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] [-certfile file] [-signer file]
11 [-recip file] [-inform SMIME|PEM|DER] [-passin arg] [-inkey file]
12 [-out file] [-outform SMIME|PEM|DER] [-content file] [-to addr] [-from
13 ad] [-subject s] [-text] [-indef] [-noindef] [-stream] [-rand file(s)]
14 [-md digest] [cert.pem]...
15
17 The smime command handles S/MIME mail. It can encrypt, decrypt, sign
18 and verify S/MIME messages.
19
21 There are six operation options that set the type of operation to be
22 performed. The meaning of the other options varies according to the
23 operation type.
24 -encrypt
26 encrypt mail for the given recipient certificates. Input file is
27 the message to be encrypted. The output file is the encrypted mail
28 in MIME format.
29 -decrypt
31 decrypt mail using the supplied certificate and private key.
32 Expects an encrypted mail message in MIME format for the input
33 file. The decrypted mail is written to the output file.
34 -sign
36 sign mail using the supplied certificate and private key. Input
37 file is the message to be signed. The signed message in MIME format
38 is written to the output file.
39 -verify
41 verify signed mail. Expects a signed mail message on input and
42 outputs the signed data. Both clear text and opaque signing is
43 supported.
44 -pk7out
46 takes an input message and writes out a PEM encoded PKCS#7
47 structure.
48 -resign
50 resign a message: take an existing message and one or more new
51 signers.
52 -in filename
54 the input message to be encrypted or signed or the MIME message to
55 be decrypted or verified.
56 -inform SMIME|PEM|DER
58 this specifies the input format for the PKCS#7 structure. The
59 default is SMIME which reads an S/MIME format message. PEM and DER
60 format change this to expect PEM and DER format PKCS#7 structures
61 instead. This currently only affects the input format of the PKCS#7
62 structure, if no PKCS#7 structure is being input (for example with
63 -encrypt or -sign) this option has no effect.
64 -out filename
66 the message text that has been decrypted or verified or the output
67 MIME format message that has been signed or verified.
68 -outform SMIME|PEM|DER
70 this specifies the output format for the PKCS#7 structure. The
71 default is SMIME which write an S/MIME format message. PEM and DER
72 format change this to write PEM and DER format PKCS#7 structures
73 instead. This currently only affects the output format of the
74 PKCS#7 structure, if no PKCS#7 structure is being output (for
75 example with -verify or -decrypt) this option has no effect.
76 -stream -indef -noindef
78 the -stream and -indef options are equivalent and enable streaming
79 I/O for encoding operations. This permits single pass processing of
80 data without the need to hold the entire contents in memory,
81 potentially supporting very large files. Streaming is automatically
82 set for S/MIME signing with detached data if the output format is
83 SMIME it is currently off by default for all other operations.
84 -noindef
86 disable streaming I/O where it would produce and indefinite length
87 constructed encoding. This option currently has no effect. In
88 future streaming will be enabled by default on all relevant
89 operations and this option will disable it.
90 -content filename
92 This specifies a file containing the detached content, this is only
93 useful with the -verify command. This is only usable if the PKCS#7
94 structure is using the detached signature form where the content is
95 not included. This option will override any content if the input
96 format is S/MIME and it uses the multipart/signed MIME content
97 type.
98 -text
100 this option adds plain text (text/plain) MIME headers to the
101 supplied message if encrypting or signing. If decrypting or
102 verifying it strips off text headers: if the decrypted or verified
103 message is not of MIME type text/plain then an error occurs.
104 -CAfile file
106 a file containing trusted CA certificates, only used with -verify.
107 -CApath dir
109 a directory containing trusted CA certificates, only used with
110 -verify. This directory must be a standard certificate directory:
111 that is a hash of each subject name (using x509 -hash) should be
112 linked to each certificate.
113 -md digest
115 digest algorithm to use when signing or resigning. If not present
116 then the default digest algorithm for the signing key will be used
117 (usually SHA1).
