doc/man1/openssl-smime.pod.in

   1 =pod
   2
   3 =begin comment
   4 {- join("\n", @autowarntext) -}
   5
   6 =end comment
   7
   8 =head1 NAME
   9
  10 openssl-smime - S/MIME utility
  11
  12 =head1 SYNOPSIS
  13
  14 B<openssl> B<smime>
  15 [B<-help>]
  16 [B<-encrypt>]
  17 [B<-decrypt>]
  18 [B<-sign>]
  19 [B<-resign>]
  20 [B<-verify>]
  21 [B<-pk7out>]
  22 [B<-binary>]
  23 [B<-crlfeol>]
  24 [B<-I<cipher>>]
  25 [B<-in> I<file>]
  26 [B<-attime> I<timestamp>]
  27 [B<-check_ss_sig>]
  28 [B<-crl_check>]
  29 [B<-crl_check_all>]
  30 [B<-explicit_policy>]
  31 [B<-extended_crl>]
  32 [B<-ignore_critical>]
  33 [B<-inhibit_any>]
  34 [B<-inhibit_map>]
  35 [B<-partial_chain>]
  36 [B<-policy> I<arg>]
  37 [B<-policy_check>]
  38 [B<-policy_print>]
  39 [B<-purpose> I<purpose>]
  40 [B<-suiteB_128>]
  41 [B<-suiteB_128_only>]
  42 [B<-suiteB_192>]
  43 [B<-trusted_first>]
  44 [B<-no_alt_chains>]
  45 [B<-use_deltas>]
  46 [B<-auth_level> I<num>]
  47 [B<-verify_depth> I<num>]
  48 [B<-verify_email> I<email>]
  49 [B<-verify_hostname> I<hostname>]
  50 [B<-verify_ip> I<ip>]
  51 [B<-verify_name> I<name>]
  52 [B<-x509_strict>]
  53 [B<-certfile> I<file>]
  54 [B<-signer> I<file>]
  55 [B<-recip> I< file>]
  56 [B<-inform> B<DER>|B<PEM>|B<SMIME>]
  57 [B<-outform> B<DER>|B<PEM>|B<SMIME>]
  58 [B<-keyform> B<DER>|B<PEM>|B<ENGINE>]
  59 [B<-passin> I<arg>]
  60 [B<-inkey> I<file_or_id>]
  61 [B<-out> I<file>]
  62 [B<-content> I<file>]
  63 [B<-to> I<addr>]
  64 [B<-from> I<ad>]
  65 [B<-subject> I<s>]
  66 [B<-text>]
  67 [B<-indef>]
  68 [B<-noindef>]
  69 [B<-stream>]
  70 [B<-md> I<digest>]
  71 {- $OpenSSL::safe::opt_trust_synopsis -}
  72 {- $OpenSSL::safe::opt_r_synopsis -}
  73 I<cert.pem> ...
  74
  75 =for openssl ifdef engine
  76
  77 =head1 DESCRIPTION
  78
  79 This command handles S/MIME mail. It can encrypt, decrypt, sign
  80 and verify S/MIME messages.
  81
  82 =head1 OPTIONS
  83
  84 There are six operation options that set the type of operation to be performed.
  85 The meaning of the other options varies according to the operation type.
  86
  87 =over 4
  88
  89 =item B<-help>
  90
  91 Print out a usage message.
  92
  93 =item B<-encrypt>
  94
  95 Encrypt mail for the given recipient certificates. Input file is the message
  96 to be encrypted. The output file is the encrypted mail in MIME format.
  97
  98 Note that no revocation check is done for the recipient cert, so if that
  99 key has been compromised, others may be able to decrypt the text.
 100
 101 =item B<-decrypt>
 102
 103 Decrypt mail using the supplied certificate and private key. Expects an
 104 encrypted mail message in MIME format for the input file. The decrypted mail
 105 is written to the output file.
 106
 107 =item B<-sign>
 108
 109 Sign mail using the supplied certificate and private key. Input file is
 110 the message to be signed. The signed message in MIME format is written
 111 to the output file.
 112
 113 =item B<-verify>
 114
 115 Verify signed mail. Expects a signed mail message on input and outputs
 116 the signed data. Both clear text and opaque signing is supported.
 117
 118 =item B<-pk7out>
 119
 120 Takes an input message and writes out a PEM encoded PKCS#7 structure.
 121
 122 =item B<-resign>
 123
 124 Resign a message: take an existing message and one or more new signers.
 125
 126 =item B<-in> I<filename>
 127
 128 The input message to be encrypted or signed or the MIME message to
 129 be decrypted or verified.
