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Manual: openssl-cms

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OPENSSL-CMS(1SSL) OpenSSL OPENSSL-CMS(1SSL)

NAME
openssl-cms - CMS command

SYNOPSIS
openssl cms [-help]

General options:

[-in filename] [-out filename] [-config configfile]

Operation options:

[-encrypt] [-decrypt] [-sign] [-verify] [-resign] [-sign_receipt] [-verify_receipt receipt] [-digest digest]
[-digest_create] [-digest_verify] [-compress] [-uncompress] [-EncryptedData_encrypt] [-EncryptedData_decrypt]
[-data_create] [-data_out] [-cmsout]

File format options:

[-inform DER|PEM|SMIME] [-outform DER|PEM|SMIME] [-rctform DER|PEM|SMIME] [-stream] [-indef] [-noindef] [-binary]
[-crlfeol] [-asciicrlf]

Keys and password options:

[-pwri_password password] [-secretkey key] [-secretkeyid id] [-inkey filename|uri] [-passin arg] [-keyopt
name:parameter] [-keyform DER|PEM|P12|ENGINE] [-engine id] [-provider name] [-provider-path path] [-provparam
[name:]key=value] [-propquery propq] [-rand files] [-writerand file]

Encryption options:

[-originator file] [-recip file] [recipient-cert ...] [-cipher] [-wrap cipher] [-aes128-wrap] [-aes192-wrap]
[-aes256-wrap] [-des3-wrap] [-debug_decrypt]

Signing options:

[-md digest] [-signer file] [-certfile file] [-cades] [-nodetach] [-nocerts] [-noattr] [-nosmimecap]
[-no_signing_time] [-receipt_request_all] [-receipt_request_first] [-receipt_request_from emailaddress]
[-receipt_request_to emailaddress]

Verification options:

[-signer file] [-content filename] [-no_content_verify] [-no_attr_verify] [-nosigs] [-noverify] [-nointern] [-cades]
[-verify_retcode] [-CAfile file] [-no-CAfile] [-CApath dir] [-no-CApath] [-CAstore uri] [-no-CAstore]

Output options:

[-keyid] [-econtent_type type] [-text] [-certsout file] [-to addr] [-from addr] [-subject subj]

Printing options:

[-noout] [-print] [-nameopt option] [-receipt_request_print]

Validation options:

[-allow_proxy_certs] [-attime timestamp] [-no_check_time] [-check_ss_sig] [-crl_check] [-crl_check_all]
[-explicit_policy] [-extended_crl] [-ignore_critical] [-inhibit_any] [-inhibit_map] [-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] [-issuer_checks]

DESCRIPTION
This command handles data in CMS format such as S/MIME v3.1 email messages. It can encrypt, decrypt, sign, verify,
compress, uncompress, and print messages.

OPTIONS
There are a number of operation options that set the type of operation to be performed: encrypt, decrypt, sign,
verify, resign, sign_receipt, verify_receipt, digest_create, digest_verify, compress, uncompress,
EncryptedData_encrypt, EncryptedData_decrypt, data_create, data_out, or cmsout. The relevance of the other options
depends on the operation type and their meaning may vary according to it.

-help
Print out a usage message.

General options
-in filename
The input message to be encrypted or signed or the message to be decrypted or verified.

-out filename
The message text that has been decrypted or verified or the output MIME format message that has been signed or
verified.

-config configfile
See "Configuration Option" in openssl(1).

Operation options
-encrypt
Encrypt data for the given recipient certificates. Input file is the message to be encrypted. The output file is
the encrypted data 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.

-decrypt
Decrypt data using the supplied certificate and private key. Expects encrypted datain MIME format for the input
file. The decrypted data is written to the output file.

-sign
Sign data using the supplied certificate and private key. Input file is the message to be signed. The signed data
in MIME format is written to the output file.

-verify
Verify signed data. Expects a signed data on input and outputs the signed data. Both clear text and opaque
signing is supported.

By default, validation of signer certificates and their chain is done w.r.t. the S/MIME signing ("smimesign")
purpose. For details see "Certificate Extensions" in openssl-verification-options(1).

-resign
Resign a message: take an existing message and one or more new signers.

-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.

-digest digest
When used with -sign, provides the digest in hexadecimal form instead of computing it from the original message
content. Cannot be combined with -in or -nodetach.

This operation is the CMS equivalent of openssl-pkeyutl(1) signing. When signing a pre-computed digest, the
security relies on the digest and its computation from the original message being trusted.

-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.

-EncryptedData_decrypt
Decrypt content using supplied symmetric key and algorithm using a CMS EncryptedData type and output the content.

-data_create
Create a CMS Data type.

-data_out
Data type and output the content.

-cmsout
Takes an input message and writes out a PEM encoded CMS structure.

File format options
-inform DER|PEM|SMIME
The input format of the CMS structure (if one is being read); the default is SMIME. See
openssl-format-options(1) for details.

-outform DER|PEM|SMIME
The output format of the CMS structure (if one is being written); the default is SMIME. See
openssl-format-options(1) for details.

-rctform DER|PEM|SMIME
The signed receipt format for use with the -receipt_verify; the default is SMIME. See openssl-format-options(1)
for details.

-stream, -indef
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.

-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.

Keys and password options
-pwri_password password
Specify password for recipient.

-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.

-inkey filename|uri
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.

-passin arg
The private key password source. For more information about the format of arg see openssl-passphrase-options(1).

-keyopt name:parameter
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.

-keyform DER|PEM|P12|ENGINE
The format of the private key file; unspecified by default. See openssl-format-options(1) for details.

