CMS(1) OpenSSL CMS(1) NNAAMMEE openssl-cms, cms - CMS utility SSYYNNOOPPSSIISS ooppeennssssll ccmmss [--eennccrryypptt] [--ddeeccrryypptt] [--ssiiggnn] [--vveerriiffyy] [--ccmmssoouutt] [--rreessiiggnn] [--ddaattaa__ccrreeaattee] [--ddaattaa__oouutt] [--ddiiggeesstt__ccrreeaattee] [--ddiiggeesstt__vveerriiffyy] [--ccoomm-- pprreessss] [--uunnccoommpprreessss] [--EEnnccrryypptteeddDDaattaa__eennccrryypptt] [--ssiiggnn__rreecceeiipptt] [--vveerr-- iiffyy__rreecceeiipptt rreecceeiipptt] [--iinn ffiilleennaammee] [--iinnffoorrmm SSMMIIMMEE||PPEEMM||DDEERR] [--rrccttffoorrmm SSMMIIMMEE||PPEEMM||DDEERR] [--oouutt ffiilleennaammee] [--oouuttffoorrmm SSMMIIMMEE||PPEEMM||DDEERR] [--ssttrreeaamm --iinnddeeff --nnooiinnddeeff] [--nnooiinnddeeff] [--ccoonntteenntt ffiilleennaammee] [--tteexxtt] [--nnoooouutt] [--pprriinntt] [--CCAAffiillee ffiillee] [--CCAAppaatthh ddiirr] [--nnoo__aalltt__cchhaaiinnss] [--mmdd ddiiggeesstt] [--[[cciipphheerr]]] [--nnooiinntteerrnn] [--nnoo__ssiiggnneerr__cceerrtt__vveerriiffyy] [--nnoocceerrttss] [--nnooaattttrr] [--nnoossmmiimmeeccaapp] [--bbiinnaarryy] [--nnooddeettaacchh] [--cceerrttffiillee ffiillee] [--cceerrttssoouutt ffiillee] [--ssiiggnneerr ffiillee] [--rreecciipp ffiillee] [--kkeeyyiidd] [--rreecceeiipptt__rreeqquueesstt__aallll --rreecceeiipptt__rreeqquueesstt__ffiirrsstt] [--rreecceeiipptt__rreeqquueesstt__ffrroomm eemmaaiillaaddddrreessss] [--rreecceeiipptt__rreeqquueesstt__ttoo eemmaaiillaaddddrreessss] [--rreecceeiipptt__rreeqquueesstt__pprriinntt] [--sseeccrreettkkeeyy kkeeyy] [--sseeccrreettkkeeyyiidd iidd] [--eeccoonn-- tteenntt__ttyyppee ttyyppee] [--iinnkkeeyy ffiillee] [--kkeeyyoopptt nnaammee::ppaarraammeetteerr] [--ppaassssiinn aarrgg] [--rraanndd ffiillee((ss))] [cceerrtt..ppeemm......] [--ttoo aaddddrr] [--ffrroomm aaddddrr] [--ssuubbjjeecctt ssuubbjj] [cert.pem]... DDEESSCCRRIIPPTTIIOONN The ccmmss command handles S/MIME v3.1 mail. It can encrypt, decrypt, sign and verify, compress and uncompress S/MIME messages. CCOOMMMMAANNDD OOPPTTIIOONNSS There are fourteen operation options that set the type of operation to be performed. The meaning of the other options varies according to the operation type. --eennccrryypptt encrypt mail for the given recipient certificates. Input file is the message to be encrypted. The output file is the encrypted mail in MIME format. The actual CMS type is EnvelopedData. Note that no revocation check is done for the recipient cert, so if that key has been compromised, others may be able to decrypt the text. --ddeeccrryypptt decrypt mail using the supplied certificate and private key. Expects an encrypted mail message in MIME format for the input file. The decrypted mail is written to the output file. --ddeebbuugg__ddeeccrryypptt this option sets the CCMMSS__DDEEBBUUGG__DDEECCRRYYPPTT flag. This option should be used with caution: see the notes section below. --ssiiggnn sign mail using the supplied certificate and private key. Input file is the message to be signed. The signed message in MIME format is written to the output file. --vveerriiffyy verify signed mail. Expects a signed mail message on input and out- puts the signed data. Both clear text and opaque signing is sup- ported. --ccmmssoouutt takes an input message and writes out a PEM encoded CMS structure. --rreessiiggnn resign a message: take an existing message and one or more new signers. --ddaattaa__ccrreeaattee Create a CMS DDaattaa type. --ddaattaa__oouutt DDaattaa type and output the content. --ddiiggeesstt__ccrreeaattee Create a CMS DDiiggeesstteeddDDaattaa type. --ddiiggeesstt__vveerriiffyy Verify a CMS DDiiggeesstteeddDDaattaa type and output the content. --ccoommpprreessss Create a CMS CCoommpprreesssseeddDDaattaa type. OpenSSL must be compiled with zzlliibb support for this option to work, otherwise it will output an error. --uunnccoommpprreessss Uncompress a CMS CCoommpprreesssseeddDDaattaa type and output the content. OpenSSL must be compiled with zzlliibb support for this option to work, otherwise it will output an error. --EEnnccrryypptteeddDDaattaa__eennccrryypptt Encrypt content using supplied symmetric key and algorithm using a CMS EEnnccrryytteeddDDaattaa type and output the content. --ssiiggnn__rreecceeiipptt Generate and output a signed receipt for the supplied message. The input message mmuusstt contain a signed receipt request. Functionality is otherwise similar to the --ssiiggnn operation. --vveerriiffyy__rreecceeiipptt rreecceeiipptt Verify a signed receipt in filename rreecceeiipptt. The input message mmuusstt contain the original receipt request. Functionality is otherwise