[8u] RFR 8147502: Digest is incorrectly truncated for ECDSA signatures when the bit length of n is less than the field size

[Martin Balao]

Hi,

I'd like to request a review for the jdk8u backport of 8147502 [1]:

 *
http://cr.openjdk.java.net/~mbalao/webrevs/8147502/8147502.webrev.jdk8u.jdk.00/

Changes:

 * SignatureDigestTruncate.java
  * Import of jdk.testlibrary.Convert
  * @library and @build jtreg tags
  * Backport of Convert.java
  * Test algorithm (changes to one with jdk8u support)
   * I've verified that the signature gets truncated with this algorithm
debugging the libsunec.so code
  * Test expected value
   * Verified with BouncyCastle
    * The curve is unsupported in NSS since 2006 (NSS 3.10)
   * I've also compared the patch against the NSS library

Patch and copyright changes were also needed.

SignatureDigestTruncate test passed.

Thanks,
Martin.-

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[1] - https://bugs.openjdk.java.net/browse/JDK-8147502