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  1. #1
    Registered User
    Join Date
    Feb 2006

    incorrect jar signature

    Hi all,

    I got a code-sign certificate from Geotrust. I signed my application using WTK 2.2. But I tried to load the app on the device it showed the following error message.

    "the midlet's security signature contains the following error: incorrect jar signature. the midlet will not be installed"

    Can anybody tell me what went wrong in the signing process.
    I found signatures with JAD file only. But not in Manifest.

    Please help me.


  2. #2
    Registered User
    Join Date
    Dec 2005

    Re: incorrect jar signature

    Hi Ravi,

    Check the text excerpt below, it may help:

    "A further problem, which the security framework is especially designed to detect, is the tampering or corruption of a MIDlet JAR file. If for any reason the JAR file has been modified, for example during the OTA transmission or while stored in a device, the integrity check depicted in Section 2.3, “Trusted MIDlets” will fail. This protects the user and the developer of maliciously or accidentally modified MIDlets. This is emulated by manually modifying the manifest file, and therefore making the SHA1 digest incorrect. Figure 9 shows this error in both the emulator and an actual device."

    You cannot modify it after the signing procedure.

    Check the doc below for more information (the information above is from section 4.3 Potential Problems and Mismatches):

    MIDP 2.0: Tutorial On Signed MIDlets v1.1

    I hope it helps!


    Juarez Jr

  3. #3
    Super Contributor
    Join Date
    Mar 2006

    Re: incorrect jar signature

    Hi aravindra,

    did u modify ur jad or jar after signing the application??

    Did u give the correct permissions in the jad file while signing the application??

    Also Please check clock settings inur phone

    The signatures are required only with the jad and it is not required in the manifest file.

    Please also use the following tutorials

    This thread may also be helpful to u


  4. #4
    Super Contributor
    Join Date
    Apr 2003
    USA, CA

    Re: incorrect jar signature

    aravindra, judging by the error message I cannot say for sure if the certificate you used to sign you midlet exists on the phone, hence could you doublecheck that the phone has it and that it can be used for Java.

    Re: your comment on signature info being only in JAD file. This is correct. signing does not make any changes in manifest file or to the jar-file in general. It only adds the certificate "fingerprint" and the calculated hash value in the JAD file.


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