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<h2>Tcl Cryptography Documentation</h2>

<dl>
    <dd><a href="#NAME">NAME</a>
	<dl><dd><b>tls</b> - binding to <b>OpenSSL</b> toolkit.</dd></dl>
    </dd>
    <dd><a href="#DESCRIPTION">DESCRIPTION</a> </dd>
    <dd><a href="#SYNOPSIS">SYNOPSIS</a> </dd>
    <dd><dl>
	    <dd><b>package require Tcl</b> <em>?8.5-?</em></dd>
	    <dd><b>package require tls</b></dd>
	    <dt>&nbsp;</dt>
	    <dd><b>tls::cipher</b> <em>name</em></dd>
	    <dd><b>tls::ciphers</b> <em>?protocol? ?verbose? ?supported?</em></dd>
	    <dd><b>tls::digests</b> <em>?name?</em></dd>
	    <dd><b>tls::macs</b></dd>
	    <dd><b>tls::protocols</b></dd>
	    <dd><b>tls::version</b></dd>
	    <dt>&nbsp;</dt>
	    <dd><b>tls::cmac</b> <b>-cipher</b> <em>name</em> <b>-key</b> <em>key ?options?</em></dd>
	    <dd><b>tls::hmac</b> <b>-digest</b> <em>name</em> <b>-key</b> <em>key ?options?</em></dd>
	    <dd><b>tls::md</b> <b>-digest</b> <em>name ?options?</em></dd>
	    <dd><b>tls::md4</b> <em>data</em></dd>
	    <dd><b>tls::md5</b> <em>data</em></dd>
	    <dd><b>tls::sha1</b> <em>data</em></dd>
	    <dd><b>tls::sha256</b> <em>data</em></dd>
	    <dd><b>tls::sha512</b> <em>data</em></dd>
	    <dd><b>tls::unstack</b> <em>channelId</em></dd>
	    <dt>&nbsp;</dt>
	    <dd><b>tls::encrypt</b> <b>-cipher</b> <em>name</em> <b>-key</b> <em>key ?options?</em></dd>
	    <dd><b>tls::decrypt</b> <b>-cipher</b> <em>name</em> <b>-key</b> <em>key ?options?</em></dd>
	</dl>
    </dd>
    <dd><a href="#OPTIONS">OPTIONS</a></dd>
    <dd><a href="#COMMANDS">COMMANDS</a></dd>
    <dd><a href="#GLOSSARY">GLOSSARY</a> </dd>
    <dd><a href="#EXAMPLES">EXAMPLES</a></dd>
    <dd><a href="#SPECIAL">SPECIAL CONSIDERATIONS</a></dd>
</dl>

<br>

<h3><a name="NAME">NAME</a></h3>

<p><strong>tls</strong> - binding to <strong>OpenSSL</strong> toolkit.</p>

<h3><a name="DESCRIPTION">DESCRIPTION</a></h3>

<p>This extension provides a generic interface to the
<a href="http://www.openssl.org/">OpenSSL</a> cryptography functions. The
provided commands can be used to ensure the confidentiality, authenticity,
and integrity of messages and data.</p>

<br>
<h3><a name="SYNOPSIS">SYNOPSIS</a></h3>

<p><b>package require Tcl 8.5-</b><br>
<b>package require tls</b><br>
<br>
<a href="#tls::cipher"><b>tls::cipher</b> <i>name</i></a><br>
<a href="#tls::ciphers"><b>tls::ciphers</b> <i>?protocol? ?verbose? ?supported?</i></a><br>
<a href="#tls::digests"><b>tls::digests</b> <i>?name?</i></a><br>
<a href="#tls::macs"><b>tls::macs</b></a><br>
<a href="#tls::protocols"><b>tls::protocols</b></a><br>
<a href="#tls::version"><b>tls::version</b></a><br>
<br>
<a href="#tls::cmac"><b>tls::cmac</b> <b>-cipher</b> <i>name</i> <b>-key</b> <i>key ?options?</i></a><br>
<a href="#tls::hmac"><b>tls::hmac</b> <b>-digest</b> <i>name</i> <b>-key</b> <i>key ?options?</i></a><br>
<a href="#tls::md"><b>tls::md</b> <b>-digest</b> <i>name ?options?</i></a><br>
<a href="#tls::md4"><b>tls::md4</b> <i>data</i></a><br>
<a href="#tls::md5"><b>tls::md5</b> <i>data</i></a><br>
<a href="#tls::sha1"><b>tls::sha1</b> <i>data</i></a><br>
<a href="#tls::sha256"><b>tls::sha256</b> <i>data</i></a><br>
<a href="#tls::sha512"><b>tls::sha512</b> <i>data</i></a><br>
<a href="#tls::unstack"><b>tls::unstack</b> <i>channelId</i></a><br>
<br>
<a href="#tls::encrypt"><b>tls::encrypt</b> <b>-cipher</b> <i>name</i> <b>-key</b> <i>key ?options?</i></a><br>
<a href="#tls::decrypt"><b>tls::decrypt</b> <b>-cipher</b> <i>name</i> <b>-key</b> <i>key ?options?</i></a><br>
</p>

