cms.pod revision 337982
1=pod 2 3=head1 NAME 4 5openssl-cms, 6cms - CMS utility 7 8=head1 SYNOPSIS 9 10B<openssl> B<cms> 11[B<-encrypt>] 12[B<-decrypt>] 13[B<-sign>] 14[B<-verify>] 15[B<-cmsout>] 16[B<-resign>] 17[B<-data_create>] 18[B<-data_out>] 19[B<-digest_create>] 20[B<-digest_verify>] 21[B<-compress>] 22[B<-uncompress>] 23[B<-EncryptedData_encrypt>] 24[B<-sign_receipt>] 25[B<-verify_receipt receipt>] 26[B<-in filename>] 27[B<-inform SMIME|PEM|DER>] 28[B<-rctform SMIME|PEM|DER>] 29[B<-out filename>] 30[B<-outform SMIME|PEM|DER>] 31[B<-stream -indef -noindef>] 32[B<-noindef>] 33[B<-content filename>] 34[B<-text>] 35[B<-noout>] 36[B<-print>] 37[B<-CAfile file>] 38[B<-CApath dir>] 39[B<-no_alt_chains>] 40[B<-md digest>] 41[B<-[cipher]>] 42[B<-nointern>] 43[B<-no_signer_cert_verify>] 44[B<-nocerts>] 45[B<-noattr>] 46[B<-nosmimecap>] 47[B<-binary>] 48[B<-nodetach>] 49[B<-certfile file>] 50[B<-certsout file>] 51[B<-signer file>] 52[B<-recip file>] 53[B<-keyid>] 54[B<-receipt_request_all -receipt_request_first>] 55[B<-receipt_request_from emailaddress>] 56[B<-receipt_request_to emailaddress>] 57[B<-receipt_request_print>] 58[B<-secretkey key>] 59[B<-secretkeyid id>] 60[B<-econtent_type type>] 61[B<-inkey file>] 62[B<-keyopt name:parameter>] 63[B<-passin arg>] 64[B<-rand file(s)>] 65[B<cert.pem...>] 66[B<-to addr>] 67[B<-from addr>] 68[B<-subject subj>] 69[cert.pem]... 70 71=head1 DESCRIPTION 72 73The B<cms> command handles S/MIME v3.1 mail. It can encrypt, decrypt, sign and 74verify, compress and uncompress S/MIME messages. 75 76=head1 COMMAND OPTIONS 77 78There are fourteen operation options that set the type of operation to be 79performed. The meaning of the other options varies according to the operation 80type. 81 82=over 4 83 84=item B<-encrypt> 85 86encrypt mail for the given recipient certificates. Input file is the message 87to be encrypted. The output file is the encrypted mail in MIME format. The 88actual CMS type is <B>EnvelopedData<B>. 89 90Note that no revocation check is done for the recipient cert, so if that 91key has been compromised, others may be able to decrypt the text. 92 93=item B<-decrypt> 94 95decrypt mail using the supplied certificate and private key. Expects an 96encrypted mail message in MIME format for the input file. The decrypted mail 97is written to the output file. 98 99=item B<-debug_decrypt> 100 101this option sets the B<CMS_DEBUG_DECRYPT> flag. This option should be used 102with caution: see the notes section below. 103 104=item B<-sign> 105 106sign mail using the supplied certificate and private key. Input file is 107the message to be signed. The signed message in MIME format is written 108to the output file. 109 110=item B<-verify> 111 112verify signed mail. Expects a signed mail message on input and outputs 113the signed data. Both clear text and opaque signing is supported. 114 115=item B<-cmsout> 116 117takes an input message and writes out a PEM encoded CMS structure. 118 119=item B<-resign> 120 121resign a message: take an existing message and one or more new signers. 122 123=item B<-data_create> 124 125Create a CMS B<Data> type. 126 127=item B<-data_out> 128 129B<Data> type and output the content. 130 131=item B<-digest_create> 132 133Create a CMS B<DigestedData> type. 134 135=item B<-digest_verify> 136 137Verify a CMS B<DigestedData> type and output the content. 138 139=item B<-compress> 140 141Create a CMS B<CompressedData> type. OpenSSL must be compiled with B<zlib> 142support for this option to work, otherwise it will output an error. 143 144=item B<-uncompress> 145 146Uncompress a CMS B<CompressedData> type and output the content. OpenSSL must be 147compiled with B<zlib> support for this option to work, otherwise it will 148output an error. 149 150=item B<-EncryptedData_encrypt> 151 152Encrypt content using supplied symmetric key and algorithm using a CMS 153B<EncrytedData> type and output the content. 154 155=item B<-sign_receipt> 156 157Generate and output a signed receipt for the supplied message. The input 158message B<must> contain a signed receipt request. Functionality is otherwise 159similar to the B<-sign> operation. 160 161=item B<-verify_receipt receipt> 162 163Verify a signed receipt in filename B<receipt>. The input message B<must> 164contain the original receipt request. Functionality is otherwise similar 165to the B<-verify> operation. 166 167=item B<-in filename> 168 169the input message to be encrypted or signed or the message to be decrypted 170or verified. 171 172=item B<-inform SMIME|PEM|DER> 173 174this specifies the input format for the CMS structure. The default 175is B<SMIME> which reads an S/MIME format message. B<PEM> and B<DER> 176format change this to expect PEM and DER format CMS structures 177instead. This currently only affects the input format of the CMS 178structure, if no CMS structure is being input (for example with 179B<-encrypt> or B<-sign>) this option has no effect. 