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[dragonfly.git] / secure / lib / libcrypto / man / EVP_EncryptInit.3
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129.\" ========================================================================
130.\"
131.IX Title "EVP_EncryptInit 3"
aac4ff6f 132.TH EVP_EncryptInit 3 "2008-09-06" "0.9.8h" "OpenSSL"
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133.SH "NAME"
134EVP_CIPHER_CTX_init, EVP_EncryptInit_ex, EVP_EncryptUpdate,
135EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate,
136EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate,
137EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length,
138EVP_CIPHER_CTX_ctrl, EVP_CIPHER_CTX_cleanup, EVP_EncryptInit,
139EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal,
140EVP_CipherInit, EVP_CipherFinal, EVP_get_cipherbyname,
141EVP_get_cipherbynid, EVP_get_cipherbyobj, EVP_CIPHER_nid,
142EVP_CIPHER_block_size, EVP_CIPHER_key_length, EVP_CIPHER_iv_length,
143EVP_CIPHER_flags, EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher,
144EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length,
145EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data,
146EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags,
147EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param,
74dab6c2 148EVP_CIPHER_CTX_set_padding \- EVP cipher routines
984263bc 149.SH "SYNOPSIS"
8b0cefbb 150.IX Header "SYNOPSIS"
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151.Vb 1
152\& #include <openssl/evp.h>
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153.Ve
154.PP
155.Vb 1
a561f9ff 156\& void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
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157.Ve
158.PP
159.Vb 6
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160\& int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
161\& ENGINE *impl, unsigned char *key, unsigned char *iv);
162\& int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
163\& int *outl, unsigned char *in, int inl);
164\& int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out,
165\& int *outl);
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166.Ve
167.PP
168.Vb 6
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169\& int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
170\& ENGINE *impl, unsigned char *key, unsigned char *iv);
171\& int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
172\& int *outl, unsigned char *in, int inl);
173\& int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
174\& int *outl);
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175.Ve
176.PP
177.Vb 6
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178\& int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
179\& ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
180\& int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
181\& int *outl, unsigned char *in, int inl);
182\& int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
183\& int *outl);
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184.Ve
185.PP
186.Vb 4
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187\& int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
188\& unsigned char *key, unsigned char *iv);
189\& int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
190\& int *outl);
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191.Ve
192.PP
193.Vb 4
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194\& int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
195\& unsigned char *key, unsigned char *iv);
196\& int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
197\& int *outl);
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198.Ve
199.PP
200.Vb 4
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201\& int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
202\& unsigned char *key, unsigned char *iv, int enc);
203\& int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
204\& int *outl);
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205.Ve
206.PP
207.Vb 4
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208\& int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
209\& int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
210\& int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
211\& int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
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212.Ve
213.PP
214.Vb 3
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215\& const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
216\& #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
217\& #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
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218.Ve
219.PP
220.Vb 7
221\& #define EVP_CIPHER_nid(e) ((e)->nid)
222\& #define EVP_CIPHER_block_size(e) ((e)->block_size)
223\& #define EVP_CIPHER_key_length(e) ((e)->key_len)
224\& #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
225\& #define EVP_CIPHER_flags(e) ((e)->flags)
226\& #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
984263bc 227\& int EVP_CIPHER_type(const EVP_CIPHER *ctx);
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228.Ve
229.PP
230.Vb 10
231\& #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
232\& #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
233\& #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
234\& #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len)
235\& #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
236\& #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
237\& #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
984263bc 238\& #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
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239\& #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags)
240\& #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE)
241.Ve
242.PP
243.Vb 2
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244\& int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
245\& int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
246.Ve
247.SH "DESCRIPTION"
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248.IX Header "DESCRIPTION"
249The \s-1EVP\s0 cipher routines are a high level interface to certain
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250symmetric ciphers.
251.PP
8b0cefbb 252\&\fIEVP_CIPHER_CTX_init()\fR initializes cipher contex \fBctx\fR.
984263bc 253.PP
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254\&\fIEVP_EncryptInit_ex()\fR sets up cipher context \fBctx\fR for encryption
255with cipher \fBtype\fR from \s-1ENGINE\s0 \fBimpl\fR. \fBctx\fR must be initialized
984263bc 256before calling this function. \fBtype\fR is normally supplied
8b0cefbb 257by a function such as \fIEVP_des_cbc()\fR. If \fBimpl\fR is \s-1NULL\s0 then the
984263bc 258default implementation is used. \fBkey\fR is the symmetric key to use
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259and \fBiv\fR is the \s-1IV\s0 to use (if necessary), the actual number of bytes
260used for the key and \s-1IV\s0 depends on the cipher. It is possible to set
261all parameters to \s-1NULL\s0 except \fBtype\fR in an initial call and supply
984263bc 262the remaining parameters in subsequent calls, all of which have \fBtype\fR
8b0cefbb 263set to \s-1NULL\s0. This is done when the default cipher parameters are not
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264appropriate.
