This is the forward direction on encryption only. Crypto++ uses the "Equivalent Inverse Cipher" (FIPS-197, Section 5.3.5, p.23), and it is not compatible with IBM hardware. The library library will need to re-work the decryption key scheduling routines. (We may be able to work around it another way, but I have not investigated it).
The strategy of "cleanup under-aligned buffers" is not scaling well. Corner cases are still turing up. The library has some corner-case breaks, like old 32-bit Intels. And it still has not solved the AltiVec and Power8 alignment problems.
For now we are backing out the changes and investigating other strategies
This commit supports the upcoming AltiVec and Power8 processor. This commit affects a number of classes due to the ubiquitous use of AES. The commit provides the data alignment requirements.
Jeffrey Walton