180 181=item B<-rctform SMIME|PEM|DER> 182 183specify the format for a signed receipt for use with the B<-receipt_verify> 184operation. 185 186=item B<-out filename> 187 188the message text that has been decrypted or verified or the output MIME 189format message that has been signed or verified. 190 191=item B<-outform SMIME|PEM|DER> 192 193this specifies the output format for the CMS structure. The default 194is B<SMIME> which writes an S/MIME format message. B<PEM> and B<DER> 195format change this to write PEM and DER format CMS structures 196instead. This currently only affects the output format of the CMS 197structure, if no CMS structure is being output (for example with 198B<-verify> or B<-decrypt>) this option has no effect. 199 200=item B<-stream -indef -noindef> 201 202the B<-stream> and B<-indef> options are equivalent and enable streaming I/O 203for encoding operations. This permits single pass processing of data without 204the need to hold the entire contents in memory, potentially supporting very 205large files. Streaming is automatically set for S/MIME signing with detached 206data if the output format is B<SMIME> it is currently off by default for all 207other operations. 208 209=item B<-noindef> 210 211disable streaming I/O where it would produce and indefinite length constructed 212encoding. This option currently has no effect. In future streaming will be 213enabled by default on all relevant operations and this option will disable it. 214 215=item B<-content filename> 216 217This specifies a file containing the detached content, this is only 218useful with the B<-verify> command. This is only usable if the CMS 219structure is using the detached signature form where the content is 220not included. This option will override any content if the input format 221is S/MIME and it uses the multipart/signed MIME content type. 222 223=item B<-text> 224 225this option adds plain text (text/plain) MIME headers to the supplied 226message if encrypting or signing. If decrypting or verifying it strips 227off text headers: if the decrypted or verified message is not of MIME 228type text/plain then an error occurs. 229 230=item B<-noout> 231 232for the B<-cmsout> operation do not output the parsed CMS structure. This 233is useful when combined with the B<-print> option or if the syntax of the CMS 234structure is being checked. 235 236=item B<-print> 237 238for the B<-cmsout> operation print out all fields of the CMS structure. This 239is mainly useful for testing purposes. 240 241=item B<-CAfile file> 242 243a file containing trusted CA certificates, only used with B<-verify>. 244 245=item B<-CApath dir> 246 247a directory containing trusted CA certificates, only used with 248B<-verify>. This directory must be a standard certificate directory: that 249is a hash of each subject name (using B<x509 -hash>) should be linked 250to each certificate. 251 252=item B<-md digest> 253 254digest algorithm to use when signing or resigning. If not present then the 255default digest algorithm for the signing key will be used (usually SHA1). 256 257=item B<-[cipher]> 258 259the encryption algorithm to use. For example triple DES (168 bits) - B<-des3> 260or 256 bit AES - B<-aes256>. Any standard algorithm name (as used by the 261EVP_get_cipherbyname() function) can also be used preceded by a dash, for 262example B<-aes_128_cbc>. See L<B<enc>|enc(1)> for a list of ciphers 263supported by your version of OpenSSL. 264 265If not specified triple DES is used. Only used with B<-encrypt> and 266B<-EncryptedData_create> commands. 267 268=item B<-nointern> 269 270when verifying a message normally certificates (if any) included in 271the message are searched for the signing certificate. With this option 272only the certificates specified in the B<-certfile> option are used. 273The supplied certificates can still be used as untrusted CAs however. 274 275=item B<-no_signer_cert_verify> 276 277do not verify the signers certificate of a signed message. 278 279=item B<-nocerts> 280 281when signing a message the signer's certificate is normally included 282with this option it is excluded. This will reduce the size of the 283signed message but the verifier must have a copy of the signers certificate 284available locally (passed using the B<-certfile> option for example). 285 286=item B<-noattr> 287 288normally when a message is signed a set of attributes are included which 289include the signing time and supported symmetric algorithms. With this 290option they are not included. 