FIX: occasional HTTPS read fails when server used ECDHE_ECDSA key method

src/mezz/prot-tls.reb

@@ -413,6 +413,18 @@ TLS-init-cipher-suite: func [
 	]
 ]
 
+pad-bin: function[
+	"Left binary padding"
+	bin [binary!]
+	len [integer!]
+][
+	if len > n: length? bin [
+		; using copy, because binary may not be at its head!
+		insert/dup copy bin 0 len - n
+	]
+	bin
+]
+
 make-TLS-error: func [
 	"Make an error for the TLS protocol"
 	message [string! block!]
@@ -1599,8 +1611,10 @@ TLS-parse-handshake-message: function [
 							rsa_fixed_dh [
 								log-more "Checking signature using RSA_fixed_DH"
 								der: decode 'der signature
-								;@@ Review: der codec skips null char, which is needed here (reason for `head` calls)!
-								signature: join head der/2/2 head der/2/4
+								n: select [secp256r1 32 secp384r1 48 secp521r1 66] ctx/pub-exp
+								x: pad-bin der/2/2 n
+								y: pad-bin der/2/4 n
+								signature: join x y
 								;? ctx/pub-key
 								;? signature
 								;? ctx/pub-key