Make SCRIPT_VERIFY_STRICTENC compatible with BIP62

* Delete canonical_tests.cpp, and move the tests to script_tests.cpp.
* Split off SCRIPT_VERIFY_DERSIG from SCRIPT_VERIFY_STRICTENC (the BIP62 part of it).
* Change signature STRICTENC/DERSIG semantics to fail the script entirely rather than the CHECKSIG result (softfork safety, and BIP62 requirement).
* Add many autogenerated tests for several odd cases.
* Mention specific BIP62 rules in the script verification flags.

1 files changed, 18 insertions, 7 deletions

diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 0ff73964ba..de5ce2ced1 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -28,14 +28,25 @@ enum
 enum
 {
     SCRIPT_VERIFY_NONE      = 0,
-    SCRIPT_VERIFY_P2SH      = (1U << 0), // evaluate P2SH (BIP16) subscripts
-    SCRIPT_VERIFY_STRICTENC = (1U << 1), // enforce strict conformance to DER and SEC2 for signatures and pubkeys
-    SCRIPT_VERIFY_LOW_S     = (1U << 2), // enforce low S values (<n/2) in signatures (depends on STRICTENC)
-    SCRIPT_VERIFY_NULLDUMMY = (1U << 3), // verify dummy stack item consumed by CHECKMULTISIG is of zero-length
-};
 
-bool IsCanonicalPubKey(const std::vector<unsigned char> &vchPubKey, unsigned int flags);
-bool IsCanonicalSignature(const std::vector<unsigned char> &vchSig, unsigned int flags);
+    // Evaluate P2SH subscripts (softfork safe, BIP16).
+    SCRIPT_VERIFY_P2SH      = (1U << 0),
+
+    // Passing a non-strict-DER signature or one with undefined hashtype to a checksig operation causes script failure.
+    // Passing a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) to checksig causes that pubkey to be
+    // skipped (not softfork safe: this flag can widen the validity of OP_CHECKSIG OP_NOT).
+    SCRIPT_VERIFY_STRICTENC = (1U << 1),
+
+    // Passing a non-strict-DER signature to a checksig operation causes script failure (softfork safe, BIP62 rule 1)
+    SCRIPT_VERIFY_DERSIG    = (1U << 2),
+
+    // Passing a non-strict-DER signature or one with S > order/2 to a checksig operation causes script failure
+    // (softfork safe, BIP62 rule 5).
+    SCRIPT_VERIFY_LOW_S     = (1U << 3),
+
+    // verify dummy stack item consumed by CHECKMULTISIG is of zero-length (softfork safe, BIP62 rule 7).
+    SCRIPT_VERIFY_NULLDUMMY = (1U << 4),
+};
 
 uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);