER_CTX_copy`, and finally configure only `iv` on the per-operation
//   context.
//
// WARNING: This API is difficult to use correctly. Use `EVP_AEAD` for AEADs.
OPENSSL_EXPORT int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx,
                                     const EVP_CIPHER *cipher, ENGINE *engine,
                                     const uint8_t *key, const uint8_t *iv,
                                     int enc);

// EVP_EncryptInit_ex calls `EVP_CipherInit_ex` with `enc` equal to one.
OPENSSL_EXPORT int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx,
                                      const EVP_CIPHER *cipher, ENGINE *impl,
                                      const uint8_t *key, const uint8_t *iv);

// EVP_DecryptInit_ex calls `EVP_CipherInit_ex` with `enc` equal to zero.
OPENSSL_EXPORT int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx,
                                      const EVP_CIPHER *cipher, ENGINE *impl,
                                      const uint8_t *key, const uint8_t *iv);


// Cipher operations.

// EVP_EncryptUpdate_ex encrypts `in_len` bytes from `in` and writes up to
// `max_out_len` bytes of ciphertext to `out`. On success, it sets `*out_len` to
// the number of output bytes and returns one. Otherwise, it returns zero.
//
// If `max_out_len` is not large enough for the output, the function will return
// zero. The size of output buffer needed depends on the cipher and the number
// of bytes encrypted by `ctx` thus far. `EVP_CIPHER_CTX_max_next_update` will
// return the maximum output for this call.
//
// In ciphers whose block size is not 1, such as CBC, individual calls to
// `EVP_EncryptUpdate_ex` may output more or less than `in_len` bytes: a single
// call to `EVP_EncryptUpdate_ex` may output at most `in_len + block_size - 1`
// bytes. Additionally, the total output across all `EVP_EncryptUpdate_ex` and
// `EVP_EncryptFinal_ex2` calls will be at most the total input plus one byte,
// rounded up to a multiple of the block size.
OPENSSL_EXPORT int EVP_EncryptUpdate_ex(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                        size_t *out_len, size_t max_out_len,
                                        const uint8_t *in, size_t in_len);

// EVP_EncryptFinal_ex2 finishes an encryption operation and writes up to
// `max_out_len` bytes of output to out. On success, it sets `*out_len` to the
// number of bytes written and returns one. Otherwise, it returns zero.
//
// If `max_out_len` is not large enough for the output, the function will return
// zero. The size of output buffer needed depends on the cipher and the number
// of bytes encrypted. `EVP_CIPHER_CTX_max_final` will return the maximum output
// for this call.
//
// If the block size is 1, there will be no final output at all; otherwise, at
// most one block of ciphertext will be written to the output.
//
// If padding is enabled (the default) and the block size is not 1, then
// standard padding is applied to create the final block. If padding is
// disabled (with `EVP_CIPHER_CTX_set_padding`) then any partial block
// remaining will cause an error. The function returns one on success and zero
// otherwise.
OPENSSL_EXPORT int EVP_EncryptFinal_ex2(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                        size_t *out_len, size_t max_out_len);

// EVP_DecryptUpdate_ex decrypts `in_len` bytes from `in` and writes up to
// `max_out_len` bytes of plaintext to `out`. On success, it sets `*out_len` to
// the number of output bytes and returns one. Otherwise, it returns zero.
//
// If `max_out_len` is not large enough for the output, the function will return
// zero. The size of output buffer needed depends on the cipher and the number
// of bytes decrypted by `ctx` thus far. `EVP_CIPHER_CTX_max_next_update` will
// return the maximum output for this call.
//
// In ciphers whose block size is not 1, such as CBC, individual calls to
// `EVP_DecryptUpdate_ex` may output more or less than `in_len` bytes: a single
// call to `EVP_DecryptUpdate_ex` may output at most `in_len + block_size - 1`
// bytes. Additionally, the total output across all `EVP_DecryptUpdate_ex` and
// `EVP_DecryptFinal_ex2` calls will be at most the total input.
//
// WARNING: if the cipher is an AEAD cipher, decrypted data should not be
// parsed or otherwise processed until success has been returned by
// `EVP_EncryptFinal_ex2`.
OPENSSL_EXPORT int EVP_DecryptUpdate_ex(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                        size_t *out_len, size_t max_out_len,
                                        const uint8_t *in, size_t in_len);

