Keytool Man Pages
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 cer-
tificates for use in self-authentication (where the user authenticates
himself/herself to other users/services) or data integrity and authen-
tication services, using digital signatures. It also allows users to
cache the public keys (in the form of certificates) of their communi-
cating 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 Cer-
tificates.) When data is digitally signed, the signature can be veri-
fied 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.
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 -identi-
tydb subcommand.
KEYSTORE ENTRIES
There are two different types of entries in a keystore:
1. key entries
Each key entry holds very sensitive cryptographic key information,
which is stored in a protected format to prevent unauthorized
access. Typically, a key stored in this type of entry is a secret
key, or a private key accompanied by the certificate "chain" for
the corresponding public key. The keytool and jarsigner(1) tools
only handle the latter type of entry, that is, private keys and
their associated certificate chains.
2. trusted certificate entries
Each trusted certificate entry contains a single public key cer-
tificate belonging to another party. It is called a "trusted cer-
tificate" because the keystore owner trusts that the public key in
the certificate indeed belongs to the identity identified by the
"subject" (owner) of the certificate. The issuer of the certifi-
cate 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-insensitive; the aliases Hugo and
hugo would refer to the same keystore entry.
An alias is specified when you add an entity to the keystore using the
-genkey subcommand to generate a key pair (public and private key) or
the -import subcommand to add a 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 pub-
lic/private key pair and wrap the public key into a self-signed cer-
tificate (see Certificate Chains) via the following command:
example% keytool -genkey -alias duke -keypass dukekeypasswd
This specifies an inital password of dukekeypasswd required by subse-
quent 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 com-
mand like the following:
example% keytool -keypasswd -alias duke -keypass\
dukekeypasswd -new newpass
This changes the password from "dukekeypasswd" to "newpass".
Note: A password should not actually be specified on a command line or
in a script unless it is for testing purposes, or you are on a secure
system. If you don't specify a required password option on a command
line, you will be prompted for it. When typing in a password at the
password prompt, the password is currently echoed (displayed exactly as
typed), so be careful not to type it in front of anyone.
KEYSTORE LOCATION
Each keytool command has a -keystore option for specifying the name and
location of the persistent keystore file for the keystore managed by
keytool. The keystore is by default stored in a file named .keystore
in the user's home directory.
KEYSTORE CREATION
A keystore is created whenever you use a -genkey, -import, or -identi-
tydb 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 keystore 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 implementa-
tions, where each implementation is that for a particular type of key-
store.
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 Microsys-
tems. 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 correspond-
ing 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 sup-
plied 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 prop-
erties file is called java.security, and it resides in the JDK security
properties directory, located at ${JAVA_HOME}/lib/security.
Each tool gets the keystore.type value and then examines all the cur-
rently-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 key-
store implementation provided by Sun). This is specified by the follow-
ing 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 subcom-
mands must be supported by a provider implementation. The default key
pair generation algorithm is "DSA". The signature algorithm is derived
from the algorithm of the underlying private key: If the 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 signature algorithm is "MD5withRSA".
When generating a DSA key pair, the key size must be in the range from
512 to 1024 bits, and must be a multiple of 64. The default key size
for any algorithm is 1024 bits.
CERTIFICATES
A certificate (also known as a public-key certificate) is a digitally
signed statement from one entity (the issuer), saying that the public
key (and some other information) of another entity (the subject) has
some
Let us expand on some of the key terms used in this sentence:
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 signatures.
Digitally Signed If some data is digitally signed it has been stored
with the "identity" of an entity, and a signature
that proves that entity knows about the data. The
data is rendered unforgeable by signing with the
entity's private key.
Identity A known way of addressing an entity. In some sys-
tems the identity is the public key, in others it
can be anything from a Unix UID to an Email address
to an X.509 Distinguished Name.
Signature A signature is computed over some data using the
private key of an entity (the signer, which in the
case of a certificate is also known as the issuer).
