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NAME
keytool - key and certificate management tool
SYNOPSIS
keytool [ subcommands ]
DESCRIPTION
keytool is a key and certificate management utility. It
enables users to administer their own public/private key
pairs and associated certificates for use in self-
authentication (where the user authenticates himself/herself
to other users/services) or data integrity and authentica-
tion services, using digital signatures. It also allows
users to cache the public keys (in the form of certificates)
of their communicating peers.
A certificate is a digitally signed statement from one
entity (person, company, and so forth), saying that the pub-
lic key (and some other information) of some other entity
has a particular value. (See Certificates.) When data is
digitally signed, the signature can be verified to check the
data integrity and authenticity. Integrity means that the
data has not been modified or tampered with, and authenti-
city means the data indeed comes from whoever claims to have
created and signed it.
keytool stores the keys and certificates in a so-called key-
store. The keytool default keystore implementation imple-
ments the keystore as a file. It protects private keys with
a password.
The jarsigner(1) tool uses information from a keystore to
generate or verify digital signatures for Java ARchive (JAR)
files. (A JAR file packages class files, images, sounds,
and/or other digital data in a single file). jarsigner(1)
verifies the digital signature of a JAR file, using the cer-
tificate that comes with it (it is included in the signature
block file of the JAR file), and then checks whether or not
the public key of that certificate is "trusted", that is, is
contained in the specified keystore.
Please note: the keytool and jarsigner(1) tools completely
replace the javakey tool provided in JDK 1.1. These new
tools provide more features than javakey, including the
ability to protect the keystore and private keys with pass-
words, and the ability to verify signatures in addition to
generating them. The new keystore architecture replaces the
identity database that javakey created and managed. It is
possible to import the information from an identity database
into a keystore, via the -identitydb subcommand.
Keystore Entries
There are two different types of entries in a keystore:
1. key entries-each holds very sensitive cryptographic key
information, which is stored in a protected format to
prevent unauthorized access. Typically, a key stored
in this type of entry is a secret key, or a private key
accompanied by the certificate "chain" for the
corresponding public key. The keytool and jarsigner(1)
tools only handle the latter type of entry, that is
private keys and their associated certificate chains.
2. trusted certificate entries-each contains a single pub-
lic key certificate belonging to another party. It is
called a "trusted certificate" because the keystore
owner trusts that the public key in the certificate
indeed belongs to the identity identified by the "sub-
ject" (owner) of the certificate. The issuer of the
certificate vouches for this, by signing the certifi-
cate.
Keystore Aliases
All keystore entries (key and trusted certificate entries)
are accessed via unique aliases. Aliases are case-
insensitive; the aliases Hugo and hugo would refer to the
same keystore entry.
An alias is specified when you add an entity to the keystore
using the -genkey subcommand to generate a key pair (public
and private key) or the -import subcommand to add a certifi-
cate or certificate chain to the list of trusted certifi-
cates. Subsequent keytool commands must use this same alias
to refer to the entity.
For example, suppose you use the alias duke to generate a
new public/private key pair and wrap the public key into a
self-signed certificate (see Certificate Chains) via the
following command:
example% keytool -genkey -alias duke -keypass dukekeypasswd
This specifies an inital password of dukekeypasswd required
by subsequent commands to access the private key assocated
with the alias duke. If you later want to change duke's
private key password, you use a command like the following:
example% keytool -keypasswd -alias duke -keypass dukekeypasswd -new newpass
This changes the password from "dukekeypasswd" to "newpass".
Please note: A password should not actually be specified on
a command line or in a script unless it is for testing
purposes, or you are on a secure system. If you don't
specify a required password option on a command line, you
will be prompted for it. When typing in a password at the
password prompt, the password is currently echoed (displayed
exactly as typed), so be careful not to type it in front of
anyone.
Keystore Location
Each keytool command has a -keystore option for specifying
the name and location of the persistent keystore file for
the keystore managed by keytool. The keystore is by default
stored in a file named .keystore in the user's home direc-
tory, as determined by the "user.home" system property. On
Solaris systems "user.home" defaults to the user's home
directory.
Keystore Creation
A keystore is created whenever you use a -genkey, -import,
or -identitydb subcommand to add data to a keystore that
doesn't yet exist.
More specifically, if you specify, in the -keystore option,
a keystore that doesn't yet exist, that keystore will be
created.
If you don't specify a -keystore option, the default key-
store is a file named .keystore in your home directory. If
that file does not yet exist, it will be created.
Keystore Implementation
The KeyStore class provided in the java.security package
supplies well-defined interfaces to access and modify the
information in a keystore. It is possible for there to be
multiple different concrete implementations, where each
implementation is that for a particular type of keystore.
Currently, there are two command-line tools (keytool and
jarsigner(1)), and also a GUI-based tool named policytool.
Since KeyStore is publicly available, JDK users can write
additional security applications that use it.
There is a built-in default implementation, provided by Sun
Microsystems. It implements the keystore as a file, utiliz-
ing a proprietary keystore type (format) named "JKS". It
protects each private key with its individual password, and
also protects the integrity of the entire keystore with a
(possibly different) password.
Keystore implementations are provider-based. More specifi-
cally, the application interfaces supplied by KeyStore are
implemented in terms of a "Service Provider Interface"
(SPI). That is, there is a corresponding abstract
KeystoreSpi class, also in the java.security package, which
defines the Service Provider Interface methods that "provid-
ers" must implement. (The term "provider" refers to a pack-
age or a set of packages that supply a concrete implementa-
tion of a subset of services that can be accessed by the
Java Security API.) Thus, to provide a keystore implementa-
tion, clients must implement a "provider" and supply a Keys-
toreSpi subclass implementation, as described in How to
Implement a Provider for the Java Cryptography Architecture.
Applications can choose different types of keystore imple-
mentations from different providers, using the "getInstance"
factory method supplied in the KeyStore class. A keystore
type defines the storage and data format of the keystore
information, and the algorithms used to protect private keys
in the keystore and the integrity of the keystore itself.
Keystore implementations of different types are not compati-
ble.
keytool works on any file-based keystore implementation.