// EVP_DecryptFinal_ex2 finishes a decryption operation and writes up to
// `max_out_len` bytes of output to out. On success, it sets `*out_len` to the
// number of bytes written and returns one. Otherwise, it returns zero.
//
// If `max_out_len` is not large enough for the output, the function will return
// zero. The size of output buffer needed depends on the cipher and the number
// of bytes decrypted. `EVP_CIPHER_CTX_max_final` will return the maximum output
// for this call.
//
// If the block size is 1, there will be no final output at all; otherwise, at
// most one block of ciphertext will be written to the output.
//
// If padding is enabled (the default) and the block size is not 1, then
// standard padding is removed from the final block.
//
// WARNING: it is unsafe to call this function after decrypting unauthenticated
// ciphertext if padding is enabled and the block size is not 1 ("padding
// oracle").
OPENSSL_EXPORT int EVP_DecryptFinal_ex2(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                        size_t *out_len, size_t max_out_len);

// EVP_CipherUpdate_ex calls either `EVP_EncryptUpdate_ex` or
// `EVP_DecryptUpdate_ex` depending on how `ctx` has been setup.
OPENSSL_EXPORT int EVP_CipherUpdate_ex(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                       size_t *out_len, size_t max_out_len,
                                       const uint8_t *in, size_t in_len);

// EVP_CipherUpdateAAD adds `in_len` bytes from `in` to the AAD. The AAD must
// be fully specified in this way before any plaintext or ciphertext is
// supplied to the other functions. Please consider moving to the `EVP_AEAD`
// APIs instead.
OPENSSL_EXPORT int EVP_CipherUpdateAAD(EVP_CIPHER_CTX *ctx, const uint8_t *in,
                                       size_t in_len);

// EVP_CipherFinal_ex2 calls either `EVP_EncryptFinal_ex2` or
// `EVP_DecryptFinal_ex2` depending on how `ctx` has been setup.
OPENSSL_EXPORT int EVP_CipherFinal_ex2(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                       size_t *out_len, size_t max_out_len);

// EVP_CIPHER_CTX_max_next_update returns the maximum number of bytes that may
// be output from `ctx` by a call to `EVP_CipherUpdate_ex` with `in_len` bytes
// of input. This takes the current state of `ctx` into account, so the output
// will change as bytes are passed in and out.
OPENSSL_EXPORT size_t EVP_CIPHER_CTX_max_next_update(const EVP_CIPHER_CTX *ctx,
                                                     size_t in_len);

// EVP_CIPHER_CTX_max_final returns the maximum number of bytes that may
// be output from `ctx` by a call to `EVP_CipherFinal_ex2`. This takes the
// current state of `ctx` into account, so the output will change as bytes are
// passed in and out.
OPENSSL_EXPORT size_t EVP_CIPHER_CTX_max_final(const EVP_CIPHER_CTX *ctx);


// Cipher context accessors.

// EVP_CIPHER_CTX_cipher returns the `EVP_CIPHER` underlying `ctx`, or NULL if
// none has been set.
OPENSSL_EXPORT const EVP_CIPHER *EVP_CIPHER_CTX_cipher(
    const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_nid returns a NID identifying the `EVP_CIPHER` underlying
// `ctx` (e.g. `NID_aes_128_gcm`). It will crash if no cipher has been
// configured.
OPENSSL_EXPORT int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_encrypting returns one if `ctx` is configured for encryption
// and zero otherwise.
OPENSSL_EXPORT int EVP_CIPHER_CTX_encrypting(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_block_size returns the block size, in bytes, of the cipher
// underlying `ctx`, or one if the cipher is a stream cipher. It will crash if
// no cipher has been configured.
OPENSSL_EXPORT unsigned EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_key_length returns the key size, in bytes, of the cipher
// underlying `ctx` or zero if no cipher has been configured.
OPENSSL_EXPORT unsigned EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_iv_length returns the IV size, in bytes, of the cipher
// underlying `ctx`. It will crash if no cipher has been configured.
OPENSSL_EXPORT unsigned EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_get_app_data returns the opaque, application data pointer for
// `ctx`, or NULL if none has been set.
OPENSSL_EXPORT void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_set_app_data sets the opaque, application data pointer for
// `ctx` to `data`.
OPENSSL_EXPORT void EVP_CIPHER_CTX_set_app_data(EVP_CIPHER_CTX *ctx,
                                                void *data);