291 292=item B<-nosmimecap> 293 294exclude the list of supported algorithms from signed attributes, other options 295such as signing time and content type are still included. 296 297=item B<-binary> 298 299normally the input message is converted to "canonical" format which is 300effectively using CR and LF as end of line: as required by the S/MIME 301specification. When this option is present no translation occurs. This 302is useful when handling binary data which may not be in MIME format. 303 304=item B<-nodetach> 305 306when signing a message use opaque signing: this form is more resistant 307to translation by mail relays but it cannot be read by mail agents that 308do not support S/MIME. Without this option cleartext signing with 309the MIME type multipart/signed is used. 310 311=item B<-certfile file> 312 313allows additional certificates to be specified. When signing these will 314be included with the message. When verifying these will be searched for 315the signers certificates. The certificates should be in PEM format. 316 317=item B<-certsout file> 318 319any certificates contained in the message are written to B<file>. 320 321=item B<-signer file> 322 323a signing certificate when signing or resigning a message, this option can be 324used multiple times if more than one signer is required. If a message is being 325verified then the signers certificates will be written to this file if the 326verification was successful. 327 328=item B<-recip file> 329 330when decrypting a message this specifies the recipients certificate. The 331certificate must match one of the recipients of the message or an error 332occurs. 333 334When encrypting a message this option may be used multiple times to specify 335each recipient. This form B<must> be used if customised parameters are 336required (for example to specify RSA-OAEP). 337 338Only certificates carrying RSA, Diffie-Hellman or EC keys are supported by this 339option. 340 341=item B<-keyid> 342 343use subject key identifier to identify certificates instead of issuer name and 344serial number. The supplied certificate B<must> include a subject key 345identifier extension. Supported by B<-sign> and B<-encrypt> options. 346 347=item B<-receipt_request_all -receipt_request_first> 348 349for B<-sign> option include a signed receipt request. Indicate requests should 350be provided by all receipient or first tier recipients (those mailed directly 351and not from a mailing list). Ignored it B<-receipt_request_from> is included. 352 353=item B<-receipt_request_from emailaddress> 354 355for B<-sign> option include a signed receipt request. Add an explicit email 356address where receipts should be supplied. 357 358=item B<-receipt_request_to emailaddress> 359 360Add an explicit email address where signed receipts should be sent to. This 361option B<must> but supplied if a signed receipt it requested. 362 363=item B<-receipt_request_print> 364 365For the B<-verify> operation print out the contents of any signed receipt 366requests. 367 368=item B<-secretkey key> 369 370specify symmetric key to use. The key must be supplied in hex format and be 371consistent with the algorithm used. Supported by the B<-EncryptedData_encrypt> 372B<-EncrryptedData_decrypt>, B<-encrypt> and B<-decrypt> options. When used 373with B<-encrypt> or B<-decrypt> the supplied key is used to wrap or unwrap the 374content encryption key using an AES key in the B<KEKRecipientInfo> type. 375 376=item B<-secretkeyid id> 377 378the key identifier for the supplied symmetric key for B<KEKRecipientInfo> type. 379This option B<must> be present if the B<-secretkey> option is used with 380B<-encrypt>. With B<-decrypt> operations the B<id> is used to locate the 381relevant key if it is not supplied then an attempt is used to decrypt any 382B<KEKRecipientInfo> structures. 383 384=item B<-econtent_type type> 385 386set the encapsulated content type to B<type> if not supplied the B<Data> type 387is used. The B<type> argument can be any valid OID name in either text or 388numerical format. 389 390=item B<-inkey file> 391 392the private key to use when signing or decrypting. This must match the 393corresponding certificate. If this option is not specified then the 394private key must be included in the certificate file specified with 395the B<-recip> or B<-signer> file. When signing this option can be used 396multiple times to specify successive keys. 397 398=item B<-keyopt name:opt> 399 400for signing and encryption this option can be used multiple times to 401set customised parameters for the preceding key or certificate. It can 402currently be used to set RSA-PSS for signing, RSA-OAEP for encryption 403or to modify default parameters for ECDH. 404 405=item B<-passin arg> 406 407the private key password source. For more information about the format of B<arg> 408see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 409 410=item B<-rand file(s)> 411 412a file or files containing random data used to seed the random number 413generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 414Multiple files can be specified separated by a OS-dependent character. 