265.PP
8b0cefbb 266\&\fIEVP_EncryptUpdate()\fR encrypts \fBinl\fR bytes from the buffer \fBin\fR and
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267writes the encrypted version to \fBout\fR. This function can be called
268multiple times to encrypt successive blocks of data. The amount
269of data written depends on the block alignment of the encrypted data:
270as a result the amount of data written may be anything from zero bytes
271to (inl + cipher_block_size \- 1) so \fBoutl\fR should contain sufficient
272room. The actual number of bytes written is placed in \fBoutl\fR.
273.PP
274If padding is enabled (the default) then \fIEVP_EncryptFinal_ex()\fR encrypts
275the \*(L"final\*(R" data, that is any data that remains in a partial block.
8b0cefbb 276It uses standard block padding (aka \s-1PKCS\s0 padding). The encrypted
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277final data is written to \fBout\fR which should have sufficient space for
278one cipher block. The number of bytes written is placed in \fBoutl\fR. After
279this function is called the encryption operation is finished and no further
280calls to \fIEVP_EncryptUpdate()\fR should be made.
281.PP
282If padding is disabled then \fIEVP_EncryptFinal_ex()\fR will not encrypt any more
283data and it will return an error if any data remains in a partial block:
aac4ff6f 284that is if the total data length is not a multiple of the block size.
984263bc 285.PP
8b0cefbb 286\&\fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptUpdate()\fR and \fIEVP_DecryptFinal_ex()\fR are the
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287corresponding decryption operations. \fIEVP_DecryptFinal()\fR will return an
288error code if padding is enabled and the final block is not correctly
289formatted. The parameters and restrictions are identical to the encryption
290operations except that if padding is enabled the decrypted data buffer \fBout\fR
291passed to \fIEVP_DecryptUpdate()\fR should have sufficient room for
292(\fBinl\fR + cipher_block_size) bytes unless the cipher block size is 1 in
293which case \fBinl\fR bytes is sufficient.
294.PP
8b0cefbb 295\&\fIEVP_CipherInit_ex()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal_ex()\fR are
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296functions that can be used for decryption or encryption. The operation
297performed depends on the value of the \fBenc\fR parameter. It should be set
298to 1 for encryption, 0 for decryption and \-1 to leave the value unchanged
8b0cefbb 299(the actual value of 'enc' being supplied in a previous call).
984263bc 300.PP
8b0cefbb 301\&\fIEVP_CIPHER_CTX_cleanup()\fR clears all information from a cipher context
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302and free up any allocated memory associate with it. It should be called
303after all operations using a cipher are complete so sensitive information
304does not remain in memory.
305.PP
8b0cefbb 306\&\fIEVP_EncryptInit()\fR, \fIEVP_DecryptInit()\fR and \fIEVP_CipherInit()\fR behave in a
984263bc 307similar way to \fIEVP_EncryptInit_ex()\fR, EVP_DecryptInit_ex and
8b0cefbb 308\&\fIEVP_CipherInit_ex()\fR except the \fBctx\fR paramter does not need to be
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309initialized and they always use the default cipher implementation.
310.PP
8b0cefbb 311\&\fIEVP_EncryptFinal()\fR, \fIEVP_DecryptFinal()\fR and \fIEVP_CipherFinal()\fR behave in a
984263bc 312similar way to \fIEVP_EncryptFinal_ex()\fR, \fIEVP_DecryptFinal_ex()\fR and
8b0cefbb 313\&\fIEVP_CipherFinal_ex()\fR except \fBctx\fR is automatically cleaned up
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314after the call.
315.PP
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316\&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
317return an \s-1EVP_CIPHER\s0 structure when passed a cipher name, a \s-1NID\s0 or an
318\&\s-1ASN1_OBJECT\s0 structure.
984263bc 319.PP
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320\&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return the \s-1NID\s0 of a cipher when
321passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR structure. The actual \s-1NID\s0
322value is an internal value which may not have a corresponding \s-1OBJECT\s0
323\&\s-1IDENTIFIER\s0.