(It treats the keytore location that is passed to it at the
command line as a filename and converts it to a FileIn-
putStream, from which it loads the keystore information.)
The jarsigner(1) and policytool tools, on the other hand,
can read a keystore from any location that can be specified
using a URL.
For keytool and jarsigner(1), you can specify a keystore
type at the command line, via the -storetype option. For
Policy Tool, you can specify a keystore type via the "Change
Keystore" command in the Edit menu.
If you don't explicitly specify a keystore type, the tools
choose a keystore implementation based simply on the value
of the keystore.type property specified in the security pro-
perties file. The security properties file is called
java.security, and it resides in the JDK security properties
directory, java.home/lib/security, where java.home is the
JDK installation directory.
Each tool gets the keystore.type value and then examines all
the currently-installed providers until it finds one that
implements keystores of that type. It then uses the keystore
implementation from that provider.
The KeyStore class defines a static method named getDefault-
Type that lets applications and applets retrieve the value
of the keystore.type property. The following line of code
creates an instance of the default keystore type (as speci-
fied in the keystore.type property):
KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
The default keystore type is "jks" (the proprietary type of
the keystore implementation provided by Sun). This is speci-
fied by the following line in the security properties file:
keystore.type=jks
To have the tools utilize a keystore implementation other
than the default, you can change that line to specify a dif-
ferent keystore type.
For example, if you have a provider package that supplies a
keystore implementation for a keystore type called "pkcs12",
change the line to
keystore.type=pkcs12
Note: case doesn't matter in keystore type designations.
For example, "JKS" would be considered the same as "jks".
Supported Algorithms and Key Sizes
keytool allows users to specify any key pair generation and
signature algorithm supplied by any of the registered cryp-
tographic service providers. That is, the -keyalg and -
sigalg options for various subcommands must be supported by
a provider implementation. The default key pair generation
algorithm is "DSA". The signature algorithm is derived from
the algorithm of the underlying private key: If the underly-
ing private key is of type "DSA", the default signature
algorithm is "SHA1withDSA", and if the underlying private
key is of type "RSA", the default signature algorithm is
"MD5withRSA".
When generating a DSA key pair, the key size must be in the
range from 512 to 1024 bits, and must be a multiple of 64.
The default key size for any algorithm is 1024 bits.
Certificates
A certificate (also known as a public-key certificate) is a
digitally signed statement from one entity (the issuer),
saying that the public key (and some other information) of
another entity (the subject) has some
Let us expand on some of the key terms used in this sen-
tence:
Public Keys These are numbers associated with a particu-
lar entity, and are intended to be known to
everyone who needs to have trusted interac-
tions with that entity. Public keys are used
to verify signatures.
Digitally Signed
If some data is digitally signed it has been
stored with the "identity" of an entity, and
a signature that proves that entity knows
about the data. The data is rendered unforge-
able by signing with the entity's private
key.
Identity A known way of addressing an entity. In some
systems the identity is the public key, in
others it can be anything from a Unix UID to
an Email address to an X.509 Distinguished
Name.
Signature A signature is computed over some data using
the private key of an entity (the signer,
which in the case of a certificate is also
known as the issuer).
Private Keys These are numbers, each of which is supposed
to be known only to the particular entity
whose private key it is (that is, it's sup-
posed to be kept secret). Private and public
keys exist in pairs in all public key cryp-
tography systems (also referred to as "public
key crypto systems"). In a typical public key
crypto system, such as DSA, a private key
corresponds to exactly one public key.
Private keys are used to compute signatures.
Entity An entity is a person, organization, program,
computer, business, bank, or something else
you are trusting to some degree.
Basically, public key cryptography requires access to users'
public keys. In a large-scale networked environment it is
impossible to guarantee that prior relationships between
communicating entities have been established or that a
trusted repository exists with all used public keys. Certi-
ficates were invented as a solution to this public key dis-
tribution problem. Now a Certification Authority (CA) can
act as a trusted third party. CAs are entities (for example,
businesses) that are trusted to sign (issue) certificates
for other entities. It is assumed that CAs will only create
valid and reliable certificates, as they are bound by legal
agreements. There are many public Certification Authorities,
such as VeriSign, Thawte, Entrust, and so on. You can also
run your own Certification Authority using products such as
the Netscape/Microsoft Certificate Servers or the Entrust CA
product for your organization.
Using keytool, it is possible to display, import, and export
certificates. It is also possible to generate self-signed
certificates.
keytool currently handles X.509 certificates.
X.509 Certificates
The X.509 standard defines what information can go into a
certificate, and describes how to write it down (the data
format). All X.509 certificates have the following data, in
addition to the signature:
Version This identifies which version of the X.509 standard
applies to this certificate, which affects what information
can be specified in it. Thus far, three versions are
defined. keytool can import and export v1, v2, and v3 certi-
ficates. It generates v1 certificates. Serial Number The
entity that created the certificate is responsible for
assigning it a serial number to distinguish it from other
certificates it issues. This information is used in numerous
ways, for example when a certificate is revoked its serial
number is placed in a Certificate Revocation List (CRL).
Signature Algorithm Identifier This identifies the algorithm
used by the CA to sign the certificate. Issuer Name The
X.500 Distinguished Name of the entity that signed the cer-
tificate. This is normally a CA. Using this certificate
implies trusting the entity that signed this certificate.
(Note that in some cases, such as root or top-level CA cer-
tificates, the issuer signs its own certificate.) Validity
Period Each certificate is valid only for a limited amount
of time. This period is described by a start date and time
and an end date and time, and can be as short as a few
seconds or almost as long as a century. The validity period
chosen depends on a number of factors, such as the strength
of the private key used to sign the certificate or the
amount one is willing to pay for a certificate. This is the
expected period that entities can rely on the public value,
if the associated private key has not been compromised.
