cms.pod revision 325337
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). 337 338=item B<-keyid> 339 340use subject key identifier to identify certificates instead of issuer name and 341serial number. The supplied certificate B<must> include a subject key 342identifier extension. Supported by B<-sign> and B<-encrypt> options. 343 344=item B<-receipt_request_all -receipt_request_first> 345 346for B<-sign> option include a signed receipt request. Indicate requests should 347be provided by all receipient or first tier recipients (those mailed directly 348and not from a mailing list). Ignored it B<-receipt_request_from> is included. 349 350=item B<-receipt_request_from emailaddress> 351 352for B<-sign> option include a signed receipt request. Add an explicit email 353address where receipts should be supplied. 354 355=item B<-receipt_request_to emailaddress> 356 357Add an explicit email address where signed receipts should be sent to. This 358option B<must> but supplied if a signed receipt it requested. 359 360=item B<-receipt_request_print> 361 362For the B<-verify> operation print out the contents of any signed receipt 363requests. 364 365=item B<-secretkey key> 366 367specify symmetric key to use. The key must be supplied in hex format and be 368consistent with the algorithm used. Supported by the B<-EncryptedData_encrypt> 369B<-EncrryptedData_decrypt>, B<-encrypt> and B<-decrypt> options. When used 370with B<-encrypt> or B<-decrypt> the supplied key is used to wrap or unwrap the 371content encryption key using an AES key in the B<KEKRecipientInfo> type. 372 373=item B<-secretkeyid id> 374 375the key identifier for the supplied symmetric key for B<KEKRecipientInfo> type. 376This option B<must> be present if the B<-secretkey> option is used with 377B<-encrypt>. With B<-decrypt> operations the B<id> is used to locate the 378relevant key if it is not supplied then an attempt is used to decrypt any 379B<KEKRecipientInfo> structures. 380 381=item B<-econtent_type type> 382 383set the encapsulated content type to B<type> if not supplied the B<Data> type 384is used. The B<type> argument can be any valid OID name in either text or 385numerical format. 386 387=item B<-inkey file> 388 389the private key to use when signing or decrypting. This must match the 390corresponding certificate. If this option is not specified then the 391private key must be included in the certificate file specified with 392the B<-recip> or B<-signer> file. When signing this option can be used 393multiple times to specify successive keys. 394 395=item B<-keyopt name:opt> 396 397for signing and encryption this option can be used multiple times to 398set customised parameters for the preceding key or certificate. It can 399currently be used to set RSA-PSS for signing, RSA-OAEP for encryption 400or to modify default parameters for ECDH. 401 402=item B<-passin arg> 403 404the private key password source. For more information about the format of B<arg> 405see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 406 407=item B<-rand file(s)> 408 409a file or files containing random data used to seed the random number 410generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 411Multiple files can be specified separated by a OS-dependent character. 412The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 413all others. 414 415=item B<cert.pem...> 416 417one or more certificates of message recipients: used when encrypting 418a message. 419 420=item B<-to, -from, -subject> 421 422the relevant mail headers. These are included outside the signed 423portion of a message so they may be included manually. If signing 424then many S/MIME mail clients check the signers certificate's email 425address matches that specified in the From: address. 426 427=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> 428 429Set various certificate chain valiadition option. See the 430L<B<verify>|verify(1)> manual page for details. 431 432=back 433 434=head1 NOTES 435 436The MIME message must be sent without any blank lines between the 437headers and the output. Some mail programs will automatically add 438a blank line. Piping the mail directly to sendmail is one way to 439achieve the correct format. 440 441The supplied message to be signed or encrypted must include the 442necessary MIME headers or many S/MIME clients wont display it 443properly (if at all). You can use the B<-text> option to automatically 444add plain text headers. 445 446A "signed and encrypted" message is one where a signed message is 447then encrypted. This can be produced by encrypting an already signed 448message: see the examples section. 449 450This version of the program only allows one signer per message but it 451will verify multiple signers on received messages. Some S/MIME clients 452choke if a message contains multiple signers. It is possible to sign 453messages "in parallel" by signing an already signed message. 454 455The options B<-encrypt> and B<-decrypt> reflect common usage in S/MIME 456clients. Strictly speaking these process CMS enveloped data: CMS 457encrypted data is used for other purposes. 458 459The B<-resign> option uses an existing message digest when adding a new 460signer. This means that attributes must be present in at least one existing 461signer using the same message digest or this operation will fail. 462 463The B<-stream> and B<-indef> options enable experimental streaming I/O support. 464As a result the encoding is BER using indefinite length constructed encoding 465and no longer DER. Streaming is supported for the B<-encrypt> operation and the 466B<-sign> operation if the content is not detached. 467 468Streaming is always used for the B<-sign> operation with detached data but 469since the content is no longer part of the CMS structure the encoding 470remains DER. 471 472If the B<-decrypt> option is used without a recipient certificate then an 473attempt is made to locate the recipient by trying each potential recipient 474in turn using the supplied private key. To thwart the MMA attack 475(Bleichenbacher's attack on PKCS #1 v1.5 RSA padding) all recipients are 476tried whether they succeed or not and if no recipients match the message 477is "decrypted" using a random key which will typically output garbage. 