diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/OpenPgpCapabilities.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/OpenPgpCapabilities.java
index 71fd3f022..36b0fc99a 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/OpenPgpCapabilities.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/OpenPgpCapabilities.java
@@ -108,7 +108,16 @@ public class OpenPgpCapabilities {
         mHasKeyImport = (v[0] & MASK_KEY_IMPORT) != 0;
         mAttriburesChangable = (v[0] & MASK_ATTRIBUTES_CHANGABLE) != 0;
 
-        mSMAESKeySize = (v[1] == 1) ? 16 : 32;
+        mSMAESKeySize = 0;
+
+        switch(v[1]) {
+        case 1:
+            mSMAESKeySize = 16;
+            break;
+        case 2:
+            mSMAESKeySize = 32;
+            break;
+        }
 
         mMaxCmdLen = (v[6] << 8) + v[7];
         mMaxRspLen = (v[8] << 8) + v[9];
@@ -142,6 +151,10 @@ public class OpenPgpCapabilities {
         return mSMAESKeySize;
     }
 
+    public boolean isHasAESSM() {
+        return isHasSM() && ((mSMAESKeySize == 16) || (mSMAESKeySize == 32));
+    }
+
     public int getMaxCmdLen() {
         return mMaxCmdLen;
     }
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/SecurityTokenHelper.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/SecurityTokenHelper.java
index c5bc4bdef..98aa82f3a 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/SecurityTokenHelper.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/SecurityTokenHelper.java
@@ -206,7 +206,7 @@ public class SecurityTokenHelper {
         mPw1ValidatedForDecrypt = false;
         mPw3Validated = false;
 
-        if (mOpenPgpCapabilities.isHasSM()) {
+        if (mOpenPgpCapabilities.isHasAESSM()) {
             try {
                 SCP11bSecureMessaging.establish(this, ctx);
             } catch (SecureMessagingException e) {