984263bc 324.PP
8b0cefbb 325\&\fIEVP_CIPHER_CTX_set_padding()\fR enables or disables padding. By default
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326encryption operations are padded using standard block padding and the
327padding is checked and removed when decrypting. If the \fBpad\fR parameter
328is zero then no padding is performed, the total amount of data encrypted
329or decrypted must then be a multiple of the block size or an error will
330occur.
331.PP
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332\&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
333length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
334structure. The constant \fB\s-1EVP_MAX_KEY_LENGTH\s0\fR is the maximum key length
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335for all ciphers. Note: although \fIEVP_CIPHER_key_length()\fR is fixed for a
336given cipher, the value of \fIEVP_CIPHER_CTX_key_length()\fR may be different
337for variable key length ciphers.
338.PP
8b0cefbb 339\&\fIEVP_CIPHER_CTX_set_key_length()\fR sets the key length of the cipher ctx.
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340If the cipher is a fixed length cipher then attempting to set the key
341length to any value other than the fixed value is an error.
342.PP
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343\&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
344length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR.
345It will return zero if the cipher does not use an \s-1IV\s0. The constant
346\&\fB\s-1EVP_MAX_IV_LENGTH\s0\fR is the maximum \s-1IV\s0 length for all ciphers.
984263bc 347.PP
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348\&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
349size of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
350structure. The constant \fB\s-1EVP_MAX_IV_LENGTH\s0\fR is also the maximum block
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351length for all ciphers.
352.PP
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353\&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the type of the passed
354cipher or context. This \*(L"type\*(R" is the actual \s-1NID\s0 of the cipher \s-1OBJECT\s0
355\&\s-1IDENTIFIER\s0 as such it ignores the cipher parameters and 40 bit \s-1RC2\s0 and
356128 bit \s-1RC2\s0 have the same \s-1NID\s0. If the cipher does not have an object
357identifier or does not have \s-1ASN1\s0 support this function will return
358\&\fBNID_undef\fR.
984263bc 359.PP
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360\&\fIEVP_CIPHER_CTX_cipher()\fR returns the \fB\s-1EVP_CIPHER\s0\fR structure when passed
361an \fB\s-1EVP_CIPHER_CTX\s0\fR structure.
984263bc 362.PP
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363\&\fIEVP_CIPHER_mode()\fR and \fIEVP_CIPHER_CTX_mode()\fR return the block cipher mode:
364\&\s-1EVP_CIPH_ECB_MODE\s0, \s-1EVP_CIPH_CBC_MODE\s0, \s-1EVP_CIPH_CFB_MODE\s0 or
365\&\s-1EVP_CIPH_OFB_MODE\s0. If the cipher is a stream cipher then
366\&\s-1EVP_CIPH_STREAM_CIPHER\s0 is returned.
984263bc 367.PP
8b0cefbb 368\&\fIEVP_CIPHER_param_to_asn1()\fR sets the AlgorithmIdentifier \*(L"parameter\*(R" based
984263bc 369on the passed cipher. This will typically include any parameters and an
8b0cefbb 370\&\s-1IV\s0. The cipher \s-1IV\s0 (if any) must be set when this call is made. This call
984263bc 371should be made before the cipher is actually \*(L"used\*(R" (before any
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372\&\fIEVP_EncryptUpdate()\fR, \fIEVP_DecryptUpdate()\fR calls for example). This function
373may fail if the cipher does not have any \s-1ASN1\s0 support.
984263bc 374.PP
8b0cefbb 375\&\fIEVP_CIPHER_asn1_to_param()\fR sets the cipher parameters based on an \s-1ASN1\s0
984263bc 376AlgorithmIdentifier \*(L"parameter\*(R". The precise effect depends on the cipher
8b0cefbb 377In the case of \s-1RC2\s0, for example, it will set the \s-1IV\s0 and effective key length.
984263bc 378This function should be called after the base cipher type is set but before
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379the key is set. For example \fIEVP_CipherInit()\fR will be called with the \s-1IV\s0 and
380key set to \s-1NULL\s0, \fIEVP_CIPHER_asn1_to_param()\fR will be called and finally
381\&\fIEVP_CipherInit()\fR again with all parameters except the key set to \s-1NULL\s0. It is
382possible for this function to fail if the cipher does not have any \s-1ASN1\s0 support
383or the parameters cannot be set (for example the \s-1RC2\s0 effective key length
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384is not supported.
