2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-smime - S/MIME utility
22 [B<-certfile> I<file>]
33 [B<-inform> B<DER>|B<PEM>|B<SMIME>]
34 [B<-outform> B<DER>|B<PEM>|B<SMIME>]
35 [B<-keyform> B<DER>|B<PEM>|B<ENGINE>]
37 [B<-inkey> I<file_or_id>]
48 {- $OpenSSL::safe::opt_trust_synopsis -}
49 {- $OpenSSL::safe::opt_engine_synopsis -}
50 {- $OpenSSL::safe::opt_r_synopsis -}
51 {- $OpenSSL::safe::opt_v_synopsis -}
52 {- $OpenSSL::safe::opt_provider_synopsis -}
55 =for openssl ifdef engine
59 This command handles S/MIME mail. It can encrypt, decrypt, sign
60 and verify S/MIME messages.
64 There are six operation options that set the type of operation to be performed.
65 The meaning of the other options varies according to the operation type.
71 Print out a usage message.
75 Encrypt mail for the given recipient certificates. Input file is the message
76 to be encrypted. The output file is the encrypted mail in MIME format.
78 Note that no revocation check is done for the recipient cert, so if that
79 key has been compromised, others may be able to decrypt the text.
83 Decrypt mail using the supplied certificate and private key. Expects an
84 encrypted mail message in MIME format for the input file. The decrypted mail
85 is written to the output file.
89 Sign mail using the supplied certificate and private key. Input file is
90 the message to be signed. The signed message in MIME format is written
95 Verify signed mail. Expects a signed mail message on input and outputs
96 the signed data. Both clear text and opaque signing is supported.
100 Takes an input message and writes out a PEM encoded PKCS#7 structure.
104 Resign a message: take an existing message and one or more new signers.
106 =item B<-in> I<filename>
108 The input message to be encrypted or signed or the MIME message to
109 be decrypted or verified.
111 =item B<-out> I<filename>
113 The message text that has been decrypted or verified or the output MIME
114 format message that has been signed or verified.
116 =item B<-inform> B<DER>|B<PEM>|B<SMIME>
118 The input format of the PKCS#7 (S/MIME) structure (if one is being read);
119 the default is B<SMIME>.
120 See L<openssl(1)/Format Options> for details.
122 =item B<-outform> B<DER>|B<PEM>|B<SMIME>
124 The output format of the PKCS#7 (S/MIME) structure (if one is being written);
125 the default is B<SMIME>.
126 See L<openssl(1)/Format Options> for details.
128 =item B<-keyform> B<DER>|B<PEM>
130 The key format; the default is B<PEM>.
131 See L<openssl(1)/Format Options> for details.
133 =item B<-stream>, B<-indef>, B<-noindef>
135 The B<-stream> and B<-indef> options are equivalent and enable streaming I/O
136 for encoding operations. This permits single pass processing of data without
137 the need to hold the entire contents in memory, potentially supporting very
138 large files. Streaming is automatically set for S/MIME signing with detached
139 data if the output format is B<SMIME> it is currently off by default for all
144 Disable streaming I/O where it would produce and indefinite length constructed
145 encoding. This option currently has no effect. In future streaming will be
146 enabled by default on all relevant operations and this option will disable it.
148 =item B<-content> I<filename>
150 This specifies a file containing the detached content, this is only
151 useful with the B<-verify> command. This is only usable if the PKCS#7
152 structure is using the detached signature form where the content is
153 not included. This option will override any content if the input format
154 is S/MIME and it uses the multipart/signed MIME content type.
158 This option adds plain text (text/plain) MIME headers to the supplied
159 message if encrypting or signing. If decrypting or verifying it strips
160 off text headers: if the decrypted or verified message is not of MIME
161 type text/plain then an error occurs.
163 =item B<-md> I<digest>
165 Digest algorithm to use when signing or resigning. If not present then the
166 default digest algorithm for the signing key will be used (usually SHA1).
170 The encryption algorithm to use. For example DES (56 bits) - B<-des>,
171 triple DES (168 bits) - B<-des3>,
172 EVP_get_cipherbyname() function) can also be used preceded by a dash, for
173 example B<-aes-128-cbc>. See L<openssl-enc(1)> for list of ciphers
174 supported by your version of OpenSSL.
