diff --git a/src/script/sigencoding.cpp b/src/script/sigencoding.cpp
index 0a76d4be44..6a591feeda 100644
--- a/src/script/sigencoding.cpp
+++ b/src/script/sigencoding.cpp
@@ -1,302 +1,306 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Copyright (c) 2017-2018 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <script/sigencoding.h>
 
 #include <pubkey.h>
 #include <script/script_flags.h>
 
 #include <boost/range/adaptor/sliced.hpp>
 
 typedef boost::sliced_range<const valtype> slicedvaltype;
 
 /**
  * A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len
  * S> <S>, where R and S are not negative (their first byte has its highest bit
  * not set), and not excessively padded (do not start with a 0 byte, unless an
  * otherwise negative number follows, in which case a single 0 byte is
  * necessary and even required).
  *
  * See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
  *
  * This function is consensus-critical since BIP66.
  */
 static bool IsValidDERSignatureEncoding(const slicedvaltype &sig) {
     // Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S]
     // * total-length: 1-byte length descriptor of everything that follows,
     // excluding the sighash byte.
     // * R-length: 1-byte length descriptor of the R value that follows.
     // * R: arbitrary-length big-endian encoded R value. It must use the
     // shortest possible encoding for a positive integers (which means no null
     // bytes at the start, except a single one when the next byte has its
     // highest bit set).
     // * S-length: 1-byte length descriptor of the S value that follows.
     // * S: arbitrary-length big-endian encoded S value. The same rules apply.
 
     // Minimum and maximum size constraints.
     if (sig.size() < 8 || sig.size() > 72) {
         return false;
     }
 
     //
     // Check that the signature is a compound structure of proper size.
     //
 
     // A signature is of type 0x30 (compound).
     if (sig[0] != 0x30) {
         return false;
     }
 
     // Make sure the length covers the entire signature.
     // Remove:
     // * 1 byte for the coupound type.
     // * 1 byte for the length of the signature.
     if (sig[1] != sig.size() - 2) {
         return false;
     }
 
     //
     // Check that R is an positive integer of sensible size.
     //
 
     // Check whether the R element is an integer.
     if (sig[2] != 0x02) {
         return false;
     }
 
     // Extract the length of the R element.
     const uint32_t lenR = sig[3];
 
     // Zero-length integers are not allowed for R.
     if (lenR == 0) {
         return false;
     }
 
     // Negative numbers are not allowed for R.
     if (sig[4] & 0x80) {
         return false;
     }
 
     // Make sure the length of the R element is consistent with the signature
     // size.
     // Remove:
     // * 1 byte for the coumpound type.
     // * 1 byte for the length of the signature.
     // * 2 bytes for the integer type of R and S.
     // * 2 bytes for the size of R and S.
     // * 1 byte for S itself.
     if (lenR > (sig.size() - 7)) {
         return false;
     }
 
     // Null bytes at the start of R are not allowed, unless R would otherwise be
     // interpreted as a negative number.
     //
     // /!\ This check can only be performed after we checked that lenR is
     //     consistent with the size of the signature or we risk to access out of
     //     bound elements.
     if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) {
         return false;
     }
 
     //
     // Check that S is an positive integer of sensible size.
     //
 
     // S's definition starts after R's definition:
     // * 1 byte for the coumpound type.
     // * 1 byte for the length of the signature.
     // * 1 byte for the size of R.
     // * lenR bytes for R itself.
     // * 1 byte to get to S.
     const uint32_t startS = lenR + 4;
 
     // Check whether the S element is an integer.
     if (sig[startS] != 0x02) {
         return false;
     }
 
     // Extract the length of the S element.
     const uint32_t lenS = sig[startS + 1];
 
     // Zero-length integers are not allowed for S.
     if (lenS == 0) {
         return false;
     }
 
     // Negative numbers are not allowed for S.
     if (sig[startS + 2] & 0x80) {
         return false;
     }
 
     // Verify that the length of S is consistent with the size of the signature
     // including metadatas:
     // * 1 byte for the integer type of S.
     // * 1 byte for the size of S.
     if (size_t(startS + lenS + 2) != sig.size()) {
         return false;
     }
 
     // Null bytes at the start of S are not allowed, unless S would otherwise be
     // interpreted as a negative number.
     //
     // /!\ This check can only be performed after we checked that lenR and lenS
     //     are consistent with the size of the signature or we risk to access
     //     out of bound elements.
     if (lenS > 1 && (sig[startS + 2] == 0x00) && !(sig[startS + 3] & 0x80)) {
         return false;
     }
 
     return true;
 }
 
+static bool IsSchnorrSig(const slicedvaltype &sig) {
+    return sig.size() == 64;
+}
+
 static bool CheckRawECDSASignatureEncoding(const slicedvaltype &sig,
                                            uint32_t flags,
                                            ScriptError *serror) {
-    if (sig.size() == 64) {
+    if (IsSchnorrSig(sig)) {
         // In an ECDSA-only context, 64-byte signatures are forbidden.
         return set_error(serror, SCRIPT_ERR_SIG_BADLENGTH);
     }
     if ((flags & (SCRIPT_VERIFY_DERSIG | SCRIPT_VERIFY_LOW_S |
                   SCRIPT_VERIFY_STRICTENC)) &&
         !IsValidDERSignatureEncoding(sig)) {
         return set_error(serror, SCRIPT_ERR_SIG_DER);
     }
 
