keytool(1) keytool(1)
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-authen-
tication (where the user authenticates himself/herself to
other users/services) or data integrity and authentication
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
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). jar-
signer(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 key-
store.
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 addi-
tion 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 for-
mat 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
public key certificate belonging to another party. It
is called a "trusted certificate" because the key-
store owner trusts that the public key in the cer-
tificate indeed belongs to the identity identified by
the "subject" (owner) of the certificate. The issuer
of the certificate vouches for this, by signing the
certificate.
Keystore Aliases
All keystore entries (key and trusted certificate entries)
are accessed via unique aliases. Aliases are case-insensi-
tive; the aliases Hugo and hugo would refer to the same
keystore entry.
An alias is specified when you add an entity to the key-
store 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:
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 "new-
pass".
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 (dis-
played 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 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,
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 specif-
ically, the application interfaces supplied by KeyStore
are implemented in terms of a "Service Provider Interface"
(SPI). That is, there is a corresponding abstract Key-
storeSpi 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 implementa-
tion, 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 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 informa-
tion.) 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 proper-
ties directory, located at ${JAVA_HOME}/lib/security.
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 getDe-
faultType 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".
Supported Algorithms and Key Sizes
keytool allows users to specify any key pair generation
and signature algorithm supplied by any of the registered
cryptographic service providers. That is, the -keyalg and
-sigalg options for various subcommands must be supported
by a provider implementation. The default key pair genera-
tion algorithm is "DSA". The signature algorithm is
derived from the algorithm of the underlying private key:
If the underlying private key is of type "DSA", the
default signature algorithm is "SHA1withDSA", and if the
underlying private key is of type "RSA", the default sig-
nature 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
particular entity, and are intended to
be known to everyone who needs to have
trusted interactions with that entity.
Public keys are used to verify signa-
tures.
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 unforgeable by sign-
ing 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 any-
thing 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 par-
ticular entity whose private key it is
(that is, it's supposed to be kept
secret). Private and public keys exist
in pairs in all public key cryptogra-
phy systems (also referred to as "pub-
lic 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. Certificates were invented as a solution to this
public key distribution 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 cer-
tificates, 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 stan-
dard applies to this certificate, which affects what
information can be specified in it. Thus far, three ver-
sions are defined. keytool can import and export v1, v2,
and v3 certificates. It generates v1 certificates. Serial
Number The entity that created the certificate is respon-
sible 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 Revo-
cation List (CRL). Signature Algorithm Identifier This
identifies the algorithm used by the CA to sign the cer-
tificate. Issuer Name The X.500 Distinguished Name of the
entity that signed the certificate. 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 certificates, 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 iden-
tifies. 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 example,
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
Information This is the public key of the entity being
named, together with an algorithm identifier which speci-
fies which public key crypto system this key belongs to
and any associated 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 cer-
tificate 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 exten-
sion and include it in the certificate. Some common exten-
sions 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 asso-
ciated with this public key, for example, DNS names, Email
addresses, IP addresses). Extensions can be marked criti-
cal 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 "keyCert-
Sign" 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.
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 (for example,
department or division) name, such as, "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, "Cali-
fornia"
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 subcom-
mands, 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 Standard
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 cer-
tificates to other applications by email or through some
other mechanism.
Certificates read by the -import and -printcert subcom-
mands 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 spec-
ified.
The -list subcommand by default prints the MD5 fingerprint
of a certificate. If the -v option is specified, the cer-
tificate 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 subcom-
mand), 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 authen-
ticating 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, authenti-
cating 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 certifi-
cate 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 infor-
mation already stored in the keystore.
A different reply format (defined by the PKCS#7 standard)
also includes the supporting certificate chain, in addi-
tion to the issued certificate. Both reply formats can be
handled by keytool.
The top-level (root) CA certificate is self-signed. How-
ever, 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 certifi-
cate to your keystore, you should view it (using the
-printcert option) and compare the displayed fingerprint
with the well-known fingerprint (obtained from a newspa-
per, the root CA's webpage, and so forth).
Importing Certificates
To import a certificate from a file, use the -import sub-
command, 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 identi-
fied 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
associated 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
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 exam-
ple, 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 mali-
cious 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.
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 pub-
lic key is being authenticated by the certificate). When-
ever 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
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:
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 sub-
command.
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
certificate 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 speci-
fied 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 under-
lying 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 cer-
tificate 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.
(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.
There are three options that may appear for all subcom-
mands 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 "key-
store.type" property in the security properties
file, which is returned by the static getDefault-
Type method in java.security.KeyStore.
-keystore keystore
The keystore (database file) location. Defaults to
the file .keystore in 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 sub-
commands 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.
-provider provider_class_name
Used to specify the name of the cryptographic ser-
vice provider's master class file when the service
provider is not listed in the security properties
file.
When retrieving information from the keystore, the pass-
word is optional; if no password is given, the integrity
of the retrieved information cannot be checked and a warn-
ing is displayed.
Be careful with passwords: See Warning Regarding Pass-
words.
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 com-
mand 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 key-
pass]
{-validity valDays} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name] {-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 sin-
gle-element certificate chain. This certificate
chain and the private key are stored in a new key-
store entry identified by alias.
keyalg specifies the algorithm to be used to gener-
ate 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 compati-
ble 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 Pass-
words.
valDays tells the number of days for which the cer-
tificate should be considered valid.
-import {-alias alias} {-file cert_file} [-keypass key-
pass]
{-noprompt} {-trustcacerts} {-storetype store-
type}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-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 key-
store entry identified by alias given, the certifi-
cate 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".
When importing a new trusted certificate, alias
must not yet exist in the keystore. Before adding
the certificate to the keystore, keytool tries to
verify it by attempting to construct a chain of
trust from that certificate to a self-signed cer-
tificate (belonging to a root CA), using trusted
certificates that are already available in the key-
store.