// EVP_CIPHER_CTX_flags returns a value which is the OR of zero or more
// `EVP_CIPH_*` flags. It will crash if no cipher has been configured.
OPENSSL_EXPORT uint32_t EVP_CIPHER_CTX_flags(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_mode returns one of the `EVP_CIPH_*` cipher mode values
// enumerated below. It will crash if no cipher has been configured.
OPENSSL_EXPORT uint32_t EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);

// EVP_CIPHER_CTX_ctrl is an `ioctl` like function. The `command` argument
// should be one of the `EVP_CTRL_*` values. The `arg` and `ptr` arguments are
// specific to the command in question.
OPENSSL_EXPORT int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int command,
                                       int arg, void *ptr);

// EVP_CIPHER_CTX_set_padding sets whether padding is enabled for `ctx` and
// returns one. Pass a non-zero `pad` to enable padding (the default) or zero
// to disable.
OPENSSL_EXPORT int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *ctx, int pad);

// EVP_CIPHER_CTX_set_key_length sets the key length for `ctx`. This is only
// valid for ciphers that can take a variable length key. It returns one on
// success and zero on error.
//
// In order to use this function, |ctx| must have been configured with an
// |EVP_CIPHER| with |EVP_CipherInit_ex|. Callers should first configure only
// the cipher, leaving |key| NULL, call |EVP_CIPHER_CTX_set_key_length|, and
// finally call |EVP_CipherInit_ex| with a NULL |cipher| and non-NULL |key|.
OPENSSL_EXPORT int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *ctx,
                                                 unsigned key_len);


// Cipher accessors.

// EVP_CIPHER_nid returns a NID identifying `cipher`. (For example,
// `NID_aes_128_gcm`.)
OPENSSL_EXPORT int EVP_CIPHER_nid(const EVP_CIPHER *cipher);

// EVP_CIPHER_block_size returns the block size, in bytes, for `cipher`, or one
// if `cipher` is a stream cipher.
OPENSSL_EXPORT unsigned EVP_CIPHER_block_size(const EVP_CIPHER *cipher);

// EVP_CIPHER_key_length returns the key size, in bytes, for `cipher`. If
// `cipher` can take a variable key length then this function returns the
// default key length and `EVP_CIPHER_flags` will return a value with
// `EVP_CIPH_VARIABLE_LENGTH` set.
OPENSSL_EXPORT unsigned EVP_CIPHER_key_length(const EVP_CIPHER *cipher);

// EVP_CIPHER_iv_length returns the IV size, in bytes, of `cipher`, or zero if
// `cipher` doesn't take an IV.
OPENSSL_EXPORT unsigned EVP_CIPHER_iv_length(const EVP_CIPHER *cipher);

// EVP_CIPHER_flags returns a value which is the OR of zero or more
// `EVP_CIPH_*` flags.
OPENSSL_EXPORT uint32_t EVP_CIPHER_flags(const EVP_CIPHER *cipher);

// EVP_CIPHER_mode returns one of the cipher mode values enumerated below.
OPENSSL_EXPORT uint32_t EVP_CIPHER_mode(const EVP_CIPHER *cipher);


// Key derivation.

