include/openssl/aes.h

// Copyright 2002-2016 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_AES_H
#define OPENSSL_HEADER_AES_H

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

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


// Raw AES functions.


#define AES_ENCRYPT 1
#define AES_DECRYPT 0

// AES_MAXNR is the maximum number of AES rounds.
#define AES_MAXNR 14

#define AES_BLOCK_SIZE 16

// aes_key_st should be an opaque type, but EVP requires that the size be
// known.
struct aes_key_st {
  uint32_t rd_key[4 * (AES_MAXNR + 1)];
  unsigned rounds;
};
typedef struct aes_key_st AES_KEY;

// AES_set_encrypt_key configures `aeskey` to encrypt with the `bits`-bit key,
// `key`. `key` must point to `bits`/8 bytes. It returns zero on success and a
// negative number if `bits` is an invalid AES key size.
//
// WARNING: this function breaks the usual return value convention.
OPENSSL_EXPORT int AES_set_encrypt_key(const uint8_t *key, unsigned bits,
                                       AES_KEY *aeskey);

// AES_set_decrypt_key configures `aeskey` to decrypt with the `bits`-bit key,
// `key`. `key` must point to `bits`/8 bytes. It returns zero on success and a
// negative number if `bits` is an invalid AES key size.
//
// WARNING: this function breaks the usual return value convention.
OPENSSL_EXPORT int AES_set_decrypt_key(const uint8_t *key, unsigned bits,
                                       AES_KEY *aeskey);

// AES_encrypt encrypts a single block from `in` to `out` with `key`. The `in`
// and `out` pointers may overlap.
OPENSSL_EXPORT void AES_encrypt(const uint8_t *in, uint8_t *out,
                                const AES_KEY *key);

// AES_decrypt decrypts a single block from `in` to `out` with `key`. The `in`
// and `out` pointers may overlap.
OPENSSL_EXPORT void AES_decrypt(const uint8_t *in, uint8_t *out,
                                const AES_KEY *key);


// Block cipher modes.

// AES_ctr128_encrypt encrypts (or decrypts, it's the same in CTR mode) `len`
// bytes from `in` to `out`. The `num` parameter must be set to zero on the
// first call and `ivec` will be incremented. This function may be called
// in-place with `in` equal to `out`, but otherwise the buffers may not
// partially overlap. A partial overlap may overwrite input data before it is
// read.
OPENSSL_EXPORT void AES_ctr128_encrypt(const uint8_t *in, uint8_t *out,
                                       size_t len, const AES_KEY *key,
                                       uint8_t ivec[AES_BLOCK_SIZE],
                                       uint8_t ecount_buf[AES_BLOCK_SIZE],
                                       unsigned int *num);

// AES_ecb_encrypt encrypts (or decrypts, if `enc` == `AES_DECRYPT`) a single,
// 16 byte block from `in` to `out`. This function may be called in-place with
// `in` equal to `out`, but otherwise the buffers may not partially overlap. A
// partial overlap may overwrite input data before it is read.
OPENSSL_EXPORT void AES_ecb_encrypt(const uint8_t *in, uint8_t *out,
                                    const AES_KEY *key, const int enc);

// AES_cbc_encrypt encrypts (or decrypts, if `enc` == `AES_DECRYPT`) `len`
// bytes from `in` to `out`. The length must be a multiple of the block size.
// This function may be called in-place with `in` equal to `out`, but otherwise
// the buffers may not partially overlap. A partial overlap may overwrite input
// data before it is read.
OPENSSL_EXPORT void AES_cbc_encrypt(const uint8_t *in, uint8_t *out, size_t len,
                                    const AES_KEY *key, uint8_t *ivec,
                                    const int enc);

// AES_ofb128_encrypt encrypts (or decrypts, it's the same in OFB mode) `len`
// bytes from `in` to `out`. The `num` parameter must be set to zero on the
// first call. This function may be called in-place with `in` equal to `out`,
// but otherwise the buffers may not partially overlap. A partial overlap may
// overwrite input data before it is read.
OPENSSL_EXPORT void AES_ofb128_encrypt(const uint8_t *in, uint8_t *out,
                                       size_t len, const AES_KEY *key,
                                       uint8_t *ivec, int *num);

// AES_cfb128_encrypt encrypts (or decrypts, if `enc` == `AES_DECRYPT`) `len`
// bytes from `in` to `out`. The `num` parameter must be set to zero on the
// first call. This function may be called in-place with `in` equal to `out`,
// but otherwise the buffers may not partially overlap. A partial overlap may
// overwrite input data before it is read.
OPENSSL_EXPORT void AES_cfb128_encrypt(const uint8_t *in, uint8_t *out,
                                       size_t len, const AES_KEY *key,
                                       uint8_t *ivec, int *num, int enc);


// AES key wrap.
//
// These functions implement AES Key Wrap mode, as defined in RFC 3394. They
// should never be used except to interoperate with existing systems that use
// this mode.

// AES_wrap_key performs AES key wrap on `in` which must be a multiple of 8
// bytes. `iv` must point to an 8 byte value or be NULL to use the default IV.
// `key` must have been configured for encryption. On success, it writes
// `in_len` + 8 bytes to `out` and returns `in_len` + 8. Otherwise, it returns
// -1.
OPENSSL_EXPORT int AES_wrap_key(const AES_KEY *key, const uint8_t *iv,
                                uint8_t *out, const uint8_t *in, size_t in_len);

// AES_unwrap_key performs AES key unwrap on `in` which must be a multiple of 8
// bytes. `iv` must point to an 8 byte value or be NULL to use the default IV.
// `key` must have been configured for decryption. On success, it writes
// `in_len` - 8 bytes to `out` and returns `in_len` - 8. Otherwise, it returns
// -1.
OPENSSL_EXPORT int AES_unwrap_key(const AES_KEY *key, const uint8_t *iv,
                                  uint8_t *out, const uint8_t *in,
                                  size_t in_len);


// AES key wrap with padding.
//
// These functions implement AES Key Wrap with Padding mode, as defined in RFC
// 5649. They should never be used except to interoperate with existing systems
// that use this mode.

// AES_wrap_key_padded performs a padded AES key wrap on `in` which must be
// between 1 and 2^32-1 bytes. `key` must have been configured for encryption.
// On success it writes at most `max_out` bytes of ciphertext to `out`, sets
// `*out_len` to the number of bytes written, and returns one. On failure it
// returns zero. To ensure success, set `max_out` to at least `in_len` + 15.
OPENSSL_EXPORT int AES_wrap_key_padded(const AES_KEY *key, uint8_t *out,
                                       size_t *out_len, size_t max_out,
                                       const uint8_t *in, size_t in_len);

// AES_unwrap_key_padded performs a padded AES key unwrap on `in` which must be
// a multiple of 8 bytes. `key` must have been configured for decryption. On
// success it writes at most `max_out` bytes to `out`, sets `*out_len` to the
// number of bytes written, and returns one. On failure it returns zero. Setting
// `max_out` to `in_len` is a sensible estimate.
OPENSSL_EXPORT int AES_unwrap_key_padded(const AES_KEY *key, uint8_t *out,
                                         size_t *out_len, size_t max_out,
                                         const uint8_t *in, size_t in_len);


#if defined(__cplusplus)
}  // extern C
#endif

#endif  // OPENSSL_HEADER_AES_H