smime.pod revision 68651
197403Sobrien=pod 2169691Skan 3169691Skan=head1 NAME 497403Sobrien 597403Sobriensmime - S/MIME utility 6132720Skan 797403Sobrien=head1 SYNOPSIS 8132720Skan 997403SobrienB<openssl> B<smime> 1097403Sobrien[B<-encrypt>] 1197403Sobrien[B<-decrypt>] 1297403Sobrien[B<-sign>] 13132720Skan[B<-verify>] 1497403Sobrien[B<-pk7out>] 1597403Sobrien[B<-des>] 1697403Sobrien[B<-des3>] 1797403Sobrien[B<-rc2-40>] 1897403Sobrien[B<-rc2-64>] 19132720Skan[B<-rc2-128>] 20169691Skan[B<-in file>] 21169691Skan[B<-certfile file>] 2297403Sobrien[B<-signer file>] 2397403Sobrien[B<-recip file>] 2497403Sobrien[B<-in file>] 2597403Sobrien[B<-inform SMIME|PEM|DER>] 2697403Sobrien[B<-passin arg>] 2797403Sobrien[B<-inkey file>] 2897403Sobrien[B<-out file>] 2997403Sobrien[B<-outform SMIME|PEM|DER>] 3097403Sobrien[B<-content file>] 3197403Sobrien[B<-to addr>] 3297403Sobrien[B<-from ad>] 33169691Skan[B<-subject s>] 3497403Sobrien[B<-text>] 3597403Sobrien[B<-rand file(s)>] 36132720Skan[cert.pem]... 37132720Skan 3897403Sobrien=head1 DESCRIPTION 3997403Sobrien 4097403SobrienThe B<smime> command handles S/MIME mail. It can encrypt, decrypt, sign and 41169691Skanverify S/MIME messages. 42169691Skan 4397403Sobrien=head1 COMMAND OPTIONS 4497403Sobrien 4597403SobrienThere are five operation options that set the type of operation to be performed. 4697403SobrienThe meaning of the other options varies according to the operation type. 4797403Sobrien 4897403Sobrien=over 4 4997403Sobrien 50169691Skan=item B<-encrypt> 51169691Skan 52169691Skanencrypt mail for the given recipient certificates. Input file is the message 53169691Skanto be encrypted. The output file is the encrypted mail in MIME format. 54169691Skan 55169691Skan=item B<-decrypt> 56169691Skan 57169691Skandecrypt mail using the supplied certificate and private key. Expects an 5897403Sobrienencrypted mail message in MIME format for the input file. The decrypted mail 5997403Sobrienis written to the output file. 6097403Sobrien 6197403Sobrien=item B<-sign> 62117397Skan 63117397Skansign mail using the supplied certificate and private key. Input file is 64117397Skanthe message to be signed. The signed message in MIME format is written 65117397Skanto the output file. 6697403Sobrien 67117397Skan=item B<-verify> 6897403Sobrien 6997403Sobrienverify signed mail. Expects a signed mail message on input and outputs 7097403Sobrienthe signed data. Both clear text and opaque signing is supported. 71171827Skan 7297403Sobrien=item B<-pk7out> 7397403Sobrien 7497403Sobrientakes an input message and writes out a PEM encoded PKCS#7 structure. 7597403Sobrien 7697403Sobrien=item B<-in filename> 7797403Sobrien 7897403Sobrienthe input message to be encrypted or signed or the MIME message to 7997403Sobrienbe decrypted or verified. 8097403Sobrien 8197403Sobrien=item B<-inform SMIME|PEM|DER> 8297403Sobrien 8397403Sobrienthis specifies the input format for the PKCS#7 structure. The default 84171827Skanis B<SMIME> which reads an S/MIME format message. B<PEM> and B<DER> 8597403Sobrienformat change this to expect PEM and DER format PKCS#7 structures 8697403Sobrieninstead. This currently only affects the input format of the PKCS#7 8797403Sobrienstructure, if no PKCS#7 structure is being input (for example with 8897403SobrienB<-encrypt> or B<-sign>) this option has no effect. 8997403Sobrien 9097403Sobrien=item B<-out filename> 9197403Sobrien 9297403Sobrienthe message text that has been decrypted or verified or the output MIME 9397403Sobrienformat message that has been signed or verified. 9497403Sobrien 9597403Sobrien=item B<-outform SMIME|PEM|DER> 96171827Skan 9797403Sobrienthis specifies the output format for the PKCS#7 structure. The default 9897403Sobrienis B<SMIME> which write an S/MIME format message. B<PEM> and B<DER> 9997403Sobrienformat change this to write PEM and DER format PKCS#7 structures 10097403Sobrieninstead. This currently only affects the output format of the PKCS#7 10197403Sobrienstructure, if no PKCS#7 structure is being output (for example with 102228780SpfgB<-verify> or B<-decrypt>) this option has no effect. 103233699Stheraven 104233699Stheraven=item B<-content filename> 105233699Stheraven 106233699StheravenThis specifies a file containing the detached content, this is only 107233699Stheravenuseful with the B<-verify> command. This is only usable if the PKCS#7 108233699Stheravenstructure is using the detached signature form where the content is 10997403Sobriennot included. This option will override any content if the input format 11097403Sobrienis S/MIME and it uses the multipart/signed MIME content type. 11197403Sobrien 11297403Sobrien=item B<-text> 11397403Sobrien 11497403Sobrienthis option adds plain text (text/plain) MIME headers to the supplied 11597403Sobrienmessage if encrypting or signing. If decrypting or verifying it strips 11697403Sobrienoff text headers: if the decrypted or verified message is not of MIME 11797403Sobrientype text/plain then an error occurs. 