." Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.

." DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

."

." This code is free software; you can redistribute it and/or modify it

." under the terms of the GNU General Public License version 2 only, as

." published by the Free Software Foundation.

."

." This code is distributed in the hope that it will be useful, but WITHOUT

." ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

." FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

." version 2 for more details (a copy is included in the LICENSE file that

." accompanied this code).

."

." You should have received a copy of the GNU General Public License version

." 2 along with this work; if not, write to the Free Software Foundation,

." Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

."

." Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

." or visit www.oracle.com if you need additional information or have any

." questions.

."

.TH jarsigner 1 "02 Jun 2010"

.LP

.SH "Name"

jarsigner \- JAR Signing and Verification Tool

.LP

.RS 3

.LP

.LP

Generates signatures for Java ARchive (JAR) files, and verifies the signatures of signed JAR files.

.LP

.RE

.SH "SYNOPSIS"

.LP

.LP

.nf

\f3

.fl

\fP\f3jarsigner\fP [ options ] jar\-file alias

.fl

\f3jarsigner\fP \-verify [ options ] jar\-file [alias...]

.fl

.fi

.LP

.LP

The jarsigner \-verify command can take zero or more keystore alias names after the jar filename. When specified, jarsigner will check that the certificate used to verify each signed entry in the jar file matches one of the keystore aliases. The aliases are defined in the keystore specified by \-keystore, or the default keystore.

.LP

.SH "DESCRIPTION"

.LP

.LP

.LP

The \f3jarsigner\fP tool is used for two purposes:

.LP

.RS 3

.TP 3

1.

to sign Java ARchive (JAR) files, and 

.TP 3

2.

to verify the signatures and integrity of signed JAR files. 

.RE

.LP

.LP

The JAR feature enables the packaging of class files, images, sounds, and other digital data in a single file for faster and easier distribution. A tool named jar(1) enables developers to produce JAR files. (Technically, any zip file can also be considered a JAR file, although when created by \f3jar\fP or processed by \f3jarsigner\fP, JAR files also contain a META\-INF/MANIFEST.MF file.)

.LP

.LP

A \f2digital signature\fP is a string of bits that is computed from some data (the data being "signed") and the private key of an entity (a person, company, etc.). Like a handwritten signature, a digital signature has many useful characteristics:

.LP

.RS 3

.TP 2

o

Its authenticity can be verified, via a computation that uses the public key corresponding to the private key used to generate the signature. 

.TP 2

o

It cannot be forged, assuming the private key is kept secret. 

.TP 2

o

It is a function of the data signed and thus can't be claimed to be the signature for other data as well. 

.TP 2

o

The signed data cannot be changed; if it is, the signature will no longer verify as being authentic. 

.RE

.LP

.LP

In order for an entity's signature to be generated for a file, the entity must first have a public/private key pair associated with it, and also one or more certificates authenticating its public key. A \f2certificate\fP is a digitally signed statement from one entity, saying that the public key of some other entity has a particular value.

.LP

.LP

\f3jarsigner\fP uses key and certificate information from a \f2keystore\fP to generate digital signatures for JAR files. A keystore is a database of private keys and their associated X.509 certificate chains authenticating the corresponding public keys. The keytool(1) utility is used to create and administer keystores.

.LP

.LP

\f3jarsigner\fP uses an entity's private key to generate a signature. The signed JAR file contains, among other things, a copy of the certificate from the keystore for the public key corresponding to the private key used to sign the file. \f3jarsigner\fP can verify the digital signature of the signed JAR file using the certificate inside it (in its signature block file).

.LP

.LP

\f3jarsigner\fP can generate signatures that include a timestamp, thus enabling systems/deployer (including Java Plug\-in) to check whether the JAR file was signed while the signing certificate was still valid. In addition, APIs will allow applications to obtain the timestamp information.

.LP

.LP

At this time, \f3jarsigner\fP can only sign JAR files created by the SDK jar(1) tool or zip files. (JAR files are the same as zip files, except they also have a META\-INF/MANIFEST.MF file. Such a file will automatically be created when \f3jarsigner\fP signs a zip file.)

.LP

.LP

The default \f3jarsigner\fP behavior is to \f2sign\fP a JAR (or zip) file. Use the \f2\-verify\fP option to instead have it \f2verify\fP a signed JAR file.

.LP

.SS 

Keystore Aliases

.LP

.RS 3

.LP

.LP

All keystore entities are accessed via unique \f2aliases\fP.

.LP

.LP

When using \f3jarsigner\fP to sign a JAR file, you must specify the alias for the keystore entry containing the private key needed to generate the signature. For example, the following will sign the JAR file named "MyJARFile.jar", using the private key associated with the alias "duke" in the keystore named "mystore" in the "working" directory. Since no output file is specified, it overwrites MyJARFile.jar with the signed JAR file.

