35 The B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and
36 verify S/MIME messages.
38 =head1 COMMAND OPTIONS
40 There are five operation options that set the type of operation to be performed.
41 The meaning of the other options varies according to the operation type.
47 encrypt mail for the given recipient certificates. Input file is the message
48 to be encrypted. The output file is the encrypted mail in MIME format.
52 decrypt mail using the supplied certificate and private key. Expects an
53 encrypted mail message in MIME format for the input file. The decrypted mail
54 is written to the output file.
58 sign mail using the supplied certificate and private key. Input file is
59 the message to be signed. The signed message in MIME format is written
64 verify signed mail. Expects a signed mail message on input and outputs
65 the signed data. Both clear text and opaque signing is supported.
69 takes an input message and writes out a PEM encoded PKCS#7 structure.
73 the input message to be encrypted or signed or the MIME message to
74 be decrypted or verified.
76 =item B<-out filename>
78 the message text that has been decrypted or verified or the output MIME
79 format message that has been signed or verified.
83 this option adds plain text (text/plain) MIME headers to the supplied
84 message if encrypting or signing. If decrypting or verifying it strips
85 off text headers: if the decrypted or verified message is not of MIME
86 type text/plain then an error occurs.
90 a file containing trusted CA certificates, only used with B<-verify>.
94 a directory containing trusted CA certificates, only used with
95 B<-verify>. This directory must be a standard certificate directory: that
96 is a hash of each subject name (using B<x509 -hash>) should be linked
99 =item B<-des -des3 -rc2-40 -rc2-64 -rc2-128>
101 the encryption algorithm to use. DES (56 bits), triple DES (168 bits)
102 or 40, 64 or 128 bit RC2 respectively if not specified 40 bit RC2 is
103 used. Only used with B<-encrypt>.
107 when verifying a message normally certificates (if any) included in
108 the message are searched for the signing certificate. With this option
109 only the certificates specified in the B<-certfile> option are used.
110 The supplied certificates can still be used as untrusted CAs however.
114 do not verify the signers certificate of a signed message.
118 do not do chain verification of signers certificates: that is don't
119 use the certificates in the signed message as untrusted CAs.
123 don't try to verify the signatures on the message.
127 when signing a message the signer's certificate is normally included
128 with this option it is excluded. This will reduce the size of the
129 signed message but the verifier must have a copy of the signers certificate
130 available locally (passed using the B<-certfile> option for example).
134 normally when a message is signed a set of attributes are included which
135 include the signing time and supported symmetric algorithms. With this
136 option they are not included.
140 normally the input message is converted to "canonical" format which is
141 effectively using CR and LF as end of line: as required by the S/MIME
142 specification. When this option is present no translation occurs. This
143 is useful when handling binary data which may not be in MIME format.
147 when signing a message use opaque signing: this form is more resistant
148 to translation by mail relays but it cannot be read by mail agents that
149 do not support S/MIME. Without this option cleartext signing with
150 the MIME type multipart/signed is used.
152 =item B<-certfile file>
154 allows additional certificates to be specified. When signing these will
155 be included with the message. When verifying these will be searched for
156 the signers certificates. The certificates should be in PEM format.
158 =item B<-signer file>
160 the signers certificate when signing a message. If a message is
161 being verified then the signers certificates will be written to this
162 file if the verification was successful.
166 the recipients certificate when decrypting a message. This certificate
167 must match one of the recipients of the message or an error occurs.
171 the private key to use when signing or decrypting. This must match the
172 corresponding certificate. If this option is not specified then the
173 private key must be included in the certificate file specified with
174 the B<-recip> or B<-signer> file.
178 one or more certificates of message recipients: used when encrypting
181 =item B<-to, -from, -subject>
183 the relevant mail headers. These are included outside the signed
184 portion of a message so they may be included manually. If signing
185 then many S/MIME mail clients check the signers certificate's email
186 address matches that specified in the From: address.
192 The MIME message must be sent without any blank lines between the
193 headers and the output. Some mail programs will automatically add
194 a blank line. Piping the mail directly to sendmail is one way to
195 achieve the correct format.
197 The supplied message to be signed or encrypted must include the
198 necessary MIME headers: or many S/MIME clients wont display it
199 properly (if at all). You can use the B<-text> option to automatically
200 add plain text headers.
202 A "signed and encrypted" message is one where a signed message is
203 then encrypted. This can be produced by encrypting an already signed
204 message: see the examples section.
206 This version of the program only allows one signer per message but it
207 will verify multiple signers on received messages. Some S/MIME clients
208 choke if a message contains multiple signers. It is possible to sign
209 messages "in parallel" by signing an already signed message.
211 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
212 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
213 encrypted data is used for other purposes.
221 the operation was completely successfully.
225 an error occurred parsing the command options.
229 one of the input files could not be read.
233 an error occurred creating the PKCS#7 file or when reading the MIME
238 an error occurred decrypting or verifying the message.
242 the message was verified correctly but an error occurred writing out
243 the signers certificates.
249 Create a cleartext signed message:
251 openssl smime -sign -in message.txt -text -out mail.msg
254 Create and opaque signed message
256 openssl smime -sign -in message.txt -text -out mail.msg -nodetach
259 Create a signed message, include some additional certificates and
260 read the private key from another file:
262 openssl smime -sign -in in.txt -text -out mail.msg
263 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
265 Send a signed message under Unix directly to sendmail, including headers:
267 openssl smime -sign -in in.txt -text -signer mycert.pem -from steve@openssl.org
268 -to someone@somewhere -subject "Signed message" | sendmail someone@somewhere
270 Verify a message and extract the signer's certificate if successful:
272 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
274 Send encrypted mail using triple DES:
276 openssl smime -encrypt -in in.txt -from steve@openssl.org -to someone@somewhere
277 -subject "Encrypted message" -des3 user.pem -out mail.msg
279 Sign and encrypt mail:
281 openssl smime -sign -in ml.txt -signer my.pem -text | openssl -encrypt -out mail.msg
282 -from steve@openssl.org -to someone@somewhere -subject "Signed and Encrypted message"
285 Note: the encryption command does not include the B<-text> option because the message
286 being encrypted already has MIME headers.
290 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
294 The MIME parser isn't very clever: it seems to handle most messages that I've thrown
295 at it but it may choke on others.
297 The code currently will only write out the signer's certificate to a file: if the
298 signer has a separate encryption certificate this must be manually extracted. There
299 should be some heuristic that determines the correct encryption certificate.
301 Ideally a database should be maintained of a certificates for each email address.
303 The code doesn't currently take note of the permitted symmetric encryption
304 algorithms as supplied in the SMIMECapabilities signed attribute. this means the
305 user has to manually include the correct encryption algorithm. It should store
306 the list of permitted ciphers in a database and only use those.
308 No revocation checking is done on the signer's certificate.
310 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
311 structures may cause parsing errors.