22 [B<-inform SMIME|PEM|DER>]
26 [B<-outform SMIME|PEM|DER>]
41 The B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and
42 verify S/MIME messages.
44 =head1 COMMAND OPTIONS
46 There are six operation options that set the type of operation to be performed.
47 The meaning of the other options varies according to the operation type.
53 encrypt mail for the given recipient certificates. Input file is the message
54 to be encrypted. The output file is the encrypted mail in MIME format.
56 Note that no revocation check is done for the recipient cert, so if that
57 key has been compromised, others may be able to decrypt the text.
61 decrypt mail using the supplied certificate and private key. Expects an
62 encrypted mail message in MIME format for the input file. The decrypted mail
63 is written to the output file.
67 sign mail using the supplied certificate and private key. Input file is
68 the message to be signed. The signed message in MIME format is written
73 verify signed mail. Expects a signed mail message on input and outputs
74 the signed data. Both clear text and opaque signing is supported.
78 takes an input message and writes out a PEM encoded PKCS#7 structure.
82 resign a message: take an existing message and one or more new signers.
86 the input message to be encrypted or signed or the MIME message to
87 be decrypted or verified.
89 =item B<-inform SMIME|PEM|DER>
91 this specifies the input format for the PKCS#7 structure. The default
92 is B<SMIME> which reads an S/MIME format message. B<PEM> and B<DER>
93 format change this to expect PEM and DER format PKCS#7 structures
94 instead. This currently only affects the input format of the PKCS#7
95 structure, if no PKCS#7 structure is being input (for example with
96 B<-encrypt> or B<-sign>) this option has no effect.
98 =item B<-out filename>
100 the message text that has been decrypted or verified or the output MIME
101 format message that has been signed or verified.
103 =item B<-outform SMIME|PEM|DER>
105 this specifies the output format for the PKCS#7 structure. The default
106 is B<SMIME> which write an S/MIME format message. B<PEM> and B<DER>
107 format change this to write PEM and DER format PKCS#7 structures
108 instead. This currently only affects the output format of the PKCS#7
109 structure, if no PKCS#7 structure is being output (for example with
110 B<-verify> or B<-decrypt>) this option has no effect.
112 =item B<-stream -indef -noindef>
114 the B<-stream> and B<-indef> options are equivalent and enable streaming I/O
115 for encoding operations. This permits single pass processing of data without
116 the need to hold the entire contents in memory, potentially supporting very
117 large files. Streaming is automatically set for S/MIME signing with detached
118 data if the output format is B<SMIME> it is currently off by default for all
123 disable streaming I/O where it would produce and indefinite length constructed
124 encoding. This option currently has no effect. In future streaming will be
125 enabled by default on all relevant operations and this option will disable it.
127 =item B<-content filename>
129 This specifies a file containing the detached content, this is only
130 useful with the B<-verify> command. This is only usable if the PKCS#7
131 structure is using the detached signature form where the content is
132 not included. This option will override any content if the input format
133 is S/MIME and it uses the multipart/signed MIME content type.
137 this option adds plain text (text/plain) MIME headers to the supplied
138 message if encrypting or signing. If decrypting or verifying it strips
139 off text headers: if the decrypted or verified message is not of MIME
140 type text/plain then an error occurs.
142 =item B<-CAfile file>
144 a file containing trusted CA certificates, only used with B<-verify>.
148 a directory containing trusted CA certificates, only used with
149 B<-verify>. This directory must be a standard certificate directory: that
150 is a hash of each subject name (using B<x509 -hash>) should be linked
155 digest algorithm to use when signing or resigning. If not present then the
156 default digest algorithm for the signing key will be used (usually SHA1).
160 the encryption algorithm to use. For example DES (56 bits) - B<-des>,
161 triple DES (168 bits) - B<-des3>,
162 EVP_get_cipherbyname() function) can also be used preceded by a dash, for
163 example B<-aes_128_cbc>. See L<B<enc>|enc(1)> for list of ciphers
164 supported by your version of OpenSSL.
166 If not specified triple DES is used. Only used with B<-encrypt>.
170 when verifying a message normally certificates (if any) included in
171 the message are searched for the signing certificate. With this option
172 only the certificates specified in the B<-certfile> option are used.
173 The supplied certificates can still be used as untrusted CAs however.
177 do not verify the signers certificate of a signed message.
181 do not do chain verification of signers certificates: that is don't
182 use the certificates in the signed message as untrusted CAs.
186 don't try to verify the signatures on the message.
190 when signing a message the signer's certificate is normally included
191 with this option it is excluded. This will reduce the size of the
192 signed message but the verifier must have a copy of the signers certificate
193 available locally (passed using the B<-certfile> option for example).
197 normally when a message is signed a set of attributes are included which
198 include the signing time and supported symmetric algorithms. With this
199 option they are not included.
203 normally the input message is converted to "canonical" format which is
204 effectively using CR and LF as end of line: as required by the S/MIME
205 specification. When this option is present no translation occurs. This
206 is useful when handling binary data which may not be in MIME format.
210 when signing a message use opaque signing: this form is more resistant
211 to translation by mail relays but it cannot be read by mail agents that
212 do not support S/MIME. Without this option cleartext signing with
213 the MIME type multipart/signed is used.
215 =item B<-certfile file>
217 allows additional certificates to be specified. When signing these will
218 be included with the message. When verifying these will be searched for
219 the signers certificates. The certificates should be in PEM format.
221 =item B<-signer file>
223 a signing certificate when signing or resigning a message, this option can be
224 used multiple times if more than one signer is required. If a message is being
225 verified then the signers certificates will be written to this file if the
226 verification was successful.
