LegacyDecryptor and LegacyDecryptorWithMAC use wrong MAC

[noloader]

Crypto++ 6.0 changed DefaultDecryptor and DefaultDecryptorWithMAC to use modern algorithms. Also see Issue 345.

At that time we also provided LegacyDecryptor and LegacyDecryptorWithMAC for folks who needed interop with the older algorithm. We botched the interop by using the new MAC (SHA256-based) instead of the old MAC (SHA1-based). Also see Update DefaultEncryptor, DefaultEncryptorWithMAC and friends.

This ticket will track the change to LegacyDecryptor and LegacyDecryptorWithMAC for SHA1-based MACs.

[noloader]

Cleared at Commit 590f8573c4ed.

[AndiDog]

Can this make it into a release soon? This has been wrong all the way between [6.0.0, 7.0.0] and without the patch, we cannot safely replace existing code to use the legacy algorithms.

[noloader]

@AndiDog,

Right now we are blocking on #649 .

I wanted to get a few more things added before the next release but I have not had time. I think its time to shit or get off the pot. We'll release as soon as we clear the AES problems on Windows.