Lines Matching defs:EAX
648 as EAX, PMAC and OMAC only require the encryption function. So far this \textit{encrypt only} functionality has only been implemented for
1158 \subsection{EAX Mode}
1159 LibTomCrypt provides support for a mode called EAX\footnote{See
1161 by the designers. First, a short description of what EAX mode is before we explain how to use it. EAX is a mode that requires a cipher,
1163 authentication\footnote{Note that since EAX only requires OMAC and CTR you may use \textit{encrypt only} cipher descriptors with this mode.}.
1167 be added at anytime during an EAX stream, and is part of the authentication tag. That is, changes in the meta-data can be detected by changes in the output tag.
1171 sized message block to send to the recipient as ciphertext. This makes the EAX mode especially suited for streaming modes
1175 \index{eax\_init()}
1177 int eax_init( eax_state *eax,
1187 Where \textit{eax} is the EAX state. The \textit{cipher} parameter is the index of the desired cipher in the descriptor table.
1192 When this function completes, the \textit{eax} state will be initialized such that you can now either have data decrypted or
1193 encrypted in EAX mode. Note: if \textit{headerlen} is zero you may pass \textit{header} as \textbf{NULL} to indicate there is no initial header data.
1196 \index{eax\_encrypt()} \index{eax\_decrypt()}
1198 int eax_encrypt( eax_state *eax,
1203 int eax_decrypt( eax_state *eax,
1208 The function \textit{eax\_encrypt} will encrypt the bytes in \textit{pt} of \textit{length} octets, and store the ciphertext in
1210 through the OMAC function. The function \textit{eax\_decrypt} decrypts \textit{ct}, and stores it in \textit{pt}. This also allows
1213 You cannot both encrypt or decrypt with the same \textit{eax} context. For bi--directional communication you will need to initialize
1214 two EAX contexts (preferably with different headers and nonces).
1217 the eax\_init() function allows you to add initial header data to the stream you can also add header data during the
1218 EAX stream with the following.
1220 \index{eax\_addheader()}
1222 int eax_addheader( eax_state *eax,
1226 This will add the \textit{length} octet from \textit{header} to the given \textit{eax} header. Once the message is finished, the
1229 \index{eax\_done()}
1231 int eax_done( eax_state *eax,
1235 This will terminate the EAX state \textit{eax}, and store up to \textit{taglen} bytes of the message tag in \textit{tag}. The function
1238 The EAX mode code can be tested to ensure it matches the test vectors by calling the following function:
1239 \index{eax\_test()}
1250 eax_state eax;
1262 if ((err = eax_init( &eax, /* context */
1274 if ((err = eax_encrypt( &eax, /* eax context */
1285 if ((err = eax_done( &eax, /* eax context */
1298 You can also perform an entire EAX state on a block of memory in a single function call with the
1302 \index{eax\_encrypt\_authenticate\_memory} \index{eax\_decrypt\_verify\_memory}
1324 Both essentially just call eax\_init() followed by eax\_encrypt() (or eax\_decrypt() respectively) and eax\_done(). The parameters
1327 The only difference is eax\_decrypt\_verify\_memory() does not emit a tag. Instead you pass it a tag as input and it compares it against
1333 . OCB is an encryption protocol that simultaneously provides authentication. It is slightly faster to use than EAX mode
1349 This mode has no \textit{Associated Data} like EAX mode does which means you cannot authenticate metadata along with the stream.
1439 EAX and OCB mode,
1542 Galois counter mode is an IEEE proposal for authenticated encryption (also it is a planned NIST standard). Like EAX and OCB mode, it can be used in a streaming capacity
1543 however, unlike EAX it cannot accept \textit{additional authentication data} (meta--data) after plaintext has been processed. This mode also only works with