Subject Name The name of the entity whose public key the
certificate identifies. This name uses the X.500 standard,
so it is intended to be unique across the Internet. This is
the X.500 Distinguished Name (DN) of the entity, for exam-
ple,
CN=Java Duke, OU=Java Software Division, O=Sun Microsystems Inc, C=US
(These refer to the subject's Common Name, Organizational
Unit, Organization, and Country.) Subject Public Key Infor-
mation This is the public key of the entity being named,
together with an algorithm identifier which specifies which
public key crypto system this key belongs to and any associ-
ated key parameters.
X.509 Version 1 has been available since 1988, is widely
deployed, and is the most generic.
X.509 Version 2 introduced the concept of subject and issuer
unique identifiers to handle the possibility of reuse of
subject and/or issuer names over time. Most certificate pro-
file documents strongly recommend that names not be reused,
and that certificates should not make use of unique identif-
iers. Version 2 certificates are not widely used.
X.509 Version 3 is the most recent (1996) and supports the
notion of extensions, whereby anyone can define an extension
and include it in the certificate. Some common extensions in
use today are: KeyUsage (limits the use of the keys to par-
ticular purposes such as "signing-only") and Alterna-
tiveNames (allows other identities to also be associated
with this public key, for example, DNS names, Email
addresses, IP addresses). Extensions can be marked critical
to indicate that the extension should be checked and
enforced/used. For example, if a certificate has the
KeyUsage extension marked critical and set to "keyCertSign"
then if this certificate is presented during SSL communica-
tion, it should be rejected, as the certificate extension
indicates that the associated private key should only be
used for signing certificates and not for SSL use.
All the data in a certificate is encoded using two related
standards called ASN.1/DER. Abstract Syntax Notation 1
describes data. The Definite Encoding Rules describe a sin-
gle way to store and transfer that data.
X.500 Distinguished Names
X.500 Distinguished Names are used to identify entities,
such as those which are named by the subject and issuer
(signer) fields of X.509 certificates. keytool supports the
following subparts:
o commonName-common name of a person, for example, "Susan
Jones"
o organizationUnit-small organization (e.g, department or
division) name, for example, "Purchasing"
o organizationName-large organization
name, for example, "ABCSystems, Inc."
o localityName-locality (city) name, for example, "Palo
Alto"
o stateName-state or province name, for example, "Califor-
nia"
o country-two-letter country code, for example, "CH"
When supplying a distinguished name string as the value of a
-dname option, as for the -genkey or -selfcert subcommands,
the string must be in the following format:
CN=cName, OU=orgUnit, O=org, L=city, S=state, C=countryCode
where all the italicized items represent actual values and
the above keywords are abbreviations for the following:
CN=commonName
OU=organizationUnit
O=organizationName
L=localityName
S=stateName
C=country
A sample distinguished name string is
CN=Mark Smith, OU=Java, O=Sun, L=Cupertino, S=California, C=US
and a sample command using such a string is
example% keytool -genkey -dname "CN=Mark Smith, OU=Java,
O=Sun, L=Cupertino, S=California, C=US" -alias mark
Case does not matter for the keyword abbreviations. For
example, CN, cn, and Cn
are all treated the same.
Order matters; each subcomponent must appear in the desig-
nated order. However, it is not necessary to have all the
subcomponents. You may use a subset, for example:
CN=Steve Meier, OU=SunSoft, O=Sun, C=US
If a distinguished name string value contains a comma, it
must be escaped by a "\" character when you specify the
string on a command line, as in
cn=peter schuster, o=Sun Microsystems\, Inc., o=sun, c=us
It is never necessary to specify a distinguished name string
on a command line. If it is needed for a command, but not
supplied on the command line, the user is prompted for each
of the subcomponents. In this case, a comma does not need
to be escaped by a "\"
The Internet RFC 1421 Certificate Encoding
Certificates are often stored using the printable encoding
format defined by the Internet RFC 1421 standard, instead of
their binary encoding. This certificate format, also known
as "Base 64 encoding", facilitates exporting certificates to
other applications by email or through some other mechanism.
Certificates read by the -import and -printcert subcommands
can be in either this format or binary encoded.
The -export subcommand by default outputs a certificate in
binary encoding, but will instead output a certificate in
the printable encoding format, if the -rfc option is speci-
fied.
The -list subcommand by default prints the MD5 fingerprint
of a certificate. If the -v option is specified, the certi-
ficate is printed in human-readable format, while if the -
rfc option is specified, the certificate is output in the
printable encoding format.
In its printable encoding format, the encoded certificate is
bounded at the beginning by
-----BEGIN CERTIFICATE-----
and at the end by
-----END CERTIFICATE-----
Certificate Chains
keytool can create and manage keystore "key" entries that
each contain a private key and an associated certificate
"chain". The first certificate in the chain contains the
public key corresponding to the private key.
When keys are first generated (see the -genkey subcommand),
the chain starts off containing a single element, a self-
signed certificate. A self-signed certificate is one for
which the issuer (signer) is the same as the subject (the
entity whose public key is being authenticated by the certi-
ficate). Whenever the -genkey subcommand is called to gen-
erate a new public/private key pair, it also wraps the pub-
lic key into a self-signed certificate.
Later, after a Certificate Signing Request (CSR) has been
generated (see the -certreq subcommand) and sent to a Cer-
tification Authority (CA), the response from the CA is
imported (see -import), and the self-signed certificate is
replaced by a chain of certificates. At the bottom of the
chain is the certificate (reply) issued by the CA authenti-
cating the subject's public key. The next certificate in the
chain is one that authenticates the CA's public key.
In many cases, this is a self-signed certificate (that is, a
certificate from the CA authenticating its own public key)
and the last certificate in the chain. In other cases, the
CA may return a chain of certificates. In this case, the
bottom certificate in the chain is the same (a certificate
signed by the CA, authenticating the public key of the key
entry), but the second certificate in the chain is a certi-
ficate signed by a different CA, authenticating the public
key of the CA you sent the CSR to. Then, the next certifi-
cate in the chain will be a certificate authenticating the
second CA's key, and so on, until a self-signed "root" cer-
tificate is reached. Each certificate in the chain (after
the first) thus authenticates the public key of the signer
of the previous certificate in the chain.