If the -trustcacerts option has been specified,
additional certificates are considered for the
chain of trust, namely the certificates in a file
named cacerts, which resides in the JDK security
properties directory, located at
${JAVA_HOME}/lib/security. The cacerts file repre-
sents a system-wide keystore with CA certificates.
System administrators can configure and manage that
file using keytool, specifying "jks" as the key-
store type. The cacerts keystore file ships with
five VeriSign root CA certificates with the follow-
ing 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 cer-
tificate (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 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 import-
ing it as a "trusted" certificate! -- see WARNING
Re: 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.
When importing a certificate reply, the certificate
reply is validated using trusted certificates from
the keystore, and optionally using the certificates
configured 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
certificate (belonging to a root CA). The certifi-
cate 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 cer-
tificate 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 key-
store password, the user is prompted for it. Be
careful with passwords: See Warning Regarding Pass-
words.
-selfcert {-alias alias} {-sigalg sigalg} {-dname dname}
{-validity valDays} [-keypass keypass]
{-storetype storetype} {-keystore keystore}
[-storepass storepass] [-provider
provider_class_name]
{-v} {-Jjavaoption}
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 key-
pass 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 Regard-
ing Passwords.
valDays tells the number of days for which the cer-
tificate should be considered valid.
-identitydb {-file idb_file} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-v} {-Jjavaoption}
Reads the JDK 1.1.x-style identity database from
the file idb_file, and adds its entries to the key-
store. 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 key-
store. 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 pub-
lic 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]
[-provider provider_class_name]
{-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 cer-
tificate requestor (usually off-line) and will
return a certificate or certificate chain, used to
replace the existing certificate chain (which ini-
tially consists of a self-signed certificate) in
the keystore.
The private key and X.500 Distinguished Name asso-
ciated 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.
-export {-alias alias} {-file cert_file} {-storetype
storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-rfc} {-v} {-Jjavaoption}
Reads (from the keystore) the certificate associ-
ated 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 print-
able encoding format, as defined by the Internet
RFC 1421 standard, if the -rfc option is specified.
If alias refers to a trusted certificate, that cer-
tificate 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.
Displaying Data
-list {-alias alias} {-storetype storetype} {-keystore
keystore}
[-storepass storepass]
[-provider provider_class_name]
{-v | -rfc} {-Jjavaoption}
Prints (to stdout) the contents of the keystore
entry identified by alias. If no alias is speci-
fied, the contents of the entire keystore are
printed.
This subcommand by default prints the MD5 finger-
print of a certificate. If the -v option is speci-
fied, 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.
-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 Inter-
net RFC 1421 standard.
Note: This option can be used independently of a
keystore.
Managing the Keystore
-keyclone {-alias alias} [-dest dest_alias] [-keypass key-
pass]
{-new new_keypass} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-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 (des-
tination) 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 dif-
ferent 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 subcommand can be used to establish multiple
certificate chains corresponding to a given key
pair, or for backup purposes.
-storepasswd {-new new_storepass} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-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: Warning Regarding Pass-
words.
-keypasswd {-alias alias} [-keypass old_keypass]
[-new new_keypass] {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-v} {-Jjavaoption}
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 com-
mand line, and the private key password is differ-
ent 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.
-delete [-alias alias] {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-provider provider_class_name]
{-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
generate the key pair. You could use a command such as the
following:
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. Multi-
ple 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 pub-
lic/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 pub-
lic key and the distinguished name information. This cer-
tificate 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 pass-
word 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 follow-
ing:
example% keytool -genkey
In this case, a keystore entry with alias mykey is cre-
ated, 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 key-
store is created if it doesn't already exist.) You will be
prompted for the distinguished name information, the key-
store 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.)
Requesting a Signed Certificate from a Certification Authority
So far all we've got is a self-signed certificate. A cer-
tificate is more likely to be trusted by others if it is
signed by a Certification Authority (CA). To get such a
signature, 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
authenticating the public key of the signer of the previ-
ous certificate in the chain.)
Importing a Certificate for the CA
You need to replace your self-signed certificate with a
certificate chain, where each certificate in the chain
authenticates the public key of the signer of the previous
certificate 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
importcommand):
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
VeriSign certificate as a trusted certificate in your key-
store. But if you request a signed certificate from a dif-
ferent CA, and a certificate authenticating that CA's pub-
lic key hasn't been added to cacerts, you will need to
import a certificate from the CA as a "trusted certifi-
cate".
A certificate from a CA is usually either self-signed, or
signed by another CA (in which case you also need a cer-
tificate 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 subcom-
mand 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 guaran-
teed that the certificate has not been replaced in transit
with somebody else's (for example, an attacker's) certifi-
cate. 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 key-
store, with the data from the file ABCCA.cer, and assigns
the alias abc to the entry.
Importing the Certificate Reply from the CA
Once you've imported a certificate authenticating the pub-
lic 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 cer-
tificate chain. This chain is the one returned by the CA
in response to your request (if the CA reply is a chain),
or one constructed (if the CA reply is a single certifi-
cate) 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 Key
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 your Key Pair
Suppose your distinguished name changes, for example
because you have changed departments or moved to a differ-
ent city. If desired, you may still use the public/private
key pair you've previously used, and yet update your dis-
tinguished 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
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 distin-
guished name. Start by generating a self-signed certifi-
cate 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
distinguished name:
example% keytool -delete -alias sMiller
SEE ALSO
jar(1), jarsigner(1)
See (or search java.sun.com) for the following:
Security in the Java 2 Platform @
http://java.sun.com/docs/books/tutorial/secu-
rity1.2/index.html
14 July 2000 keytool(1)