// EVP_BytesToKey generates a key and IV for the cipher `type` by iterating
// `md` `count` times using `data` and an optional `salt`, writing the result to
// `key` and `iv`. If not NULL, the `key` and `iv` buffers must have enough
// space to hold a key and IV for `type`, as returned by `EVP_CIPHER_key_length`
// and `EVP_CIPHER_iv_length`. This function returns the length of the key
// (without the IV) on success or zero on error.
//
// If `salt` is NULL, the empty string is used as the salt. Salt lengths other
// than 0 and 8 are not supported by this function. Either of `key` or `iv` may
// be NULL to skip that output.
//
// When the total data derived is less than the size of `md`, this function
// implements PBKDF1 from RFC 8018. Otherwise, it generalizes PBKDF1 by
// computing prepending the previous output to `data` and re-running PBKDF1 for
// further output.
//
// This function is provided for compatibility with legacy uses of PBKDF1. New
// applications should use a more modern algorithm, such as `EVP_PBE_scrypt`.
OPENSSL_EXPORT int EVP_BytesToKey(const EVP_CIPHER *type, const EVP_MD *md,
                                  const uint8_t salt[8], const uint8_t *data,
                                  size_t data_len, unsigned count, uint8_t *key,
                                  uint8_t *iv);


// Cipher modes (for `EVP_CIPHER_mode`).

#define EVP_CIPH_STREAM_CIPHER 0x0
#define EVP_CIPH_ECB_MODE 0x1
#define EVP_CIPH_CBC_MODE 0x2
#define EVP_CIPH_CFB_MODE 0x3
#define EVP_CIPH_OFB_MODE 0x4
#define EVP_CIPH_CTR_MODE 0x5
#define EVP_CIPH_GCM_MODE 0x6
#define EVP_CIPH_XTS_MODE 0x7

// The following values are never returned from `EVP_CIPHER_mode` and are
// included only to make it easier to compile code with BoringSSL.
#define EVP_CIPH_CCM_MODE 0x8
#define EVP_CIPH_OCB_MODE 0x9
#define EVP_CIPH_WRAP_MODE 0xa


// Cipher flags (for `EVP_CIPHER_flags`).

// EVP_CIPH_VARIABLE_LENGTH indicates that the cipher takes a variable length
// key.
#define EVP_CIPH_VARIABLE_LENGTH 0x40

// EVP_CIPH_ALWAYS_CALL_INIT indicates that the `init` function for the cipher
// should always be called when initialising a new operation, even if the key
// is NULL to indicate that the same key is being used.
#define EVP_CIPH_ALWAYS_CALL_INIT 0x80

// EVP_CIPH_CUSTOM_IV indicates that the cipher manages the IV itself rather
// than keeping it in the `iv` member of `EVP_CIPHER_CTX`.
#define EVP_CIPH_CUSTOM_IV 0x100

// EVP_CIPH_CTRL_INIT indicates that EVP_CTRL_INIT should be used when
// initialising an `EVP_CIPHER_CTX`.
#define EVP_CIPH_CTRL_INIT 0x200

// EVP_CIPH_FLAG_CUSTOM_CIPHER indicates that the cipher manages blocking
// itself. This causes EVP_(En|De)crypt_ex to be simple wrapper functions.
#define EVP_CIPH_FLAG_CUSTOM_CIPHER 0x400

// EVP_CIPH_FLAG_AEAD_CIPHER specifies that the cipher is an AEAD. This is an
// older version of the proper AEAD interface. See aead.h for the current
// one.
#define EVP_CIPH_FLAG_AEAD_CIPHER 0x800

// EVP_CIPH_CUSTOM_COPY indicates that the `ctrl` callback should be called
// with `EVP_CTRL_COPY` at the end of normal `EVP_CIPHER_CTX_copy`
// processing.
#define EVP_CIPH_CUSTOM_COPY 0x1000

// EVP_CIPH_FLAG_NON_FIPS_ALLOW is meaningless. In OpenSSL it permits non-FIPS
// algorithms in FIPS mode. But BoringSSL FIPS mode doesn't prohibit algorithms
// (it's up to the caller to use the FIPS module in a fashion compliant with
// their needs). Thus this exists only to allow code to compile.
#define EVP_CIPH_FLAG_NON_FIPS_ALLOW 0