-engine id
See "Engine Options" in openssl(1). This option is deprecated.

-provider name
-provider-path path
-provparam [name:]key=value
-propquery propq
See "Provider Options" in openssl(1), provider(7), and property(7).

-rand files, -writerand file
See "Random State Options" in openssl(1) for details.

Encryption and decryption options
-originator file
A certificate of the originator of the encrypted message. Necessary for decryption when Key Agreement is in use
for a shared key. Currently, not allowed for encryption.

-recip file
When decrypting a message this specifies the certificate of the recipient. The certificate must match one of the
recipients of the message.

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.

recipient-cert ...
This is an alternative to using the -recip option when encrypting a message. One or more certificate filenames
may be given.

-cipher
The encryption algorithm to use. For example, AES (256 bits) - -aes256 or triple DES (168 bits) - -des3. 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 openssl-enc(1) for a list of ciphers supported by your version of OpenSSL.

Currently, the AES variants with GCM mode are the only supported AEAD algorithms.

If not specified, AES-256-CBC is used as the default. Only used with -encrypt and -EncryptedData_encrypt
commands.

-wrap cipher
Cipher algorithm to use for key wrap when encrypting the message using Key Agreement for key transport. The
algorithm specified should be suitable for key wrap.

-aes128-wrap, -aes192-wrap, -aes256-wrap, -des3-wrap
Use AES128, AES192, AES256, or 3DES-EDE, respectively, to wrap key. Depending on the OpenSSL build options used,
-des3-wrap may not be supported.

-debug_decrypt
This option sets the CMS_DEBUG_DECRYPT flag. This option should be used with caution: see the notes section
below.

Signing options
-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 SHA-256).

-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.

-certfile file
Allows additional certificates to be specified. When signing these will be included with the message. When
verifying, these will be searched for signer certificates and will be used for chain building.

The input can be in PEM, DER, or PKCS#12 format.

-cades
When used with -sign, add an ESS signingCertificate or ESS signingCertificateV2 signed-attribute to the
SignerInfo, in order to make the signature comply with the requirements for a CAdES Basic Electronic Signature
(CAdES-BES).

-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.

-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 content type and
(optionally) signing time are still included.

-no_signing_time
Exclude the signing time from signed attributes, other options such as content type are still included.

-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 is requested.

Verification options
-signer file
If a message has been verified successfully then the signers certificate(s) will be written to this file if the
verification was successful.

-content filename
This specifies a file containing the detached content for operations taking S/MIME input, such as 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.

-no_content_verify
Do not verify signed content signatures.

-no_attr_verify
Do not verify signed attribute signatures.

-nosigs
Don't verify message signature.

-noverify
Do not verify the signers certificate of a signed message.

-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.

-cades
When used with -verify, require and check signer certificate digest. See the NOTES section for more details.

-verify_retcode
Exit nonzero on verification failure.

-CAfile file, -no-CAfile, -CApath dir, -no-CApath, -CAstore uri, -no-CAstore
See "Trusted Certificate Options" in openssl-verification-options(1) for details.

Output options
-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.

-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.

-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.

-certsout file
Any certificates contained in the input message are written to file.

-to, -from, -subject
The relevant email 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.

Printing options
-noout
For the -cmsout operation do not output the parsed CMS structure. This is useful if the syntax of the CMS
structure is being checked.

-print
For the -cmsout operation print out all fields of the CMS structure. This implies -noout. This is mainly useful
for testing purposes.

-nameopt option
For the -cmsout operation when -print option is in use, specifies printing options for string fields. For most
cases utf8 is reasonable value. See openssl-namedisplay-options(1) for details.

-receipt_request_print
For the -verify operation print out the contents of any signed receipt requests.

Validation options
-allow_proxy_certs, -attime, -no_check_time, -check_ss_sig, -crl_check, -crl_check_all, -explicit_policy,
-extended_crl, -ignore_critical, -inhibit_any, -inhibit_map, -no_alt_chains, -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 -issuer_checks
Set various options of certificate chain verification. See "Verification Options" in
openssl-verification-options(1) for details.

Any validation errors cause the command to exit.

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)).

CADES BASIC ELECTRONIC SIGNATURE (CADES-BES)
A CAdES Basic Electronic Signature (CAdES-BES), as defined in the European Standard ETSI EN 319 122-1 V1.1.1,
contains:

• The signed user data as defined in CMS (RFC 3852);

• Content-type of the EncapsulatedContentInfo value being signed;

• Message-digest of the eContent OCTET STRING within encapContentInfo being signed;

• An ESS signingCertificate or ESS signingCertificateV2 attribute, as defined in Enhanced Security Services (ESS),
RFC 2634 and RFC 5035. An ESS signingCertificate attribute only allows for SHA-1 as digest algorithm. An ESS
signingCertificateV2 attribute allows for any digest algorithm.

• The digital signature value computed on the user data and, when present, on the signed attributes.

NOTE that the -cades option applies to the -sign or -verify operations. With this option, the -verify operation
also requires that the signingCertificate attribute is present and checks that the given identifiers match the
verification trust chain built during the verification process.

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
openssl-smime(1) can only process the older PKCS#7 format. openssl cms 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_encrypt and -data_create type cannot be processed by the older openssl-smime(1)
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 a message:

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 a message using RSA-PSS:

openssl cms -sign -in message.txt -text -out mail.msg \
-signer mycert.pem -keyopt rsa_padding_mode:pss

Create an encrypted message 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

Print CMS signed binary data in human-readable form:

openssl cms -in signed.cms -binary -inform DER -cmsout -print

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.

Manual: openssl-cms

Related Commands: