SMIME(1)                            OpenSSL                           SMIME(1)



NAME
       smime - S/MIME utility

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
       openssl smime [-encrypt] [-decrypt] [-sign] [-resign] [-verify]
       [-pk7out] [-des] [-des3] [-rc2-40] [-rc2-64] [-rc2-128] [-aes128]
       [-aes192] [-aes256] [-camellia128] [-camellia192] [-camellia256] [-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] [-indef] [-noindef] [-stream] [-rand file(s)] [-md digest]
       [cert.pem]...

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

COMMAND 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.

       -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.

       -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 out-
           puts the signed data. Both clear text and opaque signing is sup-
           ported.

       -pk7out
           takes an input message and writes out a PEM encoded PKCS#7 struc-
           ture.

       -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 exam-
           ple 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, poten-
           tially 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 opera-
           tions 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 sup-
           plied 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.

       -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).

       -des -des3 -rc2-40 -rc2-64 -rc2-128 -aes128 -aes192 -aes256 -camel-
       lia128 -camellia192 -camellia256
           the encryption algorithm to use. DES (56 bits), triple DES (168
           bits), 40, 64 or 128 bit RC2, 128, 192 or 256 bit AES, or 128, 192
           or 256 bit Camellia respectively. Any other cipher name (as recog-
           nized by the EVP_get_cipherbyname() function) can also be used pre-
           ceded by a dash, for example -aes_128_cbc.

           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 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.

       -nodetach
           when signing a message use opaque signing: this form is more resis-
           tant 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 certifi-
           cates will be written to this file if the verification was success-
           ful.

       -recip file
           the recipients certificate when decrypting a message. This certifi-
           cate must match one of the recipients 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. 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 the PASS PHRASE ARGUMENTS section in openssl(1).

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

       cert.pem...
           one or more certificates of message recipients: used when encrypt-
           ing 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.

NOTES
       The MIME message must be sent without any blank lines between the head-
       ers 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 neces-
       sary 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 mes-
       sage: 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 experimental streaming I/O sup-
       port.  As a result the encoding is BER using indefinite length con-
       structed 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 encod-
       ing 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 head-
       ers:

        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 sig-
       nature 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 encryp-
       tion 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.

HISTORY
       The use of multiple -signer options and the -resign command were first
       added in OpenSSL 0.9.9



0.9.9-dev                         2008-05-09                          SMIME(1)