230 the recipients certificate when decrypting a message. This certificate
231 must match one of the recipients of the message or an error occurs.
235 the private key to use when signing or decrypting. This must match the
236 corresponding certificate. If this option is not specified then the
237 private key must be included in the certificate file specified with
238 the B<-recip> or B<-signer> file. When signing this option can be used
239 multiple times to specify successive keys.
243 the private key password source. For more information about the format of B<arg>
244 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
246 =item B<-rand file(s)>
248 a file or files containing random data used to seed the random number
249 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
250 Multiple files can be specified separated by a OS-dependent character.
251 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
256 one or more certificates of message recipients: used when encrypting
259 =item B<-to, -from, -subject>
261 the relevant mail headers. These are included outside the signed
262 portion of a message so they may be included manually. If signing
263 then many S/MIME mail clients check the signers certificate's email
264 address matches that specified in the From: address.
266 =item B<-purpose, -ignore_critical, -issuer_checks, -crl_check, -crl_check_all, -policy_check, -extended_crl, -x509_strict, -policy -check_ss_sig -no_alt_chains>
268 Set various options of certificate chain verification. See
269 L<B<verify>|verify(1)> manual page for details.
275 The MIME message must be sent without any blank lines between the
276 headers and the output. Some mail programs will automatically add
277 a blank line. Piping the mail directly to sendmail is one way to
278 achieve the correct format.
280 The supplied message to be signed or encrypted must include the
281 necessary MIME headers or many S/MIME clients wont display it
282 properly (if at all). You can use the B<-text> option to automatically
283 add plain text headers.
285 A "signed and encrypted" message is one where a signed message is
286 then encrypted. This can be produced by encrypting an already signed
287 message: see the examples section.
289 This version of the program only allows one signer per message but it
290 will verify multiple signers on received messages. Some S/MIME clients
291 choke if a message contains multiple signers. It is possible to sign
292 messages "in parallel" by signing an already signed message.
294 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
295 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
296 encrypted data is used for other purposes.
298 The B<-resign> option uses an existing message digest when adding a new
299 signer. This means that attributes must be present in at least one existing
300 signer using the same message digest or this operation will fail.
302 The B<-stream> and B<-indef> options enable experimental streaming I/O support.
303 As a result the encoding is BER using indefinite length constructed encoding
304 and no longer DER. Streaming is supported for the B<-encrypt> operation and the
305 B<-sign> operation if the content is not detached.
307 Streaming is always used for the B<-sign> operation with detached data but
308 since the content is no longer part of the PKCS#7 structure the encoding
317 the operation was completely successfully.
321 an error occurred parsing the command options.
325 one of the input files could not be read.
329 an error occurred creating the PKCS#7 file or when reading the MIME
334 an error occurred decrypting or verifying the message.
338 the message was verified correctly but an error occurred writing out
339 the signers certificates.
345 Create a cleartext signed message:
347 openssl smime -sign -in message.txt -text -out mail.msg \
350 Create an opaque signed message:
352 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
355 Create a signed message, include some additional certificates and
356 read the private key from another file:
358 openssl smime -sign -in in.txt -text -out mail.msg \
359 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
361 Create a signed message with two signers:
363 openssl smime -sign -in message.txt -text -out mail.msg \
364 -signer mycert.pem -signer othercert.pem
366 Send a signed message under Unix directly to sendmail, including headers:
368 openssl smime -sign -in in.txt -text -signer mycert.pem \
369 -from steve@openssl.org -to someone@somewhere \
370 -subject "Signed message" | sendmail someone@somewhere
372 Verify a message and extract the signer's certificate if successful:
374 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
376 Send encrypted mail using triple DES:
378 openssl smime -encrypt -in in.txt -from steve@openssl.org \
379 -to someone@somewhere -subject "Encrypted message" \
380 -des3 user.pem -out mail.msg
382 Sign and encrypt mail:
384 openssl smime -sign -in ml.txt -signer my.pem -text \
385 | openssl smime -encrypt -out mail.msg \
386 -from steve@openssl.org -to someone@somewhere \
387 -subject "Signed and Encrypted message" -des3 user.pem
389 Note: the encryption command does not include the B<-text> option because the
390 message being encrypted already has MIME headers.
394 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
396 The output from Netscape form signing is a PKCS#7 structure with the
397 detached signature format. You can use this program to verify the
398 signature by line wrapping the base64 encoded structure and surrounding
401 -----BEGIN PKCS7-----
404 and using the command:
406 openssl smime -verify -inform PEM -in signature.pem -content content.txt
408 Alternatively you can base64 decode the signature and use:
410 openssl smime -verify -inform DER -in signature.der -content content.txt
412 Create an encrypted message using 128 bit Camellia:
414 openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
416 Add a signer to an existing message:
418 openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
422 The MIME parser isn't very clever: it seems to handle most messages that I've
423 thrown at it but it may choke on others.
425 The code currently will only write out the signer's certificate to a file: if
426 the signer has a separate encryption certificate this must be manually
427 extracted. There should be some heuristic that determines the correct
428 encryption certificate.
430 Ideally a database should be maintained of a certificates for each email
433 The code doesn't currently take note of the permitted symmetric encryption
434 algorithms as supplied in the SMIMECapabilities signed attribute. This means the
435 user has to manually include the correct encryption algorithm. It should store
436 the list of permitted ciphers in a database and only use those.
438 No revocation checking is done on the signer's certificate.
440 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
441 structures may cause parsing errors.
445 The use of multiple B<-signer> options and the B<-resign> command were first
446 added in OpenSSL 1.0.0
448 The -no_alt_chains options was first added to OpenSSL 1.0.2b.