1SMIME(1) OpenSSL SMIME(1)
2
6 smime - S/MIME utility
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9 openssl smime [-encrypt] [-decrypt] [-sign] [-resign] [-verify]
10 [-pk7out] [-[cipher]] [-in file] [-CAfile file] [-CApath dir]
11 [-trusted_first] [-certfile file] [-signer file] [-recip file]
12 [-inform SMIME|PEM|DER] [-passin arg] [-inkey file] [-out file]
13 [-outform SMIME|PEM|DER] [-content file] [-to addr] [-from ad]
14 [-subject s] [-text] [-indef] [-noindef] [-stream] [-rand file(s)] [-md
15 digest] [cert.pem]...
16
18 The smime command handles S/MIME mail. It can encrypt, decrypt, sign
19 and verify S/MIME messages.
20
22 There are six operation options that set the type of operation to be
23 performed. The meaning of the other options varies according to the
24 operation type.
25 -encrypt
27 encrypt mail for the given recipient certificates. Input file is
28 the message to be encrypted. The output file is the encrypted mail
29 in MIME format.
30 -decrypt
32 decrypt mail using the supplied certificate and private key.
33 Expects an encrypted mail message in MIME format for the input
34 file. The decrypted mail is written to the output file.
35 -sign
37 sign mail using the supplied certificate and private key. Input
38 file is the message to be signed. The signed message in MIME format
39 is written to the output file.
40 -verify
42 verify signed mail. Expects a signed mail message on input and
43 outputs the signed data. Both clear text and opaque signing is
44 supported.
45 -pk7out
47 takes an input message and writes out a PEM encoded PKCS#7
48 structure.
49 -resign
51 resign a message: take an existing message and one or more new
52 signers.
53 -in filename
55 the input message to be encrypted or signed or the MIME message to
56 be decrypted or verified.
57 -inform SMIME|PEM|DER
59 this specifies the input format for the PKCS#7 structure. The
60 default is SMIME which reads an S/MIME format message. PEM and DER
61 format change this to expect PEM and DER format PKCS#7 structures
62 instead. This currently only affects the input format of the PKCS#7
63 structure, if no PKCS#7 structure is being input (for example with
64 -encrypt or -sign) this option has no effect.
65 -out filename
67 the message text that has been decrypted or verified or the output
68 MIME format message that has been signed or verified.
69 -outform SMIME|PEM|DER
71 this specifies the output format for the PKCS#7 structure. The
72 default is SMIME which write an S/MIME format message. PEM and DER
73 format change this to write PEM and DER format PKCS#7 structures
74 instead. This currently only affects the output format of the
75 PKCS#7 structure, if no PKCS#7 structure is being output (for
76 example with -verify or -decrypt) this option has no effect.
77 -stream -indef -noindef
79 the -stream and -indef options are equivalent and enable streaming
80 I/O for encoding operations. This permits single pass processing of
81 data without the need to hold the entire contents in memory,
82 potentially supporting very large files. Streaming is automatically
83 set for S/MIME signing with detached data if the output format is
84 SMIME it is currently off by default for all other operations.
85 -noindef
87 disable streaming I/O where it would produce and indefinite length
88 constructed encoding. This option currently has no effect. In
89 future streaming will be enabled by default on all relevant
90 operations and this option will disable it.
91 -content filename
93 This specifies a file containing the detached content, this is only
94 useful with the -verify command. This is only usable if the PKCS#7
95 structure is using the detached signature form where the content is
96 not included. This option will override any content if the input
97 format is S/MIME and it uses the multipart/signed MIME content
98 type.
99 -text
101 this option adds plain text (text/plain) MIME headers to the
102 supplied message if encrypting or signing. If decrypting or
103 verifying it strips off text headers: if the decrypted or verified
104 message is not of MIME type text/plain then an error occurs.
105 -CAfile file
107 a file containing trusted CA certificates, only used with -verify.
108 -CApath dir
110 a directory containing trusted CA certificates, only used with
111 -verify. This directory must be a standard certificate directory:
112 that is a hash of each subject name (using x509 -hash) should be
113 linked to each certificate.
114 -trusted_first
116 Use certificates in CA file or CA directory over certificates
117 provided in the message when building the trust chain to verify a
118 certificate. This is mainly useful in environments with Bridge CA
119 or Cross-Certified CAs.
