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