25 [B<-inform SMIME|PEM|DER>]
29 [B<-outform SMIME|PEM|DER>]
40 The B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and
41 verify S/MIME messages.
43 =head1 COMMAND OPTIONS
45 There are five operation options that set the type of operation to be performed.
46 The meaning of the other options varies according to the operation type.
52 encrypt mail for the given recipient certificates. Input file is the message
53 to be encrypted. The output file is the encrypted mail in MIME format.
57 decrypt mail using the supplied certificate and private key. Expects an
58 encrypted mail message in MIME format for the input file. The decrypted mail
59 is written to the output file.
63 sign mail using the supplied certificate and private key. Input file is
64 the message to be signed. The signed message in MIME format is written
69 verify signed mail. Expects a signed mail message on input and outputs
70 the signed data. Both clear text and opaque signing is supported.
74 takes an input message and writes out a PEM encoded PKCS#7 structure.
78 the input message to be encrypted or signed or the MIME message to
79 be decrypted or verified.
81 =item B<-inform SMIME|PEM|DER>
83 this specifies the input format for the PKCS#7 structure. The default
84 is B<SMIME> which reads an S/MIME format message. B<PEM> and B<DER>
85 format change this to expect PEM and DER format PKCS#7 structures
86 instead. This currently only affects the input format of the PKCS#7
87 structure, if no PKCS#7 structure is being input (for example with
88 B<-encrypt> or B<-sign>) this option has no effect.
90 =item B<-out filename>
92 the message text that has been decrypted or verified or the output MIME
93 format message that has been signed or verified.
95 =item B<-outform SMIME|PEM|DER>
97 this specifies the output format for the PKCS#7 structure. The default
98 is B<SMIME> which write an S/MIME format message. B<PEM> and B<DER>
99 format change this to write PEM and DER format PKCS#7 structures
100 instead. This currently only affects the output format of the PKCS#7
101 structure, if no PKCS#7 structure is being output (for example with
102 B<-verify> or B<-decrypt>) this option has no effect.
104 =item B<-content filename>
106 This specifies a file containing the detached content, this is only
107 useful with the B<-verify> command. This is only usable if the PKCS#7
108 structure is using the detached signature form where the content is
109 not included. This option will override any content if the input format
110 is S/MIME and it uses the multipart/signed MIME content type.
114 this option adds plain text (text/plain) MIME headers to the supplied
115 message if encrypting or signing. If decrypting or verifying it strips
116 off text headers: if the decrypted or verified message is not of MIME
117 type text/plain then an error occurs.
119 =item B<-CAfile file>
121 a file containing trusted CA certificates, only used with B<-verify>.
125 a directory containing trusted CA certificates, only used with
126 B<-verify>. This directory must be a standard certificate directory: that
127 is a hash of each subject name (using B<x509 -hash>) should be linked
130 =item B<-des -des3 -rc2-40 -rc2-64 -rc2-128>
132 the encryption algorithm to use. DES (56 bits), triple DES (168 bits)
133 or 40, 64 or 128 bit RC2 respectively if not specified 40 bit RC2 is
134 used. Only used with B<-encrypt>.
138 when verifying a message normally certificates (if any) included in
139 the message are searched for the signing certificate. With this option
140 only the certificates specified in the B<-certfile> option are used.
141 The supplied certificates can still be used as untrusted CAs however.
145 do not verify the signers certificate of a signed message.
149 do not do chain verification of signers certificates: that is don't
150 use the certificates in the signed message as untrusted CAs.
154 don't try to verify the signatures on the message.
158 when signing a message the signer's certificate is normally included
159 with this option it is excluded. This will reduce the size of the
160 signed message but the verifier must have a copy of the signers certificate
161 available locally (passed using the B<-certfile> option for example).
165 normally when a message is signed a set of attributes are included which
166 include the signing time and supported symmetric algorithms. With this
167 option they are not included.
171 normally the input message is converted to "canonical" format which is
172 effectively using CR and LF as end of line: as required by the S/MIME
173 specification. When this option is present no translation occurs. This
174 is useful when handling binary data which may not be in MIME format.
178 when signing a message use opaque signing: this form is more resistant
179 to translation by mail relays but it cannot be read by mail agents that
180 do not support S/MIME. Without this option cleartext signing with
181 the MIME type multipart/signed is used.
183 =item B<-certfile file>
185 allows additional certificates to be specified. When signing these will
186 be included with the message. When verifying these will be searched for
187 the signers certificates. The certificates should be in PEM format.