// Deprecated functions

// EVP_CipherInit acts like `EVP_CipherInit_ex` except that
// `EVP_CIPHER_CTX_init` is called on `cipher` first, if `cipher` is not NULL.
//
// `EVP_CIPHER_CTX_init` is used for initializing uninitialized memory in an
// `EVP_CIPHER_CTX`, e.g. if it is declared as a local variable on the stack.
// Thus this function should not be used on objects that have already been
// initialized.
//
// WARNING: This differs from OpenSSL 1.1.x, where `EVP_CipherInit` and
// `EVP_CipherInit_ex` are largely equivalent. This difference is because
// BoringSSL, like OpenSSL 1.0.x, still supports stack-allocating
// `EVP_CIPHER_CTX`. Implementing the OpenSSL 1.1.x semantics would introduce
// uninitialized reads in those callers.
OPENSSL_EXPORT int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                                  const uint8_t *key, const uint8_t *iv,
                                  int enc);

// EVP_EncryptInit calls `EVP_CipherInit` with `enc` equal to one.
//
// WARNING: See discussion in `EVP_CipherInit`.
OPENSSL_EXPORT int EVP_EncryptInit(EVP_CIPHER_CTX *ctx,
                                   const EVP_CIPHER *cipher, const uint8_t *key,
                                   const uint8_t *iv);

// EVP_DecryptInit calls `EVP_CipherInit` with `enc` equal to zero.
//
// WARNING: See discussion in `EVP_CipherInit`.
OPENSSL_EXPORT int EVP_DecryptInit(EVP_CIPHER_CTX *ctx,
                                   const EVP_CIPHER *cipher, const uint8_t *key,
                                   const uint8_t *iv);

// EVP_CipherUpdate does the same as `EVP_CipherUpdate_ex`, except that no
// output size is given and thus no bounds checking is performed.
//
// Additionally, if `ctx` is an AEAD cipher, e.g. `EVP_aes_128_gcm`, and `out`
// is NULL, this function instead behaves like `EVP_CipherUpdateAAD`.
//
// WARNING: This function does not check bounds on `out`, and correctly sizing
// the output buffer is difficult. Use `EVP_CipherUpdate_ex` or
// `EVP_CipherUpdateAAD` instead.
OPENSSL_EXPORT int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                    int *out_len, const uint8_t *in,
                                    int in_len);

// EVP_EncryptUpdate does the same as `EVP_EncryptUpdate_ex`, except that no
// output size is given and thus no bounds checking is performed.
//
// Additionally, if `ctx` is an AEAD cipher, e.g. `EVP_aes_128_gcm`, and `out`
// is NULL, this function instead behaves like `EVP_CipherUpdateAAD`.
//
// WARNING: This function does not check bounds on `out`, and correctly sizing
// the output buffer is difficult. Use `EVP_EncryptUpdate_ex` or
// `EVP_CipherUpdateAAD` instead.
OPENSSL_EXPORT int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                     int *out_len, const uint8_t *in,
                                     int in_len);

// EVP_DecryptUpdate does the same as `EVP_DecryptUpdate_ex`, except that no
// output size is given and thus no bounds checking is performed.
//
// Additionally, if `ctx` is an AEAD cipher, e.g. `EVP_aes_128_gcm`, and `out`
// is NULL, this function instead behaves like `EVP_CipherUpdateAAD`.
//
// WARNING: This function does not check bounds on out, and correctly sizing
// the output buffer is difficult. Use `EVP_DecryptUpdate_ex` or
// `EVP_CipherUpdateAAD` instead.
OPENSSL_EXPORT int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                     int *out_len, const uint8_t *in,
                                     int in_len);

// EVP_CipherFinal calls `EVP_CipherFinal_ex`.
OPENSSL_EXPORT int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                   int *out_len);

// EVP_CipherFinal_ex does the same as `EVP_CipherFinal_ex2`, except that no
// output size is given and thus no bounds checking is performed.
//
// WARNING: This function does not check bounds on out, and correctly sizing
// the output buffer is difficult. Use `EVP_CipherFinal_ex2` instead.
OPENSSL_EXPORT int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                      int *out_len);

