diff --git a/src/Makefile.am b/src/Makefile.am
index 8253c4ab14..c9adf859f4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -86,6 +86,7 @@ BITCOIN_CORE_H = \
   core_io.h \
   crypter.h \
   db.h \
+  eccryptoverify.h \
   ecwrapper.h \
   hash.h \
   init.h \
@@ -220,6 +221,7 @@ libbitcoin_common_a_SOURCES = \
   core/transaction.cpp \
   core_read.cpp \
   core_write.cpp \
+  eccryptoverify.cpp \
   ecwrapper.cpp \
   hash.cpp \
   key.cpp \
diff --git a/src/eccryptoverify.cpp b/src/eccryptoverify.cpp
new file mode 100644
index 0000000000..0a904f44ba
--- /dev/null
+++ b/src/eccryptoverify.cpp
@@ -0,0 +1,63 @@
+#include "eccryptoverify.h"
+
+namespace {
+
+int CompareBigEndian(const unsigned char *c1, size_t c1len, const unsigned char *c2, size_t c2len) {
+    while (c1len > c2len) {
+        if (*c1)
+            return 1;
+        c1++;
+        c1len--;
+    }
+    while (c2len > c1len) {
+        if (*c2)
+            return -1;
+        c2++;
+        c2len--;
+    }
+    while (c1len > 0) {
+        if (*c1 > *c2)
+            return 1;
+        if (*c2 > *c1)
+            return -1;
+        c1++;
+        c2++;
+        c1len--;
+    }
+    return 0;
+}
+
+/** Order of secp256k1's generator minus 1. */
+const unsigned char vchMaxModOrder[32] = {
+    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,
+    0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,
+    0xBF,0xD2,0x5E,0x8C,0xD0,0x36,0x41,0x40
+};
+
+/** Half of the order of secp256k1's generator minus 1. */
+const unsigned char vchMaxModHalfOrder[32] = {
+    0x7F,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+    0x5D,0x57,0x6E,0x73,0x57,0xA4,0x50,0x1D,
+    0xDF,0xE9,0x2F,0x46,0x68,0x1B,0x20,0xA0
+};
+
+const unsigned char vchZero[1] = {0};
+} // anon namespace
+
+namespace eccrypto {
+
+bool Check(const unsigned char *vch) {
+    return vch &&
+           CompareBigEndian(vch, 32, vchZero, 0) > 0 &&
+           CompareBigEndian(vch, 32, vchMaxModOrder, 32) <= 0;
+}
+
+bool CheckSignatureElement(const unsigned char *vch, int len, bool half) {
+    return vch &&
+           CompareBigEndian(vch, len, vchZero, 0) > 0 &&
+           CompareBigEndian(vch, len, half ? vchMaxModHalfOrder : vchMaxModOrder, 32) <= 0;
+}
+
+} // namespace eccrypto
diff --git a/src/eccryptoverify.h b/src/eccryptoverify.h
new file mode 100644
index 0000000000..7740e31db1
--- /dev/null
+++ b/src/eccryptoverify.h
@@ -0,0 +1,19 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_EC_CRYPTO_VERIFY_H
+#define BITCOIN_EC_CRYPTO_VERIFY_H
+
+#include <vector>
+#include <cstdlib>
+class uint256;
+
+namespace eccrypto {
+
+bool Check(const unsigned char *vch);
+bool CheckSignatureElement(const unsigned char *vch, int len, bool half);
+
+} // eccrypto namespace
+#endif
diff --git a/src/key.cpp b/src/key.cpp
index c466e84f26..925b80ba0f 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -5,6 +5,7 @@
 #include "key.h"
 
 #include "crypto/sha2.h"
+#include "eccryptoverify.h"
 #include "random.h"
 
 #ifdef USE_SECP256K1
@@ -30,60 +31,10 @@ public:
 static CSecp256k1Init instance_of_csecp256k1;
 
 #endif
-
-int CompareBigEndian(const unsigned char *c1, size_t c1len, const unsigned char *c2, size_t c2len) {
-    while (c1len > c2len) {
-        if (*c1)
-            return 1;
-        c1++;
-        c1len--;
-    }
-    while (c2len > c1len) {
-        if (*c2)
-            return -1;
-        c2++;
-        c2len--;
-    }
-    while (c1len > 0) {
-        if (*c1 > *c2)
-            return 1;
-        if (*c2 > *c1)
-            return -1;
-        c1++;
-        c2++;
-        c1len--;
-    }
-    return 0;
-}
-
-/** Order of secp256k1's generator minus 1. */
-const unsigned char vchMaxModOrder[32] = {
-    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,
-    0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,
-    0xBF,0xD2,0x5E,0x8C,0xD0,0x36,0x41,0x40
-};
-
-/** Half of the order of secp256k1's generator minus 1. */
-const unsigned char vchMaxModHalfOrder[32] = {
-    0x7F,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
-    0x5D,0x57,0x6E,0x73,0x57,0xA4,0x50,0x1D,
-    0xDF,0xE9,0x2F,0x46,0x68,0x1B,0x20,0xA0
-};
-
-const unsigned char vchZero[1] = {0};
-
 } // anon namespace
 
 bool CKey::Check(const unsigned char *vch) {
-    return CompareBigEndian(vch, 32, vchZero, 0) > 0 &&
-           CompareBigEndian(vch, 32, vchMaxModOrder, 32) <= 0;
-}
-
-bool CKey::CheckSignatureElement(const unsigned char *vch, int len, bool half) {
-    return CompareBigEndian(vch, len, vchZero, 0) > 0 &&
-           CompareBigEndian(vch, len, half ? vchMaxModHalfOrder : vchMaxModOrder, 32) <= 0;
+    return eccrypto::Check(vch);
 }
 
 void CKey::MakeNewKey(bool fCompressedIn) {
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 3625972ebf..e1e242882f 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -9,6 +9,7 @@
 #include "crypto/ripemd160.h"
 #include "crypto/sha1.h"
 #include "crypto/sha2.h"
+#include "eccryptoverify.h"
 #include "key.h"
 #include "script/script.h"
 #include "uint256.h"
@@ -122,7 +123,7 @@ bool static IsLowDERSignature(const valtype &vchSig) {
     // If the S value is above the order of the curve divided by two, its
     // complement modulo the order could have been used instead, which is
     // one byte shorter when encoded correctly.
-    if (!CKey::CheckSignatureElement(S, nLenS, true))
+    if (!eccrypto::CheckSignatureElement(S, nLenS, true))
         return error("Non-canonical signature: S value is unnecessarily high");
 
     return true;