     if ((flags & SCRIPT_VERIFY_LOW_S) && !CPubKey::CheckLowS(sig)) {
         return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
     }
 
     return true;
 }
 
 static bool CheckRawSignatureEncoding(const slicedvaltype &sig, uint32_t flags,
                                       ScriptError *serror) {
-    if (sig.size() == 64) {
+    if (IsSchnorrSig(sig)) {
         // In a generic-signature context, 64-byte signatures are interpreted
         // as Schnorr signatures (always correctly encoded).
         return true;
     }
     return CheckRawECDSASignatureEncoding(sig, flags, serror);
 }
 
 bool CheckDataSignatureEncoding(const valtype &vchSig, uint32_t flags,
                                 ScriptError *serror) {
     // Empty signature. Not strictly DER encoded, but allowed to provide a
     // compact way to provide an invalid signature for use with CHECK(MULTI)SIG
     if (vchSig.size() == 0) {
         return true;
     }
 
     return CheckRawSignatureEncoding(
         vchSig | boost::adaptors::sliced(0, vchSig.size()), flags, serror);
 }
 
 static bool CheckSighashEncoding(const valtype &vchSig, uint32_t flags,
                                  ScriptError *serror) {
     if (flags & SCRIPT_VERIFY_STRICTENC) {
         if (!GetHashType(vchSig).isDefined()) {
             return set_error(serror, SCRIPT_ERR_SIG_HASHTYPE);
         }
 
         bool usesForkId = GetHashType(vchSig).hasForkId();
         bool forkIdEnabled = flags & SCRIPT_ENABLE_SIGHASH_FORKID;
         if (!forkIdEnabled && usesForkId) {
             return set_error(serror, SCRIPT_ERR_ILLEGAL_FORKID);
         }
 
         if (forkIdEnabled && !usesForkId) {
             return set_error(serror, SCRIPT_ERR_MUST_USE_FORKID);
         }
     }
 
     return true;
 }
 
 template <typename F>
 static bool CheckTransactionSignatureEncodingImpl(const valtype &vchSig,
                                                   uint32_t flags,
                                                   ScriptError *serror, F fun) {
     // Empty signature. Not strictly DER encoded, but allowed to provide a
     // compact way to provide an invalid signature for use with CHECK(MULTI)SIG
     if (vchSig.size() == 0) {
         return true;
     }
 
     if (!fun(vchSig | boost::adaptors::sliced(0, vchSig.size() - 1), flags,
              serror)) {
         // serror is set
         return false;
     }
 
     return CheckSighashEncoding(vchSig, flags, serror);
 }
 
 bool CheckTransactionSignatureEncoding(const valtype &vchSig, uint32_t flags,
                                        ScriptError *serror) {
     return CheckTransactionSignatureEncodingImpl(
         vchSig, flags, serror,
         [](const slicedvaltype &templateSig, uint32_t templateFlags,
            ScriptError *templateSerror) {
             return CheckRawSignatureEncoding(templateSig, templateFlags,
                                              templateSerror);
         });
 }
 
 bool CheckTransactionECDSASignatureEncoding(const valtype &vchSig,
                                             uint32_t flags,
                                             ScriptError *serror) {
     return CheckTransactionSignatureEncodingImpl(
         vchSig, flags, serror,
         [](const slicedvaltype &templateSig, uint32_t templateFlags,
            ScriptError *templateSerror) {
             return CheckRawECDSASignatureEncoding(templateSig, templateFlags,
                                                   templateSerror);
         });
 }
 
 static bool IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
     switch (vchPubKey.size()) {
         case 33:
             // Compressed public key: must start with 0x02 or 0x03.
             return vchPubKey[0] == 0x02 || vchPubKey[0] == 0x03;
 
         case 65:
             // Non-compressed public key: must start with 0x04.
             return vchPubKey[0] == 0x04;
 
         default:
             // Non-canonical public key: invalid size.
             return false;
     }
 }
 
 static bool IsCompressedPubKey(const valtype &vchPubKey) {
     if (vchPubKey.size() != 33) {
         // Non-canonical public key: invalid length for compressed key
         return false;
     }
     if (vchPubKey[0] != 0x02 && vchPubKey[0] != 0x03) {
         // Non-canonical public key: invalid prefix for compressed key
         return false;
     }
     return true;
 }
 
 bool CheckPubKeyEncoding(const valtype &vchPubKey, uint32_t flags,
                          ScriptError *serror) {
     if ((flags & SCRIPT_VERIFY_STRICTENC) &&
         !IsCompressedOrUncompressedPubKey(vchPubKey)) {
         return set_error(serror, SCRIPT_ERR_PUBKEYTYPE);
     }
     // Only compressed keys are accepted when
     // SCRIPT_VERIFY_COMPRESSED_PUBKEYTYPE is enabled.
     if ((flags & SCRIPT_VERIFY_COMPRESSED_PUBKEYTYPE) &&
         !IsCompressedPubKey(vchPubKey)) {
         return set_error(serror, SCRIPT_ERR_NONCOMPRESSED_PUBKEY);
     }
     return true;
 }