// EVP_EncryptFinal calls `EVP_EncryptFinal_ex`.
OPENSSL_EXPORT int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                    int *out_len);

// EVP_EncryptFinal_ex does the same as `EVP_EncryptFinal_ex2`, except that no
// output size is given and thus no bounds checking is performed.
//
// WARNING: This function does not check bounds on out, and correctly sizing
// the output buffer is difficult. Use `EVP_EncryptFinal_ex2` instead.
OPENSSL_EXPORT int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                       int *out_len);

// EVP_DecryptFinal calls `EVP_DecryptFinal_ex`.
OPENSSL_EXPORT int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                    int *out_len);

// EVP_DecryptFinal_ex does the same as `EVP_DecryptFinal_ex2`, except that no
// output size is given and thus no bounds checking is performed.
//
// WARNING: This function does not check bounds on out, and correctly sizing
// the output buffer is difficult. Use `EVP_DecryptFinal_ex2` instead.
OPENSSL_EXPORT int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, uint8_t *out,
                                       int *out_len);

// EVP_Cipher historically exposed an internal implementation detail of `ctx`
// and should not be used. Use `EVP_CipherUpdate` and `EVP_CipherFinal_ex`
// instead.
//
// If `ctx`'s cipher does not have the `EVP_CIPH_FLAG_CUSTOM_CIPHER` flag, it
// encrypts or decrypts `in_len` bytes from `in` and writes the resulting
// `in_len` bytes to `out`. It returns one on success and zero on error.
// `in_len` must be a multiple of the cipher's block size, or the behavior is
// undefined.
//
// TODO(davidben): Rather than being undefined (it'll often round the length up
// and likely read past the buffer), just fail the operation.
//
// If `ctx`'s cipher has the `EVP_CIPH_FLAG_CUSTOM_CIPHER` flag, it runs in one
// of two modes: If `in` is non-NULL, it behaves like `EVP_CipherUpdate`. If
// `in` is NULL, it behaves like `EVP_CipherFinal_ex`. In both cases, it returns
// `*out_len` on success and -1 on error.
//
// WARNING: The two possible calling conventions of this function signal errors
// incompatibly. In the first, zero indicates an error. In the second, zero
// indicates success with zero bytes of output.
OPENSSL_EXPORT int EVP_Cipher(EVP_CIPHER_CTX *ctx, uint8_t *out,
                              const uint8_t *in, size_t in_len);

// EVP_add_cipher_alias does nothing and returns one.
OPENSSL_EXPORT int EVP_add_cipher_alias(const char *a, const char *b);

// EVP_get_cipherbyname returns an `EVP_CIPHER` given a human readable name in
// `name`, or NULL if the name is unknown. Note using this function links almost
// every cipher implemented by BoringSSL into the binary, not just the ones the
// caller requests. Size-conscious callers, such as client software, should not
// use this function.
OPENSSL_EXPORT const EVP_CIPHER *EVP_get_cipherbyname(const char *name);

// These AEADs are deprecated AES-GCM implementations that set
// `EVP_CIPH_FLAG_CUSTOM_CIPHER`. Use `EVP_aead_aes_128_gcm` and
// `EVP_aead_aes_256_gcm` instead.
//
// WARNING: Although these APIs allow streaming an individual AES-GCM operation,
// this is not secure. Until calling `EVP_DecryptFinal_ex`, the tag has not yet
// been checked and output released by `EVP_DecryptUpdate` is unauthenticated
// and easily manipulated by attackers. Callers must buffer the output and may
// not act on it until the entire operation is complete.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_gcm(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_gcm(void);

// These are deprecated, 192-bit version of AES.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_ecb(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_cbc(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_ctr(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_gcm(void);
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_ofb(void);

// EVP_des_ede3_ecb is an alias for `EVP_des_ede3`. Use the former instead.
OPENSSL_EXPORT const EVP_CIPHER *EVP_des_ede3_ecb(void);

