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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

1.1.1j                            2021-02-16                          smime(1)

openssl 1.1.1j - Generated Fri Feb 19 15:53:38 CST 2021
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