1SMIME(1) OpenSSL SMIME(1)
2
6 openssl-smime, smime - S/MIME utility
7
9 openssl smime [-help] [-encrypt] [-decrypt] [-sign] [-resign] [-verify]
10 [-pk7out] [-binary] [-crlfeol] [-cipher] [-in file] [-CAfile file]
11 [-CApath dir] [-no-CAfile] [-no-CApath] [-attime timestamp]
12 [-check_ss_sig] [-crl_check] [-crl_check_all] [-explicit_policy]
13 [-extended_crl] [-ignore_critical] [-inhibit_any] [-inhibit_map]
14 [-partial_chain] [-policy arg] [-policy_check] [-policy_print]
15 [-purpose purpose] [-suiteB_128] [-suiteB_128_only] [-suiteB_192]
16 [-trusted_first] [-no_alt_chains] [-use_deltas] [-auth_level num]
17 [-verify_depth num] [-verify_email email] [-verify_hostname hostname]
18 [-verify_ip ip] [-verify_name name] [-x509_strict] [-certfile file]
19 [-signer file] [-recip file] [-inform SMIME|PEM|DER] [-passin arg]
20 [-inkey file_or_id] [-out file] [-outform SMIME|PEM|DER] [-content
21 file] [-to addr] [-from ad] [-subject s] [-text] [-indef] [-noindef]
22 [-stream] [-rand file...] [-writerand file] [-md digest] [cert.pem]...
23
25 The smime command handles S/MIME mail. It can encrypt, decrypt, sign
26 and verify S/MIME messages.
27
29 There are six operation options that set the type of operation to be
30 performed. The meaning of the other options varies according to the
31 operation type.
32 -help
34 Print out a usage message.
35 -encrypt
37 Encrypt mail for the given recipient certificates. Input file is
38 the message to be encrypted. The output file is the encrypted mail
39 in MIME format.
40 Note that no revocation check is done for the recipient cert, so if
42 that key has been compromised, others may be able to decrypt the
43 text.
44 -decrypt
46 Decrypt mail using the supplied certificate and private key.
47 Expects an encrypted mail message in MIME format for the input
48 file. The decrypted mail is written to the output file.
49 -sign
51 Sign mail using the supplied certificate and private key. Input
52 file is the message to be signed. The signed message in MIME format
53 is written to the output file.
54 -verify
56 Verify signed mail. Expects a signed mail message on input and
57 outputs the signed data. Both clear text and opaque signing is
58 supported.
59 -pk7out
61 Takes an input message and writes out a PEM encoded PKCS#7
62 structure.
63 -resign
65 Resign a message: take an existing message and one or more new
66 signers.
67 -in filename
69 The input message to be encrypted or signed or the MIME message to
70 be decrypted or verified.
71 -inform SMIME|PEM|DER
73 This specifies the input format for the PKCS#7 structure. The
74 default is SMIME which reads an S/MIME format message. PEM and DER
75 format change this to expect PEM and DER format PKCS#7 structures
76 instead. This currently only affects the input format of the PKCS#7
77 structure, if no PKCS#7 structure is being input (for example with
78 -encrypt or -sign) this option has no effect.
79 -out filename
81 The message text that has been decrypted or verified or the output
82 MIME format message that has been signed or verified.
83 -outform SMIME|PEM|DER
85 This specifies the output format for the PKCS#7 structure. The
86 default is SMIME which write an S/MIME format message. PEM and DER
87 format change this to write PEM and DER format PKCS#7 structures
88 instead. This currently only affects the output format of the
89 PKCS#7 structure, if no PKCS#7 structure is being output (for
90 example with -verify or -decrypt) this option has no effect.
91 -stream -indef -noindef
93 The -stream and -indef options are equivalent and enable streaming
94 I/O for encoding operations. This permits single pass processing of
95 data without the need to hold the entire contents in memory,
96 potentially supporting very large files. Streaming is automatically
97 set for S/MIME signing with detached data if the output format is
98 SMIME it is currently off by default for all other operations.
99 -noindef
101 Disable streaming I/O where it would produce and indefinite length
102 constructed encoding. This option currently has no effect. In
103 future streaming will be enabled by default on all relevant
104 operations and this option will disable it.
105 -content filename
107 This specifies a file containing the detached content, this is only
108 useful with the -verify command. This is only usable if the PKCS#7
109 structure is using the detached signature form where the content is
110 not included. This option will override any content if the input
111 format is S/MIME and it uses the multipart/signed MIME content
112 type.
113 -text
115 This option adds plain text (text/plain) MIME headers to the
116 supplied message if encrypting or signing. If decrypting or
117 verifying it strips off text headers: if the decrypted or verified
118 message is not of MIME type text/plain then an error occurs.