120 -md digest
122 digest algorithm to use when signing or resigning. If not present
123 then the default digest algorithm for the signing key will be used
124 (usually SHA1).
125 -[cipher]
127 the encryption algorithm to use. For example DES (56 bits) - -des,
128 triple DES (168 bits) - -des3, EVP_get_cipherbyname() function) can
129 also be used preceded by a dash, for example -aes_128_cbc. See enc
130 for list of ciphers supported by your version of OpenSSL.
131 If not specified 40 bit RC2 is used. Only used with -encrypt.
133 -nointern
135 when verifying a message normally certificates (if any) included in
136 the message are searched for the signing certificate. With this
137 option only the certificates specified in the -certfile option are
138 used. The supplied certificates can still be used as untrusted CAs
139 however.
140 -noverify
142 do not verify the signers certificate of a signed message.
143 -nochain
145 do not do chain verification of signers certificates: that is don't
146 use the certificates in the signed message as untrusted CAs.
147 -nosigs
149 don't try to verify the signatures on the message.
150 -nocerts
152 when signing a message the signer's certificate is normally
153 included with this option it is excluded. This will reduce the size
154 of the signed message but the verifier must have a copy of the
155 signers certificate available locally (passed using the -certfile
156 option for example).
157 -noattr
159 normally when a message is signed a set of attributes are included
160 which include the signing time and supported symmetric algorithms.
161 With this option they are not included.
162 -binary
164 normally the input message is converted to "canonical" format which
165 is effectively using CR and LF as end of line: as required by the
166 S/MIME specification. When this option is present no translation
167 occurs. This is useful when handling binary data which may not be
168 in MIME format.
169 -nodetach
171 when signing a message use opaque signing: this form is more
172 resistant to translation by mail relays but it cannot be read by
173 mail agents that do not support S/MIME. Without this option
174 cleartext signing with the MIME type multipart/signed is used.
175 -certfile file
177 allows additional certificates to be specified. When signing these
178 will be included with the message. When verifying these will be
179 searched for the signers certificates. The certificates should be
180 in PEM format.
181 -signer file
183 a signing certificate when signing or resigning a message, this
184 option can be used multiple times if more than one signer is
185 required. If a message is being verified then the signers
186 certificates will be written to this file if the verification was
187 successful.
188 -recip file
190 the recipients certificate when decrypting a message. This
191 certificate must match one of the recipients of the message or an
192 error occurs.
193 -inkey file
195 the private key to use when signing or decrypting. This must match
196 the corresponding certificate. If this option is not specified then
197 the private key must be included in the certificate file specified
198 with the -recip or -signer file. When signing this option can be
199 used multiple times to specify successive keys.
200 -passin arg
202 the private key password source. For more information about the
203 format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
204 -rand file(s)
206 a file or files containing random data used to seed the random
207 number generator, or an EGD socket (see RAND_egd(3)). Multiple
208 files can be specified separated by a OS-dependent character. The
209 separator is ; for MS-Windows, , for OpenVMS, and : for all others.
210 cert.pem...
212 one or more certificates of message recipients: used when
213 encrypting a message.
214 -to, -from, -subject
216 the relevant mail headers. These are included outside the signed
217 portion of a message so they may be included manually. If signing
218 then many S/MIME mail clients check the signers certificate's email
219 address matches that specified in the From: address.
220 -purpose, -ignore_critical, -issuer_checks, -crl_check, -crl_check_all,
222 -policy_check, -extended_crl, -x509_strict, -policy -check_ss_sig
223 Set various options of certificate chain verification. See verify
224 manual page for details.
225
227 The MIME message must be sent without any blank lines between the
228 headers and the output. Some mail programs will automatically add a
229 blank line. Piping the mail directly to sendmail is one way to achieve
230 the correct format.
231 The supplied message to be signed or encrypted must include the
233 necessary MIME headers or many S/MIME clients wont display it properly
234 (if at all). You can use the -text option to automatically add plain
235 text headers.
236 A "signed and encrypted" message is one where a signed message is then
238 encrypted. This can be produced by encrypting an already signed
239 message: see the examples section.
