lotus-locus.h 7.99 KB
Newer Older
Rhys Weatherley committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223
/*
 * Copyright (C) 2020 Southern Storm Software, Pty Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#ifndef LWCRYPTO_LOTUS_LOCUS_H
#define LWCRYPTO_LOTUS_LOCUS_H

#include "aead-common.h"

/**
 * \file lotus-locus.h
 * \brief LOTUS-AEAD and LOCUS-AEAD authenticated encryption algorithms.
 *
 * LOTUS-AEAD and LOCUS-AEAD are authenticated encryption algorithms
 * that are based around a tweakable variant of the GIFT-64 block cipher
 * called TweGIFT-64.  Both AEAD algorithms have a 128-bit key, a 128-bit
 * nonce, and a 64-bit tag.
 *
 * The two algorithms have the same key initialization, associated data
 * processing, and tag generation mechanisms.  They differ in how the
 * input is encrypted with TweGIFT-64.
 *
 * LOTUS-AEAD uses a method similar to the block cipher mode OTR.
 * TweGIFT-64 is essentially converted into a 128-bit block cipher
 * using a Feistel construction and four TweGIFT-64 block operations
 * every 16 bytes of input.
 *
 * LOCUS-AEAD uses a method similar to the block cipher mode OCB
 * with two TweGIFT-64 block operations for every 8 bytes of input.
 * LOCUS-AEAD requires both the block encrypt and block decrypt
 * operations of TweGIFT-64, which increases the overall code size.
 * LOTUS-AEAD only needs the block encrypt operation.
 *
 * LOTUS-AEAD is the primary member of the family.
 *
 * References: https://www.isical.ac.in/~lightweight/lotus/
 */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief Size of the key for LOTUS-AEAD.
 */
#define LOTUS_AEAD_KEY_SIZE 16

/**
 * \brief Size of the authentication tag for LOTUS-AEAD.
 */
#define LOTUS_AEAD_TAG_SIZE 8

/**
 * \brief Size of the nonce for LOTUS-AEAD.
 */
#define LOTUS_AEAD_NONCE_SIZE 16

/**
 * \brief Size of the key for LOCUS-AEAD.
 */
#define LOCUS_AEAD_KEY_SIZE 16

/**
 * \brief Size of the authentication tag for LOCUS-AEAD.
 */
#define LOCUS_AEAD_TAG_SIZE 8

/**
 * \brief Size of the nonce for LOCUS-AEAD.
 */
#define LOCUS_AEAD_NONCE_SIZE 16

/**
 * \brief Meta-information block for the LOTUS-AEAD cipher.
 */
extern aead_cipher_t const lotus_aead_cipher;

/**
 * \brief Meta-information block for the LOCUS-AEAD cipher.
 */
extern aead_cipher_t const locus_aead_cipher;

/**
 * \brief Encrypts and authenticates a packet with LOTUS-AEAD.
 *
 * \param c Buffer to receive the output.
 * \param clen On exit, set to the length of the output which includes
 * the ciphertext and the 8 byte authentication tag.
 * \param m Buffer that contains the plaintext message to encrypt.
 * \param mlen Length of the plaintext message in bytes.
 * \param ad Buffer that contains associated data to authenticate
 * along with the packet but which does not need to be encrypted.
 * \param adlen Length of the associated data in bytes.
 * \param nsec Secret nonce - not used by this algorithm.
 * \param npub Points to the public nonce for the packet which must
 * be 16 bytes in length.
 * \param k Points to the 16 bytes of the key to use to encrypt the packet.
 *
 * \return 0 on success, or a negative value if there was an error in
 * the parameters.
 *
 * \sa lotus_aead_decrypt()
 */
int lotus_aead_encrypt
    (unsigned char *c, unsigned long long *clen,
     const unsigned char *m, unsigned long long mlen,
     const unsigned char *ad, unsigned long long adlen,
     const unsigned char *nsec,
     const unsigned char *npub,
     const unsigned char *k);

/**
 * \brief Decrypts and authenticates a packet with LOTUS-AEAD.
 *
 * \param m Buffer to receive the plaintext message on output.
 * \param mlen Receives the length of the plaintext message on output.
 * \param nsec Secret nonce - not used by this algorithm.
 * \param c Buffer that contains the ciphertext and authentication
 * tag to decrypt.
 * \param clen Length of the input data in bytes, which includes the
 * ciphertext and the 9 byte authentication tag.
 * \param ad Buffer that contains associated data to authenticate
 * along with the packet but which does not need to be encrypted.
 * \param adlen Length of the associated data in bytes.
 * \param npub Points to the public nonce for the packet which must
 * be 16 bytes in length.
 * \param k Points to the 16 bytes of the key to use to decrypt the packet.
 *
 * \return 0 on success, -1 if the authentication tag was incorrect,
 * or some other negative number if there was an error in the parameters.
 *
 * \sa lotus_aead_encrypt()
 */
int lotus_aead_decrypt
    (unsigned char *m, unsigned long long *mlen,
     unsigned char *nsec,
     const unsigned char *c, unsigned long long clen,
     const unsigned char *ad, unsigned long long adlen,
     const unsigned char *npub,
     const unsigned char *k);

/**
 * \brief Encrypts and authenticates a packet with LOCUS-AEAD.
 *
 * \param c Buffer to receive the output.
 * \param clen On exit, set to the length of the output which includes
 * the ciphertext and the 8 byte authentication tag.
 * \param m Buffer that contains the plaintext message to encrypt.
 * \param mlen Length of the plaintext message in bytes.
 * \param ad Buffer that contains associated data to authenticate
 * along with the packet but which does not need to be encrypted.
 * \param adlen Length of the associated data in bytes.
 * \param nsec Secret nonce - not used by this algorithm.
 * \param npub Points to the public nonce for the packet which must
 * be 16 bytes in length.
 * \param k Points to the 16 bytes of the key to use to encrypt the packet.
 *
 * \return 0 on success, or a negative value if there was an error in
 * the parameters.
 *
 * \sa locus_aead_decrypt()
 */
int locus_aead_encrypt
    (unsigned char *c, unsigned long long *clen,
     const unsigned char *m, unsigned long long mlen,
     const unsigned char *ad, unsigned long long adlen,
     const unsigned char *nsec,
     const unsigned char *npub,
     const unsigned char *k);

/**
 * \brief Decrypts and authenticates a packet with LOCUS-AEAD.
 *
 * \param m Buffer to receive the plaintext message on output.
 * \param mlen Receives the length of the plaintext message on output.
 * \param nsec Secret nonce - not used by this algorithm.
 * \param c Buffer that contains the ciphertext and authentication
 * tag to decrypt.
 * \param clen Length of the input data in bytes, which includes the
 * ciphertext and the 9 byte authentication tag.
 * \param ad Buffer that contains associated data to authenticate
 * along with the packet but which does not need to be encrypted.
 * \param adlen Length of the associated data in bytes.
 * \param npub Points to the public nonce for the packet which must
 * be 16 bytes in length.
 * \param k Points to the 16 bytes of the key to use to decrypt the packet.
 *
 * \return 0 on success, -1 if the authentication tag was incorrect,
 * or some other negative number if there was an error in the parameters.
 *
 * \sa locus_aead_encrypt()
 */
int locus_aead_decrypt
    (unsigned char *m, unsigned long long *mlen,
     unsigned char *nsec,
     const unsigned char *c, unsigned long long clen,
     const unsigned char *ad, unsigned long long adlen,
     const unsigned char *npub,
     const unsigned char *k);

#ifdef __cplusplus
}
#endif

#endif