 130
 131 =item B<-out> I<filename>
 132
 133 The message text that has been decrypted or verified or the output MIME
 134 format message that has been signed or verified.
 135
 136 =item B<-inform> B<DER>|B<PEM>|B<SMIME>
 137
 138 The input format of the PKCS#7 (S/MIME) structure (if one is being read);
 139 the default is B<SMIME>.
 140 See L<openssl(1)/Format Options> for details.
 141
 142 =item B<-outform> B<DER>|B<PEM>|B<SMIME>
 143
 144 The output format of the PKCS#7 (S/MIME) structure (if one is being written);
 145 the default is B<SMIME>.
 146 See L<openssl(1)/Format Options> for details.
 147
 148 =item B<-keyform> B<DER>|B<PEM>
 149
 150 The key format; the default is B<PEM>.
 151 See L<openssl(1)/Format Options> for details.
 152
 153 =item B<-stream>, B<-indef>, B<-noindef>
 154
 155 The B<-stream> and B<-indef> options are equivalent and enable streaming I/O
 156 for encoding operations. This permits single pass processing of data without
 157 the need to hold the entire contents in memory, potentially supporting very
 158 large files. Streaming is automatically set for S/MIME signing with detached
 159 data if the output format is B<SMIME> it is currently off by default for all
 160 other operations.
 161
 162 =item B<-noindef>
 163
 164 Disable streaming I/O where it would produce and indefinite length constructed
 165 encoding. This option currently has no effect. In future streaming will be
 166 enabled by default on all relevant operations and this option will disable it.
 167
 168 =item B<-content> I<filename>
 169
 170 This specifies a file containing the detached content, this is only
 171 useful with the B<-verify> command. This is only usable if the PKCS#7
 172 structure is using the detached signature form where the content is
 173 not included. This option will override any content if the input format
 174 is S/MIME and it uses the multipart/signed MIME content type.
 175
 176 =item B<-text>
 177
 178 This option adds plain text (text/plain) MIME headers to the supplied
 179 message if encrypting or signing. If decrypting or verifying it strips
 180 off text headers: if the decrypted or verified message is not of MIME
 181 type text/plain then an error occurs.
 182
 183 =item B<-md> I<digest>
 184
 185 Digest algorithm to use when signing or resigning. If not present then the
 186 default digest algorithm for the signing key will be used (usually SHA1).
 187
 188 =item B<-I<cipher>>
 189
 190 The encryption algorithm to use. For example DES  (56 bits) - B<-des>,
 191 triple DES (168 bits) - B<-des3>,
 192 EVP_get_cipherbyname() function) can also be used preceded by a dash, for
 193 example B<-aes-128-cbc>. See L<openssl-enc(1)> for list of ciphers
 194 supported by your version of OpenSSL.
 195
 196 If not specified triple DES is used. Only used with B<-encrypt>.
 197
 198 =item B<-nointern>
 199
 200 When verifying a message normally certificates (if any) included in
 201 the message are searched for the signing certificate. With this option
 202 only the certificates specified in the B<-certfile> option are used.
 203 The supplied certificates can still be used as untrusted CAs however.
 204
 205 =item B<-noverify>
 206
 207 Do not verify the signers certificate of a signed message.
 208
 209 =item B<-nochain>
 210
 211 Do not do chain verification of signers certificates: that is don't
 212 use the certificates in the signed message as untrusted CAs.
 213
 214 =item B<-nosigs>
 215
 216 Don't try to verify the signatures on the message.
 217
 218 =item B<-nocerts>
 219
 220 When signing a message the signer's certificate is normally included
 221 with this option it is excluded. This will reduce the size of the
 222 signed message but the verifier must have a copy of the signers certificate
 223 available locally (passed using the B<-certfile> option for example).
 224
 225 =item B<-noattr>
 226
 227 Normally when a message is signed a set of attributes are included which
 228 include the signing time and supported symmetric algorithms. With this
 229 option they are not included.
 230
 231 =item B<-binary>
 232
 233 Normally the input message is converted to "canonical" format which is
 234 effectively using CR and LF as end of line: as required by the S/MIME
 235 specification. When this option is present no translation occurs. This
 236 is useful when handling binary data which may not be in MIME format.
 237
 238 =item B<-crlfeol>
 239
 240 Normally the output file uses a single B<LF> as end of line. When this
 241 option is present B<CRLF> is used instead.
 242
 243 =item B<-nodetach>
 244
 245 When signing a message use opaque signing: this form is more resistant
 246 to translation by mail relays but it cannot be read by mail agents that
 247 do not support S/MIME.  Without this option cleartext signing with
 248 the MIME type multipart/signed is used.
