1SMIME(1) OpenSSL SMIME(1)
2
6 smime - S/MIME utility
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9 openssl smime [-encrypt] [-decrypt] [-sign] [-verify] [-pk7out] [-des]
10 [-des3] [-rc2-40] [-rc2-64] [-rc2-128] [-aes128] [-aes192] [-aes256]
11 [-in file] [-certfile file] [-signer file] [-recip file] [-inform
12 SMIME⎪PEM⎪DER] [-passin arg] [-inkey file] [-out file] [-outform
13 SMIME⎪PEM⎪DER] [-content file] [-to addr] [-from ad] [-subject s]
14 [-text] [-rand file(s)] [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 five 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 out‐
42 puts the signed data. Both clear text and opaque signing is sup‐
43 ported.
44 -pk7out
46 takes an input message and writes out a PEM encoded PKCS#7 struc‐
47 ture.
48 -in filename
50 the input message to be encrypted or signed or the MIME message to
51 be decrypted or verified.
52 -inform SMIME⎪PEM⎪DER
54 this specifies the input format for the PKCS#7 structure. The
55 default is SMIME which reads an S/MIME format message. PEM and DER
56 format change this to expect PEM and DER format PKCS#7 structures
57 instead. This currently only affects the input format of the PKCS#7
58 structure, if no PKCS#7 structure is being input (for example with
59 -encrypt or -sign) this option has no effect.
60 -out filename
62 the message text that has been decrypted or verified or the output
63 MIME format message that has been signed or verified.
64 -outform SMIME⎪PEM⎪DER
66 this specifies the output format for the PKCS#7 structure. The
67 default is SMIME which write an S/MIME format message. PEM and DER
68 format change this to write PEM and DER format PKCS#7 structures
69 instead. This currently only affects the output format of the
70 PKCS#7 structure, if no PKCS#7 structure is being output (for exam‐
71 ple with -verify or -decrypt) this option has no effect.
72 -content filename
74 This specifies a file containing the detached content, this is only
75 useful with the -verify command. This is only usable if the PKCS#7
76 structure is using the detached signature form where the content is
77 not included. This option will override any content if the input
78 format is S/MIME and it uses the multipart/signed MIME content
79 type.
80 -text
82 this option adds plain text (text/plain) MIME headers to the sup‐
83 plied message if encrypting or signing. If decrypting or verifying
84 it strips off text headers: if the decrypted or verified message is
85 not of MIME type text/plain then an error occurs.
86 -CAfile file
88 a file containing trusted CA certificates, only used with -verify.
89 -CApath dir
91 a directory containing trusted CA certificates, only used with
92 -verify. This directory must be a standard certificate directory:
93 that is a hash of each subject name (using x509 -hash) should be
94 linked to each certificate.
95 -des -des3 -rc2-40 -rc2-64 -rc2-128 -aes128 -aes192 -aes256
97 the encryption algorithm to use. DES (56 bits), triple DES (168
98 bits), 40, 64 or 128 bit RC2 or 128, 192 or 256 bit AES respec‐
99 tively. If not specified 40 bit RC2 is used. Only used with
100 -encrypt.
101 -nointern
103 when verifying a message normally certificates (if any) included in
104 the message are searched for the signing certificate. With this
105 option only the certificates specified in the -certfile option are
106 used. The supplied certificates can still be used as untrusted CAs
107 however.
108 -noverify
110 do not verify the signers certificate of a signed message.
111 -nochain
113 do not do chain verification of signers certificates: that is don't
114 use the certificates in the signed message as untrusted CAs.
115 -nosigs
117 don't try to verify the signatures on the message.
118 -nocerts
120 when signing a message the signer's certificate is normally
121 included with this option it is excluded. This will reduce the size
122 of the signed message but the verifier must have a copy of the
123 signers certificate available locally (passed using the -certfile
124 option for example).
125 -noattr
127 normally when a message is signed a set of attributes are included
128 which include the signing time and supported symmetric algorithms.
129 With this option they are not included.
130 -binary
132 normally the input message is converted to "canonical" format which
133 is effectively using CR and LF as end of line: as required by the
134 S/MIME specification. When this option is present no translation
135 occurs. This is useful when handling binary data which may not be
136 in MIME format.
137 -nodetach
139 when signing a message use opaque signing: this form is more resis‐
140 tant to translation by mail relays but it cannot be read by mail
141 agents that do not support S/MIME. Without this option cleartext
142 signing with the MIME type multipart/signed is used.
143 -certfile file
145 allows additional certificates to be specified. When signing these
146 will be included with the message. When verifying these will be
147 searched for the signers certificates. The certificates should be
148 in PEM format.
149 -signer file
151 the signers certificate when signing a message. If a message is
152 being verified then the signers certificates will be written to
153 this file if the verification was successful.
154 -recip file
156 the recipients certificate when decrypting a message. This certifi‐
157 cate must match one of the recipients of the message or an error
158 occurs.