176 If not specified triple DES is used. Only used with B<-encrypt>.
180 When verifying a message normally certificates (if any) included in
181 the message are searched for the signing certificate. With this option
182 only the certificates specified in the B<-certfile> option are used.
183 The supplied certificates can still be used as untrusted CAs however.
187 Do not verify the signers certificate of a signed message.
191 Do not do chain verification of signers certificates; that is, do not
192 use the certificates in the signed message as untrusted CAs.
196 Don't try to verify the signatures on the message.
200 When signing a message the signer's certificate is normally included
201 with this option it is excluded. This will reduce the size of the
202 signed message but the verifier must have a copy of the signers certificate
203 available locally (passed using the B<-certfile> option for example).
207 Normally when a message is signed a set of attributes are included which
208 include the signing time and supported symmetric algorithms. With this
209 option they are not included.
213 When signing a message use opaque signing. This form is more resistant
214 to translation by mail relays but it cannot be read by mail agents that
215 do not support S/MIME. Without this option cleartext signing with
216 the MIME type multipart/signed is used.
220 When signing a message, do not include the B<SMIMECapabilities> attribute.
224 Normally the input message is converted to "canonical" format which is
225 effectively using CR and LF as end of line: as required by the S/MIME
226 specification. When this option is present no translation occurs. This
227 is useful when handling binary data which may not be in MIME format.
231 Normally the output file uses a single B<LF> as end of line. When this
232 option is present B<CRLF> is used instead.
234 =item B<-certfile> I<file>
236 Allows additional certificates to be specified. When signing these will
237 be included with the message. When verifying these will be searched for
238 the signers certificates. The certificates should be in PEM format.
240 =item B<-signer> I<file>
242 A signing certificate when signing or resigning a message, this option can be
243 used multiple times if more than one signer is required. If a message is being
244 verified then the signers certificates will be written to this file if the
245 verification was successful.
249 Don't include signers certificate when signing.
253 Don't include any signed attributes when signing.
255 =item B<-recip> I<file>
257 The recipients certificate when decrypting a message. This certificate
258 must match one of the recipients of the message or an error occurs.
260 =item B<-inkey> I<file_or_id>
262 The private key to use when signing or decrypting. This must match the
263 corresponding certificate. If this option is not specified then the
264 private key must be included in the certificate file specified with
265 the B<-recip> or B<-signer> file. When signing this option can be used
266 multiple times to specify successive keys.
267 If no engine is used, the argument is taken as a file; if an engine is
268 specified, the argument is given to the engine as a key identifier.
270 =item B<-passin> I<arg>
272 The private key password source. For more information about the format of I<arg>
273 see L<openssl(1)/Pass Phrase Options>.
275 =item B<-to>, B<-from>, B<-subject>
277 The relevant mail headers. These are included outside the signed
278 portion of a message so they may be included manually. If signing
279 then many S/MIME mail clients check the signers certificate's email
280 address matches that specified in the From: address.
282 {- $OpenSSL::safe::opt_v_item -}
284 Any verification errors cause the command to exit.
286 {- $OpenSSL::safe::opt_trust_item -}
288 {- $OpenSSL::safe::opt_engine_item -}
290 {- $OpenSSL::safe::opt_r_item -}
292 {- $OpenSSL::safe::opt_provider_item -}
294 =item I<cert.pem> ...
296 One or more certificates of message recipients, used when encrypting
303 The MIME message must be sent without any blank lines between the
304 headers and the output. Some mail programs will automatically add
305 a blank line. Piping the mail directly to sendmail is one way to
306 achieve the correct format.
308 The supplied message to be signed or encrypted must include the
309 necessary MIME headers or many S/MIME clients won't display it
310 properly (if at all). You can use the B<-text> option to automatically
311 add plain text headers.
313 A "signed and encrypted" message is one where a signed message is
314 then encrypted. This can be produced by encrypting an already signed
315 message: see the examples section.