118171827Skan 11997403Sobrien=item B<-CAfile file> 12097403Sobrien 121171827Skana file containing trusted CA certificates, only used with B<-verify>. 122171827Skan 123171827Skan=item B<-CApath dir> 124171827Skan 125171827Skana directory containing trusted CA certificates, only used with 126171827SkanB<-verify>. This directory must be a standard certificate directory: that 127171827Skanis a hash of each subject name (using B<x509 -hash>) should be linked 128171827Skanto each certificate. 129171827Skan 130171827Skan=item B<-des -des3 -rc2-40 -rc2-64 -rc2-128> 13197403Sobrien 13297403Sobrienthe encryption algorithm to use. DES (56 bits), triple DES (168 bits) 133117397Skanor 40, 64 or 128 bit RC2 respectively if not specified 40 bit RC2 is 134117397Skanused. Only used with B<-encrypt>. 135117397Skan 136117397Skan=item B<-nointern> 13797403Sobrien 13897403Sobrienwhen verifying a message normally certificates (if any) included in 13997403Sobrienthe message are searched for the signing certificate. With this option 14097403Sobrienonly the certificates specified in the B<-certfile> option are used. 14197403SobrienThe supplied certificates can still be used as untrusted CAs however. 142171827Skan 14397403Sobrien=item B<-noverify> 14497403Sobrien 14597403Sobriendo not verify the signers certificate of a signed message. 146171827Skan 147169691Skan=item B<-nochain> 148169691Skan 14997403Sobriendo not do chain verification of signers certificates: that is don't 15097403Sobrienuse the certificates in the signed message as untrusted CAs. 15197403Sobrien 15297403Sobrien=item B<-nosigs> 15397403Sobrien 15497403Sobriendon't try to verify the signatures on the message. 15597403Sobrien 156171827Skan=item B<-nocerts> 15797403Sobrien 15897403Sobrienwhen signing a message the signer's certificate is normally included 15997403Sobrienwith this option it is excluded. This will reduce the size of the 160171827Skansigned message but the verifier must have a copy of the signers certificate 161169691Skanavailable locally (passed using the B<-certfile> option for example). 162169691Skan 16397403Sobrien=item B<-noattr> 16497403Sobrien 16597403Sobriennormally when a message is signed a set of attributes are included which 166169691Skaninclude the signing time and supported symmetric algorithms. With this 167169691Skanoption they are not included. 16897403Sobrien 16997403Sobrien=item B<-binary> 170 171normally the input message is converted to "canonical" format which is 172effectively using CR and LF as end of line: as required by the S/MIME 173specification. When this option is present no translation occurs. This 174is useful when handling binary data which may not be in MIME format. 175 176=item B<-nodetach> 177 178when signing a message use opaque signing: this form is more resistant 179to translation by mail relays but it cannot be read by mail agents that 180do not support S/MIME. Without this option cleartext signing with 181the MIME type multipart/signed is used. 182 183=item B<-certfile file> 184 185allows additional certificates to be specified. When signing these will 186be included with the message. When verifying these will be searched for 187the signers certificates. The certificates should be in PEM format. 188 189=item B<-signer file> 190 191the signers certificate when signing a message. If a message is 192being verified then the signers certificates will be written to this 193file if the verification was successful. 194 195=item B<-recip file> 196 197the recipients certificate when decrypting a message. This certificate 198must match one of the recipients of the message or an error occurs. 199 200=item B<-inkey file> 201 202the private key to use when signing or decrypting. This must match the 203corresponding certificate. If this option is not specified then the 204private key must be included in the certificate file specified with 205the B<-recip> or B<-signer> file. 206 207=item B<-passin arg> 208 209the private key password source. For more information about the format of B<arg> 210see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 211 212=item B<-rand file(s)> 213 214a file or files containing random data used to seed the random number 215generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 216Multiple files can be specified separated by a OS-dependent character. 217The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 218all others. 219 220=item B<cert.pem...> 221 222one or more certificates of message recipients: used when encrypting 223a message. 224 225=item B<-to, -from, -subject> 226 227the relevant mail headers. These are included outside the signed 228portion of a message so they may be included manually. If signing 229then many S/MIME mail clients check the signers certificate's email 230address matches that specified in the From: address. 