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diff --git a/source/crypto/Hashes.mc b/source/crypto/Hashes.mc
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+// Author:  cirakg & claude ai
+// Summary: One interface over SHA-1, SHA-256 (native) and SHA-512 (pure Monkey C).
+//
+// Connect IQ has native SHA-1 and SHA-256 (Toybox.Cryptography.Hash) but no
+// SHA-512, which source/crypto/Sha512.mc implements from FIPS 180-4. OTP code
+// asks for an algorithm by its Hashes.Algorithm value and doesn't care which
+// implementation answers.
+
+import Toybox.Cryptography;
+import Toybox.Lang;
+
+module Hashes {
+
+    // OTP and HMAC hash algorithms. The values are stored in entry records, so
+    // never renumber them.
+    enum Algorithm {
+        SHA1 = 0,
+        SHA256 = 1,
+        SHA512 = 2
+    }
+
+    // Input block size in bytes (what HMAC pads its key to).
+    function blockSize(alg as Algorithm) as Number {
+        return alg == SHA512 ? 128 : 64;
+    }
+
+    // Digest length in bytes.
+    function digestSize(alg as Algorithm) as Number {
+        if (alg == SHA1) {
+            return 20;
+        }
+        return alg == SHA256 ? 32 : 64;
+    }
+
+    // True for the three supported values (input from settings or imports is
+    // checked with this before it becomes an Algorithm).
+    function isValid(value as Number) as Boolean {
+        return value == SHA1 || value == SHA256 || value == SHA512;
+    }
+
+    // The digest of data.
+    function digest(alg as Algorithm, data as ByteArray) as ByteArray {
+        if (alg == SHA512) {
+            return Sha512.digest(data);
+        }
+        var hash = new Cryptography.Hash({
+            :algorithm => alg == SHA1 ? Cryptography.HASH_SHA1 : Cryptography.HASH_SHA256
+        });
+        if (data.size() > 0) {
+            hash.update(data);
+        }
+        return hash.digest();
+    }
+}