Provided by: openssl_3.0.10-1ubuntu2.3_amd64 bug

NAME

       openssl-smime - S/MIME command

SYNOPSIS

       openssl smime [-help] [-encrypt] [-decrypt] [-sign] [-resign] [-verify] [-pk7out]
       [-binary] [-crlfeol] [-cipher] [-in file] [-certfile file] [-signer file] [-nointern]
       [-noverify] [-nochain] [-nosigs] [-nocerts] [-noattr] [-nodetach] [-nosmimecap] [-recip
       file] [-inform DER|PEM|SMIME] [-outform DER|PEM|SMIME] [-keyform DER|PEM|P12|ENGINE]
       [-passin arg] [-inkey filename|uri] [-out file] [-content file] [-to addr] [-from ad]
       [-subject s] [-text] [-indef] [-noindef] [-stream] [-md digest] [-CAfile file]
       [-no-CAfile] [-CApath dir] [-no-CApath] [-CAstore uri] [-no-CAstore] [-engine id] [-rand
       files] [-writerand file] [-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] [-provider name] [-provider-path path]
       [-propquery propq] [-config configfile] recipcert ...

DESCRIPTION

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

OPTIONS

       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.

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

       -inform DER|PEM|SMIME
           The input format of the PKCS#7 (S/MIME) 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 PKCS#7 (S/MIME) structure (if one is being written); the
           default is SMIME.  See openssl-format-options(1) for details.

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

       -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.

       -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 openssl-enc(1) 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, do not 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.

       -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.

       -nosmimecap
           When signing a message, do not include the SMIMECapabilities attribute.

       -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.

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

       -nocerts
           Don't include signers certificate when signing.

       -noattr
           Don't include any signed attributes when signing.

       -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 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).

       -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.

       -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 verification errors cause the command to exit.

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

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

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

       -provider name
       -provider-path path
       -propquery propq
           See "Provider Options" in openssl(1), provider(7), and property(7).

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

       recipcert ...
           One or more certificates of message recipients, used when encrypting a message.

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 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.

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 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.

EXAMPLES

       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

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.

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

SEE ALSO

       ossl_store-file(7)

HISTORY

       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.

       The -engine option was deprecated in OpenSSL 3.0.

COPYRIGHT

       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.