Private Keys These are numbers, each of which is supposed to be
known only to the particular entity whose private
key it is (that is, it's supposed to be kept
secret). Private and public keys exist in pairs in
all public key cryptography systems (also referred
to as "public key crypto systems"). In a typical
public key crypto system, such as DSA, a private
key corresponds to exactly one public key. Private
keys are used to compute signatures.
Entity An entity is a person, organization, program, com-
puter, 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 guar-
antee 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 dis-
tribution problem. Now a Certification Authority (CA) can act as a
trusted third party. CAs are entities (for example, businesses) that
are trusted to sign (issue) certificates for other entities. It is
assumed that CAs will only create valid and reliable certificates, as
they are bound by legal agreements. There are many public Certification
Authorities, such as VeriSign, Thawte, Entrust, and so on. You can also
run your own Certification Authority using products such as the
Netscape/Microsoft Certificate Servers or the Entrust CA product for
your organization.
Using keytool, it is possible to display, import, and export certifi-
cates. 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 cer-
tificates have the following data, in addition to the signature:
Version
This identifies which version of the X.509 standard applies to
this certificate, which affects what information can be speci-
fied in it. Thus far, three versions 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 responsible for
assigning it a serial number to distinguish it from other cer-
tificates it issues. This information is used in numerous ways,
for example when a certificate is revoked its serial number is
placed in a Certificate Revocation List (CRL). Signature Algo-
rithm Identifier This identifies the algorithm used by the CA to
sign the certificate.
Issuer Name
The X.500 Distinguished Name of the entity that signed the cer-
tificate. This is normally a CA. Using this certificate implies
trusting the entity that signed this certificate. (Note that in
some cases, such as root or top-level CA 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 num-
ber 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 identi-
fies. 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, Organi-
zation, and Country.) Subject Public Key Information This is the pub-
lic key of the entity being named, together with an algorithm identi-
fier which specifies 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 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 associ-
ated 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 cer-
tificate has the KeyUsage extension marked critical and set to "keyC-
ertSign" then if this certificate is presented during SSL communica-
tion, it should be rejected, as the certificate extension indicates
that the associated private key should only be used for signing cer-
tificates 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 Defi-
nite 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 cer-
tificates. keytool supports the following subparts:
commonName
Common name of a person; for example, "Susan Jones".
organizationUnit
Small organization; for example, department or division name,
such as "Purchasing".
organizationName
For example, "ABCSystems, Inc."
localityName
Locality (city) name; for example, "Palo Alto".
stateName
State or province name; for example, "California".
country
Two-letter country code, for example, "CH".
When supplying a distinguished name string as the value of a -dname
option, as for the -genkey or -selfcert subcommands, the string must be
in the following format:
CN=cName, OU=orgUnit, O=org, L=city, S=state, C=countryCode
where all the hilited items represent actual values and the above key-
words 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 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 com-
mand line. If it is needed for a command, but not supplied on the com-
mand 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 certificates to other applications by email or
through some other mechanism.
Certificates read by the -import and -printcert subcommands can be in
either this format or binary encoded.
The -export subcommand by default outputs a certificate in binary
encoding, but will instead output a certificate in the printable encod-
ing format, if the -rfc option is specified.
The -list subcommand by default prints the MD5 fingerprint of a cer-
tificate. If the -v option is specified, the certificate is printed in
human-readable format, while if the -rfc option is specified, the cer-
tificate 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 certifi-
cate in the chain contains the public key corresponding to the private
key.
When keys are first generated (see the -genkey subcommand), the chain
starts off containing a single element, a self-signed certificate. A
self-signed certificate is one for which the issuer (signer) is the
same as the subject (the entity whose public key is being authenticated
by the certificate). Whenever the -genkey subcommand is called to gen-
erate 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 bot-
tom of the chain is the certificate (reply) issued by the CA authenti-
cating the subject's public key. The next certificate in the chain is
one that authenticates the CA's public key.