385.PP
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386\&\fIEVP_CIPHER_CTX_ctrl()\fR allows various cipher specific parameters to be determined
387and set. Currently only the \s-1RC2\s0 effective key length and the number of rounds of
388\&\s-1RC5\s0 can be set.
984263bc 389.SH "RETURN VALUES"
8b0cefbb 390.IX Header "RETURN VALUES"
a561f9ff
SS
391\&\fIEVP_EncryptInit_ex()\fR, \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal_ex()\fR
392return 1 for success and 0 for failure.
984263bc 393.PP
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394\&\fIEVP_DecryptInit_ex()\fR and \fIEVP_DecryptUpdate()\fR return 1 for success and 0 for failure.
395\&\fIEVP_DecryptFinal_ex()\fR returns 0 if the decrypt failed or 1 for success.
984263bc 396.PP
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397\&\fIEVP_CipherInit_ex()\fR and \fIEVP_CipherUpdate()\fR return 1 for success and 0 for failure.
398\&\fIEVP_CipherFinal_ex()\fR returns 0 for a decryption failure or 1 for success.
984263bc 399.PP
8b0cefbb 400\&\fIEVP_CIPHER_CTX_cleanup()\fR returns 1 for success and 0 for failure.
984263bc 401.PP
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402\&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
403return an \fB\s-1EVP_CIPHER\s0\fR structure or \s-1NULL\s0 on error.
984263bc 404.PP
8b0cefbb 405\&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return a \s-1NID\s0.
984263bc 406.PP
8b0cefbb 407\&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
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408size.
409.PP
8b0cefbb 410\&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
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411length.
412.PP
8b0cefbb 413\&\fIEVP_CIPHER_CTX_set_padding()\fR always returns 1.
984263bc 414.PP
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415\&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
416length or zero if the cipher does not use an \s-1IV\s0.
984263bc 417.PP
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418\&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the \s-1NID\s0 of the cipher's
419\&\s-1OBJECT\s0 \s-1IDENTIFIER\s0 or NID_undef if it has no defined \s-1OBJECT\s0 \s-1IDENTIFIER\s0.
984263bc 420.PP
8b0cefbb 421\&\fIEVP_CIPHER_CTX_cipher()\fR returns an \fB\s-1EVP_CIPHER\s0\fR structure.
984263bc 422.PP
8b0cefbb 423\&\fIEVP_CIPHER_param_to_asn1()\fR and \fIEVP_CIPHER_asn1_to_param()\fR return 1 for
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424success or zero for failure.
425.SH "CIPHER LISTING"
8b0cefbb 426.IX Header "CIPHER LISTING"
984263bc 427All algorithms have a fixed key length unless otherwise stated.
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JR
428.IP "\fIEVP_enc_null()\fR" 4
429.IX Item "EVP_enc_null()"
984263bc 430Null cipher: does nothing.
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431.IP "EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)" 4
432.IX Item "EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)"
aac4ff6f 433\&\s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
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434.IP "EVP_des_ede_cbc(void), \fIEVP_des_ede()\fR, EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)" 4
435.IX Item "EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)"
984263bc 436Two key triple \s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
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437.IP "EVP_des_ede3_cbc(void), \fIEVP_des_ede3()\fR, EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)" 4
438.IX Item "EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)"
984263bc 439Three key triple \s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
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440.IP "EVP_desx_cbc(void)" 4
441.IX Item "EVP_desx_cbc(void)"
442\&\s-1DESX\s0 algorithm in \s-1CBC\s0 mode.
443.IP "EVP_rc4(void)" 4
444.IX Item "EVP_rc4(void)"
445\&\s-1RC4\s0 stream cipher. This is a variable key length cipher with default key length 128 bits.
446.IP "EVP_rc4_40(void)" 4
447.IX Item "EVP_rc4_40(void)"
448\&\s-1RC4\s0 stream cipher with 40 bit key length. This is obsolete and new code should use \fIEVP_rc4()\fR
984263bc 449and the \fIEVP_CIPHER_CTX_set_key_length()\fR function.
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450.IP "\fIEVP_idea_cbc()\fR EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)" 4
451.IX Item "EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)"
452\&\s-1IDEA\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
453.IP "EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)" 4
454.IX Item "EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)"
455\&\s-1RC2\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
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456length cipher with an additional parameter called \*(L"effective key bits\*(R" or \*(L"effective key length\*(R".
457By default both are set to 128 bits.