 249
 250 =item B<-certfile> I<file>
 251
 252 Allows additional certificates to be specified. When signing these will
 253 be included with the message. When verifying these will be searched for
 254 the signers certificates. The certificates should be in PEM format.
 255
 256 =item B<-signer> I<file>
 257
 258 A signing certificate when signing or resigning a message, this option can be
 259 used multiple times if more than one signer is required. If a message is being
 260 verified then the signers certificates will be written to this file if the
 261 verification was successful.
 262
 263 =item B<-recip> I<file>
 264
 265 The recipients certificate when decrypting a message. This certificate
 266 must match one of the recipients of the message or an error occurs.
 267
 268 =item B<-inkey> I<file_or_id>
 269
 270 The private key to use when signing or decrypting. This must match the
 271 corresponding certificate. If this option is not specified then the
 272 private key must be included in the certificate file specified with
 273 the B<-recip> or B<-signer> file. When signing this option can be used
 274 multiple times to specify successive keys.
 275 If no engine is used, the argument is taken as a file; if an engine is
 276 specified, the argument is given to the engine as a key identifier.
 277
 278 =item B<-passin> I<arg>
 279
 280 The private key password source. For more information about the format of I<arg>
 281 see L<openssl(1)/Pass Phrase Options>.
 282
 283 =item B<-to>, B<-from>, B<-subject>
 284
 285 The relevant mail headers. These are included outside the signed
 286 portion of a message so they may be included manually. If signing
 287 then many S/MIME mail clients check the signers certificate's email
 288 address matches that specified in the From: address.
 289
 290 =item B<-attime>, B<-check_ss_sig>, B<-crl_check>, B<-crl_check_all>,
 291 B<-explicit_policy>, B<-extended_crl>, B<-ignore_critical>, B<-inhibit_any>,
 292 B<-inhibit_map>, B<-no_alt_chains>, B<-partial_chain>, B<-policy>,
 293 B<-policy_check>, B<-policy_print>, B<-purpose>, B<-suiteB_128>,
 294 B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>, B<-use_deltas>,
 295 B<-auth_level>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
 296 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
 297
 298 Set various options of certificate chain verification. See
 299 L<openssl-verify(1)> manual page for details.
 300
 301 {- $OpenSSL::safe::opt_trust_item -}
 302
 303 {- $OpenSSL::safe::opt_r_item -}
 304
 305 =item I<cert.pem> ...
 306
 307 One or more certificates of message recipients, used when encrypting
 308 a message.
 309
 310 =back
 311
 312 =head1 NOTES
 313
 314 The MIME message must be sent without any blank lines between the
 315 headers and the output. Some mail programs will automatically add
 316 a blank line. Piping the mail directly to sendmail is one way to
 317 achieve the correct format.
 318
 319 The supplied message to be signed or encrypted must include the
 320 necessary MIME headers or many S/MIME clients won't display it
 321 properly (if at all). You can use the B<-text> option to automatically
 322 add plain text headers.
 323
 324 A "signed and encrypted" message is one where a signed message is
 325 then encrypted. This can be produced by encrypting an already signed
 326 message: see the examples section.
 327
 328 This version of the program only allows one signer per message but it
 329 will verify multiple signers on received messages. Some S/MIME clients
 330 choke if a message contains multiple signers. It is possible to sign
 331 messages "in parallel" by signing an already signed message.
 332
 333 The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME
 334 clients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7
 335 encrypted data is used for other purposes.
 336
 337 The B<-resign> option uses an existing message digest when adding a new
 338 signer. This means that attributes must be present in at least one existing
 339 signer using the same message digest or this operation will fail.
 340
 341 The B<-stream> and B<-indef> options enable streaming I/O support.
 342 As a result the encoding is BER using indefinite length constructed encoding
 343 and no longer DER. Streaming is supported for the B<-encrypt> operation and the
 344 B<-sign> operation if the content is not detached.
 345
 346 Streaming is always used for the B<-sign> operation with detached data but
 347 since the content is no longer part of the PKCS#7 structure the encoding
 348 remains DER.
 349
 350 =head1 EXIT CODES
 351
 352 =over 4
 353
 354 =item Z<>0
 355
 356 The operation was completely successfully.
 357
 358 =item Z<>1
 359
 360 An error occurred parsing the command options.
 361
 362 =item Z<>2
 363
 364 One of the input files could not be read.
 365
 366 =item Z<>3
 367
 368 An error occurred creating the PKCS#7 file or when reading the MIME
 369 message.
