1 files changed, 36 insertions, 0 deletions
diff --git a/libraries/spongycastle/pkix/src/main/java/org/spongycastle/operator/DigestCalculator.java b/libraries/spongycastle/pkix/src/main/java/org/spongycastle/operator/DigestCalculator.java
new file mode 100644
index 000000000..0bb4712f5
--- /dev/null
+++ b/libraries/spongycastle/pkix/src/main/java/org/spongycastle/operator/DigestCalculator.java
@@ -0,0 +1,36 @@
+package org.spongycastle.operator;
+
+import java.io.OutputStream;
+
+import org.spongycastle.asn1.x509.AlgorithmIdentifier;
+
+/**
+ * General interface for an operator that is able to calculate a digest from
+ * a stream of output.
+ */
+public interface DigestCalculator
+{
+    /**
+     * Return the algorithm identifier representing the digest implemented by
+     * this calculator.
+     *
+     * @return algorithm id and parameters.
+     */
+    AlgorithmIdentifier getAlgorithmIdentifier();
+
+    /**
+     * Returns a stream that will accept data for the purpose of calculating
+     * a digest. Use org.spongycastle.util.io.TeeOutputStream if you want to accumulate
+     * the data on the fly as well.
+     *
+     * @return an OutputStream
+     */
+    OutputStream getOutputStream();
+
+    /**
+     * Return the digest calculated on what has been written to the calculator's output stream.
+     *
+     * @return a digest.
+     */
+    byte[] getDigest();
+}