cms - CMS utility
[-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] [-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
verify signed mail. Expects a signed mail message on input and outputs the
signed data. Both clear text and opaque signing is supported.
takes an input message and writes out a PEM encoded CMS structure.
resign a message: take an existing message and one or more new signers.
Create a CMS Data type.
Data type and output the content.
Create a CMS DigestedData type.
Verify a CMS DigestedData type and output the content.
Create a CMS CompressedData type. OpenSSL must be compiled with zlib
support for this option to work, otherwise it will output an error.
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
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_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
- -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
- -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.
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.
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.
- -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.
- -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).
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
do not verify the signers certificate of a signed message.
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).
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.
exclude the list of supported algorithms from signed attributes, other
options such as signing time and content type are still included.
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.
- -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
the recipients certificate when decrypting a message. This certificate must
match one of the recipients of the message or an error occurs.
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 receipient 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.
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
-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.
- -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
- -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
- -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(s)
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
- -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.
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
The supplied message to be signed or encrypted must include the necessary
MIME headers or many S/MIME clients wont 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 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 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.
the operation was completely successfully.
an error occurred parsing the command options.
one of the input files could not be read.
an error occurred creating the CMS file or when reading the MIME message.
an error occurred decrypting or verifying the message.
the message was verified correctly but an error occurred writing out the
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.
Additionally the -EncryptedData_create and -data_create type cannot be processed by the older smime command.
Create a cleartext signed message:
openssl cms -sign -in message.txt -text -out mail.msg \
Create an opaque signed message
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 headers:
openssl cms -sign -in in.txt -text -signer mycert.pem \
-from email@example.com -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 firstname.lastname@example.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 email@example.com -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 it with:
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
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
Ideally a database should be maintained of a certificates for each email
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
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