// EVP_aes_128_cfb128 is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_cfb128(void);

// EVP_aes_128_cfb is an alias for `EVP_aes_128_cfb128` and is only available in
// decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_cfb(void);

// EVP_aes_192_cfb128 is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_cfb128(void);

// EVP_aes_192_cfb is an alias for `EVP_aes_192_cfb128` and is only available in
// decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_cfb(void);

// EVP_aes_256_cfb128 is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_cfb128(void);

// EVP_aes_256_cfb is an alias for `EVP_aes_256_cfb128` and is only available in
// decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_256_cfb(void);

// EVP_bf_ecb is Blowfish in ECB mode and is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_bf_ecb(void);

// EVP_bf_cbc is Blowfish in CBC mode and is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_bf_cbc(void);

// EVP_bf_cfb is Blowfish in 64-bit CFB mode and is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_bf_cfb(void);

// EVP_cast5_ecb is CAST5 in ECB mode and is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_cast5_ecb(void);

// EVP_cast5_cbc is CAST5 in CBC mode and is only available in decrepit.
OPENSSL_EXPORT const EVP_CIPHER *EVP_cast5_cbc(void);

// The following flags do nothing and are included only to make it easier to
// compile code with BoringSSL.
#define EVP_CIPHER_CTX_FLAG_WRAP_ALLOW 0

// EVP_CIPHER_CTX_set_flags does nothing.
OPENSSL_EXPORT void EVP_CIPHER_CTX_set_flags(const EVP_CIPHER_CTX *ctx,
                                             uint32_t flags);


// Private functions.

// EVP_CIPH_NO_PADDING disables padding in block ciphers.
#define EVP_CIPH_NO_PADDING 0x800

// The following are `EVP_CIPHER_CTX_ctrl` commands.
#define EVP_CTRL_INIT 0x0
#define EVP_CTRL_SET_KEY_LENGTH 0x1
#define EVP_CTRL_GET_RC2_KEY_BITS 0x2
#define EVP_CTRL_SET_RC2_KEY_BITS 0x3
#define EVP_CTRL_GET_RC5_ROUNDS 0x4
#define EVP_CTRL_SET_RC5_ROUNDS 0x5
#define EVP_CTRL_RAND_KEY 0x6
#define EVP_CTRL_PBE_PRF_NID 0x7
#define EVP_CTRL_COPY 0x8
#define EVP_CTRL_AEAD_SET_IVLEN 0x9
#define EVP_CTRL_AEAD_GET_TAG 0x10
#define EVP_CTRL_AEAD_SET_TAG 0x11
#define EVP_CTRL_AEAD_SET_IV_FIXED 0x12
#define EVP_CTRL_GCM_IV_GEN 0x13
#define EVP_CTRL_AEAD_SET_MAC_KEY 0x17
// EVP_CTRL_GCM_SET_IV_INV sets the GCM invocation field, decrypt only
#define EVP_CTRL_GCM_SET_IV_INV 0x18
#define EVP_CTRL_GET_IVLEN 0x19

// The following constants are unused.
#define EVP_GCM_TLS_FIXED_IV_LEN 4
#define EVP_GCM_TLS_EXPLICIT_IV_LEN 8
#define EVP_GCM_TLS_TAG_LEN 16

// The following are legacy aliases for AEAD `EVP_CIPHER_CTX_ctrl` values.
#define EVP_CTRL_GCM_SET_IVLEN EVP_CTRL_AEAD_SET_IVLEN
#define EVP_CTRL_GCM_GET_TAG EVP_CTRL_AEAD_GET_TAG
#define EVP_CTRL_GCM_SET_TAG EVP_CTRL_AEAD_SET_TAG
#define EVP_CTRL_GCM_SET_IV_FIXED EVP_CTRL_AEAD_SET_IV_FIXED

#define EVP_MAX_KEY_LENGTH 64
#define EVP_MAX_IV_LENGTH 16
#define EVP_MAX_BLOCK_LENGTH 32

struct evp_cipher_ctx_st {
  // cipher contains the underlying cipher for this context.
  const EVP_CIPHER *cipher;

