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.\"
.IX Title "SMIME 3pm"
.TH SMIME 3pm 2024-01-10 "perl v5.38.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Crypt::SMIME \- S/MIME message signing, verification, encryption and decryption
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  use Crypt::SMIME;
\&
\&  my $plain = <<\*(AqEOF\*(Aq;
\&  From: alice@example.org
\&  To: bob@example.com
\&  Subject: Crypt::SMIME test
\&
\&  This is a test mail. Please ignore...
\&  EOF
\&
\&  my $smime = Crypt::SMIME\->new();
\&  $smime\->setPrivateKey($privkey, $crt);
\&  # $smime\->setPublicKey([$icacert]); # if need be.
\&
\&  my $signed = $smime\->sign($plain);
\&  print $signed;
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This module provides a class for handling S/MIME messages. It can sign, verify,
encrypt and decrypt messages. It requires libcrypto (<http://www.openssl.org>).
.SH EXPORTS
.IX Header "EXPORTS"
No symbols are exported by default. The following symbols can
optionally be exported:
.ie n .IP """NO_CHECK_CERTIFICATE""" 4
.el .IP \f(CWNO_CHECK_CERTIFICATE\fR 4
.IX Item "NO_CHECK_CERTIFICATE"
See "\fBcheck()\fR".
.ie n .IP """FORMAT_SMIME""" 4
.el .IP \f(CWFORMAT_SMIME\fR 4
.IX Item "FORMAT_SMIME"
.PD 0
.ie n .IP """FORMAT_ASN1""" 4
.el .IP \f(CWFORMAT_ASN1\fR 4
.IX Item "FORMAT_ASN1"
.ie n .IP """FORMAT_PEM""" 4
.el .IP \f(CWFORMAT_PEM\fR 4
.IX Item "FORMAT_PEM"
.PD
See "\fBextractCertificates()\fR".
.ie n .IP """:constants""" 4
.el .IP \f(CW:constants\fR 4
.IX Item ":constants"
Export all of the above.
.SH METHODS
.IX Header "METHODS"
.IP \fBnew()\fR 4
.IX Item "new()"
.Vb 1
\&  my $smime = Crypt::SMIME\->new();
.Ve
.Sp
The constructor takes no arguments.
.IP \fBsetPrivateKey()\fR 4
.IX Item "setPrivateKey()"
.Vb 2
\&  $smime\->setPrivateKey($key, $crt);
\&  $smime\->setPrivateKey($key, $crt, $password);
.Ve
.Sp
Store a private key and its X.509 certificate into the instance. The private key
will be used for signing and decryption. Note that this method takes a PEM
string, not a name of a file which contains a key or a certificate.
.Sp
The private key and certificate must be encoded in PEM format. The method dies
if it fails to load the key.
.IP \fBsetPrivateKeyPkcs12()\fR 4
.IX Item "setPrivateKeyPkcs12()"
.Vb 2
\&  $smime\->setPrivateKeyPkcs12($key, $pkcs12);
\&  $smime\->setPrivateKeyPkcs12($key, $pkcs12, $password);
.Ve
.Sp
Load a private key and its X.509 certificate from PKCS#12 into the instance.
The private key will be used for signing and decryption. The method dies if
it fails to load PKCS12.
.IP \fBsetPublicKey()\fR 4
.IX Item "setPublicKey()"
.Vb 2
\&  $smime\->setPublicKey($crt);
\&  $smime\->setPublicKey([$crt1, $crt2, ...]);
.Ve
.Sp
Store one or more X.509 certificates into the instance. The public keys will be
used for signing, verification and encryption.
.Sp
The certificates must be encoded in PEM format. The method dies if it fails to
load the certificates.
.IP \fBsetPublicKeyStore()\fR 4
.IX Item "setPublicKeyStore()"
.Vb 1
\&  $smime\->setPublicKeyStore($path, ...);
.Ve
.Sp
Set the paths of file or directory containing trusted certificates.
The certificate stores will be used for verification.
.Sp
The method dies if it fails to load the certificate stores.
.IP \fBsign()\fR 4
.IX Item "sign()"
.Vb 1
\&  $signed_mime = $smime\->sign($raw_mime);
.Ve
.Sp
Sign a MIME message and return an S/MIME message. The signature is always
detached.
.Sp
Any headers except \f(CW\*(C`Content\-*\*(C'\fR, \f(CW\*(C`MIME\-*\*(C'\fR and \f(CW\*(C`Subject\*(C'\fR will be moved to the
top-level of the MIME message. \f(CW\*(C`Subject\*(C'\fR header will be copied to both of the
plain text part and the top-level for mail clients which can't properly handle
S/MIME messages.
.Sp
The resulting message will be tainted if any of the original MIME
message, the private key or its certificate is tainted.
.IP \fBsignonly()\fR 4
.IX Item "signonly()"
.Vb 1
\&  $sign = $smime\->signonly($prepared_mime);
.Ve
.Sp
Generate a signature from a MIME message. The resulting signature is encoded in
Base64. The MIME message to be passed to this method should be preprocessed
beforehand by the \fBprepareSmimeMessage()\fR method. You would rarely need to call
this method directly.
.Sp
The resulting signature will be tainted if any of the original MIME
message, the private key or its certificate is tainted.
.IP \fBprepareSmimeMessage()\fR 4
.IX Item "prepareSmimeMessage()"
.Vb 2
\&  ($prepared_mime, $outer_header)
\&      = $smime\->prepareSmimeMessage($source_mime);
.Ve
.Sp
Preprocess a MIME message to be signed. \f(CW$prepared_mime\fR will be a string
containing the processed MIME message, and \f(CW$outer_header\fR will be a string
that is a list of headers to be moved to the top-level of MIME message. You
would rarely need to call this method directly.
.Sp
The entity body of \f(CW$source_mime\fR will be directly copied to
\&\f(CW$prepared_mime\fR. Any headers of \f(CW$source_mime\fR except \f(CW\*(C`Content\-*\*(C'\fR, \f(CW\*(C`MIME\-*\*(C'\fR
and \f(CW\*(C`Subject\*(C'\fR will be copied to \f(CW$prepared_mime\fR, and those excluded headers
will be copied to \f(CW$outer_header\fR. Note that the \f(CW\*(C`Subject\*(C'\fR header will be
copied to both side exceptionally.
.IP \fBcheck()\fR 4
.IX Item "check()"
.Vb 1
\&  use Crypt::SMIME qw(:constants);
\&
\&  $source_mime = $smime\->check($signed_mime);
\&  $source_mime = $smime\->check($signed_mime, $flags);
.Ve
.Sp
Verify a signature of S/MIME message and return a MIME message. The method dies
if it fails to verify it.
.Sp
When the option \f(CW\*(C`Crypt::SMIME::NO_CHECK_CERTIFICATE\*(C'\fR is given as
\&\f(CW$flags\fR, the signer's certificate chain is not verified. The default
value for \f(CW$flags\fR is \f(CW0\fR, which performs all the verifications.
.Sp
The resulting message will be tainted if the original S/MIME message,
the \f(CW$flags\fR, verification time ("\fBsetAtTime()\fR") or at least one
of the provided public keys are tainted.
.IP \fBencrypt()\fR 4
.IX Item "encrypt()"
.Vb 1
\&  $encrypted_mime = $smime\->encrypt($raw_mime);
.Ve
.Sp
Encrypt a MIME message and return a S/MIME message.
.Sp
Any headers except \f(CW\*(C`Content\-*\*(C'\fR, \f(CW\*(C`MIME\-*\*(C'\fR and \f(CW\*(C`Subject\*(C'\fR will be moved to the
top-level of the MIME message. \f(CW\*(C`Subject\*(C'\fR header will be copied to both of the
plain text part and the top-level for mail clients which can't properly handle
S/MIME messages.
.Sp
The resulting message will be tainted if the original MIME message or
at least one public key is tainted.
.IP \fBdecrypt()\fR 4
.IX Item "decrypt()"
.Vb 1
\&  $decrypted_mime = $smime\->decrypt($encrypted_mime);
.Ve
.Sp
Decrypt an S/MIME and return a MIME message. This method dies if it fails to
decrypt it.
.Sp
The resulting message will be tainted if any of the original S/MIME
message, the private key or its certificate is tainted.
.IP \fBisSigned()\fR 4
.IX Item "isSigned()"
.Vb 1
\&  $is_signed = $smime\->isSigned($mime);
.Ve
.Sp
Return true if the given string is a signed S/MIME message. Note that if the
message was encrypted after signing, this method returns false because in that
case the signature is hidden in the encrypted message.
.IP \fBisEncrypted()\fR 4
.IX Item "isEncrypted()"
.Vb 1
\&  $is_encrypted = $smime\->isEncrypted($mime);
.Ve
.Sp
Return true if the given string is an encrypted S/MIME message. Note that if the
message was signed with non-detached signature after encryption, this method
returns false because in that case the encrypted message is hidden in the
signature.
.IP \fBsetAtTime()\fR 4
.IX Item "setAtTime()"
.Vb 2
\&  $yesterday = time \- (60*60*24);
\&  $smime\->setAtTime($yesterday);
.Ve
.Sp
Set the time to use for verification. Default is to use the current time.
Must be an unix epoch timestamp.
.SH FUNCTIONS
.IX Header "FUNCTIONS"
.IP \fBextractCertificates()\fR 4
.IX Item "extractCertificates()"
.Vb 1
\&  use Crypt::SMIME qw(:constants);
\&
\&  @certs = @{Crypt::SMIME::extractCertificates($data)};
\&  @certs = @{Crypt::SMIME::extractCertificates($data, FORMAT_SMIME)};
.Ve
.Sp
Get all X.509 certificates (and CRLs, if any) included in S/MIME
message or PKCS#7 object \f(CW$data\fR. Optional \f(CW$type\fR parameter may
specify type of data:
\&\f(CW\*(C`Crypt::SMIME::FORMAT_SMIME\*(C'\fR (default) for S/MIME message;
\&\f(CW\*(C`Crypt::SMIME::FORMAT_ASN1\*(C'\fR for binary format;
\&\f(CW\*(C`Crypt::SMIME::FORMAT_PEM\*(C'\fR for PEM format.
.IP \fBgetSigners()\fR 4
.IX Item "getSigners()"
.Vb 2
\&  @certs = @{Crypt::SMIME::getSigners($data)};
\&  @certs = @{Crypt::SMIME::getSigners($data, $type)};
.Ve
.Sp
Get X.509 certificates of signers included in S/MIME message or PKCS#7 object.
Optional \f(CW$type\fR parameter may specify type of data.
.Sp
Note that any public keys returned by this function are not verified.
\&\fBcheck()\fR should be executed to ensure public keys are valid.
.SH AUTHOR
.IX Header "AUTHOR"
Copyright 2006\-2014 YMIRLINK Inc. All Rights Reserved.
.PP
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself
.PP
Bug reports and comments to: tl@tripletail.jp