Many CAs only return the issued certificate, with no sup-
porting chain, especially when there is a flat hierarchy (no
intermediates CAs). In this case, the certificate chain must
be established from trusted certificate information already
stored in the keystore.
A different reply format (defined by the PKCS#7 standard)
also includes the supporting certificate chain, in addition
to the issued certificate. Both reply formats can be handled
by keytool.
The top-level (root) CA certificate is self-signed. However,
the trust into the root's public key does not come from the
root certificate itself (anybody could generate a self-
signed certificate with the distinguished name of say, the
VeriSign root CA!), but from other sources like a newspaper.
The root CA public key is widely known. The only reason it
is stored in a certificate is because this is the format
understood by most tools, so the certificate in this case is
only used as a "vehicle" to transport the root CA's public
key. Before you add the root CA certificate to your key-
store, you should view it (using the -printcert option) and
compare the displayed fingerprint with the well-known
fingerprint (obtained from a newspaper, the root CA's web-
page, and so forth).
Importing Certificates
To import a certificate from a file, use the -import subcom-
mand, as in
example% keytool -import -alias joe -file jcertfile.cer
This sample command imports the certificate(s) in the file
jcertfile.cer and stores it in the keystore entry identified
by the alias joe.
You import a certificate for two reasons:
1. to add it to the list of trusted certificates, or
2. to import a certificate reply received from a CA as the
result of submitting a Certificate Signing Request (see
the -certreq subcommand) to that CA.
Which type of import is intended is indicated by the value
of the -alias option. If the alias exists in the database,
and identifies an entry with a private key, then it is
assumed you want to import a certificate reply. keytool
checks whether the public key in the certificate reply
matches the public key stored with the alias, and exits if
they are different. If the alias identifies the other type
of keystore entry, the certificate will not be imported. If
the alias does not exist, then it will be created and asso-
ciated with the imported certificate.
WARNING Regarding Importing Trusted Certificates
IMPORTANT: Be sure to check a certificate very carefully
before importing it as a trusted certificate!
View it first (using the -printcert subcommand, or the -
import subcommand without the -noprompt option), and make
sure that the displayed certificate fingerprint(s) match the
expected ones. For example, suppose someone sends or emails
you a certificate, and you put it in a file named
/tmp/cert.Beforeyou consider adding the certificate to your
list of trusted certificates, you can execute a -printcert
subcommand to view its fingerprints, as in
example% keytool -printcert -file /tmp/cert
Owner: CN=ll, OU=ll, O=ll, L=ll, S=ll, C=ll
Issuer: CN=ll, OU=ll, O=ll, L=ll, S=ll, C=ll
Serial Number: 59092b34
Valid from: Thu Sep 25 18:01:13 PDT 1997 until: Wed Dec 24 17:01:13 PST 1997
Certificate Fingerprints:
MD5: 11:81:AD:92:C8:E5:0E:A2:01:2E:D4:7A:D7:5F:07:6F
SHA1: 20:B6:17:FA:EF:E5:55:8A:D0:71:1F:E8:D6:9D:C0:37:13:0E:5E:FE
Then call or otherwise contact the person who sent the cer-
tificate, and compare the fingerprint(s) that you see with
the ones that they show. Only if the fingerprints are equal
is it guaranteed that the certificate has not been replaced
in transit with somebody else's (for example, an attacker's)
certificate. If such an attack took place, and you did not
check the certificate before you imported it, you would end
up trusting anything the attacker has signed (for example, a
JAR file with malicious class files inside).
Note: it is not required that you execute a -printcert sub-
command prior to importing a certificate, since before
adding a certificate to the list of trusted certificates in
the keystore, the -import subcommand prints out the certifi-
cate information and prompts you to verify it. You then have
the option of aborting the import operation. Note, however,
this is only the case if you invoke the -import subcommand
without the -noprompt option. If the -noprompt option is
given, there is no interaction with the user.
Exporting Certificates
To export a certificate to a file, use the -export subcom-
mand, as in
example% keytool -export -alias jane -file janecertfile.cer
This sample command exports jane's certificate to the file
janecertfile.cer. That is, if jane is the alias for a key
entry, the command exports the certificate at the bottom of
the certificate chain in that keystore entry. This is the
certificate that authenticates jane's public key.
If, instead, jane is the alias for a trusted certificate
entry, then that trusted certificate is exported.
Displaying Certificates
To print out the contents of a keystore entry, use the -list
subcommand, as in
example% keytool -list -alias joe
If you don't specify an alias, as in
example% keytool -list
the contents of the entire keystore are printed.
To display the contents of a certificate stored in a file,
use the -printcert subcommand, as in
example% keytool -printcert -file certfile.cer
This displays information about the certificate stored in
the file certfile.cer.
Note: This works independently of a keystore, that is, you
do not need a keystore in order to display a certificate
that's stored in a file.
Generating a Self-signed Certificate
A self-signed certificate is one for which the issuer
(signer) is the same as the subject (the entity whose public
key is being authenticated by the certificate). Whenever the
-genkey subcommand is called to generate a new
public/private key pair, it also wraps the public key into a
self-signed certificate.
You may occasionally wish to generate a new self-signed cer-
tificate. For example, you may want to use the same key pair
under a different identity (distinguished name). For exam-
ple, suppose you change departments. You can then:
1. copy (clone) the original key entry. See -keyclone.
2. generate a new self-signed certificate for the cloned
entry, using your new distinguished name. See below.
3. generate a Certificate Signing Requests for the cloned
entry, and import the reply certificate or certificate
chain. See the -certreq and -import subcommand.
4. delete the original (now obsolete) entry. See -delete.
To generate a self-signed certificate, use the -selfcert
subcommand, as in
example% keytool -selfcert -alias dukeNew -keypass b92kqmp
-dname "cn=Duke Smith, ou=Purchasing, o=BlueSoft, c=US"
The generated certificate is stored as a single-element cer-
tificate chain in the keystore entry identified by the
specified alias (in this case dukeNew) where it replaces the
existing certificate chain.