118 -[cipher]
120 the encryption algorithm to use. For example DES (56 bits) - -des,
121 triple DES (168 bits) - -des3, EVP_get_cipherbyname() function) can
122 also be used preceded by a dash, for example -aes_128_cbc. See enc
123 for list of ciphers supported by your version of OpenSSL.
124 If not specified 40 bit RC2 is used. Only used with -encrypt.
126 -nointern
128 when verifying a message normally certificates (if any) included in
129 the message are searched for the signing certificate. With this
130 option only the certificates specified in the -certfile option are
131 used. The supplied certificates can still be used as untrusted CAs
132 however.
133 -noverify
135 do not verify the signers certificate of a signed message.
136 -nochain
138 do not do chain verification of signers certificates: that is don't
139 use the certificates in the signed message as untrusted CAs.
140 -nosigs
142 don't try to verify the signatures on the message.
143 -nocerts
145 when signing a message the signer's certificate is normally
146 included with this option it is excluded. This will reduce the size
147 of the signed message but the verifier must have a copy of the
148 signers certificate available locally (passed using the -certfile
149 option for example).
150 -noattr
152 normally when a message is signed a set of attributes are included
153 which include the signing time and supported symmetric algorithms.
154 With this option they are not included.
155 -binary
157 normally the input message is converted to "canonical" format which
158 is effectively using CR and LF as end of line: as required by the
159 S/MIME specification. When this option is present no translation
160 occurs. This is useful when handling binary data which may not be
161 in MIME format.
162 -nodetach
164 when signing a message use opaque signing: this form is more
165 resistant to translation by mail relays but it cannot be read by
166 mail agents that do not support S/MIME. Without this option
167 cleartext signing with the MIME type multipart/signed is used.
168 -certfile file
170 allows additional certificates to be specified. When signing these
171 will be included with the message. When verifying these will be
172 searched for the signers certificates. The certificates should be
173 in PEM format.
174 -signer file
176 a signing certificate when signing or resigning a message, this
177 option can be used multiple times if more than one signer is
178 required. If a message is being verified then the signers
179 certificates will be written to this file if the verification was
180 successful.
181 -recip file
183 the recipients certificate when decrypting a message. This
184 certificate must match one of the recipients of the message or an
185 error occurs.
186 -inkey file
188 the private key to use when signing or decrypting. This must match
189 the corresponding certificate. If this option is not specified then
190 the private key must be included in the certificate file specified
191 with the -recip or -signer file. When signing this option can be
192 used multiple times to specify successive keys.
193 -passin arg
195 the private key password source. For more information about the
196 format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
197 -rand file(s)
199 a file or files containing random data used to seed the random
200 number generator, or an EGD socket (see RAND_egd(3)). Multiple
201 files can be specified separated by a OS-dependent character. The
202 separator is ; for MS-Windows, , for OpenVMS, and : for all others.
203 cert.pem...
205 one or more certificates of message recipients: used when
206 encrypting a message.
207 -to, -from, -subject
209 the relevant mail headers. These are included outside the signed
210 portion of a message so they may be included manually. If signing
211 then many S/MIME mail clients check the signers certificate's email
212 address matches that specified in the From: address.
213 -purpose, -ignore_critical, -issuer_checks, -crl_check, -crl_check_all,
215 -policy_check, -extended_crl, -x509_strict, -policy -check_ss_sig
216 Set various options of certificate chain verification. See verify
217 manual page for details.
218
220 The MIME message must be sent without any blank lines between the
221 headers and the output. Some mail programs will automatically add a
222 blank line. Piping the mail directly to sendmail is one way to achieve
223 the correct format.
224 The supplied message to be signed or encrypted must include the
226 necessary MIME headers or many S/MIME clients wont display it properly
227 (if at all). You can use the -text option to automatically add plain
228 text headers.
229 A "signed and encrypted" message is one where a signed message is then
231 encrypted. This can be produced by encrypting an already signed
232 message: see the examples section.
233 This version of the program only allows one signer per message but it
235 will verify multiple signers on received messages. Some S/MIME clients
236 choke if a message contains multiple signers. It is possible to sign
237 messages "in parallel" by signing an already signed message.