<br>
<h3><a name="OPTIONS">OPTIONS</a></h3>

<p>The following options are used by the cryptography commands.</p>
<br>
<h4>Cryptographic Options</h4>

<dl>
    <dt><a name="-cipher"><strong>-cipher</strong> <em>name</em></a></dt>
    <dd>Name of cryptographic cipher to use. Used by encrypt/decrypt command
    and CMAC &amp; GMAC hash algorithms. For CMAC it must be one of AES-128-CBC,
    AES-192-CBC, AES-256-CBC or DES-EDE3-CBC. For GMAC it should be a GCM mode
    cipher e.g. AES-128-GCM. See <a href="#tls::ciphers"><b>tls::ciphers</b></a>
    for the valid values.</dd>
</dl>

<dl>
    <dt><a name="-digest"><strong>-digest</strong> <em>name</em></a></dt>
    <dd>Name of hash function (aka message digest) to use.
    See <a href="#tls::digests"><b>tls::digests</b></a> for the valid values.</dd>
</dl>

<dl>
    <dt><a name="-iterations"><strong>-iterations</strong> <em>count</em></a></dt>
    <dd>Number (integer) of iterations on the password to use in deriving the
    encryption key. Default is 10000. Some KDF implementations require an
    iteration count.</dd>
</dl>

<dl>
    <dt><a name="-iv"><strong>-iv</strong> <em>string</em></a></dt>
    <dd>Initialization vector (IV) to use. Required for some ciphers and GMAC.
    Cipher modes CBC, CFB, OFB and CTR all need an IV while ECB mode does not.
    A new, random IV should be created for each use. Think of the IV as a nonce
    (number used once), it's public but random and unpredictable. See the
   <a href="#tls::cipher"><b>tls::cipher</b></a> command for iv size and
    when required.</dd>
</dl>

<dl>
    <dt><a name="-key"><strong>-key</strong> <em>string</em></a></dt>
    <dd>Encryption key to use for cryptography function. Can be a binary or
    text string. Longer keys provide better protection. Used by ciphers, HMAC,
    some CMAC, and some KDF implementations. Key lengths less than <b>key_length</b>
    size may be padded or rejected. See the
    <a href="#tls::cipher"><b>tls::cipher</b></a> command for key size.</dd>
</dl>

<dl>
    <dt><a name="-mac"><strong>-mac</strong> <em>name</em></a></dt>
    <dd>Name of Message Authentication Code (MAC) to use.
    See <a href="#tls::mac"><b>tls::macs</b></a> for the valid values.</dd>
</dl>

<dl>
    <dt><a name="-password"><strong>-password</strong> <em>string</em></a></dt>
    <dd>Password to use for some KDF functions.</dd>
</dl>

<dl>
    <dt><a name="-properties"><strong>-properties</strong> <em>list</em></a></dt>
    <dd>List of additional properties to pass to cryptography function.</dd>
</dl>

<dl>
    <dt><a name="-salt"><strong>-salt</strong> <em>string</em></a></dt>
    <dd>Specifies salt value to use when encrypting data. Default is to use a
    randomly generated value. This option is used by BLAKE2 MAC and some KDF
    implementations use a non-secret unique cryptographic salt.</dd>
</dl>

<dl>
    <dt><a name="-size"><strong>-size</strong> <em>number</em></a></dt>
    <dd>Set the output hash size in bytes. Used by KMAC128 or KMAC256 to specify
    an output length. The default sizes are 32 or 64 bytes respectively.</dd>
</dl>

<dl>
    <dt><a name="-xof"><strong>-xof</strong> <em>boolean</em></a></dt>
    <dd>Set whether to use XOF. This option is used by KMAC.</dd>
</dl>