415The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 416all others. 417 418=item B<cert.pem...> 419 420one or more certificates of message recipients: used when encrypting 421a message. 422 423=item B<-to, -from, -subject> 424 425the relevant mail headers. These are included outside the signed 426portion of a message so they may be included manually. If signing 427then many S/MIME mail clients check the signers certificate's email 428address matches that specified in the From: address. 429 430=item B<-purpose, -ignore_critical, -issuer_checks, -crl_check, -crl_check_all, -policy_check, -extended_crl, -x509_strict, -policy -check_ss_sig -no_alt_chains> 431 432Set various certificate chain valiadition option. See the 433L<B<verify>|verify(1)> manual page for details. 434 435=back 436 437=head1 NOTES 438 439The MIME message must be sent without any blank lines between the 440headers and the output. Some mail programs will automatically add 441a blank line. Piping the mail directly to sendmail is one way to 442achieve the correct format. 443 444The supplied message to be signed or encrypted must include the 445necessary MIME headers or many S/MIME clients wont display it 446properly (if at all). You can use the B<-text> option to automatically 447add plain text headers. 448 449A "signed and encrypted" message is one where a signed message is 450then encrypted. This can be produced by encrypting an already signed 451message: see the examples section. 452 453This version of the program only allows one signer per message but it 454will verify multiple signers on received messages. Some S/MIME clients 455choke if a message contains multiple signers. It is possible to sign 456messages "in parallel" by signing an already signed message. 457 458The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME 459clients. Strictly speaking these process CMS enveloped data: CMS 460encrypted data is used for other purposes. 461 462The B<-resign> option uses an existing message digest when adding a new 463signer. This means that attributes must be present in at least one existing 464signer using the same message digest or this operation will fail. 465 466The B<-stream> and B<-indef> options enable experimental streaming I/O support. 467As a result the encoding is BER using indefinite length constructed encoding 468and no longer DER. Streaming is supported for the B<-encrypt> operation and the 469B<-sign> operation if the content is not detached. 470 471Streaming is always used for the B<-sign> operation with detached data but 472since the content is no longer part of the CMS structure the encoding 473remains DER. 474 475If the B<-decrypt> option is used without a recipient certificate then an 476attempt is made to locate the recipient by trying each potential recipient 477in turn using the supplied private key. To thwart the MMA attack 478(Bleichenbacher's attack on PKCS #1 v1.5 RSA padding) all recipients are 479tried whether they succeed or not and if no recipients match the message 480is "decrypted" using a random key which will typically output garbage. 481The B<-debug_decrypt> option can be used to disable the MMA attack protection 482and return an error if no recipient can be found: this option should be used 483with caution. For a fuller description see L<CMS_decrypt(3)|CMS_decrypt(3)>). 484 485=head1 EXIT CODES 486 487=over 4 488 489=item Z<>0 490 491the operation was completely successfully. 492 493=item Z<>1 494 495an error occurred parsing the command options. 496 497=item Z<>2 498 499one of the input files could not be read. 500 501=item Z<>3 502 503an error occurred creating the CMS file or when reading the MIME 504message. 505 506=item Z<>4 507 508an error occurred decrypting or verifying the message. 509 510=item Z<>5 511 512the message was verified correctly but an error occurred writing out 513the signers certificates. 514 515=back 516 517=head1 COMPATIBILITY WITH PKCS#7 format. 518 519The B<smime> utility can only process the older B<PKCS#7> format. The B<cms> 520utility supports Cryptographic Message Syntax format. Use of some features 521will result in messages which cannot be processed by applications which only 522support the older format. These are detailed below. 523 524The use of the B<-keyid> option with B<-sign> or B<-encrypt>. 