Add support for DER encoded x509 certificate

[emarashliev]

Fixes #85

[tanner0101]

This change looks great, thanks. Just a couple of small nits. Would you mind creating a version of this against the master branch (for Vapor 4)?

[emarashliev]

@tanner0101 Thanks for the feedback! And yes, I'll create a version of this against the master branch.

[tanner0101]

The linux-mysql CI test can be fixed by changing this line to clone 3 instead of master
https://github.com/vapor/crypto/blob/3/circle.yml#L58

[emarashliev]

@tanner0101 Again, thank you for the feedback! The things you mentioned are fixed.

[emarashliev]

@tanner0101 I opened one more pull request #89 as well, with this functionality but adapted for Vapor 4, against the master branch.

[tanner0101]

Thanks!

[kevinschlieper]

@tanner0101 It seems to me that this merge causes a build error on Linux when using Swift >= 5.0 and since Vapor 3 is using the latest version of open-crypto, the Vapor 3 build now also fails on Linux when building with Swift 5.

The Linux tests in this branch are still using Swift 4.2, but you can verify the problem by using this Dockerfile instead:

FROM swift:5.0
COPY Sources/ Sources/
COPY Tests/ Tests/
COPY Package.swift Package.swift
RUN apt-get update && apt-get -y install openssl libssl-dev
ENTRYPOINT swift build

I haven't had a chance to look into a possible fix, yet, but here are the error messages when building with Swift 5:

/Sources/Crypto/RSA/RSAKey.swift:127:96: error: use of undeclared type 'X509'
             guard let x509 = derDecoded.withByteBuffer({ bufferPointer -> UnsafeMutablePointer<X509>? in
                                                                                               ^~~~
/Sources/Crypto/RSA/RSAKey.swift:127:56: error: cannot convert value of type '(_) -> <<error type>>' to expected argument type '(BytesBufferPointer) -> _' (aka '(UnsafeBufferPointer<UInt8>) -> _')
             guard let x509 = derDecoded.withByteBuffer({ bufferPointer -> UnsafeMutablePointer<X509>? in
                                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[tanner0101]

@kevinschlieper ah yeah looks like this PR didn't take OpenSSL 1.1's breaking changes into account. I've pushed a release here that should fix it: https://github.com/vapor/open-crypto/releases/tag/3.4.1

[kevinschlieper]

@tanner0101 Thanks for the quick fix, Tanner. Everything is working as expected now.