USAGE
The various subcommands and their options are listed and
described below . Note:
o All subcommand and option names are preceded by a minus
sign (-).
o The options for each subcommand may be provided in any
order.
o All items not italicized or in braces or square brackets
are required to appear as is.
o Braces surrounding an option generally signify that a
default value will be used if the option is not specified
on the command line. Braces are also used around the -v,
-rfc, and -J options, which only have meaning if they
appear on the command line (that is, they don't have any
"default" values other than not existing).
o Brackets surrounding an option signify that the user is
prompted for the value(s) if the option is not specified
on the command line. (For a -keypass option, if you do not
specify the option on the command line, keytool will first
attempt to use the keystore password to recover the
private key, and if this fails, will then prompt you for
the private key password.)
o Items in italics (option values) represent the actual
values that must be supplied. For example, here is the
format of the -printcert subcommand:
example% keytool -printcert {-file cert_file} {-v}
When specifying a -printcert subcommand, replace cert_file
with the actual file name, as in:
example% keytool -printcert -file VScert.cer
o Option values must be quoted if they contain a blank
(space).
o The -help subcommand is the default. Thus, the command
line
example% keytool
is equivalent to
example% keytool -help
Option Defaults
Below are the defaults for various option values.
-alias "mykey"
-keyalg "DSA"
-keysize 1024
-validity 90
-keystore the file named .keystore in the user's home directory
-file stdin if reading, stdout if writing
The signature algorithm ( -sigalg option) is derived from
the algorithm of the underlying private key: If the underly-
ing private key is of type "DSA", the -sigalg private key is
of type "RSA", -sigalg defaults to "MD5withRSA".
Options that Appear for Most Subcommands
The -v option can appear for all subcommands except -help.
If it appears, it signifies "verbose" mode; detailed certi-
ficate information will be output.
There is also a -Jjavaoption option that may appear for any
subcommand. If it appears, the specified -javaoption string
is passed through directly to the Java interpreter. ( key-
tool is actually a "wrapper" around the interpreter.) This
option should not contain any spaces. It is useful for
adjusting the execution environment or memory usage. For a
list of possible interpreter options, type
java -h
or
java -X
at the command line.
There are three options that may appear for all subcommands
operating on a keystore:
-storetype storetype
This qualifier specifies the type of keystore to be
instantiated. The default keystore type is the one that
is specified as the value of the "keystore.type" pro-
perty in the security properties file, which is
returned by the static getDefaultType method in
java.security.KeyStore.
-keystore keystore
The keystore (database file) location. Defaults to the
file .keystore in the user's home directory, as deter-
mined by the user.home system property. On Solaris sys-
tems user.home defaults to the user's home directory.
-storepass storepass
The password which is used to protect the integrity of
the keystore. storepass must be at least 6 characters
long. It must be provided to all subcommands that
access the keystore contents. For such subcommands, if
a -storepass option is not provided at the command
line, the user is prompted for it.
When retrieving information from the keystore, the password
is optional; if no password is given, the integrity of the
retrieved information cannot be checked and a warning is
displayed.
Be careful with passwords-see Warning Regarding Passwords.
Warning Regarding Passwords
Most subcommands operating on a keystore require the store
password. Some subcommands require a private key password.
Passwords can be specified on the command line (in the
-storepass and -keypass options, respectively). However, a
password should not be specified on a command line or in a
script unless it is for testing purposes, or you are on a
secure system.
If you don't specify a required password option on a command
line, you will be prompted for it. When typing in a password
at the password prompt, the password is currently echoed
(displayed exactly as typed), so be careful not to type it
in front of anyone.
SUBCOMMANDS
See also USAGE.
Adding Data to the Keystore
-genkey {-alias alias} {-keyalg keyalg} {-keysize keysize}
{-sigalg sigalg} [-dname dname] [-keypass keypass]
{-validity valDays} {-storetype storetype}
{-keystore keystore} [-storepass storepass] {-v}
{-Jjavaoption}
Generates a key pair (a public key and associated
private key). Wraps the public key into an X.509 v1
self-signed certificate, which is stored as a single-
element certificate chain. This certificate chain and
the private key are stored in a new keystore entry
identified by alias.
keyalg specifies the algorithm to be used to generate
the key pair, and keysize specifies the size of each
key to be generated. sigalg specifies the algorithm
that should be used to sign the self-signed certifi-
cate; this algorithm must be compatible with keyalg.
See Supported Algorithms and Key Sizes.
dname specifies the X.500 Distinguished Name to be
associated with alias, and is used as the issuer and
subject fields in the self-signed certificate. If no
distinguished name is provided at the command line, the
user will be prompted for one.
keypass is a password used to protect the private key
of the generated key pair. If no password is provided,
the user is prompted for it. If you press RETURN at the
prompt, the key password is set to the same password as
that used for the keystore. keypass must be at least 6
characters long. Be careful with passwords-see Warning
Regarding Passwords.
valDays tells the number of days for which the certifi-
cate should be considered valid.
-import {-alias alias} {-file cert_file} [-keypass keypass]
{-noprompt} {-trustcacerts} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
{-v} {-Jjavaoption}
Reads the certificate or certificate chain (where the
latter is supplied in a PKCS#7 formatted reply) from
the file cert_file, and stores it in the keystore entry
identified by alias given, the certificate or PKCS#7
reply is read from stdin. keytool can import X.509 v1,
v2, and v3 certificates, and PKCS#7 formatted certifi-
cate chains consisting of certificates of that type.
The data to be imported must be provided either in
binary encoding format, or in printable encoding format
(also known as Base64 encoding) as defined by the
Internet RFC 1421 standard. In the latter case, the
encoding must be bounded at the beginning by a string
that starts with "-----BEGIN", and bounded at the end
by a string that starts with "-----END".
When importing a new trusted certificate, alias must
not yet exist in the keystore. Before adding the certi-
ficate to the keystore, keytool tries to verify it by
attempting to construct a chain of trust from that cer-
tificate to a self-signed certificate (belonging to a
root CA), using trusted certificates that are already
available in the keystore.