119 -CAfile file
121 A file containing trusted CA certificates, only used with -verify.
122 -CApath dir
124 A directory containing trusted CA certificates, only used with
125 -verify. This directory must be a standard certificate directory:
126 that is a hash of each subject name (using x509 -hash) should be
127 linked to each certificate.
128 -no-CAfile
130 Do not load the trusted CA certificates from the default file
131 location.
132 -no-CApath
134 Do not load the trusted CA certificates from the default directory
135 location.
136 -md digest
138 Digest algorithm to use when signing or resigning. If not present
139 then the default digest algorithm for the signing key will be used
140 (usually SHA1).
141 -cipher
143 The encryption algorithm to use. For example DES (56 bits) - -des,
144 triple DES (168 bits) - -des3, EVP_get_cipherbyname() function) can
145 also be used preceded by a dash, for example -aes-128-cbc. See enc
146 for list of ciphers supported by your version of OpenSSL.
147 If not specified triple DES is used. Only used with -encrypt.
149 -nointern
151 When verifying a message normally certificates (if any) included in
152 the message are searched for the signing certificate. With this
153 option only the certificates specified in the -certfile option are
154 used. The supplied certificates can still be used as untrusted CAs
155 however.
156 -noverify
158 Do not verify the signers certificate of a signed message.
159 -nochain
161 Do not do chain verification of signers certificates: that is don't
162 use the certificates in the signed message as untrusted CAs.
163 -nosigs
165 Don't try to verify the signatures on the message.
166 -nocerts
168 When signing a message the signer's certificate is normally
169 included with this option it is excluded. This will reduce the size
170 of the signed message but the verifier must have a copy of the
171 signers certificate available locally (passed using the -certfile
172 option for example).
173 -noattr
175 Normally when a message is signed a set of attributes are included
176 which include the signing time and supported symmetric algorithms.
177 With this option they are not included.
178 -binary
180 Normally the input message is converted to "canonical" format which
181 is effectively using CR and LF as end of line: as required by the
182 S/MIME specification. When this option is present no translation
183 occurs. This is useful when handling binary data which may not be
184 in MIME format.
185 -crlfeol
187 Normally the output file uses a single LF as end of line. When this
188 option is present CRLF is used instead.
189 -nodetach
191 When signing a message use opaque signing: this form is more
192 resistant to translation by mail relays but it cannot be read by
193 mail agents that do not support S/MIME. Without this option
194 cleartext signing with the MIME type multipart/signed is used.
195 -certfile file
197 Allows additional certificates to be specified. When signing these
198 will be included with the message. When verifying these will be
199 searched for the signers certificates. The certificates should be
200 in PEM format.
201 -signer file
203 A signing certificate when signing or resigning a message, this
204 option can be used multiple times if more than one signer is
205 required. If a message is being verified then the signers
206 certificates will be written to this file if the verification was
207 successful.
208 -recip file
210 The recipients certificate when decrypting a message. This
211 certificate must match one of the recipients of the message or an
212 error occurs.
213 -inkey file_or_id
215 The private key to use when signing or decrypting. This must match
216 the corresponding certificate. If this option is not specified then
217 the private key must be included in the certificate file specified
218 with the -recip or -signer file. When signing this option can be
219 used multiple times to specify successive keys. If no engine is
220 used, the argument is taken as a file; if an engine is specified,
221 the argument is given to the engine as a key identifier.
222 -passin arg
224 The private key password source. For more information about the
225 format of arg see "Pass Phrase Options" in openssl(1).
226 -rand file...
228 A file or files containing random data used to seed the random
229 number generator. Multiple files can be specified separated by an
230 OS-dependent character. The separator is ; for MS-Windows, , for
231 OpenVMS, and : for all others.
232 [-writerand file]
234 Writes random data to the specified file upon exit. This can be
235 used with a subsequent -rand flag.
236 cert.pem...
238 One or more certificates of message recipients: used when
239 encrypting a message.
240 -to, -from, -subject
242 The relevant mail headers. These are included outside the signed
243 portion of a message so they may be included manually. If signing
244 then many S/MIME mail clients check the signers certificate's email
245 address matches that specified in the From: address.
246 -attime, -check_ss_sig, -crl_check, -crl_check_all, -explicit_policy,
248 -extended_crl, -ignore_critical, -inhibit_any, -inhibit_map,
249 -no_alt_chains, -partial_chain, -policy, -policy_check, -policy_print,
250 -purpose, -suiteB_128, -suiteB_128_only, -suiteB_192, -trusted_first,
251 -use_deltas, -auth_level, -verify_depth, -verify_email,
252 -verify_hostname, -verify_ip, -verify_name, -x509_strict
253 Set various options of certificate chain verification. See
254 verify(1) manual page for details.
255
257 The MIME message must be sent without any blank lines between the
258 headers and the output. Some mail programs will automatically add a
259 blank line. Piping the mail directly to sendmail is one way to achieve
260 the correct format.
