Provided by: openssl_1.1.1f-1ubuntu2.24_amd64 
NAME
openssl-cms, cms - CMS utility
SYNOPSIS
openssl cms [-help] [-encrypt] [-decrypt] [-sign] [-verify] [-cmsout] [-resign] [-data_create]
[-data_out] [-digest_create] [-digest_verify] [-compress] [-uncompress] [-EncryptedData_encrypt]
[-sign_receipt] [-verify_receipt receipt] [-in filename] [-inform SMIME|PEM|DER] [-rctform SMIME|PEM|DER]
[-out filename] [-outform SMIME|PEM|DER] [-stream -indef -noindef] [-noindef] [-content filename] [-text]
[-noout] [-print] [-CAfile file] [-CApath dir] [-no-CAfile] [-no-CApath] [-attime timestamp]
[-check_ss_sig] [-crl_check] [-crl_check_all] [-explicit_policy] [-extended_crl] [-ignore_critical]
[-inhibit_any] [-inhibit_map] [-no_check_time] [-partial_chain] [-policy arg] [-policy_check]
[-policy_print] [-purpose purpose] [-suiteB_128] [-suiteB_128_only] [-suiteB_192] [-trusted_first]
[-no_alt_chains] [-use_deltas] [-auth_level num] [-verify_depth num] [-verify_email email]
[-verify_hostname hostname] [-verify_ip ip] [-verify_name name] [-x509_strict] [-md digest] [-cipher]
[-nointern] [-noverify] [-nocerts] [-noattr] [-nosmimecap] [-binary] [-crlfeol] [-asciicrlf] [-nodetach]
[-certfile file] [-certsout file] [-signer file] [-recip file] [-keyid] [-receipt_request_all]
[-receipt_request_first] [-receipt_request_from emailaddress] [-receipt_request_to emailaddress]
[-receipt_request_print] [-secretkey key] [-secretkeyid id] [-econtent_type type] [-inkey file] [-keyopt
name:parameter] [-passin arg] [-rand file...] [-writerand file] [cert.pem...] [-to addr] [-from addr]
[-subject subj] [cert.pem]...
DESCRIPTION
The cms command handles S/MIME v3.1 mail. It can encrypt, decrypt, sign and verify, compress and
uncompress S/MIME messages.
OPTIONS
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.
-help
Print out a usage message.
-encrypt
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 <B>EnvelopedData<B>.
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.
-decrypt
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.
-debug_decrypt
This option sets the CMS_DEBUG_DECRYPT flag. This option should be used with caution: see the notes
section below.
-sign
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.
-verify
Verify signed mail. Expects a signed mail message on input and outputs the signed data. Both clear
text and opaque signing is supported.
-cmsout
Takes an input message and writes out a PEM encoded CMS structure.
-resign
Resign a message: take an existing message and one or more new signers.
-data_create
Create a CMS Data type.
-data_out
Data type and output the content.
-digest_create
Create a CMS DigestedData type.
-digest_verify
Verify a CMS DigestedData type and output the content.
-compress
Create a CMS CompressedData type. OpenSSL must be compiled with zlib support for this option to work,
otherwise it will output an error.
-uncompress
Uncompress a CMS CompressedData type and output the content. OpenSSL must be compiled with zlib
support for this option to work, otherwise it will output an error.
-EncryptedData_encrypt
Encrypt content using supplied symmetric key and algorithm using a CMS EncryptedData type and output
the content.
-sign_receipt
Generate and output a signed receipt for the supplied message. The input message must contain a
signed receipt request. Functionality is otherwise similar to the -sign operation.
-verify_receipt receipt
Verify a signed receipt in filename receipt. The input message must contain the original receipt
request. Functionality is otherwise similar to the -verify operation.
-in filename
The input message to be encrypted or signed or the message to be decrypted or verified.
-inform SMIME|PEM|DER
This specifies the input format for the CMS structure. The default is SMIME which reads an S/MIME
format message. PEM and DER 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 -encrypt or -sign) this option has no effect.