similar to the --vveerriiffyy operation. --iinn ffiilleennaammee the input message to be encrypted or signed or the message to be decrypted or verified. --iinnffoorrmm SSMMIIMMEE||PPEEMM||DDEERR this specifies the input format for the CMS structure. The default is SSMMIIMMEE which reads an S/MIME format message. PPEEMM and DDEERR format change this to expect PEM and DER format CMS structures instead. This currently only affects the input format of the CMS structure, if no CMS structure is being input (for example with --eennccrryypptt or --ssiiggnn) this option has no effect. --rrccttffoorrmm SSMMIIMMEE||PPEEMM||DDEERR specify the format for a signed receipt for use with the --rreecceeiipptt__vveerriiffyy operation. --oouutt ffiilleennaammee the message text that has been decrypted or verified or the output MIME format message that has been signed or verified. --oouuttffoorrmm SSMMIIMMEE||PPEEMM||DDEERR this specifies the output format for the CMS structure. The default is SSMMIIMMEE which writes an S/MIME format message. PPEEMM and DDEERR format change this to write PEM and DER format CMS structures instead. This currently only affects the output format of the CMS structure, if no CMS structure is being output (for example with --vveerriiffyy or --ddeeccrryypptt) this option has no effect. --ssttrreeaamm --iinnddeeff --nnooiinnddeeff the --ssttrreeaamm and --iinnddeeff options are equivalent and enable streaming I/O for encoding operations. This permits single pass processing of data without the need to hold the entire contents in memory, poten- tially supporting very large files. Streaming is automatically set for S/MIME signing with detached data if the output format is SSMMIIMMEE it is currently off by default for all other operations. --nnooiinnddeeff disable streaming I/O where it would produce and indefinite length constructed encoding. This option currently has no effect. In future streaming will be enabled by default on all relevant opera- tions and this option will disable it. --ccoonntteenntt ffiilleennaammee This specifies a file containing the detached content, this is only useful with the --vveerriiffyy command. This is only usable if the CMS structure is using the detached signature form where the content is not included. This option will override any content if the input format is S/MIME and it uses the multipart/signed MIME content type. --tteexxtt this option adds plain text (text/plain) MIME headers to the sup- plied message if encrypting or signing. If decrypting or verifying it strips off text headers: if the decrypted or verified message is not of MIME type text/plain then an error occurs. --nnoooouutt for the --ccmmssoouutt operation do not output the parsed CMS structure. This is useful when combined with the --pprriinntt option or if the syn- tax of the CMS structure is being checked. --pprriinntt for the --ccmmssoouutt operation print out all fields of the CMS struc- ture. This is mainly useful for testing purposes. --CCAAffiillee ffiillee a file containing trusted CA certificates, only used with --vveerriiffyy. --CCAAppaatthh ddiirr a directory containing trusted CA certificates, only used with --vveerriiffyy. This directory must be a standard certificate directory: that is a hash of each subject name (using xx550099 --hhaasshh) should be linked to each certificate. --mmdd ddiiggeesstt digest algorithm to use when signing or resigning. If not present then the default digest algorithm for the signing key will be used (usually SHA1). --[[cciipphheerr]] the encryption algorithm to use. For example triple DES (168 bits) - --ddeess33 or 256 bit AES - --aaeess225566. Any standard algorithm name (as used by the _E_V_P___g_e_t___c_i_p_h_e_r_b_y_n_a_m_e_(_) function) can also be used pre- ceded by a dash, for example --aaeess__112288__ccbbcc. See eenncc for a list of ciphers supported by your version of OpenSSL. If not specified triple DES is used. Only used with --eennccrryypptt and --EEnnccrryypptteeddDDaattaa__ccrreeaattee commands. --nnooiinntteerrnn when verifying a message normally certificates (if any) included in the message are searched for the signing certificate. With this option only the certificates specified in the --cceerrttffiillee option are used. The supplied certificates can still be used as untrusted CAs however. --nnoo__ssiiggnneerr__cceerrtt__vveerriiffyy do not verify the signers certificate of a signed message. --nnoocceerrttss when signing a message the signer's certificate is normally included with this option it is excluded. This will reduce the size of the signed message but the verifier must