In many cases, this is a self-signed certificate (that is, a certifi-
cate from the CA authenticating its own public key) and the last cer-
tificate 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 certifi-
cate 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 cer-
tificate 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 certifi-
cate. 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 dis-
tinguished name of say, the VeriSign root CA!), but from other sources
like a newspaper. The root CA public key is widely known. The only rea-
son it is stored in a certificate is because this is the format under-
stood 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).
IMPORTING CERTIFICATES
To import a certificate from a file, use the -import subcommand, as in
example% keytool -import -alias joe -file jcertfile.cer
This sample command imports the certificate(s) in the file jcert-
file.cer and stores it in the keystore entry identified by the alias
joe.
You import a certificate for two reasons:
1. to add it to the list of trusted certificates, or
2. to import a certificate reply received from a CA as the result of
submitting a Certificate Signing Request (see the -certreq subcom-
mand) 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 cer-
tificate reply. keytool checks whether the public key in the certifi-
cate 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 cer-
tificate.
WARNING REGARDING IMPORTING TRUSTED CERTIFICATES
IMPORTANT: Be sure to check a certificate very carefully before import-
ing it as a trusted certificate!
o View it first (using the -printcert subcommand, or the -import sub-
command without the -noprompt option), and make sure that the dis-
played certificate fingerprint(s) match the expected ones. For exam-
ple, suppose someone sends or emails you a certificate, and you put
it in a file named /tmp/cert.Beforeyou consider adding the certifi-
cate to your list of trusted certificates, you can execute a -print-
cert 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
o 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 exam-
ple, 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 sub-
command 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 sub-
command 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 subcommand, as in
example% keytool -export -alias jane -file janecertfile.cer
This sample command exports jane's certificate to the file janecert-
file.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 pub-
lic 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 subcom-
mand, as in
example% keytool -list -alias joe
If you don't specify an alias, as in
example% keytool -list
the contents of the entire keystore are printed.
To display the contents of a certificate stored in a file, use the
-printcert subcommand, as in
example% keytool -printcert -file certfile.cer
This displays information about the certificate stored in the file
certfile.cer.
Note: This works independently of a keystore, that is, you do not need
a keystore in order to display a certificate that's stored in a file.
GENERATING A SELF-SIGNED CERTIFICATE
A self-signed certificate is one for which the issuer (signer) is the
same as the subject (the entity whose public key is being authenticated
by the certificate). Whenever the -genkey subcommand is called to gen-
erate 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 depart-
ments. You can then:
1. Copy (clone) the original key entry. See -keyclone.
2. Generate a new self-signed certificate for the cloned entry, using
your new distinguished name. See below.
3. Generate a Certificate Signing Requests for the cloned entry, and
import the reply certificate or certificate chain. See the
-certreq and -import subcommand.
4. Delete the original (now obsolete) entry. See -delete.
To generate a self-signed certificate, use the -selfcert subcommand, as
in
example% keytool -selfcert -alias dukeNew -keypass b92kqmp
-dname "cn=Duke Smith, ou=Purchasing, o=BlueSoft, c=US"
The generated certificate is stored as a single-element 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 specified on the command line.
Braces are also used around the -v, -rfc, and -J options, which only
have meaning if they appear on the command line (that is, they don't
have any "default" values other than not existing).
o Brackets surrounding an option signify that the user is prompted for
the value(s) if the option is not specified on the command line. (For
a -keypass option, if you do not specify the option on the command
line, keytool will first attempt to use the keystore password to
recover the private key, and if this fails, will then prompt you for
the private key password.)
o Items in italics (option values) represent the actual values that
must be supplied. For example, here is the format of the -printcert
subcommand:
example% keytool -printcert {-file cert_file} {-v}
When specifying a -printcert subcommand, replace cert_file with the
actual file name, as in:
example% keytool -printcert -file VScert.cer
o Option values must be quoted if they contain a blank (space).
o The -help subcommand is the default. Thus, the command line
example% keytool
is equivalent to
example% keytool -help
OPTION DEFAULTS
Below are the defaults for various option values.