If the -trustcacerts option has been specified, addi-
tional certificates are considered for the chain of
trust, namely the certificates in a file named cacerts,
which resides in the JDK security properties directory,
java.home/lib/security,where java.home is the JDK ins-
tallation directory. The cacerts file represents a
system-wide keystore with CA certificates. System
administrators can configure and manage that file using
keytool, specifying "jks" as the keystore type. The
cacerts keystore file ships with five VeriSign root CA
certificates with the following X.500 distinguished
names:
1. OU=Class 1 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
2. OU=Class 2 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
3. OU=Class 3 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
4. OU=Class 4 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
5. OU=Secure Server Certification Authority, O="RSA
Data Security, Inc.", C=US
The initial password of the cacerts keystore file is
"changeit". System administrators should change that
password and the default access permission of that file
upon installing the JDK.
If keytool fails to establish a trust path from the
certificate to be imported up to a self-signed certifi-
cate (either from the keystore or the cacerts file),
the certificate information is printed out, and the
user is prompted to verify it, for example, by compar-
ing the displayed certificate fingerprints with the
fingerprints obtained from some other (trusted) source
of information, which might be the certificate owner
himself/herself. Be very careful to ensure the certifi-
cate is valid prior to importing it as a "trusted" cer-
tificate! -- see WARNING Re: Importing Trusted Certi-
ficates. The user then has the option of aborting the
import operation. If the -noprompt option is given,
however, there will be no interaction with the user.
When importing a certificate reply, the certificate
reply is validated using trusted certificates from the
keystore, and optionally using the certificates config-
ured in the cacerts keystore file (if the -trustcacerts
option was specified).
If the reply is a single X.509 certificate, keytool
attempts to establish a trust chain, starting at the
certificate reply and ending at a self-signed certifi-
cate (belonging to a root CA). The certificate reply
and the hierarchy of certificates used to authenticate
the certificate reply form the new certificate chain of
alias.
If the reply is a PKCS#7 formatted certificate chain,
the chain is first ordered (with the user certificate
first and the self-signed root CA certificate last),
before keytool attempts to match the root CA certifi-
cate provided in the reply with any of the trusted cer-
tificates in the keystore or the cacerts keystore file
(if the -trustcacerts option was specified). If no
match can be found, the information of the root CA cer-
tificate is printed out, and the user is prompted to
verify it, for example, by comparing the displayed cer-
tificate fingerprints with the fingerprints obtained
from some other (trusted) source of information, which
might be the root CA itself. The user then has the
option of aborting the import operation. If the
-noprompt option is given, however, there will be no
interaction with the user.
The new certificate chain of alias replaces the old
certificate chain associated with this entry. The old
chain can only be replaced if a valid keypass, the
password used to protect the private key of the entry,
is supplied. If no password is provided, and the
private key password is different from the keystore
password, the user is prompted for it. Be careful with
passwords-see Warning Regarding Passwords.
-selfcert {-alias alias} {-sigalg sigalg} {-dname dname}
{-validity valDays} [-keypass keypass]
{-storetype storetype} {-keystore keystore}
[-storepass storepass] {-v} {-Jjavaoption}
Generates an X.509 v1 self-signed certificate, using
keystore information including the private key and pub-
lic key associated with alias. If dname is supplied at
the command line, it is used as the X.500 Distinguished
Name for both the issuer and subject of the certifi-
cate. Otherwise, the X.500 Distinguished Name associ-
ated with alias (at the bottom of its existing certifi-
cate chain) is used.
The generated certificate is stored as a single-element
certificate chain in the keystore entry identified by
alias, where it replaces the existing certificate
chain.
sigalg specifies the algorithm that should be used to
sign the certificate. See Supported Algorithms and Key
Sizes.
In order to access the private key, the appropriate
password must be provided, since private keys are pro-
tected in the keystore with a password. If keypass is
not provided at the command line, and is different from
the password used to protect the integrity of the key-
store, the user is prompted for it. Be careful with
passwords-see Warning Regarding Passwords.
valDays tells the number of days for which the certifi-
cate should be considered valid.
-identitydb {-file idb_file} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
{-v} {-Jjavaoption}
Reads the JDK 1.1.x-style identity database from the
file idb_file, and adds its entries to the keystore. If
no file is given, the identity database is read from
stdin. If a keystore does not exist, it is created.
Only identity database entries ("identities") that were
marked as trusted will be imported in the keystore. All
other identities will be ignored. For each trusted
identity, a keystore entry will be created. The
identity's name is used as the alias for the keystore
entry.
The private keys from trusted identities will all be
encrypted under the same password, storepass. This is
the same password that is used to protect the
keystore's integrity. Users can later assign individual
passwords to those private keys by using the -keypasswd
keytool command option.
An identity in an identity database may hold more than
one certificate, each certifying the same public key.
But a keystore key entry for a private key has that
private key and a single "certificate chain" (initially
just a single certificate), where the first certificate
in the chain contains the public key corresponding to
the private key. When importing the information from an
identity, only the first certificate of the identity is
stored in the keystore. This is because an identity's
name in an identity database is used as the alias for
its corresponding keystore entry, and alias names are
unique within a keystore,
Exporting Data
-certreq {-alias alias} {-sigalg sigalg}
{-file certreq_file} [-keypass keypass]
{-storetype storetype} {-keystore keystore}
[-storepass storepass] {-v} {-Jjavaoption}
Generates a Certificate Signing Request (CSR), using
the PKCS#10 format.
A CSR is intended to be sent to a certificate authority
(CA). The CA will authenticate the certificate reques-
tor (usually off-line) and will return a certificate or
certificate chain, used to replace the existing certi-
ficate chain (which initially consists of a self-signed
certificate) in the keystore.
The private key and X.500 Distinguished Name associated
with alias are used to create the PKCS#10 certificate
request. In order to access the private key, the
appropriate password must be provided, since private
keys are protected in the keystore with a password. If
keypass is not provided at the command line, and is
different from the password used to protect the
integrity of the keystore, the user is prompted for it.
Be careful with passwords-see Warning Regarding Pass-
words.
sigalg specifies the algorithm that should be used to
sign the CSR. See Supported Algorithms and Key Sizes.