have a copy of the signers certificate available locally (passed using the --cceerrttffiillee option for example). --nnooaattttrr normally when a message is signed a set of attributes are included which include the signing time and supported symmetric algorithms. With this option they are not included. --nnoossmmiimmeeccaapp exclude the list of supported algorithms from signed attributes, other options such as signing time and content type are still included. --bbiinnaarryy normally the input message is converted to "canonical" format which is effectively using CR and LF as end of line: as required by the S/MIME specification. When this option is present no translation occurs. This is useful when handling binary data which may not be in MIME format. --nnooddeettaacchh when signing a message use opaque signing: this form is more resis- tant to translation by mail relays but it cannot be read by mail agents that do not support S/MIME. Without this option cleartext signing with the MIME type multipart/signed is used. --cceerrttffiillee ffiillee allows additional certificates to be specified. When signing these will be included with the message. When verifying these will be searched for the signers certificates. The certificates should be in PEM format. --cceerrttssoouutt ffiillee any certificates contained in the message are written to ffiillee. --ssiiggnneerr ffiillee a signing certificate when signing or resigning a message, this option can be used multiple times if more than one signer is required. If a message is being verified then the signers certifi- cates will be written to this file if the verification was success- ful. --rreecciipp ffiillee when decrypting a message this specifies the recipients certifi- cate. The certificate must match one of the recipients of the mes- sage or an error occurs. When encrypting a message this option may be used multiple times to specify each recipient. This form mmuusstt be used if customised param- eters are required (for example to specify RSA-OAEP). Only certificates carrying RSA, Diffie-Hellman or EC keys are sup- ported by this option. --kkeeyyiidd use subject key identifier to identify certificates instead of issuer name and serial number. The supplied certificate mmuusstt include a subject key identifier extension. Supported by --ssiiggnn and --eennccrryypptt options. --rreecceeiipptt__rreeqquueesstt__aallll --rreecceeiipptt__rreeqquueesstt__ffiirrsstt for --ssiiggnn option include a signed receipt request. Indicate requests should be provided by all receipient or first tier recipi- ents (those mailed directly and not from a mailing list). Ignored it --rreecceeiipptt__rreeqquueesstt__ffrroomm is included. --rreecceeiipptt__rreeqquueesstt__ffrroomm eemmaaiillaaddddrreessss for --ssiiggnn option include a signed receipt request. Add an explicit email address where receipts should be supplied. --rreecceeiipptt__rreeqquueesstt__ttoo eemmaaiillaaddddrreessss Add an explicit email address where signed receipts should be sent to. This option mmuusstt but supplied if a signed receipt it requested. --rreecceeiipptt__rreeqquueesstt__pprriinntt For the --vveerriiffyy operation print out the contents of any signed receipt requests. --sseeccrreettkkeeyy kkeeyy specify symmetric key to use. The key must be supplied in hex for- mat and be consistent with the algorithm used. Supported by the --EEnnccrryypptteeddDDaattaa__eennccrryypptt --EEnnccrrrryypptteeddDDaattaa__ddeeccrryypptt, --eennccrryypptt and --ddeeccrryypptt options. When used with --eennccrryypptt or --ddeeccrryypptt the supplied key is used to wrap or unwrap the content encryption key using an AES key in the KKEEKKRReecciippiieennttIInnffoo type. --sseeccrreettkkeeyyiidd iidd the key identifier for the supplied symmetric key for KKEEKKRReecciippii-- eennttIInnffoo type. This option mmuusstt be present if the --sseeccrreettkkeeyy option is used with --eennccrryypptt. With --ddeeccrryypptt operations the iidd is used to locate the relevant key if it is not supplied then an attempt is used to decrypt any KKEEKKRReecciippiieennttIInnffoo structures. --eeccoonntteenntt__ttyyppee ttyyppee set the encapsulated content type to ttyyppee if not supplied the DDaattaa type is used. The ttyyppee argument can be any valid OID name in either text or numerical format. --iinnkkeeyy ffiillee the private key to use when signing or decrypting. This must match the corresponding certificate. If this option is not specified then the private key must be included in the certificate file specified with the --rreecciipp or --ssiiggnneerr file. When signing this