Extend the HOWTO on creating certificates, and add a HOWTO in creating keys.

[openssl.git] / doc / HOWTO / keys.txt

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+<DRAFT!>
+                       HOWTO keys
+
+1. Introduction
+
+Keys are the basis of public key algorithms and PKI.  Keys usually
+come in pairs, with one half being the public key and the other half
+being the private key.  With OpenSSL, the private key contains the
+public key information as well, so a public key doesn't need to be
+generated separately.
+
+Public keys come in several flavors, using different cryptographic
+algorithms.  The most popular ones associated with certificates are
+RSA and DSA, and this HOWTO will show how to generate each of them.
+
+
+2. To generate a RSA key
+
+A RSA key can be used both for encryption and for signing.
+
+Generating a key for the RSA algorithm is quite easy, all you have to
+do is the following:
+
+  openssl genrsa -des3 -out privkey.pem 2048
+
+With this variant, you will be prompted for a protecting password.  If
+you don't want your key to be protected by a password, remove the flag
+'-des3' from the command line above.
+
+    NOTE: if you intend to use the key together with a server
+    certificate, it may be a good thing to avoid protecting it
+    with a password, since that would mean someone would have to
+    type in the password every time the server needs to access
+    the key.
+
+The number 2048 is the size of the key, in bits.  Today, 2048 or
+higher is recommended for RSA keys, as fewer amount of bits is
+consider insecure or to be insecure pretty soon.
+
+
+3. To generate a DSA key
+
+A DSA key can be used both for signing only.  This is important to
+keep in mind to know what kind of purposes a certificate request with
+a DSA key can really be used for.
+
+Generating a key for the DSA algorithm is a two-step process.  First,
+you have to generate parameters from which to generate the key:
+
+  openssl dsaparam -out dsaparam.pem 2048
+
+The number 2048 is the size of the key, in bits.  Today, 2048 or
+higher is recommended for DSA keys, as fewer amount of bits is
+consider insecure or to be insecure pretty soon.
+
+When that is done, you can generate a key using the parameters in
+question (actually, several keys can be generated from the same
+parameters):
+
+  openssl gendsa -des3 -out privkey.pem dsaparam.pem
+
+With this variant, you will be prompted for a protecting password.  If
+you don't want your key to be protected by a password, remove the flag
+'-des3' from the command line above.
+
+    NOTE: if you intend to use the key together with a server
+    certificate, it may be a good thing to avoid protecting it
+    with a password, since that would mean someone would have to
+    type in the password every time the server needs to access
+    the key.
+
+-- 
+Richard Levitte