SMIME(1)                    OpenSSL                    SMIME(1)





NAME
       smime - S/MIME utility

SYNOPSIS
       openssl smime [-encrypt] [-decrypt] [-sign] [-verify]
       [-pk7out] [-des] [-des3] [-rc2-40] [-rc2-64] [-rc2-128]
       [-in file] [-certfile file] [-signer file] [-recip
       file] [-inform SMIME|PEM|DER] [-passin arg] [-inkey
       file] [-out file] [-outform SMIME|PEM|DER] [-content
       file] [-to addr] [-from ad] [-subject s] [-text] [-rand
       file(s)] [cert.pem]...

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

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

       -encrypt
           encrypt mail for the given recipient certificates.
           Input file is the message to be encrypted. The out-
           put file is the encrypted mail in MIME format.

       -decrypt
           decrypt mail using the supplied certificate and pri-
           vate 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 out-
           put 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.

       -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 for-
           mat 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 for-
           mat of the PKCS#7 structure, if no PKCS#7 structure
           is being output (for example with -verify or
           -decrypt) this option has no effect.

       -content filename
           This specifies a file containing the detached con-
           tent, 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 multi-
           part/signed MIME content type.

       -text
           this option adds plain text (text/plain) MIME head-
           ers to the supplied message if encrypting or sign-
           ing. 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 sub-
           ject name (using x509 -hash) should be linked to
           each certificate.

       -des -des3 -rc2-40 -rc2-64 -rc2-128
           the encryption algorithm to use. DES (56 bits),
           triple DES (168 bits) or 40, 64 or 128 bit RC2
           respectively if not specified 40 bit RC2 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 cer-
           tificates 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 certifi-
           cates: 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 "canoni-
           cal" format which is effectively using CR and LF as
           end of line: as required by the S/MIME specifica-
           tion. When this option is present no translation
           occurs. This is useful when handling binary data
           which may not be in MIME format.

       -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 sign-
           ers certificates. The certificates should be in PEM
           format.

       -signer file
           the signers certificate when signing a message. If a
           message is being verified then the signers certifi-
           cates will be written to this file if the verifica-
           tion was successful.

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

       -inkey file
           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.

       -passin arg
           the private key password source. For more informa-
           tion about the format of arg see the PASS PHRASE
           ARGUMENTS section in openssl(1).

       -rand file(s)
           a file or files containing random data used to seed
           the random number generator, or an EGD socket (see
           RAND_egd(3)).  Multiple files can be specified sepa-
           rated by a OS-dependent character.  The separator is
           ; for MS-Windows, , for OpenVMS, and : for all oth-
           ers.

       cert.pem...
           one or more certificates of message recipients: used
           when encrypting a message.

       -to, -from, -subject
           the relevant mail headers. These are included out-
           side 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.

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 wont 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 con-
       tains 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.

EXIT CODES
       o   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 mes-
           sage.

       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 and opaque signed message

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

       Create a signed message, include some additional cer-
       tificates 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

       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 struc-
       ture 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

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 cer-
       tificate to a file: if the signer has a separate encryp-
       tion 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 certifi-
       cates 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 algo-
       rithm. It should store the list of permitted ciphers in
       a database and only use those.

       No revocation checking is done on the signer's certifi-
       cate.

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



0.9.7c                     2002-11-09                  SMIME(1)