478The B<-debug_decrypt> option can be used to disable the MMA attack protection 479and return an error if no recipient can be found: this option should be used 480with caution. For a fuller description see L<CMS_decrypt(3)|CMS_decrypt(3)>). 481 482=head1 EXIT CODES 483 484=over 4 485 486=item Z<>0 487 488the operation was completely successfully. 489 490=item Z<>1 491 492an error occurred parsing the command options. 493 494=item Z<>2 495 496one of the input files could not be read. 497 498=item Z<>3 499 500an error occurred creating the CMS file or when reading the MIME 501message. 502 503=item Z<>4 504 505an error occurred decrypting or verifying the message. 506 507=item Z<>5 508 509the message was verified correctly but an error occurred writing out 510the signers certificates. 511 512=back 513 514=head1 COMPATIBILITY WITH PKCS#7 format. 515 516The B<smime> utility can only process the older B<PKCS#7> format. The B<cms> 517utility supports Cryptographic Message Syntax format. Use of some features 518will result in messages which cannot be processed by applications which only 519support the older format. These are detailed below. 520 521The use of the B<-keyid> option with B<-sign> or B<-encrypt>. 522 523The B<-outform PEM> option uses different headers. 524 525The B<-compress> option. 526 527The B<-secretkey> option when used with B<-encrypt>. 528 529The use of PSS with B<-sign>. 530 531The use of OAEP or non-RSA keys with B<-encrypt>. 532 533Additionally the B<-EncryptedData_create> and B<-data_create> type cannot 534be processed by the older B<smime> command. 535 536=head1 EXAMPLES 537 538Create a cleartext signed message: 539 540 openssl cms -sign -in message.txt -text -out mail.msg \ 541 -signer mycert.pem 542 543Create an opaque signed message 544 545 openssl cms -sign -in message.txt -text -out mail.msg -nodetach \ 546 -signer mycert.pem 547 548Create a signed message, include some additional certificates and 549read the private key from another file: 550 551 openssl cms -sign -in in.txt -text -out mail.msg \ 552 -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem 553 554Create a signed message with two signers, use key identifier: 555 556 openssl cms -sign -in message.txt -text -out mail.msg \ 557 -signer mycert.pem -signer othercert.pem -keyid 558 559Send a signed message under Unix directly to sendmail, including headers: 560 561 openssl cms -sign -in in.txt -text -signer mycert.pem \ 562 -from steve@openssl.org -to someone@somewhere \ 563 -subject "Signed message" | sendmail someone@somewhere 564 565Verify a message and extract the signer's certificate if successful: 566 567 openssl cms -verify -in mail.msg -signer user.pem -out signedtext.txt 568 569Send encrypted mail using triple DES: 570 571 openssl cms -encrypt -in in.txt -from steve@openssl.org \ 572 -to someone@somewhere -subject "Encrypted message" \ 573 -des3 user.pem -out mail.msg 574 575Sign and encrypt mail: 576 577 openssl cms -sign -in ml.txt -signer my.pem -text \ 578 | openssl cms -encrypt -out mail.msg \ 579 -from steve@openssl.org -to someone@somewhere \ 580 -subject "Signed and Encrypted message" -des3 user.pem 581 582Note: the encryption command does not include the B<-text> option because the 583message being encrypted already has MIME headers. 584 585Decrypt mail: 586 587 openssl cms -decrypt -in mail.msg -recip mycert.pem -inkey key.pem 588 589The output from Netscape form signing is a PKCS#7 structure with the 590detached signature format. You can use this program to verify the 591signature by line wrapping the base64 encoded structure and surrounding 592it with: 593 594 -----BEGIN PKCS7----- 595 -----END PKCS7----- 596 597and using the command, 598 599 openssl cms -verify -inform PEM -in signature.pem -content content.txt 600 601alternatively you can base64 decode the signature and use 602 603 openssl cms -verify -inform DER -in signature.der -content content.txt 604 605Create an encrypted message using 128 bit Camellia: 606 607 openssl cms -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem 608 609Add a signer to an existing message: 610 611 openssl cms -resign -in mail.msg -signer newsign.pem -out mail2.msg 612 613Sign mail using RSA-PSS: 614 615 openssl cms -sign -in message.txt -text -out mail.msg \ 616 -signer mycert.pem -keyopt rsa_padding_mode:pss 617 618Create encrypted mail using RSA-OAEP: 619 620 openssl cms -encrypt -in plain.txt -out mail.msg \ 621 -recip cert.pem -keyopt rsa_padding_mode:oaep 622 623Use SHA256 KDF with an ECDH certificate: 624 625 openssl cms -encrypt -in plain.txt -out mail.msg \ 626 -recip ecdhcert.pem -keyopt ecdh_kdf_md:sha256 627 628=head1 BUGS 629 630The MIME parser isn't very clever: it seems to handle most messages that I've 631thrown at it but it may choke on others. 632 633The code currently will only write out the signer's certificate to a file: if 634the signer has a separate encryption certificate this must be manually 635extracted. There should be some heuristic that determines the correct 636encryption certificate. 637 638Ideally a database should be maintained of a certificates for each email 639address. 640 641The code doesn't currently take note of the permitted symmetric encryption 642algorithms as supplied in the SMIMECapabilities signed attribute. this means the 643user has to manually include the correct encryption algorithm. It should store 644the list of permitted ciphers in a database and only use those. 645 646No revocation checking is done on the signer's certificate. 647 648=head1 HISTORY 649 650The use of multiple B<-signer> options and the B<-resign> command were first 651added in OpenSSL 1.0.0 652 653The B<keyopt> option was first added in OpenSSL 1.1.0 654 655The use of B<-recip> to specify the recipient when encrypting mail was first 656added to OpenSSL 1.1.0 657 658Support for RSA-OAEP and RSA-PSS was first added to OpenSSL 1.1.0. 659 660The use of non-RSA keys with B<-encrypt> and B<-decrypt> was first added 661to OpenSSL 1.1.0. 662 663The -no_alt_chains options was first added to OpenSSL 1.0.2b. 664 665=cut 666