240 This version of the program only allows one signer per message but it
242 will verify multiple signers on received messages. Some S/MIME clients
243 choke if a message contains multiple signers. It is possible to sign
244 messages "in parallel" by signing an already signed message.
245 The options -encrypt and -decrypt reflect common usage in S/MIME
247 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
248 encrypted data is used for other purposes.
249 The -resign option uses an existing message digest when adding a new
251 signer. This means that attributes must be present in at least one
252 existing signer using the same message digest or this operation will
253 fail.
254 The -stream and -indef options enable experimental streaming I/O
256 support. As a result the encoding is BER using indefinite length
257 constructed encoding and no longer DER. Streaming is supported for the
258 -encrypt operation and the -sign operation if the content is not
259 detached.
260 Streaming is always used for the -sign operation with detached data but
262 since the content is no longer part of the PKCS#7 structure the
263 encoding remains DER.
264
266 0 the operation was completely successfully.
267 1 an error occurred parsing the command options.
269 2 one of the input files could not be read.
271 3 an error occurred creating the PKCS#7 file or when reading the MIME
273 message.
274 4 an error occurred decrypting or verifying the message.
276 5 the message was verified correctly but an error occurred writing
278 out the signers certificates.
279
281 Create a cleartext signed message:
282 openssl smime -sign -in message.txt -text -out mail.msg \
284 -signer mycert.pem
285 Create an opaque signed message:
287 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
289 -signer mycert.pem
290 Create a signed message, include some additional certificates and read
292 the private key from another file:
293 openssl smime -sign -in in.txt -text -out mail.msg \
295 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
296 Create a signed message with two signers:
298 openssl smime -sign -in message.txt -text -out mail.msg \
300 -signer mycert.pem -signer othercert.pem
301 Send a signed message under Unix directly to sendmail, including
303 headers:
304 openssl smime -sign -in in.txt -text -signer mycert.pem \
306 -from steve@openssl.org -to someone@somewhere \
307 -subject "Signed message" | sendmail someone@somewhere
308 Verify a message and extract the signer's certificate if successful:
310 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
312 Send encrypted mail using triple DES:
314 openssl smime -encrypt -in in.txt -from steve@openssl.org \
316 -to someone@somewhere -subject "Encrypted message" \
317 -des3 user.pem -out mail.msg
318 Sign and encrypt mail:
320 openssl smime -sign -in ml.txt -signer my.pem -text \
322 | openssl smime -encrypt -out mail.msg \
323 -from steve@openssl.org -to someone@somewhere \
324 -subject "Signed and Encrypted message" -des3 user.pem
325 Note: the encryption command does not include the -text option because
327 the message being encrypted already has MIME headers.
328 Decrypt mail:
330 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
332 The output from Netscape form signing is a PKCS#7 structure with the
334 detached signature format. You can use this program to verify the
335 signature by line wrapping the base64 encoded structure and surrounding
336 it with:
337 -----BEGIN PKCS7-----
339 -----END PKCS7-----
340 and using the command:
342 openssl smime -verify -inform PEM -in signature.pem -content content.txt
344 Alternatively you can base64 decode the signature and use:
346 openssl smime -verify -inform DER -in signature.der -content content.txt
348 Create an encrypted message using 128 bit Camellia:
350 openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
352 Add a signer to an existing message:
354 openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
356
358 The MIME parser isn't very clever: it seems to handle most messages
359 that I've thrown at it but it may choke on others.
360 The code currently will only write out the signer's certificate to a
362 file: if the signer has a separate encryption certificate this must be
363 manually extracted. There should be some heuristic that determines the
364 correct encryption certificate.
365 Ideally a database should be maintained of a certificates for each
367 email address.
368 The code doesn't currently take note of the permitted symmetric
370 encryption algorithms as supplied in the SMIMECapabilities signed
371 attribute. This means the user has to manually include the correct
372 encryption algorithm. It should store the list of permitted ciphers in
373 a database and only use those.
374 No revocation checking is done on the signer's certificate.
376 The current code can only handle S/MIME v2 messages, the more complex
378 S/MIME v3 structures may cause parsing errors.
379
381 The use of multiple -signer options and the -resign command were first
382 added in OpenSSL 1.0.0
3831.0.1e 2017-03-22 SMIME(1)