1 | /**
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2 | * \file chacha20.h
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3 | *
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4 | * \brief This file contains ChaCha20 definitions and functions.
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5 | *
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6 | * ChaCha20 is a stream cipher that can encrypt and decrypt
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7 | * information. ChaCha was created by Daniel Bernstein as a variant of
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8 | * its Salsa cipher https://cr.yp.to/chacha/chacha-20080128.pdf
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9 | * ChaCha20 is the variant with 20 rounds, that was also standardized
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10 | * in RFC 7539.
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11 | *
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12 | * \author Daniel King <damaki.gh@gmail.com>
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13 | */
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14 |
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15 | /* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved.
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16 | * SPDX-License-Identifier: Apache-2.0
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17 | *
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18 | * Licensed under the Apache License, Version 2.0 (the "License"); you may
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19 | * not use this file except in compliance with the License.
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20 | * You may obtain a copy of the License at
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21 | *
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22 | * http://www.apache.org/licenses/LICENSE-2.0
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23 | *
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24 | * Unless required by applicable law or agreed to in writing, software
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25 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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26 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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27 | * See the License for the specific language governing permissions and
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28 | * limitations under the License.
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29 | *
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30 | * This file is part of Mbed TLS (https://tls.mbed.org)
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31 | */
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32 |
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33 | #ifndef MBEDTLS_CHACHA20_H
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34 | #define MBEDTLS_CHACHA20_H
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35 |
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36 | #if !defined(MBEDTLS_CONFIG_FILE)
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37 | #include "config.h"
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38 | #else
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39 | #include MBEDTLS_CONFIG_FILE
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40 | #endif
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41 |
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42 | #include <stdint.h>
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43 | #include <stddef.h>
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44 |
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45 | #define MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA -0x0051 /**< Invalid input parameter(s). */
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46 |
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47 | /* MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE is deprecated and should not be
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48 | * used. */
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49 | #define MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE -0x0053 /**< Feature not available. For example, s part of the API is not implemented. */
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50 |
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51 | /* MBEDTLS_ERR_CHACHA20_HW_ACCEL_FAILED is deprecated and should not be used.
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52 | */
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53 | #define MBEDTLS_ERR_CHACHA20_HW_ACCEL_FAILED -0x0055 /**< Chacha20 hardware accelerator failed. */
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54 |
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55 | #ifdef __cplusplus
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56 | extern "C" {
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57 | #endif
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58 |
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59 | #if !defined(MBEDTLS_CHACHA20_ALT)
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60 |
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61 | typedef struct mbedtls_chacha20_context
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62 | {
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63 | uint32_t state[16]; /*! The state (before round operations). */
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64 | uint8_t keystream8[64]; /*! Leftover keystream bytes. */
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65 | size_t keystream_bytes_used; /*! Number of keystream bytes already used. */
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66 | }
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67 | mbedtls_chacha20_context;
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68 |
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69 | #else /* MBEDTLS_CHACHA20_ALT */
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70 | #include "chacha20_alt.h"
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71 | #endif /* MBEDTLS_CHACHA20_ALT */
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72 |
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73 | /**
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74 | * \brief This function initializes the specified ChaCha20 context.
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75 | *
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76 | * It must be the first API called before using
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77 | * the context.
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78 | *
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79 | * It is usually followed by calls to
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80 | * \c mbedtls_chacha20_setkey() and
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81 | * \c mbedtls_chacha20_starts(), then one or more calls to
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82 | * to \c mbedtls_chacha20_update(), and finally to
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83 | * \c mbedtls_chacha20_free().
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84 | *
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85 | * \param ctx The ChaCha20 context to initialize.
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86 | * This must not be \c NULL.
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87 | */
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88 | void mbedtls_chacha20_init( mbedtls_chacha20_context *ctx );
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89 |
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90 | /**
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91 | * \brief This function releases and clears the specified
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92 | * ChaCha20 context.
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93 | *
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94 | * \param ctx The ChaCha20 context to clear. This may be \c NULL,
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95 | * in which case this function is a no-op. If it is not
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96 | * \c NULL, it must point to an initialized context.
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97 | *
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98 | */
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99 | void mbedtls_chacha20_free( mbedtls_chacha20_context *ctx );
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100 |
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101 | /**
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102 | * \brief This function sets the encryption/decryption key.
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103 | *
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104 | * \note After using this function, you must also call
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105 | * \c mbedtls_chacha20_starts() to set a nonce before you
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106 | * start encrypting/decrypting data with
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107 | * \c mbedtls_chacha_update().
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108 | *
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109 | * \param ctx The ChaCha20 context to which the key should be bound.
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110 | * It must be initialized.
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111 | * \param key The encryption/decryption key. This must be \c 32 Bytes
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112 | * in length.
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113 | *
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114 | * \return \c 0 on success.