-rctform SMIME|PEM|DER
Specify the format for a signed receipt for use with the -receipt_verify operation.
-out filename
The message text that has been decrypted or verified or the output MIME format message that has been
signed or verified.
-outform SMIME|PEM|DER
This specifies the output format for the CMS structure. The default is SMIME which writes an S/MIME
format message. PEM and DER 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 -verify or -decrypt) this option has no effect.
-stream -indef -noindef
The -stream and -indef 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,
potentially supporting very large files. Streaming is automatically set for S/MIME signing with
detached data if the output format is SMIME it is currently off by default for all other operations.
-noindef
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 operations
and this option will disable it.
-content filename
This specifies a file containing the detached content, this is only useful with the -verify 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.
-text
This option adds plain text (text/plain) MIME headers to the supplied 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.
-noout
For the -cmsout operation do not output the parsed CMS structure. This is useful when combined with
the -print option or if the syntax of the CMS structure is being checked.
-print
For the -cmsout operation print out all fields of the CMS structure. This is mainly useful for
testing purposes.
-CAfile file
A file containing trusted CA certificates, only used with -verify.
-CApath dir
A directory containing trusted CA certificates, only used with -verify. This directory must be a
standard certificate directory: that is a hash of each subject name (using x509 -hash) should be
linked to each certificate.
-no-CAfile
Do not load the trusted CA certificates from the default file location
-no-CApath
Do not load the trusted CA certificates from the default directory location
-md digest
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).
-cipher
The encryption algorithm to use. For example triple DES (168 bits) - -des3 or 256 bit AES - -aes256.
Any standard algorithm name (as used by the EVP_get_cipherbyname() function) can also be used
preceded by a dash, for example -aes-128-cbc. See enc(1) for a list of ciphers supported by your
version of OpenSSL.
If not specified triple DES is used. Only used with -encrypt and -EncryptedData_create commands.
-nointern
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 -certfile option are
used. The supplied certificates can still be used as untrusted CAs however.
-noverify
Do not verify the signers certificate of a signed message.
-nocerts
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 -certfile option for example).
-noattr
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.
-nosmimecap
Exclude the list of supported algorithms from signed attributes, other options such as signing time
and content type are still included.
-binary
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.
-crlfeol
Normally the output file uses a single LF as end of line. When this option is present CRLF is used
instead.
-asciicrlf
When signing use ASCII CRLF format canonicalisation. This strips trailing whitespace from all lines,
deletes trailing blank lines at EOF and sets the encapsulated content type. This option is normally
used with detached content and an output signature format of DER. This option is not normally needed
when verifying as it is enabled automatically if the encapsulated content format is detected.
-nodetach
When signing a message use opaque signing: this form is more resistant 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.
-certfile file
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.
-certsout file
Any certificates contained in the message are written to file.
-signer file
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 certificates will
be written to this file if the verification was successful.
-recip file
When decrypting a message this specifies the recipients certificate. The certificate must match one
of the recipients of the message or an error occurs.
When encrypting a message this option may be used multiple times to specify each recipient. This form
must be used if customised parameters are required (for example to specify RSA-OAEP).
Only certificates carrying RSA, Diffie-Hellman or EC keys are supported by this option.
-keyid
Use subject key identifier to identify certificates instead of issuer name and serial number. The
supplied certificate must include a subject key identifier extension. Supported by -sign and -encrypt
options.
-receipt_request_all, -receipt_request_first
For -sign option include a signed receipt request. Indicate requests should be provided by all
recipient or first tier recipients (those mailed directly and not from a mailing list). Ignored it
-receipt_request_from is included.
-receipt_request_from emailaddress
For -sign option include a signed receipt request. Add an explicit email address where receipts
should be supplied.
-receipt_request_to emailaddress
Add an explicit email address where signed receipts should be sent to. This option must but supplied
if a signed receipt it requested.
-receipt_request_print
For the -verify operation print out the contents of any signed receipt requests.