261 The supplied message to be signed or encrypted must include the
263 necessary MIME headers or many S/MIME clients won't display it properly
264 (if at all). You can use the -text option to automatically add plain
265 text headers.
266 A "signed and encrypted" message is one where a signed message is then
268 encrypted. This can be produced by encrypting an already signed
269 message: see the examples section.
270 This version of the program only allows one signer per message but it
272 will verify multiple signers on received messages. Some S/MIME clients
273 choke if a message contains multiple signers. It is possible to sign
274 messages "in parallel" by signing an already signed message.
275 The options -encrypt and -decrypt reflect common usage in S/MIME
277 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
278 encrypted data is used for other purposes.
279 The -resign option uses an existing message digest when adding a new
281 signer. This means that attributes must be present in at least one
282 existing signer using the same message digest or this operation will
283 fail.
284 The -stream and -indef options enable streaming I/O support. As a
286 result the encoding is BER using indefinite length constructed encoding
287 and no longer DER. Streaming is supported for the -encrypt operation
288 and the -sign operation if the content is not detached.
289 Streaming is always used for the -sign operation with detached data but
291 since the content is no longer part of the PKCS#7 structure the
292 encoding remains DER.
293
295 0 The operation was completely successfully.
296 1 An error occurred parsing the command options.
298 2 One of the input files could not be read.
300 3 An error occurred creating the PKCS#7 file or when reading the MIME
302 message.
303 4 An error occurred decrypting or verifying the message.
305 5 The message was verified correctly but an error occurred writing
307 out the signers certificates.
308
310 Create a cleartext signed message:
311 openssl smime -sign -in message.txt -text -out mail.msg \
313 -signer mycert.pem
314 Create an opaque signed message:
316 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
318 -signer mycert.pem
319 Create a signed message, include some additional certificates and read
321 the private key from another file:
322 openssl smime -sign -in in.txt -text -out mail.msg \
324 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
325 Create a signed message with two signers:
327 openssl smime -sign -in message.txt -text -out mail.msg \
329 -signer mycert.pem -signer othercert.pem
330 Send a signed message under Unix directly to sendmail, including
332 headers:
333 openssl smime -sign -in in.txt -text -signer mycert.pem \
335 -from steve@openssl.org -to someone@somewhere \
336 -subject "Signed message" | sendmail someone@somewhere
337 Verify a message and extract the signer's certificate if successful:
339 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
341 Send encrypted mail using triple DES:
343 openssl smime -encrypt -in in.txt -from steve@openssl.org \
345 -to someone@somewhere -subject "Encrypted message" \
346 -des3 user.pem -out mail.msg
347 Sign and encrypt mail:
349 openssl smime -sign -in ml.txt -signer my.pem -text \
351 | openssl smime -encrypt -out mail.msg \
352 -from steve@openssl.org -to someone@somewhere \
353 -subject "Signed and Encrypted message" -des3 user.pem
354 Note: the encryption command does not include the -text option because
356 the message being encrypted already has MIME headers.
357 Decrypt mail:
359 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
361 The output from Netscape form signing is a PKCS#7 structure with the
363 detached signature format. You can use this program to verify the
364 signature by line wrapping the base64 encoded structure and surrounding
365 it with:
366 -----BEGIN PKCS7-----
368 -----END PKCS7-----
369 and using the command:
371 openssl smime -verify -inform PEM -in signature.pem -content content.txt
373 Alternatively you can base64 decode the signature and use:
375 openssl smime -verify -inform DER -in signature.der -content content.txt
377 Create an encrypted message using 128 bit Camellia:
379 openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
381 Add a signer to an existing message:
383 openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
385
387 The MIME parser isn't very clever: it seems to handle most messages
388 that I've thrown at it but it may choke on others.
389 The code currently will only write out the signer's certificate to a
391 file: if the signer has a separate encryption certificate this must be
392 manually extracted. There should be some heuristic that determines the
393 correct encryption certificate.
394 Ideally a database should be maintained of a certificates for each
396 email address.
397 The code doesn't currently take note of the permitted symmetric
399 encryption algorithms as supplied in the SMIMECapabilities signed
400 attribute. This means the user has to manually include the correct
401 encryption algorithm. It should store the list of permitted ciphers in
402 a database and only use those.
403 No revocation checking is done on the signer's certificate.
405 The current code can only handle S/MIME v2 messages, the more complex
407 S/MIME v3 structures may cause parsing errors.
408
410 The use of multiple -signer options and the -resign command were first
411 added in OpenSSL 1.0.0
412 The -no_alt_chains option was added in OpenSSL 1.1.0.
414
416 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
417 Licensed under the OpenSSL license (the "License"). You may not use
419 this file except in compliance with the License. You can obtain a copy
420 in the file LICENSE in the source distribution or at
421 <https://www.openssl.org/source/license.html>.
4221.1.1l 2021-09-15 SMIME(1)