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115 | * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if ctx or key is NULL.
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116 | */
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117 | int mbedtls_chacha20_setkey( mbedtls_chacha20_context *ctx,
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118 | const unsigned char key[32] );
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119 |
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120 | /**
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121 | * \brief This function sets the nonce and initial counter value.
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122 | *
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123 | * \note A ChaCha20 context can be re-used with the same key by
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124 | * calling this function to change the nonce.
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125 | *
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126 | * \warning You must never use the same nonce twice with the same key.
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127 | * This would void any confidentiality guarantees for the
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128 | * messages encrypted with the same nonce and key.
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129 | *
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130 | * \param ctx The ChaCha20 context to which the nonce should be bound.
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131 | * It must be initialized and bound to a key.
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132 | * \param nonce The nonce. This must be \c 12 Bytes in size.
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133 | * \param counter The initial counter value. This is usually \c 0.
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134 | *
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135 | * \return \c 0 on success.
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136 | * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if ctx or nonce is
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137 | * NULL.
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138 | */
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139 | int mbedtls_chacha20_starts( mbedtls_chacha20_context* ctx,
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140 | const unsigned char nonce[12],
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141 | uint32_t counter );
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142 |
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143 | /**
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144 | * \brief This function encrypts or decrypts data.
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145 | *
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146 | * Since ChaCha20 is a stream cipher, the same operation is
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147 | * used for encrypting and decrypting data.
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148 | *
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149 | * \note The \p input and \p output pointers must either be equal or
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150 | * point to non-overlapping buffers.
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151 | *
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152 | * \note \c mbedtls_chacha20_setkey() and
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153 | * \c mbedtls_chacha20_starts() must be called at least once
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154 | * to setup the context before this function can be called.
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155 | *
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156 | * \note This function can be called multiple times in a row in
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157 | * order to encrypt of decrypt data piecewise with the same
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158 | * key and nonce.
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159 | *
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160 | * \param ctx The ChaCha20 context to use for encryption or decryption.
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161 | * It must be initialized and bound to a key and nonce.
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162 | * \param size The length of the input data in Bytes.
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163 | * \param input The buffer holding the input data.
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164 | * This pointer can be \c NULL if `size == 0`.
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165 | * \param output The buffer holding the output data.
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166 | * This must be able to hold \p size Bytes.
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167 | * This pointer can be \c NULL if `size == 0`.
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168 | *
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169 | * \return \c 0 on success.
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170 | * \return A negative error code on failure.
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171 | */
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172 | int mbedtls_chacha20_update( mbedtls_chacha20_context *ctx,
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173 | size_t size,
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174 | const unsigned char *input,
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175 | unsigned char *output );
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176 |
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177 | /**
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178 | * \brief This function encrypts or decrypts data with ChaCha20 and
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179 | * the given key and nonce.
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180 | *
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181 | * Since ChaCha20 is a stream cipher, the same operation is
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182 | * used for encrypting and decrypting data.
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183 | *
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184 | * \warning You must never use the same (key, nonce) pair more than
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185 | * once. This would void any confidentiality guarantees for
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186 | * the messages encrypted with the same nonce and key.
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187 | *
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188 | * \note The \p input and \p output pointers must either be equal or
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189 | * point to non-overlapping buffers.
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190 | *
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191 | * \param key The encryption/decryption key.
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192 | * This must be \c 32 Bytes in length.
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193 | * \param nonce The nonce. This must be \c 12 Bytes in size.
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194 | * \param counter The initial counter value. This is usually \c 0.
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195 | * \param size The length of the input data in Bytes.
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196 | * \param input The buffer holding the input data.
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197 | * This pointer can be \c NULL if `size == 0`.
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198 | * \param output The buffer holding the output data.
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199 | * This must be able to hold \p size Bytes.
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200 | * This pointer can be \c NULL if `size == 0`.
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201 | *
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202 | * \return \c 0 on success.
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203 | * \return A negative error code on failure.
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204 | */
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205 | int mbedtls_chacha20_crypt( const unsigned char key[32],
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206 | const unsigned char nonce[12],
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207 | uint32_t counter,
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208 | size_t size,
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209 | const unsigned char* input,
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210 | unsigned char* output );
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211 |
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212 | #if defined(MBEDTLS_SELF_TEST)
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213 | /**
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214 | * \brief The ChaCha20 checkup routine.
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215 | *
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216 | * \return \c 0 on success.
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217 | * \return \c 1 on failure.
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218 | */
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219 | int mbedtls_chacha20_self_test( int verbose );
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220 | #endif /* MBEDTLS_SELF_TEST */
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221 |
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222 | #ifdef __cplusplus
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223 | }
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224 | #endif
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225 |
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226 | #endif /* MBEDTLS_CHACHA20_H */
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