keytool - Unix, Linux Command

A certificate is a digitally signed statement from one entity
(person, company, and so forth), saying that the public 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 authenticity means the data indeed comes from whoever
claims to have created and signed it.


keytool stores the keys and certificates in a so-called keystore.
The
keytool default keystore implementation implements 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 certificate 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 passwords, 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.


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 certificate or certificate chain to the list of
trusted certificates. 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:



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:



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.


Note that the input stream from the -keystore
option is passed to the
KeyStore.load method. If NONE is specified as the
URL, then a null stream is passed
to the KeyStore.load method. NONE should be specified
if the KeyStore is not
file-based, for example, if it resides on a hardware token device.


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
keystore is a file named
.keystore in your home
directory.
If that file does not yet exist, it will be created.


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,
utilizing 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 specifically, 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 "providers" must implement.
(The term "provider" refers to a package or a set of packages that
supply a concrete implementation of a subset of services
that can be accessed by the Java Security API.)  Thus, to
provide a keystore implementation, clients must
implement a "provider" and supply a
KeystoreSpi subclass
implementation, as described in How to Implement a
Provider for the Java Cryptography Architecture.


Applications can choose different types of keystore
implementations 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 compatible.


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
FileInputStream, 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 properties 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
getDefaultType 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 specified 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
specified 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 different 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".


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.


Let us expand on some of the key terms used in this
sentence:


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.

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.)


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 profile documents strongly
recommend that names not be reused, and that
certificates should not make use of unique
identifiers. 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 particular purposes such as
"signing-only") and AlternativeNames (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 communication, 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 single way
to store and transfer that data.



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



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 designated 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 "\"


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
specified.


The
-list subcommand by default prints the MD5
fingerprint of a certificate. If the
-v option
is specified, the certificate 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-----


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 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.


Later, after a Certificate Signing Request
(CSR) has been generated (see the
-certreq subcommand) and sent to a Certification 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 authenticating 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 certificate signed by a different
CA, authenticating the public key of the CA
you sent the CSR to. Then, the next
certificate in the chain will be a certificate
authenticating the second CA’s key, and so on,
until a self-signed "root" certificate 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 supporting 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 keystore, 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
webpage, and so forth).



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:




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



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 certificate, 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 subcommand 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 certificate 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.



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.



keytool -list -alias joe


If you don’t specify an alias, as in



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



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.


You may occasionally wish to generate a new
self-signed certificate. For example, you may
want to use the same key pair under a
different identity (distinguished name). For
example, suppose you change departments. You
can then:



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 certificate chain in the
keystore entry identified by the specified
alias (in this case dukeNew) where it
replaces the existing certificate chain.

keytool -printcert {-file cert_file} {-v}

keytool -printcert -file VScert.cer

keytool


is equivalent to



keytool -help



-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
underlying private key is of type "DSA", the
-sigalg private key is of type "RSA",
-sigalg defaults to
"MD5withRSA".


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.
(keytool 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.


These options may appear for all commands
operating on a keystore:


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.


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 certificate; 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
certificate should be considered valid.


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 .If no file is
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 certificate
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".


You import a certification 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 command) to that CA.


If the
-trustcacerts option has been specified,
additional certificates are considered for the
chain of trust, namely the certificates in a file named
cacerts. 

If keytool fails to establish a trust
path from the certificate to
be imported up to a self-signed
certificate (either from the
keystore or the "cacerts" file),
the certificate information is
printed out, and the user is prompted
to verify it, e.g., by
comparing 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 certificate is valid
prior to importing it as a "trusted" certificate! -- see WARNING
Regarding Importing Trusted Certificates. 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 methods of determining whether the certificate reply is
trusted are described in the following:


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
certificate (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 certificate provided in the reply with
any of the trusted certificates 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 certificate is
printed out, and the user is prompted to verify it,
for example, by comparing the displayed certificate
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. 

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 several root CA certificates
with the following aliases and X.500 owner distinguished names:


Alias: thawtepersonalfreemailca
Owner DN:
EmailAddress=personal-freemail@thawte.com,
CN=Thawte Personal Freemail CA,
OU=Certification Services Division,
O=Thawte Consulting, L=Cape Town, ST=Western Cape,
C=ZA


Alias: thawtepersonalbasicca
Owner DN: EmailAddress=personal-basic@thawte.com,
CN=Thawte Personal Basic CA,
OU=Certification Services Division,
O=Thawte Consulting, L=Cape Town, ST=Western Cape,
C=ZA


