crypto: getDecoder throws "AssertionError: Cannot change encoding" when encoding is "utf-8".

[dtinth]

Hello,

In lib/crypto.js, the assert in getDecoder function is inadequate:

assert(decoder.encoding === encoding, 'Cannot change encoding');

When encoding is "utf-8", it gets passed to new StringDecoder(encoding). However, the StringDecoder interprets "utf-8" as "utf8", and sets the encoding property as "utf8", thus making the assertion fail.

An example code that would make it throw an AssertionError:

require('crypto').createDecipher('bf','').update('','hex','utf-8')

If I use "utf8" instead of "utf-8", it won't throw an AssertionError.

[bnoordhuis]

Fixed in 82b3524.