<br>
<h4>Input/Output Options</h4>

<dl>
    <dt><a name="-chan"><strong>-chan</strong> <em>channelId</em></a></dt>
    <dt><a name="-chan"><strong>-channel</strong> <em>channelId</em></a></dt>
    <dd>Add the cryptographic transformation on top of channel
	<em>channelId</em>. Automatically sets channel to binary mode. Works
	like <b>chan push</b> to create a stacked channel. If the command
	<b>fileevent</b> is to be used for channel event monitoring, all
	channels in the stack should be set to non-blocking mode. If not,
	the system may hang while waiting for data. When done, use either the
	close command or <a href="#tls::unstack"><strong>tls::unstack</strong></a>
	to remove the transform from the channel. Additional transforms cannot
	be added to channel. Example code:</dd></dl>
    <blockquote><code>
		set ch [open test_file.txt rb]<br>
		::tls::digest -digest sha256 -chan $ch<br>
		set dat ""<br>
		while {![eof $ch]} {append dat [read $ch 4096]}<br>
		close $ch<br>
		puts $dat
    </code></blockquote>

<dl>
    <dt><a name="-command"><strong>-command</strong> <em>cmdName</em></a></dt>
    <dd>Create and return <em>cmdName</em> which is used to incrementally add
	data to a cryptographic function. To add data to the function, call
	&quot;<em>cmdName</em> <b>update</b> <em>data</em>&quot;, where
	<em>data</em> is the data to add. When done, call
	&quot;<em>cmdName</em> <b>finalize</b>&quot; to return the resulting
	value and delete <em>cmdName</em>. Example code:</dd></dl>
    <blockquote><code>
		set cmd [::tls::digest -digest sha256 -command ::tls::temp]<br>
		set dat ""<br>
		append dat [$cmd update "Some data. "]<br>
		append dat [$cmd update "More data."]<br>
		append dat [$cmd finalize]<br>
		puts $dat
    </code></blockquote>

<dl>
    <dt><a name="-data"><strong>-data</strong> <em>string</em></a></dt>
    <dd>Perform the cryptographic function on <em>data</em> and return the
    result. Example code:</dd></dl>
    <blockquote><code>
		set md [::tls::digest sha256 "Some example data."]<br>
		puts $md
    </code></blockquote>

<dl>
    <dt><a name="-file"><strong>-file</strong> <em>filename</em></a></dt>
    <dt><a name="-file"><strong>-filename</strong> <em>filename</em></a></dt>
    <dd>Perform the cryptographic function on file <em>filename</em> and return
    the result. This operation will open file, read the file data, close the
    file, and return the result using the TCL file APIs, so VFS files are
    supported. Example code:</dd></dl>
    <blockquote><code>
		set md [::tls::digest -digest sha256 -file test_file.txt]<br>
		puts $md
    </code></blockquote>

<dl>
    <dt><a name="-infile"><strong>-infile</strong> <em>filename</em></a></dt>
    <dd>Specifies the file to use as data input source. This option uses the
    TCL file APIs, so VFS files are supported. Example code:</dd></dl>
    <blockquote><code>
		::tls::encrypt -cipher aes-128-cbc -key "Test key"
		-infile unencrypted.txt -outfile encrypted.dat
    </code></blockquote>

<dl>
    <dt><a name="-outfile"><strong>-outfile</strong> <em>filename</em></a></dt>
    <dd>Specifies the file to output the encryption results to. This option
    uses the TCL file APIs, so VFS files are supported. Example code:</dd></dl>
    <blockquote><code>
		::tls::decrypt -cipher aes-128-cbc -key "Test key"
		-infile encrypted.dat -outfile unencrypted.txt
    </code></blockquote>

<dl>
    <dt><a name="-keyfile"><strong>-keyfile</strong> <em>filename</em></a></dt>
    <dd>Specifies the file to get the encryption key from.</dd></dl>

<br>

<h4>Format Options</h4>

<dl>
    <dt><a name="-base64"><strong>-base64</strong></a></dt>
    <dd>Base64 encode data after encryption or decode before decryption.</dd>
</dl>

<dl>
    <dt><a name="-bin"><strong>-bin</strong></a></dt>
    <dt><a name="-bin"><strong>-binary</strong></a></dt>
    <dd>Output result of function as a binary string.</dd>
</dl>

<dl>
    <dt><a name="-hex"><strong>-hex</strong></a></dt>
    <dt><a name="-hex"><strong>-hexadecimal</strong></a></dt>
    <dd>Output result of function as a hexadecimal string. This is the default
	option unless otherwise specified.</dd>
</dl>

<br>
<h3><a name="COMMANDS">COMMANDS</a></h3>

<p>The following commands provide access to the OpenSSL cryptography functions.</p>

<dl>

<h4>Info Commands</h4>

    <dt><a name="tls::cipher"><strong>tls::cipher</strong> <em>name</em></a></dt>
    <dd>Return a list of property names and values describing cipher
	<i>name</i>. Properties include name, description, block_size,
	key_length, iv_length, type, and mode list.</dd>