option can be used multiple times to specify successive keys. --kkeeyyoopptt nnaammee::oopptt for signing and encryption this option can be used multiple times to set customised parameters for the preceding key or certificate. It can currently be used to set RSA-PSS for signing, RSA-OAEP for encryption or to modify default parameters for ECDH. --ppaassssiinn aarrgg the private key password source. For more information about the format of aarrgg see the PPAASSSS PPHHRRAASSEE AARRGGUUMMEENNTTSS section in _o_p_e_n_s_s_l(1). --rraanndd ffiillee((ss)) a file or files containing random data used to seed the random num- ber generator, or an EGD socket (see _R_A_N_D___e_g_d(3)). Multiple files can be specified separated by a OS-dependent character. The sepa- rator is ;; for MS-Windows, ,, for OpenVMS, and :: for all others. cceerrtt..ppeemm...... one or more certificates of message recipients: used when encrypt- ing a message. --ttoo,, --ffrroomm,, --ssuubbjjeecctt the relevant mail headers. These are included outside the signed portion of a message so they may be included manually. If signing then many S/MIME mail clients check the signers certificate's email address matches that specified in the From: address. --ppuurrppoossee,, --iiggnnoorree__ccrriittiiccaall,, --iissssuueerr__cchheecckkss,, --ccrrll__cchheecckk,, --ccrrll__cchheecckk__aallll,, --ppoolliiccyy__cchheecckk,, --eexxtteennddeedd__ccrrll,, --xx550099__ssttrriicctt,, --ppoolliiccyy --cchheecckk__ssss__ssiigg --nnoo__aalltt__cchhaaiinnss Set various certificate chain valiadition option. See the vveerriiffyy manual page for details. NNOOTTEESS The MIME message must be sent without any blank lines between the head- ers and the output. Some mail programs will automatically add a blank line. Piping the mail directly to sendmail is one way to achieve the correct format. The supplied message to be signed or encrypted must include the neces- sary MIME headers or many S/MIME clients wont display it properly (if at all). You can use the --tteexxtt option to automatically add plain text headers. A "signed and encrypted" message is one where a signed message is then encrypted. This can be produced by encrypting an already signed mes- sage: see the examples section. This version of the program only allows one signer per message but it will verify multiple signers on received messages. Some S/MIME clients choke if a message contains multiple signers. It is possible to sign messages "in parallel" by signing an already signed message. The options --eennccrryypptt and --ddeeccrryypptt reflect common usage in S/MIME clients. Strictly speaking these process CMS enveloped data: CMS encrypted data is used for other purposes. The --rreessiiggnn option uses an existing message digest when adding a new signer. This means that attributes must be present in at least one existing signer using the same message digest or this operation will fail. The --ssttrreeaamm and --iinnddeeff options enable experimental streaming I/O sup- port. As a result the encoding is BER using indefinite length con- structed encoding and no longer DER. Streaming is supported for the --eennccrryypptt operation and the --ssiiggnn operation if the content is not detached. Streaming is always used for the --ssiiggnn operation with detached data but since the content is no longer part of the CMS structure the encoding remains DER. If the --ddeeccrryypptt option is used without a recipient certificate then an attempt is made to locate the recipient by trying each potential recip- ient in turn using the supplied private key. To thwart the MMA attack (Bleichenbacher's attack on PKCS #1 v1.5 RSA padding) all recipients are tried whether they succeed or not and if no recipients match the message is "decrypted" using a random key which will typically output garbage. The --ddeebbuugg__ddeeccrryypptt option can be used to disable the MMA attack protection and return an error if no recipient can be found: this option should be used with caution. For a fuller description see _C_M_S___d_e_c_r_y_p_t(3)). EEXXIITT CCOODDEESS 0 the operation was completely successfully. 1 an error occurred parsing the command options. 2 one of the input files could not be read. 3 an error occurred creating the CMS file or when reading the MIME message. 4 an error occurred decrypting or verifying the message. 