525 526The B<-outform PEM> option uses different headers. 527 528The B<-compress> option. 529 530The B<-secretkey> option when used with B<-encrypt>. 531 532The use of PSS with B<-sign>. 533 534The use of OAEP or non-RSA keys with B<-encrypt>. 535 536Additionally the B<-EncryptedData_create> and B<-data_create> type cannot 537be processed by the older B<smime> command. 538 539=head1 EXAMPLES 540 541Create a cleartext signed message: 542 543 openssl cms -sign -in message.txt -text -out mail.msg \ 544 -signer mycert.pem 545 546Create an opaque signed message 547 548 openssl cms -sign -in message.txt -text -out mail.msg -nodetach \ 549 -signer mycert.pem 550 551Create a signed message, include some additional certificates and 552read the private key from another file: 553 554 openssl cms -sign -in in.txt -text -out mail.msg \ 555 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem 556 557Create a signed message with two signers, use key identifier: 558 559 openssl cms -sign -in message.txt -text -out mail.msg \ 560 -signer mycert.pem -signer othercert.pem -keyid 561 562Send a signed message under Unix directly to sendmail, including headers: 563 564 openssl cms -sign -in in.txt -text -signer mycert.pem \ 565 -from steve@openssl.org -to someone@somewhere \ 566 -subject "Signed message" | sendmail someone@somewhere 567 568Verify a message and extract the signer's certificate if successful: 569 570 openssl cms -verify -in mail.msg -signer user.pem -out signedtext.txt 571 572Send encrypted mail using triple DES: 573 574 openssl cms -encrypt -in in.txt -from steve@openssl.org \ 575 -to someone@somewhere -subject "Encrypted message" \ 576 -des3 user.pem -out mail.msg 577 578Sign and encrypt mail: 579 580 openssl cms -sign -in ml.txt -signer my.pem -text \ 581 | openssl cms -encrypt -out mail.msg \ 582 -from steve@openssl.org -to someone@somewhere \ 583 -subject "Signed and Encrypted message" -des3 user.pem 584 585Note: the encryption command does not include the B<-text> option because the 586message being encrypted already has MIME headers. 587 588Decrypt mail: 589 590 openssl cms -decrypt -in mail.msg -recip mycert.pem -inkey key.pem 591 592The output from Netscape form signing is a PKCS#7 structure with the 593detached signature format. You can use this program to verify the 594signature by line wrapping the base64 encoded structure and surrounding 595it with: 596 597 -----BEGIN PKCS7----- 598 -----END PKCS7----- 599 600and using the command, 601 602 openssl cms -verify -inform PEM -in signature.pem -content content.txt 603 604alternatively you can base64 decode the signature and use 605 606 openssl cms -verify -inform DER -in signature.der -content content.txt 607 608Create an encrypted message using 128 bit Camellia: 609 610 openssl cms -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem 611 612Add a signer to an existing message: 613 614 openssl cms -resign -in mail.msg -signer newsign.pem -out mail2.msg 615 616Sign mail using RSA-PSS: 617 618 openssl cms -sign -in message.txt -text -out mail.msg \ 619 -signer mycert.pem -keyopt rsa_padding_mode:pss 620 621Create encrypted mail using RSA-OAEP: 622 623 openssl cms -encrypt -in plain.txt -out mail.msg \ 624 -recip cert.pem -keyopt rsa_padding_mode:oaep 625 626Use SHA256 KDF with an ECDH certificate: 627 628 openssl cms -encrypt -in plain.txt -out mail.msg \ 629 -recip ecdhcert.pem -keyopt ecdh_kdf_md:sha256 630 631=head1 BUGS 632 633The MIME parser isn't very clever: it seems to handle most messages that I've 634thrown at it but it may choke on others. 635 636The code currently will only write out the signer's certificate to a file: if 637the signer has a separate encryption certificate this must be manually 638extracted. There should be some heuristic that determines the correct 639encryption certificate. 640 641Ideally a database should be maintained of a certificates for each email 642address. 643 644The code doesn't currently take note of the permitted symmetric encryption 645algorithms as supplied in the SMIMECapabilities signed attribute. this means the 646user has to manually include the correct encryption algorithm. It should store 647the list of permitted ciphers in a database and only use those. 648 649No revocation checking is done on the signer's certificate. 650 651=head1 HISTORY 652 653The use of multiple B<-signer> options and the B<-resign> command were first 654added in OpenSSL 1.0.0. 655 656The B<keyopt> option was first added in OpenSSL 1.0.2. 657 658Support for RSA-OAEP and RSA-PSS was first added to OpenSSL 1.0.2. 659 660The use of non-RSA keys with B<-encrypt> and B<-decrypt> was first added 661to OpenSSL 1.0.2. 662 663The -no_alt_chains options was first added to OpenSSL 1.0.2b. 664 665=cut 666