The CSR is stored in the file certreq_file. If no file
is given, the CSR is output to stdout.
Use the import command to import the response from the
CA.
-export {-alias alias} {-file cert_file}
{-storetype storetype} {-keystore keystore}
[-storepass storepass] {-rfc} {-v} {-Jjavaoption}
Reads (from the keystore) the certificate associated
with alias, and stores it in the file cert_file.
If no file is given, the certificate is output to
stdout.
The certificate is by default output in binary encod-
ing, but will instead be output in the printable encod-
ing format, as defined by the Internet RFC 1421 stan-
dard, if the -rfc option is specified.
If alias refers to a trusted certificate, that certifi-
cate is output. Otherwise, alias refers to a key entry
with an associated certificate chain. In that case, the
first certificate in the chain is returned. This certi-
ficate authenticates the public key of the entity
addressed by alias.
Displaying Data
-list {-alias alias} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
{-v | -rfc} {-Jjavaoption}
Prints (to stdout) the contents of the keystore entry
identified by alias.Ifno alias is specified, the con-
tents of the entire keystore are printed.
This subcommand by default prints the MD5 fingerprint
of a certificate. If the -v option is specified, the
certificate is printed in human-readable format, with
additional information such as the owner, issuer, and
serial number. If the -rfc option is specified, certi-
ficate contents are printed using the printable encod-
ing format, as defined by the Internet RFC 1421 stan-
dard
You cannot specify both -v and -rfc.
-printcert {-file cert_file} {-v} {-Jjavaoption}
Reads the certificate from the file cert_file, and
prints its contents in a human-readable format. If no
file is given, the certificate is read from stdin.
The certificate may be either binary encoded or in
printable encoding format, as defined by the Internet
RFC 1421 standard.
Note: This option can be used independently of a key-
store.
Managing the Keystore
-keyclone {-alias alias} [-dest dest_alias]
[-keypass keypass] {-new new_keypass}
{-storetype storetype} {-keystore keystore}
[-storepass storepass] {-v} {-Jjavaoption}
Creates a new keystore entry, which has the same
private key and certificate chain as the original
entry.
The original entry is identified by alias (which
defaults to "mykey" if not provided). The new (destina-
tion) entry is identified by dest_alias. If no desti-
nation alias is supplied at the command line, the user
is prompted for it.
If the private key password is different from the key-
store password, then the entry will only be cloned if a
valid keypass is supplied. This is the password used to
protect the private key associated with alias command
line, and the private key password is different from
the keystore password, the user is prompted for it. The
private key in the cloned entry may be protected with a
different password, if desired. If no -new option is
supplied at the command line, the user is prompted for
the new entry's password (and may choose to let it be
the same as for the cloned entry's private key).
Be careful with passwords-see Warning Regarding Pass-
words.
This subcommand can be used to establish multiple cer-
tificate chains corresponding to a given key pair, or
for backup purposes.
-storepasswd {-new new_storepass} {-storetype storetype}
{-keystore keystore} [-storepass storepass] {-v}
{-Jjavaoption}
Changes the password used to protect the integrity of
the keystore contents. The new password is
new_storepass, which must be at least 6 characters
long.
Be careful with passwords-see Warning Regarding Pass-
words.
-keypasswd {-alias alias} [-keypass old_keypass]
[-new new_keypass] {-storetype storetype}
{-keystore keystore} [-storepass storepass]
{-v} {-Jjavaoption}
Changes the password under which the private key iden-
tified by alias is protected, from old_keypass to
new_keypass.
If the -keypass option is not provided at the command
line, and the private key password is different from
the keystore password, the user is prompted for it.
If the -new option is not provided at the command line,
the user is prompted for it.
Be careful with passwords-see Warning Regarding Pass-
words.
-delete [-alias alias] {-storetype storetype}
{-keystore keystore} [-storepass storepass] {-v}
{-Jjavaoption}
Deletes from the keystore the entry identified by
alias. The user is prompted for the alias, if no alias
is provided at the command line.
Getting Help
-help
EXAMPLES
Suppose you want to create a keystore for managing your
public/private key pair and certificates from entities you
trust.
Generating Your Key Pair
The first thing you need to do is create a keystore and gen-
erate the key pair. You could use a command such as the fol-
lowing:
example% keytool -genkey -dname "cn=Mark Jones, ou=Java, o=Sun, c=US"
-alias business -keypass kpi135 -keystore /working/mykeystore
-storepass ab987c -validity 180
(Please note: This must be typed as a single line. Multiple
lines are used in the examples just for legibility pur-
poses.)
This command creates the keystore named mykeystore in the
working directory (assuming it doesn't already exist), and
assigns it the password ab987c. It generates a
public/private key pair for the entity whose "distinguished
name" has a common name of MarkJones, organizational unit of
Java, organization of Sun and two-letter country code of US.
It uses the default "DSA" key generation algorithm to create
the keys, both 1024 bits long.
It creates a self-signed certificate (using the default
"SHA1withDSA" signature algorithm) that includes the public
key and the distinguished name information. This certificate
will be valid for 180 days, and is associated with the
private key in a keystore entry referred to by the alias
business. The private key is assigned the password kpi135.
The command could be significantly shorter if option
defaults were accepted. As a matter of fact, no options are
required; defaults are used for unspecified options that
have default values, and you are prompted for any required
values. Thus, you could simply have the following:
example% keytool -genkey
In this case, a keystore entry with alias mykey is created,
with a newly-generated key pair and a certificate that is
valid for 90 days. This entry is placed in the keystore
named .keystore in your home directory. (The keystore is
created if it doesn't already exist.) You will be prompted
for the distinguished name information, the keystore pass-
word, and the private key password.
The rest of the examples assume you executed the -genkey
command without options specified, and that you responded to
the prompts with values equal to those given in the first -
genkey command, above (a private key password of kpi135, and
so forth.)
