RFR: JDK-8280703 CipherCore.doFinal(...) causes potentially massive byte[] allocations during decryption [v2]

[Sebastian Stenzel]

> Related to #411, however it turns out that for unpadded ciphers, there is no need to allocate `internalOutput`, if `output` provides sufficient capacity.
> 
> For padded ciphers, only the unpadded cleartext is expected to be copied to the output buffer. In this case, there is no way around the temporary buffer (without major changes).
> 
> While a small change, please review with care, as I might be missing some security-relevant side effect (such as: don't copy cleartext to output buffer before validating the a tag - just as an example, even if there is no authentication involved in this method).
> 
> I have some test failures in Tier 1 tests, but these seem to be unrelated. Tests for `com.sun.crypto` and `javax.crypto` run fine:
> 
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR   
>    jtreg:test/jdk/com/sun/crypto                       141   141     0     0   
>    jtreg:test/jdk/javax/crypto                          56    56     0     0   
> ==============================
> TEST SUCCESS

Sebastian Stenzel has updated the pull request incrementally with one additional commit since the last revision:

  updated copyright header

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7230/files
  - new: https://git.openjdk.java.net/jdk/pull/7230/files/520fec52..ffef8362

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7230&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7230&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7230.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7230/head:pull/7230

PR: https://git.openjdk.java.net/jdk/pull/7230