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.
  - -help
- Print out a usage message.
- -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.
    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.
- -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.
- -pk7out
- Takes an input message and writes out a PEM encoded PKCS#7 structure.
- -resign
- Resign a message: take an existing message and one or more new
    signers.
- -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.
- -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.
- -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 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.
- -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.
- -no-CAfile
- Do not load the trusted CA certificates from the default file
    location.
- -no-CApath
- Do not load the trusted CA certificates from the default directory
      location.
- -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 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. 
- -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.
- -noverify
- Do not verify the signers certificate of a signed message.
- -nochain
- Do not do chain verification of signers certificates: that is don't use
      the certificates in the signed message as untrusted CAs.
- -nosigs
- Don't try to verify the signatures on the 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.
- -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.
- -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
- 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 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.
- -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 the PASS PHRASE ARGUMENTS section 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.
- 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.
- -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
    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 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
      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.
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
    headers:
 openssl smime -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 smime -verify -in mail.msg -signer user.pem -out signedtext.txt
Send encrypted mail using triple DES:
 openssl smime -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 smime -sign -in ml.txt -signer my.pem -text \
        | openssl smime -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 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 2000-2017 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
    <https://www.openssl.org/source/license.html>.