Alias: thawtepersonalpremiumca
Owner DN:
EmailAddress=personal-premium@thawte.com,
CN=Thawte Personal Premium CA,
OU=Certification Services Division,
O=Thawte Consulting, L=Cape Town, ST=Western Cape,
C=ZA


Alias: thawteserverca
Owner DN: EmailAddress=server-certs@thawte.com,
CN=Thawte Server CA,
OU=Certification Services Division,
O=Thawte Consulting cc, L=Cape Town, ST=Western
Cape, C=ZA


Alias: thawtepremiumserverca
Owner DN: EmailAddress=premium-server@thawte.com,
CN=Thawte Premium Server CA,
OU=Certification Services Division,
O=Thawte Consulting cc, L=Cape Town, ST=Western
Cape, C=ZA


Alias: verisignclass1ca
Owner DN: OU=Class 1 Public Primary Certification
Authority,
O="VeriSign, Inc.", C=US


Alias: verisignclass2ca
Owner DN: OU=Class 2 Public Primary Certification
Authority,
O="VeriSign, Inc.", C=US


Alias: verisignclass3ca
Owner DN: OU=Class 3 Public Primary Certification
Authority,
O="VeriSign, Inc.", C=US


Alias: verisignclass4ca
Owner DN: OU=Class 4 Public Primary Certification
Authority,
O="VeriSign, Inc.", C=US


Alias: verisignserverca
Owner DN: OU=Secure Server Certification Authority,
O="RSA Data Security, Inc.", C=US


Alias: baltimorecodesigningca
Owner DN: CN=Baltimore CyberTrust Code Signing Root,
OU=CyberTrust, O=Baltimore, C=IE


Alias: gtecybertrustca
Owner DN: CN=GTE CyberTrust Root,
O=GTE Corporation, C=US


Alias: gtecybertrust5ca
Owner DN: CN=GTE CyberTrust Root 5,
OU="GTE CyberTrust Solutions, Inc.", O=GTE Corporation,
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 SDK.


IMPORTANT: Verify Your cacerts File
Since you trust the CAs in the cacerts file as
entities for signing and issuing certificates to other
entities, you must manage the cacerts file
carefully. The cacerts file should contain only
certificates of the CAs you trust. It is your
responsibility to verify the trusted root CA
certificates bundled in the cacerts file and make
your own trust decisions. To remove an untrusted
CA certificate from the cacerts file, use the delete
option of the keytool command. You can find the
You can find the  cacerts file in the JRE installation directory.
Contact your system administrator if you do not
have permission to edit this file.


Generates an X.509 v1 self-signed certificate,
using keystore information including the private
key and public 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 certificate. Otherwise, the X.500
Distinguished Name associated with
alias (at the
bottom of its existing certificate 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
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 Passwords. 

valDays tells the number of days for which the
certificate should be considered valid.



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,


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 requestor (usually off-line) and will
return a certificate or certificate chain, used to
replace the existing certificate 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 Passwords. 

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.


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
encoding, but will instead be output in the
printable encoding format, as defined by the
Internet RFC 1421 standard, if the
-rfc option is
specified.


If
alias refers to a trusted certificate, that
certificate 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 certificate authenticates the public
key of the entity addressed by
alias. 

Prints (to stdout) the contents of the keystore
entry identified by
alias. If no
alias is specified, the contents of the entire keystore are printed.


This command 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,
certificate contents are printed using the
printable encoding format, as defined by the
Internet RFC 1421 standard


You cannot specify both
-v and
-rfc. 

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
keystore.


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
(destination) entry is identified by
dest_alias. If no destination
alias is supplied at the command
line, the user is prompted for it.


If the private key password is different from the
keystore 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. If no key password is supplied at the
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 Passwords. 

This command can be used to establish multiple
certificate chains corresponding to a given key
pair, or for backup purposes.


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:
Warning Regarding Passwords. 

Changes the password under which the private key
identified 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 Passwords. 

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.



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 purposes.)


This command creates the keystore named
mykeystore in the
working directory (assuming it does not 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:



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 password,
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.)



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 authenticating the public key
of the signer of the previous certificate in the chain.)


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
importcommand): 

A certificate from a CA is usually either self-signed,
or signed by another CA (in which case you also need a
certificate 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:



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.


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: 


keytool -import -trustcacerts -file VSMarkJ.cer


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: 


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
signature.



"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 distinguished name by doing the following.
First, copy (clone) your key entry:



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 provided at the command
line.) Now you need to change the certificate 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:



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:



keytool -certreq -alias sMillerNew


When you get the CA certificate reply, import it:



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
distinguished name:



keytool -delete -alias sMiller

jar (1)
jar (1)
jarsigner (1)
jarsigner (1)

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