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458.IP "EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)" 4
459.IX Item "EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)"
460\&\s-1RC2\s0 algorithm in \s-1CBC\s0 mode with a default key length and effective key length of 40 and 64 bits.
984263bc 461These are obsolete and new code should use \fIEVP_rc2_cbc()\fR, \fIEVP_CIPHER_CTX_set_key_length()\fR and
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462\&\fIEVP_CIPHER_CTX_ctrl()\fR to set the key length and effective key length.
463.IP "EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);" 4
464.IX Item "EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);"
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465Blowfish encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
466length cipher.
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467.IP "EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)" 4
468.IX Item "EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)"
469\&\s-1CAST\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
984263bc 470length cipher.
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471.IP "EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)" 4
472.IX Item "EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)"
473\&\s-1RC5\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key length
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474cipher with an additional \*(L"number of rounds\*(R" parameter. By default the key length is set to 128
475bits and 12 rounds.
476.SH "NOTES"
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477.IX Header "NOTES"
478Where possible the \fB\s-1EVP\s0\fR interface to symmetric ciphers should be used in
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479preference to the low level interfaces. This is because the code then becomes
480transparent to the cipher used and much more flexible.
481.PP
8b0cefbb 482\&\s-1PKCS\s0 padding works by adding \fBn\fR padding bytes of value \fBn\fR to make the total
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483length of the encrypted data a multiple of the block size. Padding is always
484added so if the data is already a multiple of the block size \fBn\fR will equal
485the block size. For example if the block size is 8 and 11 bytes are to be
486encrypted then 5 padding bytes of value 5 will be added.
487.PP
488When decrypting the final block is checked to see if it has the correct form.
489.PP
490Although the decryption operation can produce an error if padding is enabled,
491it is not a strong test that the input data or key is correct. A random block
492has better than 1 in 256 chance of being of the correct format and problems with
493the input data earlier on will not produce a final decrypt error.
494.PP
495If padding is disabled then the decryption operation will always succeed if
496the total amount of data decrypted is a multiple of the block size.
497.PP
498The functions \fIEVP_EncryptInit()\fR, \fIEVP_EncryptFinal()\fR, \fIEVP_DecryptInit()\fR,
8b0cefbb 499\&\fIEVP_CipherInit()\fR and \fIEVP_CipherFinal()\fR are obsolete but are retained for
984263bc 500compatibility with existing code. New code should use \fIEVP_EncryptInit_ex()\fR,
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501\&\fIEVP_EncryptFinal_ex()\fR, \fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptFinal_ex()\fR,
502\&\fIEVP_CipherInit_ex()\fR and \fIEVP_CipherFinal_ex()\fR because they can reuse an
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503existing context without allocating and freeing it up on each call.
504.SH "BUGS"
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JR
505.IX Header "BUGS"
506For \s-1RC5\s0 the number of rounds can currently only be set to 8, 12 or 16. This is
507a limitation of the current \s-1RC5\s0 code rather than the \s-1EVP\s0 interface.
984263bc 508.PP
8b0cefbb 509\&\s-1EVP_MAX_KEY_LENGTH\s0 and \s-1EVP_MAX_IV_LENGTH\s0 only refer to the internal ciphers with
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510default key lengths. If custom ciphers exceed these values the results are
511unpredictable. This is because it has become standard practice to define a
8b0cefbb 512generic key as a fixed unsigned char array containing \s-1EVP_MAX_KEY_LENGTH\s0 bytes.
984263bc 513.PP
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514The \s-1ASN1\s0 code is incomplete (and sometimes inaccurate) it has only been tested
515for certain common S/MIME ciphers (\s-1RC2\s0, \s-1DES\s0, triple \s-1DES\s0) in \s-1CBC\s0 mode.
984263bc 516.SH "EXAMPLES"
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517.IX Header "EXAMPLES"
518Get the number of rounds used in \s-1RC5:\s0
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519.PP
520.Vb 2
521\& int nrounds;
522\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &nrounds);
523.Ve
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524.PP
525Get the \s-1RC2\s0 effective key length:
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526.PP
527.Vb 2
528\& int key_bits;
529\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &key_bits);
530.Ve
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531.PP
532Set the number of rounds used in \s-1RC5:\s0
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533.PP
534.Vb 2
535\& int nrounds;
536\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, nrounds, NULL);
537.Ve
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538.PP
539Set the effective key length used in \s-1RC2:\s0
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MD
540.PP
541.Vb 2
542\& int key_bits;
543\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, key_bits, NULL);
544.Ve
8b0cefbb 545.PP
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546Encrypt a string using blowfish:
547.PP
aac4ff6f 548.Vb 14
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549\& int do_crypt(char *outfile)
550\& {
551\& unsigned char outbuf[1024];
552\& int outlen, tmplen;
553\& /* Bogus key and IV: we'd normally set these from
554\& * another source.
