24 [B<-inform SMIME|PEM|DER>]
28 [B<-outform SMIME|PEM|DER>]
43 The B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and
44 verify S/MIME messages.
46 =head1 COMMAND OPTIONS
48 There are six operation options that set the type of operation to be performed.
49 The meaning of the other options varies according to the operation type.
55 encrypt mail for the given recipient certificates. Input file is the message
56 to be encrypted. The output file is the encrypted mail in MIME format.
60 decrypt mail using the supplied certificate and private key. Expects an
61 encrypted mail message in MIME format for the input file. The decrypted mail
62 is written to the output file.
66 sign mail using the supplied certificate and private key. Input file is
67 the message to be signed. The signed message in MIME format is written
72 verify signed mail. Expects a signed mail message on input and outputs
73 the signed data. Both clear text and opaque signing is supported.
77 takes an input message and writes out a PEM encoded PKCS#7 structure.
81 resign a message: take an existing message and one or more new signers.
85 the input message to be encrypted or signed or the MIME message to
86 be decrypted or verified.
88 =item B<-inform SMIME|PEM|DER>
90 this specifies the input format for the PKCS#7 structure. The default
91 is B<SMIME> which reads an S/MIME format message. B<PEM> and B<DER>
92 format change this to expect PEM and DER format PKCS#7 structures
93 instead. This currently only affects the input format of the PKCS#7
94 structure, if no PKCS#7 structure is being input (for example with
95 B<-encrypt> or B<-sign>) this option has no effect.
97 =item B<-out filename>
99 the message text that has been decrypted or verified or the output MIME
100 format message that has been signed or verified.
102 =item B<-outform SMIME|PEM|DER>
104 this specifies the output format for the PKCS#7 structure. The default
105 is B<SMIME> which write an S/MIME format message. B<PEM> and B<DER>
106 format change this to write PEM and DER format PKCS#7 structures
107 instead. This currently only affects the output format of the PKCS#7
108 structure, if no PKCS#7 structure is being output (for example with
109 B<-verify> or B<-decrypt>) this option has no effect.
111 =item B<-stream -indef -noindef>
113 the B<-stream> and B<-indef> options are equivalent and enable streaming I/O
114 for encoding operations. This permits single pass processing of data without
115 the need to hold the entire contents in memory, potentially supporting very
116 large files. Streaming is automatically set for S/MIME signing with detached
117 data if the output format is B<SMIME> it is currently off by default for all
122 disable streaming I/O where it would produce and indefinite length constructed
123 encoding. This option currently has no effect. In future streaming will be
124 enabled by default on all relevant operations and this option will disable it.
126 =item B<-content filename>
128 This specifies a file containing the detached content, this is only
129 useful with the B<-verify> command. This is only usable if the PKCS#7
130 structure is using the detached signature form where the content is
131 not included. This option will override any content if the input format
132 is S/MIME and it uses the multipart/signed MIME content type.
136 this option adds plain text (text/plain) MIME headers to the supplied
137 message if encrypting or signing. If decrypting or verifying it strips
138 off text headers: if the decrypted or verified message is not of MIME
139 type text/plain then an error occurs.
141 =item B<-CAfile file>
143 a file containing trusted CA certificates, only used with B<-verify>.
147 a directory containing trusted CA certificates, only used with
148 B<-verify>. This directory must be a standard certificate directory: that
149 is a hash of each subject name (using B<x509 -hash>) should be linked
154 digest algorithm to use when signing or resigning. If not present then the
155 default digest algorithm for the signing key will be used (usually SHA1).
159 the encryption algorithm to use. For example DES (56 bits) - B<-des>,
160 triple DES (168 bits) - B<-des3>,
161 EVP_get_cipherbyname() function) can also be used preceded by a dash, for
162 example B<-aes_128_cbc>. See L<B<enc>|enc(1)> for list of ciphers
163 supported by your version of OpenSSL.
165 If not specified triple DES is used. Only used with B<-encrypt>.
169 when verifying a message normally certificates (if any) included in
170 the message are searched for the signing certificate. With this option
171 only the certificates specified in the B<-certfile> option are used.
172 The supplied certificates can still be used as untrusted CAs however.
176 do not verify the signers certificate of a signed message.
180 do not do chain verification of signers certificates: that is don't
181 use the certificates in the signed message as untrusted CAs.
185 don't try to verify the signatures on the message.
189 when signing a message the signer's certificate is normally included
190 with this option it is excluded. This will reduce the size of the
191 signed message but the verifier must have a copy of the signers certificate
192 available locally (passed using the B<-certfile> option for example).
196 normally when a message is signed a set of attributes are included which
197 include the signing time and supported symmetric algorithms. With this
198 option they are not included.
202 normally the input message is converted to "canonical" format which is
203 effectively using CR and LF as end of line: as required by the S/MIME
204 specification. When this option is present no translation occurs. This
205 is useful when handling binary data which may not be in MIME format.
209 when signing a message use opaque signing: this form is more resistant
210 to translation by mail relays but it cannot be read by mail agents that
211 do not support S/MIME. Without this option cleartext signing with
212 the MIME type multipart/signed is used.
214 =item B<-certfile file>
216 allows additional certificates to be specified. When signing these will
217 be included with the message. When verifying these will be searched for
218 the signers certificates. The certificates should be in PEM format.
220 =item B<-signer file>
222 a signing certificate when signing or resigning a message, this option can be
223 used multiple times if more than one signer is required. If a message is being
224 verified then the signers certificates will be written to this file if the
225 verification was successful.
