Panic in certigo/lib.explainCipher about certigo HOT 5 CLOSED

Sure maybe sometime this week or next.

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@csstaub are you running 1.11 or have you built from master? There hasn't been a new release since Nov '18.

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I ran into this issue as well, installing from brew install certigo, and did some debugging and there are two problems.

1. On v1.11.0, lib.lookup returns UNKNOWN_304 for TLS 1.3. lib.explainCipher does a
   split on _WITH_ but the array is only populated with one element and it
   is assumed that kexAndCipher has two elements.

   Note: This was fixed in master @ 79de7d2

2. cipherSuites is missing support for some TLS 1.3 cipher suites.

Quick, insecure fix

Checkout master branch.

Patch

tls13_ciphers.patch

diff --git a/lib/tls.go b/lib/tls.go
index a9fefcd..5c0855d 100644
--- a/lib/tls.go
+++ b/lib/tls.go
@@ -206,4 +206,10 @@ var cipherSuites = map[uint16]description{
 	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: {"", "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", good},
 	tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305:    {"", "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305", good},
 	tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305:  {"", "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305", good},
+
+	tls.TLS_AES_128_GCM_SHA256:       {"", "TLS_AES_128_GCM_SHA256", good},
+	tls.TLS_AES_256_GCM_SHA384:       {"", "TLS_AES_256_GCM_SHA384", good},
+	tls.TLS_CHACHA20_POLY1305_SHA256: {"", "TLS_CHACHA20_POLY1305_SHA256", good},
+
+	tls.TLS_FALLBACK_SCSV: {"", "TLS_FALLBACK_SCSV", insecure},
 }

Apply

git apply tls13_ciphers.patch

Build

go build -o certigo-with-tls13-ciphers

Validate

TODO: Why is Cipher Suite still empty? Maybe this isn't fixed yet..

./certigo-with-tls13-ciphers connect --verbose squareup.com:443
** TLS Connection **
Version: TLS 1.3
Cipher Suite:

...

Possible Future TODO

As of go1.14rc1 (golang/go@0ee22d9), it looks like there now exists a tls.CipherSuites which looks something like

func CipherSuites() []*CipherSuite {
	return []*CipherSuite{
		{TLS_RSA_WITH_3DES_EDE_CBC_SHA, "TLS_RSA_WITH_3DES_EDE_CBC_SHA", supportedUpToTLS12, false},
		{TLS_RSA_WITH_AES_128_CBC_SHA, "TLS_RSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, false},
		...
		{TLS_AES_128_GCM_SHA256, "TLS_AES_128_GCM_SHA256", supportedOnlyTLS13, false},
		{TLS_AES_256_GCM_SHA384, "TLS_AES_256_GCM_SHA384", supportedOnlyTLS13, false},
		...
	}
}

It may prove useful to use this instead of maintaining a map of hand-maintained cipher suites when go1.14 is released.

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@jason-riddle thanks for looking into this! 💯 Would you like to turn your patch into a PR?

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This has been fixed via #208 and released in 1.12.1

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