    <dt><a name="tls::ciphers"><strong>tls::ciphers</strong>
    <em>?protocol? ?verbose? ?supported?</em></a></dt>
    <dd>Without any args, returns a list of all symmetric ciphers for use with
	the <a href="#-cipher"><b>-cipher</b></a> option. With <em>protocol</em>,
	only the ciphers supported for that protocol are returned. See
	<b>tls::protocols</b> command for the supported protocols. If
	<em>verbose</em> is specified as true then a verbose, human readable
	list is returned with additional information on the cipher. If
	<em>supported</em> is specified as true, then only the ciphers
	supported for protocol will be listed.</dd>

    <dt><a name="tls::digests"><strong>tls::digests</strong> <em>?name?</em></a></dt>
    <dd>Without <em>name</em>, returns a list of the supported message digests
	(aka hash algorithms) for use with the <a href="#-digest"><b>-digest</b></a>
	option. With <em>name</em>, returns a list of
	property names and values describing message digest <i>name</i>. Properties
	include name, description, size, block_size, type, and flags list.</dd>

    <dt><a name="tls::kdfs"><strong>tls::kdfs</strong></a></dt>
    <dd>Returns a list of the available Key Derivation Function (KDF)
	algorithms.</dd>

    <dt><a name="tls::macs"><strong>tls::macs</strong></a></dt>
    <dd>Returns a list of the available Message Authentication Codes (MAC)
	for use with the <a href="#-key"><b>-key</b></a> option.</dd>

    <dt><a name="tls::protocols"><strong>tls::protocols</strong></a></dt>
    <dd>Returns a list of supported protocols. Valid values are:
	<b>ssl2</b>, <b>ssl3</b>, <b>tls1</b>, <b>tls1.1</b>, <b>tls1.2</b>,
	and <b>tls1.3</b>. Exact list depends on OpenSSL version and
	compile time flags.</dd>

    <dt><a name="tls::version"><strong>tls::version</strong></a></dt>
    <dd>Returns the OpenSSL version string.</dd>

<br>

<h4>Message Digest (MD) and Message Authentication Code (MAC) Commands</h4>

    <dt><a name="tls::cmac"><strong>tls::cmac</strong>
	<em>?</em><b>-cipher</b><em>? name</em>
	<b>-key</b> <em>key ?</em><b>-bin</b>|<b>-hex</b><em>?
	[</em><b>-chan</b> <em>channelId |</em> <b>-command</b> <em>cmdName |</em>
	<b>-file</b> <em>filename | ?</em><b>-data</b><em>? data]</em></a></dt>
    <dd>Calculate the Cipher-based Message Authentication Code (CMAC) where
	<em>key</em> is a shared key and output the result per the I/O options
	in the specified format. MACs are used to ensure authenticity and the
	integrity of data. See <a href="#OPTIONS"><b>options</b></a> for usage
	info. Option <b>-key</b> is only used for some ciphers.</dd>

    <dt><a name="tls::hmac"><strong>tls::hmac</strong>
	<em>?</em><b>-digest</b><em>? name</em>
	<b>-key</b> <em>key ?</em><b>-bin</b>|<b>-hex</b><em>?
	[</em><b>-chan</b> <em>channelId |</em> <b>-command</b> <em>cmdName |</em>
	<b>-file</b> <em>filename | ?</em><b>-data</b><em>? data]</em></a></dt>
    <dd>Calculate the Hash-based Message Authentication Code (HMAC) where
	<em>key</em> is a shared secret key and output the result per the I/O
	options in the specified format. The cryptographic strength depends
	upon the size of the key and the security of the hash function used.
	See <a href="#OPTIONS"><b>options</b></a> for usage info.</dd>

    <dt><a name="tls::mac"><strong>tls::mac</strong>
	<em>?</em><b>-mac</b><em>? name</em> <b>-cipher</b> <em>name</em>
	<b>-digest</b> <em>name</em> <b>-key</b> <em>key ?</em>
	<b>-bin</b>|<b>-hex</b><em>?
	[</em><b>-chan</b> <em>channelId |</em> <b>-command</b> <em>cmdName |</em>
	<b>-file</b> <em>filename | ?</em><b>-data</b><em>? data]</em></a></dt>
    <dd>(OpenSSL 3.0+) Calculate the Message Authentication Code (MAC) where
	<em>key</em> is a shared key and output the result per the I/O options
	in the specified format. MACs are used to ensure authenticity and
	the integrity of data. See <a href="#OPTIONS"><b>options</b></a>
	for usage info.</dd>