229 the recipients certificate when decrypting a message. This certificate
230 must match one of the recipients of the message or an error occurs.
234 the private key to use when signing or decrypting. This must match the
235 corresponding certificate. If this option is not specified then the
236 private key must be included in the certificate file specified with
237 the B<-recip> or B<-signer> file. When signing this option can be used
238 multiple times to specify successive keys.
242 the private key password source. For more information about the format of B<arg>
243 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
245 =item B<-rand file(s)>
247 a file or files containing random data used to seed the random number
248 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
249 Multiple files can be specified separated by a OS-dependent character.
250 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
255 one or more certificates of message recipients: used when encrypting
258 =item B<-to, -from, -subject>
260 the relevant mail headers. These are included outside the signed
261 portion of a message so they may be included manually. If signing
262 then many S/MIME mail clients check the signers certificate's email
263 address matches that specified in the From: address.
265 =item B<-purpose, -ignore_critical, -issuer_checks, -crl_check, -crl_check_all, -policy_check, -extended_crl, -x509_strict, -policy -check_ss_sig, -trusted_first>
267 Set various options of certificate chain verification. See
268 L<B<verify>|verify(1)> manual page for details.
274 The MIME message must be sent without any blank lines between the
275 headers and the output. Some mail programs will automatically add
276 a blank line. Piping the mail directly to sendmail is one way to
277 achieve the correct format.
279 The supplied message to be signed or encrypted must include the
280 necessary MIME headers or many S/MIME clients wont display it
281 properly (if at all). You can use the B<-text> option to automatically
282 add plain text headers.
284 A "signed and encrypted" message is one where a signed message is
285 then encrypted. This can be produced by encrypting an already signed
286 message: see the examples section.
288 This version of the program only allows one signer per message but it
289 will verify multiple signers on received messages. Some S/MIME clients
290 choke if a message contains multiple signers. It is possible to sign
291 messages "in parallel" by signing an already signed message.
293 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
294 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
295 encrypted data is used for other purposes.
297 The B<-resign> option uses an existing message digest when adding a new
298 signer. This means that attributes must be present in at least one existing
299 signer using the same message digest or this operation will fail.
301 The B<-stream> and B<-indef> options enable experimental streaming I/O support.
302 As a result the encoding is BER using indefinite length constructed encoding
303 and no longer DER. Streaming is supported for the B<-encrypt> operation and the
304 B<-sign> operation if the content is not detached.
306 Streaming is always used for the B<-sign> operation with detached data but
307 since the content is no longer part of the PKCS#7 structure the encoding
316 the operation was completely successfully.
320 an error occurred parsing the command options.
324 one of the input files could not be read.
328 an error occurred creating the PKCS#7 file or when reading the MIME
333 an error occurred decrypting or verifying the message.
337 the message was verified correctly but an error occurred writing out
338 the signers certificates.
344 Create a cleartext signed message:
346 openssl smime -sign -in message.txt -text -out mail.msg \
349 Create an opaque signed message:
351 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
354 Create a signed message, include some additional certificates and
355 read the private key from another file:
357 openssl smime -sign -in in.txt -text -out mail.msg \
358 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
360 Create a signed message with two signers:
362 openssl smime -sign -in message.txt -text -out mail.msg \
363 -signer mycert.pem -signer othercert.pem
365 Send a signed message under Unix directly to sendmail, including headers:
367 openssl smime -sign -in in.txt -text -signer mycert.pem \
368 -from steve@openssl.org -to someone@somewhere \
369 -subject "Signed message" | sendmail someone@somewhere
371 Verify a message and extract the signer's certificate if successful:
373 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
375 Send encrypted mail using triple DES:
377 openssl smime -encrypt -in in.txt -from steve@openssl.org \
378 -to someone@somewhere -subject "Encrypted message" \
379 -des3 user.pem -out mail.msg
381 Sign and encrypt mail:
383 openssl smime -sign -in ml.txt -signer my.pem -text \
384 | openssl smime -encrypt -out mail.msg \
385 -from steve@openssl.org -to someone@somewhere \
386 -subject "Signed and Encrypted message" -des3 user.pem
388 Note: the encryption command does not include the B<-text> option because the
389 message being encrypted already has MIME headers.
393 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
395 The output from Netscape form signing is a PKCS#7 structure with the
396 detached signature format. You can use this program to verify the
397 signature by line wrapping the base64 encoded structure and surrounding
400 -----BEGIN PKCS7-----
403 and using the command:
405 openssl smime -verify -inform PEM -in signature.pem -content content.txt
407 Alternatively you can base64 decode the signature and use:
409 openssl smime -verify -inform DER -in signature.der -content content.txt
411 Create an encrypted message using 128 bit Camellia:
413 openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
415 Add a signer to an existing message:
417 openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
421 The MIME parser isn't very clever: it seems to handle most messages that I've
422 thrown at it but it may choke on others.
424 The code currently will only write out the signer's certificate to a file: if
425 the signer has a separate encryption certificate this must be manually
426 extracted. There should be some heuristic that determines the correct
427 encryption certificate.
429 Ideally a database should be maintained of a certificates for each email
432 The code doesn't currently take note of the permitted symmetric encryption
433 algorithms as supplied in the SMIMECapabilities signed attribute. This means the
434 user has to manually include the correct encryption algorithm. It should store
435 the list of permitted ciphers in a database and only use those.
437 No revocation checking is done on the signer's certificate.
439 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
440 structures may cause parsing errors.
444 The use of multiple B<-signer> options and the B<-resign> command were first
445 added in OpenSSL 1.0.0