159 -inkey file
161 the private key to use when signing or decrypting. This must match
162 the corresponding certificate. If this option is not specified then
163 the private key must be included in the certificate file specified
164 with the -recip or -signer file.
165 -passin arg
167 the private key password source. For more information about the
168 format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
169 -rand file(s)
171 a file or files containing random data used to seed the random num‐
172 ber generator, or an EGD socket (see RAND_egd(3)). Multiple files
173 can be specified separated by a OS-dependent character. The sepa‐
174 rator is ; for MS-Windows, , for OpenVMS, and : for all others.
175 cert.pem...
177 one or more certificates of message recipients: used when encrypt‐
178 ing a message.
179 -to, -from, -subject
181 the relevant mail headers. These are included outside the signed
182 portion of a message so they may be included manually. If signing
183 then many S/MIME mail clients check the signers certificate's email
184 address matches that specified in the From: address.
185
187 The MIME message must be sent without any blank lines between the head‐
188 ers and the output. Some mail programs will automatically add a blank
189 line. Piping the mail directly to sendmail is one way to achieve the
190 correct format.
191 The supplied message to be signed or encrypted must include the neces‐
193 sary MIME headers or many S/MIME clients wont display it properly (if
194 at all). You can use the -text option to automatically add plain text
195 headers.
196 A "signed and encrypted" message is one where a signed message is then
198 encrypted. This can be produced by encrypting an already signed mes‐
199 sage: see the examples section.
200 This version of the program only allows one signer per message but it
202 will verify multiple signers on received messages. Some S/MIME clients
203 choke if a message contains multiple signers. It is possible to sign
204 messages "in parallel" by signing an already signed message.
205 The options -encrypt and -decrypt reflect common usage in S/MIME
207 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
208 encrypted data is used for other purposes.
209
211 0 the operation was completely successfully.
212 1 an error occurred parsing the command options.
214 2 one of the input files could not be read.
216 3 an error occurred creating the PKCS#7 file or when reading the MIME
218 message.
219 4 an error occurred decrypting or verifying the message.
221 5 the message was verified correctly but an error occurred writing
223 out the signers certificates.
224
226 Create a cleartext signed message:
227 openssl smime -sign -in message.txt -text -out mail.msg \
229 -signer mycert.pem
230 Create and opaque signed message
232 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
234 -signer mycert.pem
235 Create a signed message, include some additional certificates and read
237 the private key from another file:
238 openssl smime -sign -in in.txt -text -out mail.msg \
240 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
241 Send a signed message under Unix directly to sendmail, including head‐
243 ers:
244 openssl smime -sign -in in.txt -text -signer mycert.pem \
246 -from steve@openssl.org -to someone@somewhere \
247 -subject "Signed message" ⎪ sendmail someone@somewhere
248 Verify a message and extract the signer's certificate if successful:
250 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
252 Send encrypted mail using triple DES:
254 openssl smime -encrypt -in in.txt -from steve@openssl.org \
256 -to someone@somewhere -subject "Encrypted message" \
257 -des3 user.pem -out mail.msg
258 Sign and encrypt mail:
260 openssl smime -sign -in ml.txt -signer my.pem -text \
262 ⎪ openssl smime -encrypt -out mail.msg \
263 -from steve@openssl.org -to someone@somewhere \
264 -subject "Signed and Encrypted message" -des3 user.pem
265 Note: the encryption command does not include the -text option because
267 the message being encrypted already has MIME headers.
268 Decrypt mail:
270 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
272 The output from Netscape form signing is a PKCS#7 structure with the
274 detached signature format. You can use this program to verify the sig‐
275 nature by line wrapping the base64 encoded structure and surrounding it
276 with:
277 -----BEGIN PKCS7-----
279 -----END PKCS7-----
280 and using the command,
282 openssl smime -verify -inform PEM -in signature.pem -content content.txt
284 alternatively you can base64 decode the signature and use
286 openssl smime -verify -inform DER -in signature.der -content content.txt
288
290 The MIME parser isn't very clever: it seems to handle most messages
291 that I've thrown at it but it may choke on others.
292 The code currently will only write out the signer's certificate to a
294 file: if the signer has a separate encryption certificate this must be
295 manually extracted. There should be some heuristic that determines the
296 correct encryption certificate.
297 Ideally a database should be maintained of a certificates for each
299 email address.
300 The code doesn't currently take note of the permitted symmetric encryp‐
302 tion algorithms as supplied in the SMIMECapabilities signed attribute.
303 this means the user has to manually include the correct encryption
304 algorithm. It should store the list of permitted ciphers in a database
305 and only use those.
306 No revocation checking is done on the signer's certificate.
308 The current code can only handle S/MIME v2 messages, the more complex
310 S/MIME v3 structures may cause parsing errors.
3110.9.8b 2004-02-26 SMIME(1)