555\& */
556\& unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
557\& unsigned char iv[] = {1,2,3,4,5,6,7,8};
558\& char intext[] = "Some Crypto Text";
559\& EVP_CIPHER_CTX ctx;
560\& FILE *out;
561\& EVP_CIPHER_CTX_init(&ctx);
562\& EVP_EncryptInit_ex(&ctx, EVP_bf_cbc(), NULL, key, iv);
aac4ff6f
PA
563.Ve
564.PP
565.Vb 25
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566\& if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext)))
567\& {
568\& /* Error */
569\& return 0;
570\& }
571\& /* Buffer passed to EVP_EncryptFinal() must be after data just
572\& * encrypted to avoid overwriting it.
573\& */
574\& if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen))
575\& {
576\& /* Error */
577\& return 0;
578\& }
579\& outlen += tmplen;
580\& EVP_CIPHER_CTX_cleanup(&ctx);
581\& /* Need binary mode for fopen because encrypted data is
582\& * binary data. Also cannot use strlen() on it because
583\& * it wont be null terminated and may contain embedded
584\& * nulls.
585\& */
586\& out = fopen(outfile, "wb");
587\& fwrite(outbuf, 1, outlen, out);
588\& fclose(out);
589\& return 1;
590\& }
591.Ve
8b0cefbb 592.PP
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593The ciphertext from the above example can be decrypted using the \fBopenssl\fR
594utility with the command line:
595.PP
8b0cefbb 596.Vb 1
aac4ff6f 597\& S<openssl bf -in cipher.bin -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 -d>
8b0cefbb
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598.Ve
599.PP
600General encryption, decryption function example using \s-1FILE\s0 I/O and \s-1RC2\s0 with an
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60180 bit key:
602.PP
aac4ff6f 603.Vb 16
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604\& int do_crypt(FILE *in, FILE *out, int do_encrypt)
605\& {
606\& /* Allow enough space in output buffer for additional block */
607\& inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
608\& int inlen, outlen;
609\& /* Bogus key and IV: we'd normally set these from
610\& * another source.
611\& */
612\& unsigned char key[] = "0123456789";
613\& unsigned char iv[] = "12345678";
614\& /* Don't set key or IV because we will modify the parameters */
615\& EVP_CIPHER_CTX_init(&ctx);
616\& EVP_CipherInit_ex(&ctx, EVP_rc2(), NULL, NULL, NULL, do_encrypt);
617\& EVP_CIPHER_CTX_set_key_length(&ctx, 10);
618\& /* We finished modifying parameters so now we can set key and IV */
619\& EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
aac4ff6f
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620.Ve
621.PP
622.Vb 19
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623\& for(;;)
624\& {
625\& inlen = fread(inbuf, 1, 1024, in);
626\& if(inlen <= 0) break;
627\& if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen))
628\& {
629\& /* Error */
a561f9ff 630\& EVP_CIPHER_CTX_cleanup(&ctx);
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631\& return 0;
632\& }
633\& fwrite(outbuf, 1, outlen, out);
634\& }
635\& if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen))
636\& {
637\& /* Error */
a561f9ff 638\& EVP_CIPHER_CTX_cleanup(&ctx);
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639\& return 0;
640\& }
641\& fwrite(outbuf, 1, outlen, out);
aac4ff6f
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642.Ve
643.PP
644.Vb 3
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645\& EVP_CIPHER_CTX_cleanup(&ctx);
646\& return 1;
647\& }
648.Ve
649.SH "SEE ALSO"
74dab6c2 650.IX Header "SEE ALSO"
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651\&\fIevp\fR\|(3)
652.SH "HISTORY"
74dab6c2 653.IX Header "HISTORY"
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654\&\fIEVP_CIPHER_CTX_init()\fR, \fIEVP_EncryptInit_ex()\fR, \fIEVP_EncryptFinal_ex()\fR,
655\&\fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptFinal_ex()\fR, \fIEVP_CipherInit_ex()\fR,
656\&\fIEVP_CipherFinal_ex()\fR and \fIEVP_CIPHER_CTX_set_padding()\fR appeared in
657OpenSSL 0.9.7.