5 the message was verified correctly but an error occurred writing out the signers certificates. CCOOMMPPAATTIIBBIILLIITTYY WWIITTHH PPKKCCSS##77 ffoorrmmaatt.. The ssmmiimmee utility can only process the older PPKKCCSS##77 format. The ccmmss utility supports Cryptographic Message Syntax format. Use of some fea- tures will result in messages which cannot be processed by applications which only support the older format. These are detailed below. The use of the --kkeeyyiidd option with --ssiiggnn or --eennccrryypptt. The --oouuttffoorrmm PPEEMM option uses different headers. The --ccoommpprreessss option. The --sseeccrreettkkeeyy option when used with --eennccrryypptt. The use of PSS with --ssiiggnn. The use of OAEP or non-RSA keys with --eennccrryypptt. Additionally the --EEnnccrryypptteeddDDaattaa__ccrreeaattee and --ddaattaa__ccrreeaattee type cannot be processed by the older ssmmiimmee command. EEXXAAMMPPLLEESS Create a cleartext signed message: openssl cms -sign -in message.txt -text -out mail.msg \ -signer mycert.pem Create an opaque signed message openssl cms -sign -in message.txt -text -out mail.msg -nodetach \ -signer mycert.pem Create a signed message, include some additional certificates and read the private key from another file: openssl cms -sign -in in.txt -text -out mail.msg \ -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem Create a signed message with two signers, use key identifier: openssl cms -sign -in message.txt -text -out mail.msg \ -signer mycert.pem -signer othercert.pem -keyid Send a signed message under Unix directly to sendmail, including head- ers: openssl cms -sign -in in.txt -text -signer mycert.pem \ -from steve@openssl.org -to someone@somewhere \ -subject "Signed message" | sendmail someone@somewhere Verify a message and extract the signer's certificate if successful: openssl cms -verify -in mail.msg -signer user.pem -out signedtext.txt Send encrypted mail using triple DES: openssl cms -encrypt -in in.txt -from steve@openssl.org \ -to someone@somewhere -subject "Encrypted message" \ -des3 user.pem -out mail.msg Sign and encrypt mail: openssl cms -sign -in ml.txt -signer my.pem -text \ | openssl cms -encrypt -out mail.msg \ -from steve@openssl.org -to someone@somewhere \ -subject "Signed and Encrypted message" -des3 user.pem Note: the encryption command does not include the --tteexxtt option because the message being encrypted already has MIME headers. Decrypt mail: openssl cms -decrypt -in mail.msg -recip mycert.pem -inkey key.pem The output from Netscape form signing is a PKCS#7 structure with the detached signature format. You can use this program to verify the sig- nature by line wrapping the base64 encoded structure and surrounding it with: -----BEGIN PKCS7----- -----END PKCS7----- and using the command, openssl cms -verify -inform PEM -in signature.pem -content content.txt alternatively you can base64 decode the signature and use openssl cms -verify -inform DER -in signature.der -content content.txt Create an encrypted message using 128 bit Camellia: openssl cms -encrypt -in plain.txt -camellia128 -out mail.msg cert.pem Add a signer to an existing message: openssl cms -resign -in mail.msg -signer newsign.pem -out mail2.msg Sign mail using RSA-PSS: openssl cms -sign -in message.txt -text -out mail.msg \ -signer mycert.pem -keyopt rsa_padding_mode:pss Create encrypted mail using RSA-OAEP: openssl cms -encrypt -in plain.txt -out mail.msg \ -recip cert.pem -keyopt rsa_padding_mode:oaep Use SHA256 KDF with an ECDH certificate: openssl cms -encrypt -in plain.txt -out mail.msg \ -recip ecdhcert.pem -keyopt ecdh_kdf_md:sha256 BBUUGGSS The MIME parser isn't very clever: it seems to handle most messages that I've thrown at it but it may choke on others. The code currently will only write out the signer's certificate to a file: if the signer has a separate encryption certificate this must be manually extracted. There should be some heuristic that determines the correct encryption certificate. Ideally a database should be maintained of a certificates for each email address. The code doesn't currently take note of the permitted symmetric encryp- tion algorithms as supplied in the SMIMECapabilities signed attribute. this means the user has to manually include the correct encryption algorithm. It should store the list of permitted ciphers in a database and only use those. No revocation checking is done on the signer's certificate. HHIISSTTOORRYY The use of multiple --ssiiggnneerr options and the --rreessiiggnn command were first added in OpenSSL 1.0.0. The kkeeyyoopptt option was first added in OpenSSL 1.0.2. Support for RSA-OAEP and RSA-PSS was first added to OpenSSL 1.0.2. The use of non-RSA keys with --eennccrryypptt and --ddeeccrryypptt was first added to OpenSSL 1.0.2. The -no_alt_chains options was first added to OpenSSL 1.0.2b. 1.0.2u 2019-12-20 CMS(1)