-alias "mykey"
-keyalg "DSA"
-keysize 1024
-validity 90
-keystore The file named .keystore in the user's home directory.
-file stdin if reading, stdout if writing.
The signature algorithm (-sigalg option) is derived from the algorithm
of the underlying private key: If the underlying 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 certificate 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 subcommands operating
on a keystore:
-storetype storetype
This qualifier specifies the type of keystore to be instanti-
ated. The default keystore type is the one that is specified as
the value of the "keystore.type" property in the security prop-
erties file, which is returned by the static getDefaultType
method in java.security.KeyStore.
-keystore keystore
The keystore (database file) location. Defaults to the file
.keystore in the user's home directory.
-storepass storepass
The password which is used to protect the integrity of the key-
store. storepass must be at least 6 characters long. It must
be provided to all subcommands that access the keystore con-
tents. For such subcommands, if a -storepass option is not pro-
vided at the command line, the user is prompted for it.
-provider provider_class_name
Used to specify the name of the cryptographic service provider's
master class file when the service provider is not listed in the
security properties file.
When retrieving information from the keystore, the password is
optional; if no password is given, the integrity of the retrieved
information cannot be checked and a warning is displayed.
Be careful with passwords: See Warning Regarding Passwords.
WARNING REGARDING PASSWORDS
Most subcommands operating on a keystore require the store password.
Some subcommands require a private key password.
Passwords can be specified on the command line (in the -storepass and
-keypass options, respectively). However, a password should not be
specified on a command line or in a script unless it is for testing
purposes, or you are on a secure system.
If you don't specify a required password option on a command line, you
will be prompted for it. When typing in a password at the password
prompt, the password is currently echoed (displayed exactly as typed),
so be careful not to type it in front of anyone.
SUBCOMMANDS
See also USAGE.
Adding Data to the Keystore
-genkey {-alias alias} {-keyalg keyalg} {-keysize keysize}
{-sigalg sigalg} [-dname dname] [-keypass keypass]
{-validity valDays} {-storetype storetype}
{-keystore keystore} [-storepass storepass]
[-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 single-element certificate chain. This cer-
tificate 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 gener-
ated. sigalg specifies the algorithm that should be used to
sign the self-signed certificate; this algorithm must be compat-
ible 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 key-
store. 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.
-import {-alias alias} {-file cert_file} [-keypass keypass]
{-noprompt} {-trustcacerts} {-storetype storetype}
{-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 keystore entry identified by alias given,
the certificate or PKCS#7 reply is read from stdin. keytool can
import X.509 v1, v2, and v3 certificates, and PKCS#7 formatted
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 key-
store, keytool tries to verify it by attempting to construct a
chain of trust from that certificate to a self-signed certifi-
cate (belonging to a root CA), using trusted certificates that
are already available in the keystore.
If the -trustcacerts option has been specified, additional cer-
tificates are considered for the chain of trust, namely the cer-
tificates in a file named cacerts, which resides in the JDK
security properties directory, located at ${JAVA_HOME}/lib/secu-
rity. The cacerts file represents a system-wide keystore with
CA certificates. System administrators can configure and manage
that file using keytool, specifying "jks" as the keystore type.
The cacerts keystore file ships with five VeriSign root CA cer-
tificates with the following X.500 distinguished names:
1. OU=Class 1 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
2. OU=Class 2 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
3. OU=Class 3 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
4. OU=Class 4 Public Primary Certification Authority,
O="VeriSign, Inc.", C=US
5. OU=Secure Server Certification Authority, O="RSA Data Secu-
rity, 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 certificate (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 infor-
mation, 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 key-
store 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 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 infor-
mation, 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 pro-
vided, 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 Passwords.
-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 cer-
tificate chain) is used.
The generated certificate is stored as a single-element certifi-
cate 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 key-
store 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.