.LP

.nf

\f3

.fl

    jarsigner \-keystore /working/mystore \-storepass myspass

.fl

      \-keypass dukekeypasswd MyJARFile.jar duke 

.fl

\fP

.fi

.LP

.LP

Keystores are protected with a password, so the store password (in this case "myspass") must be specified. You will be prompted for it if you don't specify it on the command line. Similarly, private keys are protected in a keystore with a password, so the private key's password (in this case "dukekeypasswd") must be specified, and you will be prompted for it if you don't specify it on the command line and it isn't the same as the store password.

.LP

.RE

.SS 

Keystore Location

.LP

.RS 3

.LP

.LP

\f3jarsigner\fP has a \f2\-keystore\fP option for specifying the URL of the keystore to be used. The keystore is by default stored in a file named \f2.keystore\fP in the user's home directory, as determined by the \f2user.home\fP system property. On Solaris systems \f2user.home\fP defaults to the user's home directory.

.LP

.LP

Note that the input stream from the \f2\-keystore\fP option is passed to the \f2KeyStore.load\fP method. If \f2NONE\fP is specified as the URL, then a null stream is passed to the \f2KeyStore.load\fP method. \f2NONE\fP should be specified if the \f2KeyStore\fP is not file\-based, for example, if it resides on a hardware token device.

.LP

.RE

.SS 

Keystore Implementation

.LP

.RS 3

.LP

.LP

The \f2KeyStore\fP class provided in the \f2java.security\fP 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 \f2type\fP of keystore.

.LP

.LP

Currently, there are two command\-line tools that make use of keystore implementations (\f3keytool\fP and \f3jarsigner\fP), and also a GUI\-based tool named \f3Policy Tool\fP. Since \f2KeyStore\fP is publicly available, Java 2 SDK users can write additional security applications that use it.

.LP

.LP

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.

.LP

.LP

Keystore implementations are provider\-based. More specifically, the application interfaces supplied by \f2KeyStore\fP are implemented in terms of a "Service Provider Interface" (SPI). That is, there is a corresponding abstract \f2KeystoreSpi\fP class, also in the \f2java.security\fP 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 

.na

\f2How to Implement a Provider for the Java Cryptography Architecture\fP @

.fi

http://java.sun.com/javase/6/docs/technotes/guides/security/crypto/HowToImplAProvider.html.

.LP

.LP

Applications can choose different \f2types\fP of keystore implementations from different providers, using the "getInstance" factory method supplied in the \f2KeyStore\fP 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.

.LP

.LP

\f3keytool\fP 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 \f3jarsigner\fP and \f3policytool\fP tools, on the other hand, can read a keystore from any location that can be specified using a URL.

.LP

.LP

For \f3jarsigner\fP and \f3keytool\fP, you can specify a keystore type at the command line, via the \f2\-storetype\fP option. For \f3Policy Tool\fP, you can specify a keystore type via the "Change Keystore" command in the Edit menu.

.LP

.LP

If you don't explicitly specify a keystore type, the tools choose a keystore implementation based simply on the value of the \f2keystore.type\fP property specified in the security properties file. The security properties file is called \f2java.security\fP, and it resides in the SDK security properties directory, \f2java.home\fP/lib/security, where \f2java.home\fP is the runtime environment's directory (the \f2jre\fP directory in the SDK or the top\-level directory of the Java 2 Runtime Environment).

.LP

.LP

Each tool gets the \f2keystore.type\fP 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.

.LP

.LP

The \f2KeyStore\fP class defines a static method named \f2getDefaultType\fP that lets applications and applets retrieve the value of the \f2keystore.type\fP property. The following line of code creates an instance of the default keystore type (as specified in the \f2keystore.type\fP property):

.LP

.nf

\f3

.fl

    KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());

.fl

\fP

.fi

.LP

.LP

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:

.LP

.nf

\f3

.fl

    keystore.type=jks

.fl

\fP

.fi

.LP

.LP

Note: Case doesn't matter in keystore type designations. For example, "JKS" would be considered the same as "jks".

.LP

.LP

To have the tools utilize a keystore implementation other than the default, 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

.LP

.nf

\f3

.fl

    keystore.type=pkcs12

.fl

\fP

.fi

.LP

.LP

Note that if you us the PKCS#11 provider package, you should refer to the 

.na

\f2KeyTool and JarSigner\fP @

.fi

http://java.sun.com/javase/6/docs/technotes/guides/security/p11guide.html#KeyToolJarSigner section of the Java PKCS#11 Reference Guide for details.