189 =item B<-signer file>
191 the signers certificate when signing a message. If a message is
192 being verified then the signers certificates will be written to this
193 file if the verification was successful.
197 the recipients certificate when decrypting a message. This certificate
198 must match one of the recipients of the message or an error occurs.
202 the private key to use when signing or decrypting. This must match the
203 corresponding certificate. If this option is not specified then the
204 private key must be included in the certificate file specified with
205 the B<-recip> or B<-signer> file.
209 the private key password source. For more information about the format of B<arg>
210 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
212 =item B<-rand file(s)>
214 a file or files containing random data used to seed the random number
215 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
216 Multiple files can be specified separated by a OS-dependent character.
217 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
222 one or more certificates of message recipients: used when encrypting
225 =item B<-to, -from, -subject>
227 the relevant mail headers. These are included outside the signed
228 portion of a message so they may be included manually. If signing
229 then many S/MIME mail clients check the signers certificate's email
230 address matches that specified in the From: address.
236 The MIME message must be sent without any blank lines between the
237 headers and the output. Some mail programs will automatically add
238 a blank line. Piping the mail directly to sendmail is one way to
239 achieve the correct format.
241 The supplied message to be signed or encrypted must include the
242 necessary MIME headers or many S/MIME clients wont display it
243 properly (if at all). You can use the B<-text> option to automatically
244 add plain text headers.
246 A "signed and encrypted" message is one where a signed message is
247 then encrypted. This can be produced by encrypting an already signed
248 message: see the examples section.
250 This version of the program only allows one signer per message but it
251 will verify multiple signers on received messages. Some S/MIME clients
252 choke if a message contains multiple signers. It is possible to sign
253 messages "in parallel" by signing an already signed message.
255 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
256 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
257 encrypted data is used for other purposes.
265 the operation was completely successfully.
269 an error occurred parsing the command options.
273 one of the input files could not be read.
277 an error occurred creating the PKCS#7 file or when reading the MIME
282 an error occurred decrypting or verifying the message.
286 the message was verified correctly but an error occurred writing out
287 the signers certificates.
293 Create a cleartext signed message:
295 openssl smime -sign -in message.txt -text -out mail.msg \
298 Create and opaque signed message
300 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
303 Create a signed message, include some additional certificates and
304 read the private key from another file:
306 openssl smime -sign -in in.txt -text -out mail.msg \
307 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
309 Send a signed message under Unix directly to sendmail, including headers:
311 openssl smime -sign -in in.txt -text -signer mycert.pem \
312 -from steve@openssl.org -to someone@somewhere \
313 -subject "Signed message" | sendmail someone@somewhere
315 Verify a message and extract the signer's certificate if successful:
317 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
319 Send encrypted mail using triple DES:
321 openssl smime -encrypt -in in.txt -from steve@openssl.org \
322 -to someone@somewhere -subject "Encrypted message" \
323 -des3 user.pem -out mail.msg
325 Sign and encrypt mail:
327 openssl smime -sign -in ml.txt -signer my.pem -text \
328 | openssl -encrypt -out mail.msg \
329 -from steve@openssl.org -to someone@somewhere \
330 -subject "Signed and Encrypted message" -des3 user.pem
332 Note: the encryption command does not include the B<-text> option because the message
333 being encrypted already has MIME headers.
337 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
339 The output from Netscape form signing is a PKCS#7 structure with the
340 detached signature format. You can use this program to verify the
341 signature by line wrapping the base64 encoded structure and surrounding
347 and using the command,
349 openssl smime -verify -inform PEM -in signature.pem -content content.txt
351 alternatively you can base64 decode the signature and use
353 openssl smime -verify -inform DER -in signature.der -content content.txt
357 The MIME parser isn't very clever: it seems to handle most messages that I've thrown
358 at it but it may choke on others.
360 The code currently will only write out the signer's certificate to a file: if the
361 signer has a separate encryption certificate this must be manually extracted. There
362 should be some heuristic that determines the correct encryption certificate.
364 Ideally a database should be maintained of a certificates for each email address.
366 The code doesn't currently take note of the permitted symmetric encryption
367 algorithms as supplied in the SMIMECapabilities signed attribute. this means the
368 user has to manually include the correct encryption algorithm. It should store
369 the list of permitted ciphers in a database and only use those.
371 No revocation checking is done on the signer's certificate.
373 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
374 structures may cause parsing errors.