Requesting a Signed Certificate from a
So far all we've got is a self-signed certificate. A certi-
ficate is more likely to be trusted by others if it is
signed by a Certification Authority (CA). To get such a sig-
nature, you first generate a Certificate Signing Request
(CSR), via the following:
example% keytool -certreq -file MarkJ.csr
This creates a CSR (for the entity identified by the default
alias mykey and puts the request in the file named
MarkJ.csr. Submit this file to a CA, such as VeriSign, Inc.
The CA will authenticate you, the requestor (usually off-
line), and then will return a certificate, signed by them,
authenticating your public key. (In some cases, they will
actually return a chain of certificates, each one authenti-
cating the public key of the signer of the previous certifi-
cate in the chain.)
Importing a Certificate for the CA
You need to replace your self-signed certificate with a cer-
tificate chain, where each certificate in the chain authen-
ticates the public key of the signer of the previous certi-
ficate in the chain, up to a "root" CA.
Before you import the certificate reply from a CA, you need
one or more "trusted certificates" in your keystore or in
the cacerts keystore file (which is described in importcom-
mand):
o If the certificate reply is a certificate chain, you just
need the top certificate of the chain (that is, the "root"
CA certificate authenticating that CA's public key).
o If the certificate reply is a single certificate, you need
a certificate for the issuing CA (the one that signed it),
and if that certificate is not self-signed, you need a
certificate for its signer, and so on, up to a self-signed
"root" CA certificate.
The cacerts keystore file ships with five VeriSign root CA
certificates, so you probably won't need to import a Ver-
iSign certificate as a trusted certificate in your keystore.
But if you request a signed certificate from a different CA,
and a certificate authenticating that CA's public key hasn't
been added to cacerts, you will need to import a certificate
from the CA as a "trusted certificate".
A certificate from a CA is usually either self-signed, or
signed by another CA (in which case you also need a certifi-
cate authenticating that CA's public key). Suppose company
ABC, Inc., is a CA, and you obtain a file named ABCCA.cer
that is purportedly a self-signed certificate from ABC,
authenticating that CA's public key.
Be very careful to ensure the certificate is valid prior to
importing it as a "trusted" certificate! View it first
(using the -printcert subcommand, or the -import subcommand
without the -noprompt option), and make sure that the
displayed certificate fingerprint(s) match the expected
ones. You can call the person who sent the certificate, and
compare the fingerprint(s) that you see with the ones that
they show (or that a secure public key repository shows).
Only if the fingerprints are equal is it guaranteed that the
certificate has not been replaced in transit with somebody
else's (for example, an attacker's) certificate. If such an
attack took place, and you did not check the certificate
before you imported it, you would end up trusting anything
the attacker has signed.
If you trust that the certificate is valid, then you can add
it to your keystore via the following:
example% keytool -import -alias abc -file ABCCA.cer
This creates a "trusted certificate" entry in the keystore,
with the data from the file ABCCA.cer, and assigns the alias
abc to the entry.
Importing the Certificate Reply from the
Once you've imported a certificate authenticating the public
key of the CA you submitted your certificate signing request
to (or there's already such a certificate in the cacerts
file), you can import the certificate reply and thereby
replace your self-signed certificate with a certificate
chain. This chain is the one returned by the CA in response
to your request (if the CA reply is a chain), or one con-
structed (if the CA reply is a single certificate) using the
certificate reply and trusted certificates that are already
available in the keystore where you import the reply or in
the cacerts keystore file.
For example, suppose you sent your certificate signing
request to VeriSign. You can then import the reply via the
following, which assumes the returned certificate is named
VSMarkJ.cer:
example% keytool -import -trustcacerts -file VSMarkJ.cer
Exporting a Certificate Authenticating Your Public
Suppose you have used the jarsigner(1) tool to sign a Java
ARchive (JAR) file. Clients that want to use the file will
want to authenticate your signature.
One way they can do this is by first importing your public
key certificate into their keystore as a "trusted" entry.
You can export the certificate and supply it to your
clients. As an example, you can copy your certificate to a
file named MJ.cer via the following, assuming the entry is
aliased by mykey:
example% keytool -export -alias mykey -file MJ.cer
Given that certificate, and the signed JAR file, a client
can use the jarsigner(1) tool to authenticate your signa-
ture.
Changing Your Distinguished Name but Keeping
Suppose your distinguished name changes, for example because
you have changed departments or moved to a different city.
If desired, you may still use the public/private key pair
you've previously used, and yet update your distinguished
name. For example, suppose your name is Susan Miller, and
you created your initial key entry with the alias sMiller
and the distinguished name
"cn=Susan Miller, ou=Finance Department, o=BlueSoft, c=us"
Suppose you change from the Finance Department to the
Accounting Department. You can still use the previously-
generated public/private key pair and yet update your dis-
tinguished name by doing the following. First, copy (clone)
your key entry:
example% keytool -keyclone -alias sMiller -dest sMillerNew
(This prompts for the store password and for the initial and
destination private key passwords, since they aren't pro-
vided at the command line.) Now you need to change the cer-
tificate chain associated with the copy, so that the first
certificate in the chain uses your different distinguished
name. Start by generating a self-signed certificate with
the appropriate name:
example% keytool -selfcert -alias sMillerNew
-dname "cn=Susan Miller, ou=Accounting Department, o=BlueSoft, c=us"
Then generate a Certificate Signing Request based on the
information in this new certificate:
example% keytool -certreq -alias sMillerNew
When you get the CA certificate reply, import it:
example% keytool -import -alias sMillerNew -file VSSMillerNew.cer
After importing the certificate reply, you may want to
remove the initial key entry that used your old dis-
tinguished name:
example% keytool -delete -alias sMiller
ATTRIBUTES
See attributes(5) for a description of the following attri-
butes:
______________________________________
| ATTRIBUTE TYPE| ATTRIBUTE VALUE |
|_______________|______________________|_
| Availability | SUNWjvrt, SUNWjvdev|
|_______________|_____________________|
SEE ALSO
jar(1), jarsigner(1)
See (or search java.sun.com) for the following:
Security in JDK 1.2 @
http://java.sun.com/docs/books/tutorial/security1.2/index.html
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