.LP

.RE

.SS 

Supported Algorithms

.LP

.RS 3

.LP

.LP

By default, \f3jarsigner\fP signs a JAR file using either

.LP

.RS 3

.TP 2

o

DSA (Digital Signature Algorithm) with the SHA\-1 digest algorithm, or 

.TP 2

o

the RSA algorithm with the SHA\-256 digest algorithm. 

.RE

.LP

.LP

That is, if the signer's public and private keys are DSA keys, \f3jarsigner\fP will sign the JAR file using the "SHA1withDSA" algorithm. If the signer's keys are RSA keys, \f3jarsigner\fP will attempt to sign the JAR file using the "SHA256withRSA" algorithm.

.LP

.LP

These default signature algorithms can be overridden using the \f2\-sigalg\fP option.

.LP

.RE

.SS 

The Signed JAR File

.LP

.RS 3

.LP

.LP

When \f3jarsigner\fP is used to sign a JAR file, the output signed JAR file is exactly the same as the input JAR file, except that it has two additional files placed in the META\-INF directory:

.LP

.RS 3

.TP 2

o

a signature file, with a .SF extension, and 

.TP 2

o

a signature block file, with a .DSA extension. 

.RE

.LP

.LP

The base file names for these two files come from the value of the \f2\-sigFile\fP option. For example, if the option appears as

.LP

.nf

\f3

.fl

  \-sigFile MKSIGN

.fl

\fP

.fi

.LP

.LP

the files are named "MKSIGN.SF" and "MKSIGN.DSA".

.LP

.LP

If no \f2\-sigfile\fP option appears on the command line, the base file name for the .SF and .DSA files will be the first 8 characters of the alias name specified on the command line, all converted to upper case. If the alias name has fewer than 8 characters, the full alias name is used. If the alias name contains any characters that are not allowed in a signature file name, each such character is converted to an underscore ("_") character in forming the file name. Legal characters include letters, digits, underscores, and hyphens.

.LP

\f3The Signature (.SF) File\fP

.LP

.RS 3

.LP

.LP

A signature file (the .SF file) looks similar to the manifest file that is always included in a JAR file when \f3jarsigner\fP is used to sign the file. That is, for each source file included in the JAR file, the .SF file has three lines, just as in the manifest file, listing the following:

.LP

.RS 3

.TP 2

o

the file name, 

.TP 2

o

the name of the digest algorithm used (SHA), and 

.TP 2

o

a SHA digest value. 

.RE

.LP

.LP

In the manifest file, the SHA digest value for each source file is the digest (hash) of the binary data in the source file. In the .SF file, on the other hand, the digest value for a given source file is the hash of the three lines in the manifest file for the source file.

.LP

.LP

The signature file also, by default, includes a header containing a hash of the whole manifest file. The presence of the header enables verification optimization, as described in JAR File Verification.

.LP

.RE

\f3The Signature Block (.DSA) File\fP

.LP

.RS 3

.LP

.LP

The .SF file is signed and the signature is placed in the .DSA file. The .DSA file also contains, encoded inside it, the certificate or certificate chain from the keystore which authenticates the public key corresponding to the private key used for signing.

.LP

.RE

.RE

.SS 

Signature Timestamp

.LP

.RS 3

.LP

.LP

\f2jarsigner\fP tool can now generate and store a signature timestamp when signing a JAR file. In addition, \f2jarsigner\fP supports alternative signing mechanisms. This behavior is optional and is controlled by the user at the time of signing through these options:

.LP

.RS 3

.TP 2

o

\f2\-tsa url\fP 

.TP 2

o

\f2\-tsacert alias\fP 

.TP 2

o

\f2\-altsigner class\fP 

.TP 2

o

\f2\-altsignerpath classpathlist\fP 

.RE

.LP

.LP

Each of these options is detailed in the Options section below.

.LP

.RE

.SS 

JAR File Verification

.LP

.RS 3

.LP

.LP

A successful JAR file verification occurs if the signature(s) are valid, and none of the files that were in the JAR file when the signatures were generated have been changed since then. JAR file verification involves the following steps:

.LP

.RS 3

.TP 3

1.

Verify the signature of the .SF file itself. 

.LP

That is, the verification ensures that the signature stored in each signature block (.DSA) file was in fact generated using the private key corresponding to the public key whose certificate (or certificate chain) also appears in the .DSA file. It also ensures that the signature is a valid signature of the corresponding signature (.SF) file, and thus the .SF file has not been tampered with.  

.TP 3

2.

Verify the digest listed in each entry in the .SF file with each corresponding section in the manifest. 

