openssl cms [-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_alt_chains] [-md
digest] [-[cipher]] [-nointern] [-no_signer_cert_verify] [-nocerts]
[-noattr] [-nosmimecap] [-binary] [-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] [-passin arg] [-rand file(s)]
[cert.pem...] [-to addr] [-from addr] [-subject subj] [cert.pem]...
The cms command handles S/MIME v3.1 mail. It can encrypt, decrypt, sign
and verify, compress and uncompress S/MIME messages.
There are fourteen operation options that set the type of operation to
be performed. The meaning of the other options varies according to the
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>.
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.
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 signed mail. Expects a signed mail message on input and
outputs the signed data. Both clear text and opaque signing is
takes an input message and writes out a PEM encoded CMS structure.
resign a message: take an existing message and one or more new
Create a CMS CompressedData type. OpenSSL must be compiled with
zlib support for this option to work, otherwise it will output an
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.
Encrypt suppled content using supplied symmetric key and algorithm
using a CMS EncrytedData type and output the content.
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 a signed receipt in filename receipt. The input message must
contain the original receipt request. Functionality is otherwise
similar to the -verify operation.
the input message to be encrypted or signed or the message to be
decrypted or verified.
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.
specify the format for a signed receipt for use with the
the message text that has been decrypted or verified or the output
MIME format message that has been signed or verified.
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
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
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.
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.
for the -cmsout operation print out all fields of the CMS
structure. This is mainly useful for testing purposes.
a file containing trusted CA certificates, only used with -verify.
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.
digest algorithm to use when signing or resigning. If not present
then the default digest algorithm for the signing key will be used
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 for a list of
ciphers supported by your version of OpenSSL.
If not specified triple DES is used. Only used with -encrypt and
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
which include the signing time and supported symmetric algorithms.
With this option they are not included.
exclude the list of supported algorithms from signed attributes,
other options such as signing time and content type are still
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.
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.
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.
any certificates contained in the message are written to 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
the recipients certificate when decrypting a message. This
certificate must match one of the recipients of the message or an
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
for -sign option include a signed receipt request. Indicate
requests should be provided by all receipient or first tier
recipients (those mailed directly and not from a mailing list).
Ignored it -receipt_request_from is included.
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 -EncrryptedData_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.
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.
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.
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.
the private key password source. For more information about the
format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
a file or files containing random data used to seed the random
number generator, or an EGD socket (see RAND_egd(3)). Multiple
files can be specified separated by a OS-dependent character. The
separator is ; for MS-Windows, , for OpenVMS, and : for all others.
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.
-purpose, -ignore_critical, -issuer_checks, -crl_check, -crl_check_all,
-policy_check, -extended_crl, -x509_strict, -policy -check_ss_sig
Set various certificate chain valiadition option. See the verify
manual page for details.
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
The -stream and -indef options enable experimental 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
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
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
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
The use of the -keyid option with -sign or -encrypt.
The -outform PEM option uses different headers.
The -compress option.
openssl cms -sign -in message.txt -text -out mail.msg -nodetach \
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
openssl cms -sign -in in.txt -text -signer mycert.pem \
-from firstname.lastname@example.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 email@example.com \
-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 firstname.lastname@example.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.
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
Add a signer to an existing message:
openssl cms -resign -in mail.msg -signer newsign.pem -out mail2.msg
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
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.
The use of multiple -signer options and the -resign command were first
added in OpenSSL 1.0.0
The -no_alt_chains options was first added to OpenSSL 1.0.1n and
1.0.1f 2018-12-04 CMS(1SSL)
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