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Trail: Security in Java 2 SDK 1.2
Lesson: Exchanging Files

## Verify the JAR File Signature

> Now that you, acting as Ruth, have imported Stan's public key certificate into the `ruthstore` keystore as a "trusted certificate," you can use the `jarsigner` tool to verify the authenticity of the JAR file signature.

> When you verify a signed JAR file, you verify that the signature is valid and that the JAR file has not been tampered with. You can do this for the `sContract.jar` file via the following command:

> >     jarsigner -verify -verbose -keystore ruthstore sContract.jar

> You should see something like the following:

> >            183 Fri Jul 31 10:49:54 PDT 1998 META-INF/SIGNLEGAL.SF
> >            1542 Fri Jul 31 10:49:54 PDT 1998 META-INF/SIGNLEGAL.DSA
> >            0 Fri Jul 31 10:49:18 PDT 1998 META-INF/
> >     smk    1147 Wed Jul 29 16:06:12 PDT 1998 contract

> >      s = signature was verified
> >      m = entry is listed in manifest
> >      k = at least one certificate was found in keystore
> >      i = at least one certificate was found in identity scope

> >     jar verified.

> Be sure to run the command with the `-verbose` option to get enough information to ensure that
> - the contract file is among the files in the JAR file that were signed and its signature was verified (that's what the `s` signifies), and

> - the public key used to verify the signature is in the specified keystore and thus trusted by you (that's what the `k` signifies).

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