  // app_data is a pointer to opaque, user data.
  void *app_data;  // application stuff

  // cipher_data points to the `cipher` specific state.
  void *cipher_data;

  // key_len contains the length of the key, which may differ from
  // `cipher->key_len` if the cipher can take a variable key length.
  unsigned key_len;

  // encrypt is one if encrypting and zero if decrypting.
  int encrypt;

  // flags contains the OR of zero or more `EVP_CIPH_*` flags, above.
  uint32_t flags;

  // oiv contains the original IV value.
  uint8_t oiv[EVP_MAX_IV_LENGTH];

  // iv contains the current IV value, which may have been updated.
  uint8_t iv[EVP_MAX_IV_LENGTH];

  // buf contains a partial block which is used by, for example, CTR mode to
  // store unused keystream bytes.
  uint8_t buf[EVP_MAX_BLOCK_LENGTH];

  // buf_len contains the number of bytes of a partial block contained in
  // `buf`.
  int buf_len;

  // num contains the number of bytes of `iv` which are valid for modes that
  // manage partial blocks themselves.
  unsigned num;

  // final_used is non-zero if the `final` buffer contains plaintext.
  int final_used;

  uint8_t final[EVP_MAX_BLOCK_LENGTH];  // possible final block

  // Has this structure been rendered unusable by a failure.
  int poisoned;
} /* EVP_CIPHER_CTX */;

typedef struct evp_cipher_info_st {
  const EVP_CIPHER *cipher;
  unsigned char iv[EVP_MAX_IV_LENGTH];
} EVP_CIPHER_INFO;


#if defined(__cplusplus)
}  // extern C

#if !defined(BORINGSSL_NO_CXX)
extern "C++" {

BSSL_NAMESPACE_BEGIN

BORINGSSL_MAKE_DELETER(EVP_CIPHER_CTX, EVP_CIPHER_CTX_free)

using ScopedEVP_CIPHER_CTX =
    internal::StackAllocated<EVP_CIPHER_CTX, int, EVP_CIPHER_CTX_init,
                             EVP_CIPHER_CTX_cleanup>;

BSSL_NAMESPACE_END

}  // extern C++
#endif

#endif

#define CIPHER_R_AES_KEY_SETUP_FAILED 100
#define CIPHER_R_BAD_DECRYPT 101
#define CIPHER_R_BAD_KEY_LENGTH 102
#define CIPHER_R_BUFFER_TOO_SMALL 103
#define CIPHER_R_CTRL_NOT_IMPLEMENTED 104
#define CIPHER_R_CTRL_OPERATION_NOT_IMPLEMENTED 105
#define CIPHER_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH 106
#define CIPHER_R_INITIALIZATION_ERROR 107
#define CIPHER_R_INPUT_NOT_INITIALIZED 108
#define CIPHER_R_INVALID_AD_SIZE 109
#define CIPHER_R_INVALID_KEY_LENGTH 110
#define CIPHER_R_INVALID_NONCE_SIZE 111
#define CIPHER_R_INVALID_OPERATION 112
#define CIPHER_R_IV_TOO_LARGE 113
#define CIPHER_R_NO_CIPHER_SET 114
#define CIPHER_R_OUTPUT_ALIASES_INPUT 115
#define CIPHER_R_TAG_TOO_LARGE 116
#define CIPHER_R_TOO_LARGE 117
#define CIPHER_R_UNSUPPORTED_AD_SIZE 118
#define CIPHER_R_UNSUPPORTED_INPUT_SIZE 119
#define CIPHER_R_UNSUPPORTED_KEY_SIZE 120
#define CIPHER_R_UNSUPPORTED_NONCE_SIZE 121
#define CIPHER_R_UNSUPPORTED_TAG_SIZE 122
#define CIPHER_R_WRONG_FINAL_BLOCK_LENGTH 123
#define CIPHER_R_NO_DIRECTION_SET 124
#define CIPHER_R_INVALID_NONCE 125

#endif  // OPENSSL_HEADER_CIPHER_H