24 [B<-inform SMIME|PEM|DER>]
28 [B<-outform SMIME|PEM|DER>]
39 The B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and
40 verify S/MIME messages.
42 =head1 COMMAND OPTIONS
44 There are five operation options that set the type of operation to be performed.
45 The meaning of the other options varies according to the operation type.
51 encrypt mail for the given recipient certificates. Input file is the message
52 to be encrypted. The output file is the encrypted mail in MIME format.
56 decrypt mail using the supplied certificate and private key. Expects an
57 encrypted mail message in MIME format for the input file. The decrypted mail
58 is written to the output file.
62 sign mail using the supplied certificate and private key. Input file is
63 the message to be signed. The signed message in MIME format is written
68 verify signed mail. Expects a signed mail message on input and outputs
69 the signed data. Both clear text and opaque signing is supported.
73 takes an input message and writes out a PEM encoded PKCS#7 structure.
77 the input message to be encrypted or signed or the MIME message to
78 be decrypted or verified.
80 =item B<-inform SMIME|PEM|DER>
82 this specifies the input format for the PKCS#7 structure. The default
83 is B<SMIME> which reads an S/MIME format message. B<PEM> and B<DER>
84 format change this to expect PEM and DER format PKCS#7 structures
85 instead. This currently only affects the input format of the PKCS#7
86 structure, if no PKCS#7 structure is being input (for example with
87 B<-encrypt> or B<-sign>) this option has no effect.
89 =item B<-out filename>
91 the message text that has been decrypted or verified or the output MIME
92 format message that has been signed or verified.
94 =item B<-outform SMIME|PEM|DER>
96 this specifies the output format for the PKCS#7 structure. The default
97 is B<SMIME> which write an S/MIME format message. B<PEM> and B<DER>
98 format change this to write PEM and DER format PKCS#7 structures
99 instead. This currently only affects the output format of the PKCS#7
100 structure, if no PKCS#7 structure is being output (for example with
101 B<-verify> or B<-decrypt>) this option has no effect.
103 =item B<-content filename>
105 This specifies a file containing the detached content, this is only
106 useful with the B<-verify> command. This is only usable if the PKCS#7
107 structure is using the detached signature form where the content is
108 not included. This option will override any content if the input format
109 is S/MIME and it uses the multipart/signed MIME content type.
113 this option adds plain text (text/plain) MIME headers to the supplied
114 message if encrypting or signing. If decrypting or verifying it strips
115 off text headers: if the decrypted or verified message is not of MIME
116 type text/plain then an error occurs.
118 =item B<-CAfile file>
120 a file containing trusted CA certificates, only used with B<-verify>.
124 a directory containing trusted CA certificates, only used with
125 B<-verify>. This directory must be a standard certificate directory: that
126 is a hash of each subject name (using B<x509 -hash>) should be linked
129 =item B<-des -des3 -rc2-40 -rc2-64 -rc2-128>
131 the encryption algorithm to use. DES (56 bits), triple DES (168 bits)
132 or 40, 64 or 128 bit RC2 respectively if not specified 40 bit RC2 is
133 used. Only used with B<-encrypt>.
137 when verifying a message normally certificates (if any) included in
138 the message are searched for the signing certificate. With this option
139 only the certificates specified in the B<-certfile> option are used.
140 The supplied certificates can still be used as untrusted CAs however.
144 do not verify the signers certificate of a signed message.
148 do not do chain verification of signers certificates: that is don't
149 use the certificates in the signed message as untrusted CAs.
153 don't try to verify the signatures on the message.
157 when signing a message the signer's certificate is normally included
158 with this option it is excluded. This will reduce the size of the
159 signed message but the verifier must have a copy of the signers certificate
160 available locally (passed using the B<-certfile> option for example).
164 normally when a message is signed a set of attributes are included which
165 include the signing time and supported symmetric algorithms. With this
166 option they are not included.
170 normally the input message is converted to "canonical" format which is
171 effectively using CR and LF as end of line: as required by the S/MIME
172 specification. When this option is present no translation occurs. This
173 is useful when handling binary data which may not be in MIME format.
177 when signing a message use opaque signing: this form is more resistant
178 to translation by mail relays but it cannot be read by mail agents that
179 do not support S/MIME. Without this option cleartext signing with
180 the MIME type multipart/signed is used.
182 =item B<-certfile file>
184 allows additional certificates to be specified. When signing these will
185 be included with the message. When verifying these will be searched for
186 the signers certificates. The certificates should be in PEM format.
