smime(1openssl) 						      OpenSSL							   smime(1openssl)

NAME

       smime - S/MIME utility

SYNOPSIS

       openssl smime [-encrypt] [-decrypt] [-sign] [-verify] [-pk7out] [-des] [-des3] [-rc2-40] [-rc2-64] [-rc2-128] [-aes128] [-aes192] [-aes256]
       [-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 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 outputs 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 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 format of the PKCS#7 struc-
	   ture, 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 for-
	   mat 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.

       -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.

       -des -des3 -rc2-40 -rc2-64 -rc2-128 -aes128 -aes192 -aes256
	   the encryption algorithm to use. DES (56 bits), triple DES (168 bits), 40, 64 or 128 bit RC2 or 128, 192 or 256 bit AES 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 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 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
	   the signers certificate when signing a message. 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
	   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 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 number generator, or an EGD socket (see RAND_egd(3)).  Multiple files
	   can be specified separated by a OS-dependent character.  The separator is ; for MS-Windows, , for OpenVMS, and : for all others.

       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.

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 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.

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 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 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

       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 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

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.

OpenSSL-0.9.8							    Oct 11 2005 						   smime(1openssl)