MAN page from Trustix openssl-0.9.7m-1tr.i586.rpm


Section: OpenSSL (1)
Updated: 2004-02-27


smime - S/MIME utility 


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]... 


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


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 mail for the given recipient certificates. Input file is the messageto be encrypted. The output file is the encrypted mail in MIME format.
decrypt mail using the supplied certificate and private key. Expects anencrypted mail message in MIME format for the input file. The decrypted mailis written to the output file.
sign mail using the supplied certificate and private key. Input file isthe message to be signed. The signed message in MIME format is writtento the output file.
verify signed mail. Expects a signed mail message on input and outputsthe signed data. Both clear text and opaque signing is supported.
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 tobe decrypted or verified.
this specifies the input format for the PKCS#7 structure. The defaultis SMIME which reads an S/MIME format message. PEM and DERformat change this to expect PEM and DER format PKCS#7 structuresinstead. This currently only affects the input format of the PKCS#7structure, 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 MIMEformat message that has been signed or verified.
-outform SMIME|PEM|DER
this specifies the output format for the PKCS#7 structure. The defaultis SMIME which write an S/MIME format message. PEM and DERformat change this to write PEM and DER format PKCS#7 structuresinstead. This currently only affects the output format of the PKCS#7structure, 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 onlyuseful with the -verify command. This is only usable if the PKCS#7structure is using the detached signature form where the content isnot included. This option will override any content if the input formatis S/MIME and it uses the multipart/signed MIME content type.
this option adds plain text (text/plain) MIME headers to the suppliedmessage if encrypting or signing. If decrypting or verifying it stripsoff 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: thatis a hash of each subject name (using x509 -hash) should be linkedto 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 notspecified 40 bit RC2 is used. Only used with -encrypt.
when verifying a message normally certificates (if any) included inthe message are searched for the signing certificate. With this optiononly the certificates specified in the -certfile option are used.The supplied certificates can still be used as untrusted CAs however.
do not verify the signers certificate of a signed message.
do not do chain verification of signers certificates: that is don'tuse the certificates in the signed message as untrusted CAs.
don't try to verify the signatures on the message.
when signing a message the signer's certificate is normally includedwith this option it is excluded. This will reduce the size of thesigned message but the verifier must have a copy of the signers certificateavailable locally (passed using the -certfile option for example).
normally when a message is signed a set of attributes are included whichinclude the signing time and supported symmetric algorithms. With thisoption they are not included.
normally the input message is converted to ``canonical'' format which iseffectively using CR and LF as end of line: as required by the S/MIMEspecification. When this option is present no translation occurs. Thisis useful when handling binary data which may not be in MIME format.
when signing a message use opaque signing: this form is more resistantto translation by mail relays but it cannot be read by mail agents thatdo not support S/MIME. Without this option cleartext signing withthe MIME type multipart/signed is used.
-certfile file
allows additional certificates to be specified. When signing these willbe included with the message. When verifying these will be searched forthe signers certificates. The certificates should be in PEM format.
-signer file
the signers certificate when signing a message. If a message isbeing verified then the signers certificates will be written to thisfile if the verification was successful.
-recip file
the recipients certificate when decrypting a message. This certificatemust 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 thecorresponding certificate. If this option is not specified then theprivate key must be included in the certificate file specified withthe -recip or -signer file.
-passin arg
the private key password source. For more information about the format of argsee the PASS PHRASE ARGUMENTS section in openssl(1).
-rand file(s)
a file or files containing random data used to seed the random numbergenerator, 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 : forall others.
one or more certificates of message recipients: used when encryptinga message.
-to, -from, -subject
the relevant mail headers. These are included outside the signedportion of a message so they may be included manually. If signingthen many S/MIME mail clients check the signers certificate's emailaddress matches that specified in the From: address.


The MIME message must be sent without any blank lines between theheaders and the output. Some mail programs will automatically adda blank line. Piping the mail directly to sendmail is one way toachieve the correct format.

The supplied message to be signed or encrypted must include thenecessary MIME headers or many S/MIME clients wont display itproperly (if at all). You can use the -text option to automaticallyadd plain text headers.

A ``signed and encrypted'' message is one where a signed message isthen encrypted. This can be produced by encrypting an already signedmessage: see the examples section.

This version of the program only allows one signer per message but itwill verify multiple signers on received messages. Some S/MIME clientschoke if a message contains multiple signers. It is possible to signmessages ``in parallel'' by signing an already signed message.

The options -encrypt and -decrypt reflect common usage in S/MIMEclients. Strictly speaking these process PKCS#7 enveloped data: PKCS#7encrypted data is used for other purposes. 


the operation was completely successfully.
an error occurred parsing the command options.
one of the input files could not be read.
an error occurred creating the PKCS#7 file or when reading the MIMEmessage.
an error occurred decrypting or verifying the message.
the message was verified correctly but an error occurred writing outthe signers certificates.


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 andread 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 -to someoneAATTsomewhere \        -subject "Signed message" | sendmail someoneAATTsomewhere

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 \        -to someoneAATTsomewhere -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 -to someoneAATTsomewhere \        -subject "Signed and Encrypted message" -des3 user.pem

Note: the encryption command does not include the -text option because the messagebeing 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 thedetached signature format. You can use this program to verify thesignature by line wrapping the base64 encoded structure and surroundingit 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


The MIME parser isn't very clever: it seems to handle most messages that I've thrownat it but it may choke on others.

The code currently will only write out the signer's certificate to a file: if thesigner has a separate encryption certificate this must be manually extracted. Thereshould 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 encryptionalgorithms as supplied in the SMIMECapabilities signed attribute. this means theuser has to manually include the correct encryption algorithm. It should storethe 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 v3structures may cause parsing errors.




This document was created byman2html,using the manual pages.