188 =item B<-signer file>
190 the signers certificate when signing a message. If a message is
191 being verified then the signers certificates will be written to this
192 file if the verification was successful.
196 the recipients certificate when decrypting a message. This certificate
197 must match one of the recipients of the message or an error occurs.
201 the private key to use when signing or decrypting. This must match the
202 corresponding certificate. If this option is not specified then the
203 private key must be included in the certificate file specified with
204 the B<-recip> or B<-signer> file.
208 the private key password source. For more information about the format of B<arg>
209 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
211 =item B<-rand file(s)>
213 a file or files containing random data used to seed the random number
214 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
215 Multiple files can be specified separated by a OS-dependent character.
216 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
221 one or more certificates of message recipients: used when encrypting
224 =item B<-to, -from, -subject>
226 the relevant mail headers. These are included outside the signed
227 portion of a message so they may be included manually. If signing
228 then many S/MIME mail clients check the signers certificate's email
229 address matches that specified in the From: address.
235 The MIME message must be sent without any blank lines between the
236 headers and the output. Some mail programs will automatically add
237 a blank line. Piping the mail directly to sendmail is one way to
238 achieve the correct format.
240 The supplied message to be signed or encrypted must include the
241 necessary MIME headers or many S/MIME clients wont display it
242 properly (if at all). You can use the B<-text> option to automatically
243 add plain text headers.
245 A "signed and encrypted" message is one where a signed message is
246 then encrypted. This can be produced by encrypting an already signed
247 message: see the examples section.
249 This version of the program only allows one signer per message but it
250 will verify multiple signers on received messages. Some S/MIME clients
251 choke if a message contains multiple signers. It is possible to sign
252 messages "in parallel" by signing an already signed message.
254 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
255 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
256 encrypted data is used for other purposes.
264 the operation was completely successfully.
268 an error occurred parsing the command options.
272 one of the input files could not be read.
276 an error occurred creating the PKCS#7 file or when reading the MIME
281 an error occurred decrypting or verifying the message.
285 the message was verified correctly but an error occurred writing out
286 the signers certificates.
292 Create a cleartext signed message:
294 openssl smime -sign -in message.txt -text -out mail.msg \
297 Create and opaque signed message
299 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
302 Create a signed message, include some additional certificates and
303 read the private key from another file:
305 openssl smime -sign -in in.txt -text -out mail.msg \
306 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
308 Send a signed message under Unix directly to sendmail, including headers:
310 openssl smime -sign -in in.txt -text -signer mycert.pem \
311 -from steve@openssl.org -to someone@somewhere \
312 -subject "Signed message" | sendmail someone@somewhere
314 Verify a message and extract the signer's certificate if successful:
316 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
318 Send encrypted mail using triple DES:
320 openssl smime -encrypt -in in.txt -from steve@openssl.org \
321 -to someone@somewhere -subject "Encrypted message" \
322 -des3 user.pem -out mail.msg
324 Sign and encrypt mail:
326 openssl smime -sign -in ml.txt -signer my.pem -text \
327 | openssl smime -encrypt -out mail.msg \
328 -from steve@openssl.org -to someone@somewhere \
329 -subject "Signed and Encrypted message" -des3 user.pem
331 Note: the encryption command does not include the B<-text> option because the message
332 being encrypted already has MIME headers.
336 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
338 The output from Netscape form signing is a PKCS#7 structure with the
339 detached signature format. You can use this program to verify the
340 signature by line wrapping the base64 encoded structure and surrounding
343 -----BEGIN PKCS7-----
346 and using the command,
348 openssl smime -verify -inform PEM -in signature.pem -content content.txt
350 alternatively you can base64 decode the signature and use
352 openssl smime -verify -inform DER -in signature.der -content content.txt
356 The MIME parser isn't very clever: it seems to handle most messages that I've thrown
357 at it but it may choke on others.
359 The code currently will only write out the signer's certificate to a file: if the
360 signer has a separate encryption certificate this must be manually extracted. There
361 should be some heuristic that determines the correct encryption certificate.
363 Ideally a database should be maintained of a certificates for each email address.
365 The code doesn't currently take note of the permitted symmetric encryption
366 algorithms as supplied in the SMIMECapabilities signed attribute. this means the
367 user has to manually include the correct encryption algorithm. It should store
368 the list of permitted ciphers in a database and only use those.
370 No revocation checking is done on the signer's certificate.
372 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
373 structures may cause parsing errors.