 370
 371 =item Z<>4
 372
 373 An error occurred decrypting or verifying the message.
 374
 375 =item Z<>5
 376
 377 The message was verified correctly but an error occurred writing out
 378 the signers certificates.
 379
 380 =back
 381
 382 =head1 EXAMPLES
 383
 384 Create a cleartext signed message:
 385
 386  openssl smime -sign -in message.txt -text -out mail.msg \
 387         -signer mycert.pem
 388
 389 Create an opaque signed message:
 390
 391  openssl smime -sign -in message.txt -text -out mail.msg -nodetach \
 392         -signer mycert.pem
 393
 394 Create a signed message, include some additional certificates and
 395 read the private key from another file:
 396
 397  openssl smime -sign -in in.txt -text -out mail.msg \
 398         -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem
 399
 400 Create a signed message with two signers:
 401
 402  openssl smime -sign -in message.txt -text -out mail.msg \
 403         -signer mycert.pem -signer othercert.pem
 404
 405 Send a signed message under Unix directly to sendmail, including headers:
 406
 407  openssl smime -sign -in in.txt -text -signer mycert.pem \
 408         -from steve@openssl.org -to someone@somewhere \
 409         -subject "Signed message" | sendmail someone@somewhere
 410
 411 Verify a message and extract the signer's certificate if successful:
 412
 413  openssl smime -verify -in mail.msg -signer user.pem -out signedtext.txt
 414
 415 Send encrypted mail using triple DES:
 416
 417  openssl smime -encrypt -in in.txt -from steve@openssl.org \
 418         -to someone@somewhere -subject "Encrypted message" \
 419         -des3 user.pem -out mail.msg
 420
 421 Sign and encrypt mail:
 422
 423  openssl smime -sign -in ml.txt -signer my.pem -text \
 424         | openssl smime -encrypt -out mail.msg \
 425         -from steve@openssl.org -to someone@somewhere \
 426         -subject "Signed and Encrypted message" -des3 user.pem
 427
 428 Note: the encryption command does not include the B<-text> option because the
 429 message being encrypted already has MIME headers.
 430
 431 Decrypt mail:
 432
 433  openssl smime -decrypt -in mail.msg -recip mycert.pem -inkey key.pem
 434
 435 The output from Netscape form signing is a PKCS#7 structure with the
 436 detached signature format. You can use this program to verify the
 437 signature by line wrapping the base64 encoded structure and surrounding
 438 it with:
 439
 440  -----BEGIN PKCS7-----
 441  -----END PKCS7-----
 442
 443 and using the command:
 444
 445  openssl smime -verify -inform PEM -in signature.pem -content content.txt
 446
 447 Alternatively you can base64 decode the signature and use:
 448
 449  openssl smime -verify -inform DER -in signature.der -content content.txt
 450
 451 Create an encrypted message using 128 bit Camellia:
 452
 453  openssl smime -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem
 454
 455 Add a signer to an existing message:
 456
 457  openssl smime -resign -in mail.msg -signer newsign.pem -out mail2.msg
 458
 459 =head1 BUGS
 460
 461 The MIME parser isn't very clever: it seems to handle most messages that I've
 462 thrown at it but it may choke on others.
 463
 464 The code currently will only write out the signer's certificate to a file: if
 465 the signer has a separate encryption certificate this must be manually
 466 extracted. There should be some heuristic that determines the correct
 467 encryption certificate.
 468
 469 Ideally a database should be maintained of a certificates for each email
 470 address.
 471
 472 The code doesn't currently take note of the permitted symmetric encryption
 473 algorithms as supplied in the SMIMECapabilities signed attribute. This means the
 474 user has to manually include the correct encryption algorithm. It should store
 475 the list of permitted ciphers in a database and only use those.
 476
 477 No revocation checking is done on the signer's certificate.
 478
 479 The current code can only handle S/MIME v2 messages, the more complex S/MIME v3
 480 structures may cause parsing errors.
 481
 482 =head1 HISTORY
 483
 484 The use of multiple B<-signer> options and the B<-resign> command were first
 485 added in OpenSSL 1.0.0
 486
 487 The -no_alt_chains option was added in OpenSSL 1.1.0.
 488
 489 =head1 COPYRIGHT
 490
 491 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
 492
 493 Licensed under the Apache License 2.0 (the "License").  You may not use
 494 this file except in compliance with the License.  You can obtain a copy
 495 in the file LICENSE in the source distribution or at
 496 L<https://www.openssl.org/source/license.html>.
 497
 498 =cut