317 This version of the program only allows one signer per message but it
318 will verify multiple signers on received messages. Some S/MIME clients
319 choke if a message contains multiple signers. It is possible to sign
320 messages "in parallel" by signing an already signed message.
322 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
323 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
324 encrypted data is used for other purposes.
326 The B<-resign> option uses an existing message digest when adding a new
327 signer. This means that attributes must be present in at least one existing
328 signer using the same message digest or this operation will fail.
330 The B<-stream> and B<-indef> options enable streaming I/O support.
331 As a result the encoding is BER using indefinite length constructed encoding
332 and no longer DER. Streaming is supported for the B<-encrypt> operation and the
333 B<-sign> operation if the content is not detached.
335 Streaming is always used for the B<-sign> operation with detached data but
336 since the content is no longer part of the PKCS#7 structure the encoding
345 The operation was completely successfully.
349 An error occurred parsing the command options.
353 One of the input files could not be read.
357 An error occurred creating the PKCS#7 file or when reading the MIME
362 An error occurred decrypting or verifying the message.
366 The message was verified correctly but an error occurred writing out
367 the signers certificates.
373 Create a cleartext signed message:
375 openssl smime -sign -in message.txt -text -out mail.msg \
378 Create an opaque signed message:
380 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
383 Create a signed message, include some additional certificates and
384 read the private key from another file:
386 openssl smime -sign -in in.txt -text -out mail.msg \
387 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
389 Create a signed message with two signers:
391 openssl smime -sign -in message.txt -text -out mail.msg \
392 -signer mycert.pem -signer othercert.pem
394 Send a signed message under Unix directly to sendmail, including headers:
396 openssl smime -sign -in in.txt -text -signer mycert.pem \
397 -from steve@openssl.org -to someone@somewhere \
398 -subject "Signed message" | sendmail someone@somewhere
400 Verify a message and extract the signer's certificate if successful:
402 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
404 Send encrypted mail using triple DES:
406 openssl smime -encrypt -in in.txt -from steve@openssl.org \
407 -to someone@somewhere -subject "Encrypted message" \
408 -des3 user.pem -out mail.msg
410 Sign and encrypt mail:
412 openssl smime -sign -in ml.txt -signer my.pem -text \
413 | openssl smime -encrypt -out mail.msg \
414 -from steve@openssl.org -to someone@somewhere \
415 -subject "Signed and Encrypted message" -des3 user.pem
417 Note: the encryption command does not include the B<-text> option because the
418 message being encrypted already has MIME headers.
422 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
424 The output from Netscape form signing is a PKCS#7 structure with the
425 detached signature format. You can use this program to verify the
426 signature by line wrapping the base64 encoded structure and surrounding
429 -----BEGIN PKCS7-----
432 and using the command:
434 openssl smime -verify -inform PEM -in signature.pem -content content.txt
436 Alternatively you can base64 decode the signature and use:
438 openssl smime -verify -inform DER -in signature.der -content content.txt
440 Create an encrypted message using 128 bit Camellia:
442 openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
444 Add a signer to an existing message:
446 openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
450 The MIME parser isn't very clever: it seems to handle most messages that I've
451 thrown at it but it may choke on others.
453 The code currently will only write out the signer's certificate to a file: if
454 the signer has a separate encryption certificate this must be manually
455 extracted. There should be some heuristic that determines the correct
456 encryption certificate.
458 Ideally a database should be maintained of a certificates for each email
461 The code doesn't currently take note of the permitted symmetric encryption
462 algorithms as supplied in the SMIMECapabilities signed attribute. This means the
463 user has to manually include the correct encryption algorithm. It should store
464 the list of permitted ciphers in a database and only use those.
466 No revocation checking is done on the signer's certificate.
468 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
469 structures may cause parsing errors.
473 L<ossl_store-file(7)>
477 The use of multiple B<-signer> options and the B<-resign> command were first
478 added in OpenSSL 1.0.0
480 The -no_alt_chains option was added in OpenSSL 1.1.0.
484 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
486 Licensed under the Apache License 2.0 (the "License"). You may not use
487 this file except in compliance with the License. You can obtain a copy
488 in the file LICENSE in the source distribution or at
489 L<https://www.openssl.org/source/license.html>.