-secretkey key
Specify symmetric key to use. The key must be supplied in hex format and be consistent with the
algorithm used. Supported by the -EncryptedData_encrypt -EncryptedData_decrypt, -encrypt and -decrypt
options. When used with -encrypt or -decrypt the supplied key is used to wrap or unwrap the content
encryption key using an AES key in the KEKRecipientInfo type.
-secretkeyid id
The key identifier for the supplied symmetric key for KEKRecipientInfo type. This option must be
present if the -secretkey option is used with -encrypt. With -decrypt operations the id is used to
locate the relevant key if it is not supplied then an attempt is used to decrypt any KEKRecipientInfo
structures.
-econtent_type type
Set the encapsulated content type to type if not supplied the Data type is used. The type argument
can be any valid OID name in either text or numerical format.
-inkey file
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 -recip or -signer file. When signing this option can be used multiple times to specify
successive keys.
-keyopt name:opt
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.
-passin arg
The private key password source. For more information about the format of arg see the PASS PHRASE
ARGUMENTS section in openssl(1).
-rand file...
A file or files containing random data used to seed the random number generator. Multiple files can
be specified separated by an OS-dependent character. The separator is ; for MS-Windows, , for
OpenVMS, and : for all others.
[-writerand file]
Writes random data to the specified file upon exit. This can be used with a subsequent -rand flag.
cert.pem...
One or more certificates of message recipients: used when encrypting a message.
-to, -from, -subject
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.
-attime, -check_ss_sig, -crl_check, -crl_check_all, -explicit_policy, -extended_crl, -ignore_critical,
-inhibit_any, -inhibit_map, -no_alt_chains, -no_check_time, -partial_chain, -policy, -policy_check,
-policy_print, -purpose, -suiteB_128, -suiteB_128_only, -suiteB_192, -trusted_first, -use_deltas,
-auth_level, -verify_depth, -verify_email, -verify_hostname, -verify_ip, -verify_name, -x509_strict
Set various certificate chain validation options. See the verify(1) manual page for details.
NOTES
The MIME message must be sent without any blank lines between the headers 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 necessary MIME headers or many S/MIME
clients won't display it properly (if at all). You can use the -text 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 message: 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 -encrypt and -decrypt reflect common usage in S/MIME clients. Strictly speaking these process
CMS enveloped data: CMS encrypted data is used for other purposes.
The -resign 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 -stream and -indef options enable streaming I/O support. As a result the encoding is BER using
indefinite length constructed encoding and no longer DER. Streaming is supported for the -encrypt
operation and the -sign operation if the content is not detached.
Streaming is always used for the -sign operation with detached data but since the content is no longer
part of the CMS structure the encoding remains DER.
If the -decrypt option is used without a recipient certificate then an attempt is made to locate the
recipient by trying each potential recipient 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 -debug_decrypt 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 CMS_decrypt(3)).
EXIT CODES
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.
COMPATIBILITY WITH PKCS#7 format.
The smime utility can only process the older PKCS#7 format. The cms utility supports Cryptographic
Message Syntax format. Use of some features will result in messages which cannot be processed by
applications which only support the older format. These are detailed below.
The use of the -keyid option with -sign or -encrypt.
The -outform PEM option uses different headers.
The -compress option.
The -secretkey option when used with -encrypt.
The use of PSS with -sign.
The use of OAEP or non-RSA keys with -encrypt.
Additionally the -EncryptedData_create and -data_create type cannot be processed by the older smime
command.
EXAMPLES
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 headers:
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 -text 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 signature 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
BUGS
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 encryption 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.
HISTORY
The use of multiple -signer options and the -resign command were first added in OpenSSL 1.0.0.
The keyopt option was added in OpenSSL 1.0.2.
Support for RSA-OAEP and RSA-PSS was added in OpenSSL 1.0.2.
The use of non-RSA keys with -encrypt and -decrypt was added in OpenSSL 1.0.2.
The -no_alt_chains option was added in OpenSSL 1.0.2b.
COPYRIGHT
Copyright 2008-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with
the License. You can obtain a copy in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
1.1.1f 2025-02-05 CMS(1SSL)