.LP

The .SF file by default includes a header containing a hash of the entire manifest file. When the header is present, then the verification can check to see whether or not the hash in the header indeed matches the hash of the manifest file. If that is the case, verification proceeds to the next step. 

.LP

If that is not the case, a less optimized verification is required to ensure that the hash in each source file information section in the .SF file equals the hash of its corresponding section in the manifest file (see The Signature (.SF) File). 

.LP

One reason the hash of the manifest file that is stored in the .SF file header may not equal the hash of the current manifest file would be because one or more files were added to the JAR file (using the \f2jar\fP tool) after the signature (and thus the .SF file) was generated. When the \f2jar\fP tool is used to add files, the manifest file is changed (sections are added to it for the new files), but the .SF file is not. A verification is still considered successful if none of the files that were in the JAR file when the signature was generated have been changed since then, which is the case if the hashes in the non\-header sections of the .SF file equal the hashes of the corresponding sections in the manifest file.  

.TP 3

3.

Read each file in the JAR file that has an entry in the .SF file. While reading, compute the file's digest, and then compare the result with the digest for this file in the manifest section. The digests should be the same, or verification fails. 

.RE

.LP

.LP

If any serious verification failures occur during the verification process, the process is stopped and a security exception is thrown. It is caught and displayed by \f3jarsigner\fP.

.LP

.RE

.SS 

Multiple Signatures for a JAR File

.LP

.RS 3

.LP

.LP

A JAR file can be signed by multiple people simply by running the \f3jarsigner\fP tool on the file multiple times, specifying the alias for a different person each time, as in:

.LP

.nf

\f3

.fl

  jarsigner myBundle.jar susan

.fl

  jarsigner myBundle.jar kevin

.fl

\fP

.fi

.LP

.LP

When a JAR file is signed multiple times, there are multiple .SF and .DSA files in the resulting JAR file, one pair for each signature. Thus, in the example above, the output JAR file includes files with the following names:

.LP

.nf

\f3

.fl

  SUSAN.SF

.fl

  SUSAN.DSA

.fl

  KEVIN.SF

.fl

  KEVIN.DSA

.fl

\fP

.fi

.LP

.LP

Note: It is also possible for a JAR file to have mixed signatures, some generated by the JDK 1.1 \f3javakey\fP tool and others by \f3jarsigner\fP. That is, \f3jarsigner\fP can be used to sign JAR files already previously signed using \f3javakey\fP.

.LP

.RE

.SH "OPTIONS"

.LP

.LP

.LP

The various \f3jarsigner\fP options are listed and described below. Note:

.LP

.RS 3

.TP 2

o

All option names are preceded by a minus sign (\-). 

.TP 2

o

The options may be provided in any order. 

.TP 2

o

Items in italics (option values) represent the actual values that must be supplied. 

.TP 2

o

The \f2\-keystore\fP, \f2\-storepass\fP, \f2\-keypass\fP, \f2\-sigfile\fP, \f2\-sigalg\fP, \f2\-digestalg\fP, and \f2\-signedjar\fP options are only relevant when signing a JAR file, not when verifying a signed JAR file. Similarly, an alias is only specified on the command line when signing a JAR file. 

.RE

.LP

.RS 3

.TP 3

\-keystore url 

Specifies the URL that tells the keystore location. This defaults to the file \f2.keystore\fP in the user's home directory, as determined by the "user.home" system property. 

.LP

A keystore is required when signing, so you must explicitly specify one if the default keystore does not exist (or you want to use one other than the default). 

.LP

A keystore is \f2not\fP required when verifying, but if one is specified, or the default exists, and the \f2\-verbose\fP option was also specified, additional information is output regarding whether or not any of the certificates used to verify the JAR file are contained in that keystore. 

.LP

Note: the \f2\-keystore\fP argument can actually be a file name (and path) specification rather than a URL, in which case it will be treated the same as a "file:" URL. That is, 

.nf

\f3

.fl

  \-keystore \fP\f4filePathAndName\fP\f3

.fl

\fP

.fi

is treated as equivalent to 

.nf

\f3

.fl

  \-keystore file:\fP\f4filePathAndName\fP\f3

.fl

\fP

.fi

If the Sun PKCS#11 provider has been configured in the \f2java.security\fP security properties file (located in the JRE's \f2$JAVA_HOME/lib/security\fP directory), then keytool and jarsigner can operate on the PKCS#11 token by specifying these options: 

.RS 3

.TP 2

o

\f2\-keystore NONE\fP 

.TP 2

o

\f2\-storetype PKCS11\fP 

.RE

For example, this command lists the contents of the configured PKCS#11 token: 

.RS 3

.LP

.nf