231 232=back 233 234=head1 NOTES 235 236The MIME message must be sent without any blank lines between the 237headers and the output. Some mail programs will automatically add 238a blank line. Piping the mail directly to sendmail is one way to 239achieve the correct format. 240 241The supplied message to be signed or encrypted must include the 242necessary MIME headers or many S/MIME clients wont display it 243properly (if at all). You can use the B<-text> option to automatically 244add plain text headers. 245 246A "signed and encrypted" message is one where a signed message is 247then encrypted. This can be produced by encrypting an already signed 248message: see the examples section. 249 250This version of the program only allows one signer per message but it 251will verify multiple signers on received messages. Some S/MIME clients 252choke if a message contains multiple signers. It is possible to sign 253messages "in parallel" by signing an already signed message. 254 255The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME 256clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7 257encrypted data is used for other purposes. 258 259=head1 EXIT CODES 260 261=over 4 262 263=item 0 264 265the operation was completely successfully. 266 267=item 1 268 269an error occurred parsing the command options. 270 271=item 2 272 273one of the input files could not be read. 274 275=item 3 276 277an error occurred creating the PKCS#7 file or when reading the MIME 278message. 279 280=item 4 281 282an error occurred decrypting or verifying the message. 283 284=item 5 285 286the message was verified correctly but an error occurred writing out 287the signers certificates. 288 289=back 290 291=head1 EXAMPLES 292 293Create a cleartext signed message: 294 295 openssl smime -sign -in message.txt -text -out mail.msg \ 296 -signer mycert.pem 297 298Create and opaque signed message 299 300 openssl smime -sign -in message.txt -text -out mail.msg -nodetach \ 301 -signer mycert.pem 302 303Create a signed message, include some additional certificates and 304read the private key from another file: 305 306 openssl smime -sign -in in.txt -text -out mail.msg \ 307 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem 308 309Send a signed message under Unix directly to sendmail, including headers: 310 311 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 314 315Verify a message and extract the signer's certificate if successful: 316 317 openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt 318 319Send encrypted mail using triple DES: 320 321 openssl smime -encrypt -in in.txt -from steve@openssl.org \ 322 -to someone@somewhere -subject "Encrypted message" \ 323 -des3 user.pem -out mail.msg 324 325Sign and encrypt mail: 326 327 openssl smime -sign -in ml.txt -signer my.pem -text \ 328 | openssl smime -encrypt -out mail.msg \ 329 -from steve@openssl.org -to someone@somewhere \ 330 -subject "Signed and Encrypted message" -des3 user.pem 331 332Note: the encryption command does not include the B<-text> option because the message 333being encrypted already has MIME headers. 334 335Decrypt mail: 336 337 openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem 338 339The output from Netscape form signing is a PKCS#7 structure with the 340detached signature format. You can use this program to verify the 341signature by line wrapping the base64 encoded structure and surrounding 342it with: 343 344 -----BEGIN PKCS7---- 345 -----END PKCS7---- 346 347and using the command, 348 349 openssl smime -verify -inform PEM -in signature.pem -content content.txt 350 351alternatively you can base64 decode the signature and use 352 353 openssl smime -verify -inform DER -in signature.der -content content.txt 354 355=head1 BUGS 356 357The MIME parser isn't very clever: it seems to handle most messages that I've thrown 358at it but it may choke on others. 359 360The code currently will only write out the signer's certificate to a file: if the 361signer has a separate encryption certificate this must be manually extracted. There 362should be some heuristic that determines the correct encryption certificate. 363 364Ideally a database should be maintained of a certificates for each email address. 365 366The code doesn't currently take note of the permitted symmetric encryption 367algorithms as supplied in the SMIMECapabilities signed attribute. this means the 368user has to manually include the correct encryption algorithm. It should store 369the list of permitted ciphers in a database and only use those. 370 371No revocation checking is done on the signer's certificate. 372 373The current code can only handle S/MIME v2 messages, the more complex S/MIME v3 374structures may cause parsing errors. 375 376=cut 377