36 The B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and
37 verify S/MIME messages.
39 =head1 COMMAND OPTIONS
41 There are five operation options that set the type of operation to be performed.
42 The meaning of the other options varies according to the operation type.
48 encrypt mail for the given recipient certificates. Input file is the message
49 to be encrypted. The output file is the encrypted mail in MIME format.
53 decrypt mail using the supplied certificate and private key. Expects an
54 encrypted mail message in MIME format for the input file. The decrypted mail
55 is written to the output file.
59 sign mail using the supplied certificate and private key. Input file is
60 the message to be signed. The signed message in MIME format is written
65 verify signed mail. Expects a signed mail message on input and outputs
66 the signed data. Both clear text and opaque signing is supported.
70 takes an input message and writes out a PEM encoded PKCS#7 structure.
74 the input message to be encrypted or signed or the MIME message to
75 be decrypted or verified.
77 =item B<-out filename>
79 the message text that has been decrypted or verified or the output MIME
80 format message that has been signed or verified.
84 this option adds plain text (text/plain) MIME headers to the supplied
85 message if encrypting or signing. If decrypting or verifying it strips
86 off text headers: if the decrypted or verified message is not of MIME
87 type text/plain then an error occurs.
91 a file containing trusted CA certificates, only used with B<-verify>.
95 a directory containing trusted CA certificates, only used with
96 B<-verify>. This directory must be a standard certificate directory: that
97 is a hash of each subject name (using B<x509 -hash>) should be linked
100 =item B<-des -des3 -rc2-40 -rc2-64 -rc2-128>
102 the encryption algorithm to use. DES (56 bits), triple DES (168 bits)
103 or 40, 64 or 128 bit RC2 respectively if not specified 40 bit RC2 is
104 used. Only used with B<-encrypt>.
108 when verifying a message normally certificates (if any) included in
109 the message are searched for the signing certificate. With this option
110 only the certificates specified in the B<-certfile> option are used.
111 The supplied certificates can still be used as untrusted CAs however.
115 do not verify the signers certificate of a signed message.
119 do not do chain verification of signers certificates: that is don't
120 use the certificates in the signed message as untrusted CAs.
124 don't try to verify the signatures on the message.
128 when signing a message the signer's certificate is normally included
129 with this option it is excluded. This will reduce the size of the
130 signed message but the verifier must have a copy of the signers certificate
131 available locally (passed using the B<-certfile> option for example).
135 normally when a message is signed a set of attributes are included which
136 include the signing time and supported symmetric algorithms. With this
137 option they are not included.
141 normally the input message is converted to "canonical" format which is
142 effectively using CR and LF as end of line: as required by the S/MIME
143 specification. When this option is present no translation occurs. This
144 is useful when handling binary data which may not be in MIME format.
148 when signing a message use opaque signing: this form is more resistant
149 to translation by mail relays but it cannot be read by mail agents that
150 do not support S/MIME. Without this option cleartext signing with
151 the MIME type multipart/signed is used.
153 =item B<-certfile file>
155 allows additional certificates to be specified. When signing these will
156 be included with the message. When verifying these will be searched for
157 the signers certificates. The certificates should be in PEM format.
159 =item B<-signer file>
161 the signers certificate when signing a message. If a message is
162 being verified then the signers certificates will be written to this
163 file if the verification was successful.
167 the recipients certificate when decrypting a message. This certificate
168 must match one of the recipients of the message or an error occurs.
172 the private key to use when signing or decrypting. This must match the
173 corresponding certificate. If this option is not specified then the
174 private key must be included in the certificate file specified with
175 the B<-recip> or B<-signer> file.
177 =item B<-rand file(s)>
179 a file or files containing random data used to seed the random number
180 generator. Multiple files can be specified separated by a OS-dependent
181 character. For MS-Windows, the separator is B<;>. For OpenVMS, it's
182 B<,>. For all others, it's B<:>.
186 one or more certificates of message recipients: used when encrypting
189 =item B<-to, -from, -subject>
191 the relevant mail headers. These are included outside the signed
192 portion of a message so they may be included manually. If signing
193 then many S/MIME mail clients check the signers certificate's email
194 address matches that specified in the From: address.
200 The MIME message must be sent without any blank lines between the
201 headers and the output. Some mail programs will automatically add
202 a blank line. Piping the mail directly to sendmail is one way to
203 achieve the correct format.
205 The supplied message to be signed or encrypted must include the
206 necessary MIME headers: or many S/MIME clients wont display it
207 properly (if at all). You can use the B<-text> option to automatically
208 add plain text headers.
210 A "signed and encrypted" message is one where a signed message is
211 then encrypted. This can be produced by encrypting an already signed
212 message: see the examples section.
214 This version of the program only allows one signer per message but it
215 will verify multiple signers on received messages. Some S/MIME clients
216 choke if a message contains multiple signers. It is possible to sign
217 messages "in parallel" by signing an already signed message.
219 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
220 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
221 encrypted data is used for other purposes.
229 the operation was completely successfully.
233 an error occurred parsing the command options.
237 one of the input files could not be read.
241 an error occurred creating the PKCS#7 file or when reading the MIME
246 an error occurred decrypting or verifying the message.
250 the message was verified correctly but an error occurred writing out
251 the signers certificates.
257 Create a cleartext signed message:
259 openssl smime -sign -in message.txt -text -out mail.msg \
262 Create and opaque signed message
264 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
267 Create a signed message, include some additional certificates and
268 read the private key from another file:
270 openssl smime -sign -in in.txt -text -out mail.msg \
271 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
273 Send a signed message under Unix directly to sendmail, including headers:
275 openssl smime -sign -in in.txt -text -signer mycert.pem \
276 -from steve@openssl.org -to someone@somewhere \
277 -subject "Signed message" | sendmail someone@somewhere
279 Verify a message and extract the signer's certificate if successful:
281 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
283 Send encrypted mail using triple DES:
285 openssl smime -encrypt -in in.txt -from steve@openssl.org \
286 -to someone@somewhere -subject "Encrypted message" \
287 -des3 user.pem -out mail.msg
289 Sign and encrypt mail:
291 openssl smime -sign -in ml.txt -signer my.pem -text \
292 | openssl -encrypt -out mail.msg \
293 -from steve@openssl.org -to someone@somewhere \
294 -subject "Signed and Encrypted message" -des3 user.pem
296 Note: the encryption command does not include the B<-text> option because the message
297 being encrypted already has MIME headers.
301 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
305 The MIME parser isn't very clever: it seems to handle most messages that I've thrown
306 at it but it may choke on others.
308 The code currently will only write out the signer's certificate to a file: if the
309 signer has a separate encryption certificate this must be manually extracted. There
310 should be some heuristic that determines the correct encryption certificate.
312 Ideally a database should be maintained of a certificates for each email address.
314 The code doesn't currently take note of the permitted symmetric encryption
315 algorithms as supplied in the SMIMECapabilities signed attribute. this means the
316 user has to manually include the correct encryption algorithm. It should store
317 the list of permitted ciphers in a database and only use those.
319 No revocation checking is done on the signer's certificate.
321 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
322 structures may cause parsing errors.