238 The options -encrypt and -decrypt reflect common usage in S/MIME
240 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
241 encrypted data is used for other purposes.
242 The -resign option uses an existing message digest when adding a new
244 signer. This means that attributes must be present in at least one
245 existing signer using the same message digest or this operation will
246 fail.
247 The -stream and -indef options enable experimental streaming I/O
249 support. As a result the encoding is BER using indefinite length
250 constructed encoding and no longer DER. Streaming is supported for the
251 -encrypt operation and the -sign operation if the content is not
252 detached.
253 Streaming is always used for the -sign operation with detached data but
255 since the content is no longer part of the PKCS#7 structure the
256 encoding remains DER.
257
259 0 the operation was completely successfully.
260 1 an error occurred parsing the command options.
262 2 one of the input files could not be read.
264 3 an error occurred creating the PKCS#7 file or when reading the MIME
266 message.
267 4 an error occurred decrypting or verifying the message.
269 5 the message was verified correctly but an error occurred writing
271 out the signers certificates.
272
274 Create a cleartext signed message:
275 openssl smime -sign -in message.txt -text -out mail.msg \
277 -signer mycert.pem
278 Create an opaque signed message:
280 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
282 -signer mycert.pem
283 Create a signed message, include some additional certificates and read
285 the private key from another file:
286 openssl smime -sign -in in.txt -text -out mail.msg \
288 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
289 Create a signed message with two signers:
291 openssl smime -sign -in message.txt -text -out mail.msg \
293 -signer mycert.pem -signer othercert.pem
294 Send a signed message under Unix directly to sendmail, including
296 headers:
297 openssl smime -sign -in in.txt -text -signer mycert.pem \
299 -from steve@openssl.org -to someone@somewhere \
300 -subject "Signed message" | sendmail someone@somewhere
301 Verify a message and extract the signer's certificate if successful:
303 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
305 Send encrypted mail using triple DES:
307 openssl smime -encrypt -in in.txt -from steve@openssl.org \
309 -to someone@somewhere -subject "Encrypted message" \
310 -des3 user.pem -out mail.msg
311 Sign and encrypt mail:
313 openssl smime -sign -in ml.txt -signer my.pem -text \
315 | openssl smime -encrypt -out mail.msg \
316 -from steve@openssl.org -to someone@somewhere \
317 -subject "Signed and Encrypted message" -des3 user.pem
318 Note: the encryption command does not include the -text option because
320 the message being encrypted already has MIME headers.
321 Decrypt mail:
323 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
325 The output from Netscape form signing is a PKCS#7 structure with the
327 detached signature format. You can use this program to verify the
328 signature by line wrapping the base64 encoded structure and surrounding
329 it with:
330 -----BEGIN PKCS7-----
332 -----END PKCS7-----
333 and using the command:
335 openssl smime -verify -inform PEM -in signature.pem -content content.txt
337 Alternatively you can base64 decode the signature and use:
339 openssl smime -verify -inform DER -in signature.der -content content.txt
341 Create an encrypted message using 128 bit Camellia:
343 openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
345 Add a signer to an existing message:
347 openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
349
351 The MIME parser isn't very clever: it seems to handle most messages
352 that I've thrown at it but it may choke on others.
353 The code currently will only write out the signer's certificate to a
355 file: if the signer has a separate encryption certificate this must be
356 manually extracted. There should be some heuristic that determines the
357 correct encryption certificate.
358 Ideally a database should be maintained of a certificates for each
360 email address.
361 The code doesn't currently take note of the permitted symmetric
363 encryption algorithms as supplied in the SMIMECapabilities signed
364 attribute. This means the user has to manually include the correct
365 encryption algorithm. It should store the list of permitted ciphers in
366 a database and only use those.
367 No revocation checking is done on the signer's certificate.
369 The current code can only handle S/MIME v2 messages, the more complex
371 S/MIME v3 structures may cause parsing errors.
372
374 The use of multiple -signer options and the -resign command were first
375 added in OpenSSL 1.0.0
3761.0.0e 2010-10-04 SMIME(1)