/usr/man/cat.1/cms.1
CMS(1) OpenSSL CMS(1)
NAME
openssl-cms, cms - CMS utility
SYNOPSIS
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] [-keyopt name:parameter] [-passin arg] [-rand
file(s)] [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.
COMMAND 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.
-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
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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 EncrytedData 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.
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-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
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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.
-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
for a list of ciphers supported by your version of
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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.
-no_signer_cert_verify
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.
-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
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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 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.
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-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
-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 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(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.
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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.
-crl_check_all, -policy_check, -extended_crl, -x509_strict,
-policy -check_ss_sig -no_alt_chains
-purpose, -ignore_critical, -issuer_checks, -crl_check,
Set various certificate chain valiadition option. See
the verify 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 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.
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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.
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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
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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.
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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 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 -encrypt and -decrypt was first
added to OpenSSL 1.0.2.
The -no_alt_chains options was first added to OpenSSL
1.0.2b.
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See also openssl-cms(1)
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