    <dt><a name="tls::md"><strong>tls::md</strong>
	<em>?</em><b>-digest</b><em>? name ?</em><b>-bin</b>|<b>-hex</b><em>?
	[</em><b>-chan</b> <em>channelId |</em> <b>-command</b> <em>cmdName |</em>
	<b>-file</b> <em>filename | ?</em><b>-data</b><em>? data]</em></a></dt>
    <dd>Calculate the message digest (MD) using hash function <em>name</em>
	and output the result per the I/O options in the specified format.
	MDs are used to ensure the integrity of data. See
	<a href="#OPTIONS"><b>options</b></a> for usage info.</dd>

    <dt><a name="tls::md4"><strong>tls::md4</strong> <em>data</em></a></dt>
    <dd>Returns the MD4 message-digest for <em>data</em> as a hex string.</dd>

    <dt><a name="tls::md5"><strong>tls::md5</strong> <em>data</em></a></dt>
    <dd>Returns the MD5 message-digest for <em>data</em> as a hex string.</dd>

    <dt><a name="tls::sha1"><strong>tls::sha1</strong> <em>data</em></a></dt>
    <dd>Returns the SHA1 secure hash algorithm digest for <em>data</em> as a hex string.</dd>

    <dt><a name="tls::sha256"><strong>tls::sha256</strong> <em>data</em></a></dt>
    <dd>Returns the SHA-2 SHA256 secure hash algorithm digest for <em>data</em> as a hex string.</dd>

    <dt><a name="tls::sha512"><strong>tls::sha512</strong> <em>data</em></a></dt>
    <dd>Returns the SHA-2 SHA512 secure hash algorithm digest for <em>data</em> as a hex string.</dd>

    <dt><a name="tls::unstack"><strong>tls::unstack</strong> <em>channelId</em></a></dt>
    <dd>Removes the top level cryptographic transform from channel <em>channelId</em>.</dd>

<br>

<h4>Encryption and Decryption Commands</h4>

    <dt><a name="tls::encrypt"><strong>tls::encrypt</strong>
	<b>-cipher</b> <em>name</em> <b>-key</b> <em>key ?</em><b>-iv</b> <em>string?
	[</em><b>-chan</b> <em>channelId |</em> <b>-command</b> <em>cmdName |</em>
	<b>-infile</b> <em>filename</em> <b>-outfile</b> <em>filename |</em>
	<b>-data</b><em> data]</em></a></dt>
    <dd>Encrypt the data using cipher <em>cipher</em> and output the result per
	the I/O options. Ciphers are used to create the cipher text from the
	input data. See <a href="#OPTIONS"><b>options</b></a> for usage
	info. Option <b>-iv</b> is only used for some ciphers. See the
	&quot;<b>tls::cipher</b> <em>cipher</em>&quot; command for key and iv
	sizes and when the iv is used (iv_length &gt; 0).</dd>

    <dt><a name="tls::decrypt"><strong>tls::decrypt</strong>
	<b>-cipher</b> <em>name</em> <b>-key</b> <em>key ?</em><b>-iv</b> <em>string?
	[</em><b>-chan</b> <em>channelId |</em> <b>-command</b> <em>cmdName |</em>
	<b>-infile</b> <em>filename</em> <b>-outfile</b> <em>filename |</em>
	<b>-data</b><em> data]</em></a></dt>
    <dd>Decrypt the data using cipher <em>cipher</em> and output the result per
	the I/O options. This command is the opposite of the <b>tls::encrypt</b>
	command. See <a href="#OPTIONS"><b>options</b></a> for usage
	info. Option <b>-iv</b> is only used for some ciphers. See the
	&quot;<b>tls::cipher</b> <em>cipher</em>&quot; command for key and iv
	sizes and when the iv is used (iv_length &gt; 0).</dd>
</dl>

<br>
<h3><a name="GLOSSARY">GLOSSARY</a></h3>

<p>The following is a list of the terminology used in this package along with
brief definitions. For more details, please consult with the OpenSSL documentation.</p>


<br>
<h3><a name="EXAMPLES">EXAMPLES</a></h3>

<p>TBS</p>

<pre><code>
package require http
package require tls

http::register https 443 [list ::tls::socket -autoservername true -require true -cadir /etc/ssl/certs]

set tok [http::geturl https://www.tcl.tk/]
</code></pre>

<br>
<h3><a name="SPECIAL">SPECIAL CONSIDERATIONS</a></h3>

<p>The capabilities of this package can vary enormously based upon how your
OpenSSL library was configured and built. New versions may obsolete older
ciphers, digests, MACs, etc. or change default values. Use the
info commands to obtain the supported values.</p>
<br>

<pre>
Copyright &copy; 2023 Brian O'Hagan.
</pre>
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