Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
SMIME(1)			    OpenSSL			      SMIME(1)

       openssl-smime, smime - S/MIME utility

       openssl smime [-help] [-encrypt]	[-decrypt] [-sign] [-resign] [-verify]
       [-pk7out] [-binary] [-crlfeol] [-cipher]	[-in file] [-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]
       [-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] [-certfile file]
       [-signer	file] [-recip  file] [-inform SMIME|PEM|DER] [-passin arg]
       [-inkey file_or_id] [-out file] [-outform SMIME|PEM|DER]	[-content
       file] [-to addr]	[-from ad] [-subject s]	[-text]	[-indef] [-noindef]
       [-stream] [-rand	file...]  [-writerand file] [-md digest] [cert.pem]...

       The smime command handles S/MIME	mail. It can encrypt, decrypt, sign
       and verify S/MIME messages.

       There are six operation options that set	the type of operation to be
       performed.  The meaning of the other options varies according to	the
       operation type.

	   Print out a usage message.

	   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.

	   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

	   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 PKCS#7

	   Resign a message: take an existing message and one or more new

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

       -inform SMIME|PEM|DER
	   This	specifies the input format for the PKCS#7 structure. The
	   default is SMIME which reads	an S/MIME format message. PEM and DER
	   format change this to expect	PEM and	DER format PKCS#7 structures
	   instead. This currently only	affects	the input format of the	PKCS#7
	   structure, if no PKCS#7 structure is	being input (for example with
	   -encrypt or -sign) this option has no effect.

       -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 PKCS#7 structure. The
	   default is SMIME which write	an S/MIME format message. PEM and DER
	   format change this to write PEM and DER format PKCS#7 structures
	   instead. This currently only	affects	the output format of the
	   PKCS#7 structure, if	no PKCS#7 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 PKCS#7
	   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.

       -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.

	   Do not load the trusted CA certificates from	the default file

	   Do not load the trusted CA certificates from	the default directory

       -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	DES  (56 bits) - -des,
	   triple DES (168 bits) - -des3, EVP_get_cipherbyname() function) can
	   also	be used	preceded by a dash, for	example	-aes-128-cbc. See enc
	   for list of ciphers supported by your version of OpenSSL.

	   If not specified triple DES is used.	Only used with -encrypt.

	   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

	   Do not verify the signers certificate of a signed message.

	   Do not do chain verification	of signers certificates: that is don't
	   use the certificates	in the signed message as untrusted CAs.

	   Don't try to	verify the signatures on the 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.

	   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.

	   Normally the	output file uses a single LF as	end of line. When this
	   option is present CRLF is used instead.

	   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.

       -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

       -recip file
	   The recipients certificate when decrypting a	message. This
	   certificate must match one of the recipients	of the message or an
	   error occurs.

       -inkey file_or_id
	   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.  If no engine is
	   used, the argument is taken as a file; if an	engine is specified,
	   the argument	is given to the	engine as a key	identifier.

       -passin arg
	   The private key password source. For	more information about the
	   format of arg see "Pass Phrase Options" 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.

	   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, -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 options of certificate chain verification. See
	   verify(1) 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 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	PKCS#7 enveloped data: PKCS#7
       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 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 PKCS#7 structure the
       encoding	remains	DER.

       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 PKCS#7 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.

       Create a	cleartext signed message:

	openssl	smime -sign -in	message.txt -text -out mail.msg	\
	       -signer mycert.pem

       Create an opaque	signed message:

	openssl	smime -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	smime -sign -in	in.txt -text -out mail.msg \
	       -signer mycert.pem -inkey mykey.pem -certfile mycerts.pem

       Create a	signed message with two	signers:

	openssl	smime -sign -in	message.txt -text -out mail.msg	\
	       -signer mycert.pem -signer othercert.pem

       Send a signed message under Unix	directly to sendmail, including

	openssl	smime -sign -in	in.txt -text -signer mycert.pem	\
	       -from -to someone@somewhere \
	       -subject	"Signed	message" | sendmail someone@somewhere

       Verify a	message	and extract the	signer's certificate if	successful:

	openssl	smime -verify -in mail.msg -signer user.pem -out signedtext.txt

       Send encrypted mail using triple	DES:

	openssl	smime -encrypt -in in.txt -from \
	       -to someone@somewhere -subject "Encrypted message" \
	       -des3 user.pem -out mail.msg

       Sign and	encrypt	mail:

	openssl	smime -sign -in	ml.txt -signer my.pem -text \
	       | openssl smime -encrypt	-out mail.msg \
	       -from -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	smime -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	smime -verify -inform PEM -in signature.pem -content content.txt

       Alternatively you can base64 decode the signature and use:

	openssl	smime -verify -inform DER -in signature.der -content content.txt

       Create an encrypted message using 128 bit Camellia:

	openssl	smime -encrypt -in plain.txt -camellia128 -out mail.msg	cert.pem

       Add a signer to an existing message:

	openssl	smime -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
       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.

       The current code	can only handle	S/MIME v2 messages, the	more complex
       S/MIME v3 structures may	cause parsing errors.

       The use of multiple -signer options and the -resign command were	first
       added in	OpenSSL	1.0.0

       The -no_alt_chains option was added in OpenSSL 1.1.0.

       Copyright 2000-2021 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

1.1.1k				  2021-03-25			      SMIME(1)


Want to link to this manual page? Use this URL:

home | help