-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 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 identi-
ties 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 cer-
tificate, 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 cor-
responding 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 certificate requestor (usually off-
line) and will return a certificate or certificate chain, used
to replace the existing certificate chain (which initially con-
sists 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.
-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 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 associ-
ated 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 specified, the contents of the entire
keystore are printed.
This subcommand by default prints the MD5 fingerprint of a cer-
tificate. 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.
-printcert {-file cert_file} {-v} {-Jjavaoption}
Reads the certificate from the file cert_file, and prints its
contents in a human-readable format. If no file is given, the
certificate is read from stdin.
The certificate may be either binary encoded or in printable
encoding format, as defined by the Internet RFC 1421 standard.
Note: This option can be used independently of a keystore.
MANAGING THE KEYSTORE
-keyclone {-alias alias} [-dest dest_alias] [-keypass keypass]
{-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 (destination) entry is identi-
fied 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 pass-
word, 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 subcommand can be used to establish multiple certificate
chains corresponding to a given key pair, or for backup pur-
poses.
-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 key-
store contents. The new password is new_storepass, which must be
at least 6 characters long.
Be careful with passwords: Warning Regarding Passwords.
-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 command line, and
the private key password is different from the keystore pass-
word, 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. 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, organiza-
tional 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 fol-
lowing:
example% keytool -genkey
In this case, a keystore entry with alias mykey is created, with a
newly-generated key pair and a certificate that is valid for 90 days.
This entry is placed in the keystore named .keystore in your home
directory. (The keystore is created if it doesn't already exist.) You
will be prompted for the distinguished name information, the keystore
password, and the private key password.
The rest of the examples assume you executed the -genkey command with-
out options specified, and that you responded to the prompts with val-
ues 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 certificate 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 Certifi-
cate 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 previous 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 the -import command):
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 certifi-
cate for the issuing CA (the one that signed it), and if that cer-
tificate 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 certifi-
cates, so you probably won't need to import a VeriSign certificate as a
trusted certificate in your keystore. But if you request a signed cer-
tificate from a different CA, and a certificate authenticating that
CA's public key hasn't been added to cacerts, you will need to import a
certificate from the CA as a "trusted certificate".
A certificate from a CA is usually either self-signed, or signed by
another CA (in which case you also need a 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 cer-
tificate 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 sub-
command, 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 finger-
prints are equal is it guaranteed that the certificate has not been
replaced in transit with somebody else's (for example, an attacker's)
certificate. If such an attack took place, and you did not check the
certificate before you imported it, you would end up trusting anything
the attacker has signed.
If you trust that the certificate is valid, then you can add it to your
keystore via the following:
example% keytool -import -alias abc -file ABCCA.cer
This creates a "trusted certificate" entry in the keystore, with the
data from the file ABCCA.cer, and assigns the alias abc to the entry.
Importing the Certificate Reply from the CA
Once you've imported a certificate authenticating the public key of the
CA you submitted your certificate signing request to (or there's
already such a certificate in the cacerts file), you can import the
certificate reply and thereby replace your self-signed certificate with
a certificate chain. This chain is the one returned by the CA in
response to your request (if the CA reply is a chain), or one con-
structed (if the CA reply is a single certificate) using the certifi-
cate 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 certifi-
cate into their keystore as a "trusted" entry. You can export the cer-
tificate 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 signature.
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 different city. If desired, you may
still use the public/private key pair you've previously used, and yet
update your distinguished name. For example, suppose your name is Susan
Miller, and you created your initial key entry with the alias sMiller
and the distinguished name
"cn=Susan Miller, ou=Finance Department, o=BlueSoft, c=us"
Suppose you change from the Finance Department to the Accounting
Department. You can still use the previously-generated public/private
key pair and yet update your distinguished 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 destina-
tion 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:
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 ini-
tial key entry that used your old distinguished name:
example% keytool -delete -alias sMiller
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