1 files changed, 126 insertions, 0 deletions
diff --git a/libraries/spongycastle/pkix/src/main/java/org/spongycastle/cert/X509ExtensionUtils.java b/libraries/spongycastle/pkix/src/main/java/org/spongycastle/cert/X509ExtensionUtils.java
new file mode 100644
index 000000000..54f56adb8
--- /dev/null
+++ b/libraries/spongycastle/pkix/src/main/java/org/spongycastle/cert/X509ExtensionUtils.java
@@ -0,0 +1,126 @@
+package org.spongycastle.cert;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+import org.spongycastle.asn1.ASN1OctetString;
+import org.spongycastle.asn1.x509.AuthorityKeyIdentifier;
+import org.spongycastle.asn1.x509.Extension;
+import org.spongycastle.asn1.x509.GeneralName;
+import org.spongycastle.asn1.x509.GeneralNames;
+import org.spongycastle.asn1.x509.SubjectKeyIdentifier;
+import org.spongycastle.asn1.x509.SubjectPublicKeyInfo;
+import org.spongycastle.operator.DigestCalculator;
+
+/**
+ * General utility class for creating calculated extensions using the standard methods.
+ * <p>
+ * <b>Note:</b> This class is not thread safe!
+ * </p>
+ */
+public class X509ExtensionUtils
+{
+    private DigestCalculator calculator;
+
+    public X509ExtensionUtils(DigestCalculator calculator)
+    {
+        this.calculator = calculator;
+    }
+
+    public AuthorityKeyIdentifier createAuthorityKeyIdentifier(
+        X509CertificateHolder certHolder)
+    {
+        if (certHolder.getVersionNumber() != 3)
+        {
+            GeneralName genName = new GeneralName(certHolder.getIssuer());
+            SubjectPublicKeyInfo info = certHolder.getSubjectPublicKeyInfo();
+
+            return new AuthorityKeyIdentifier(
+                           calculateIdentifier(info), new GeneralNames(genName), certHolder.getSerialNumber());
+        }
+        else
+        {
+            GeneralName             genName = new GeneralName(certHolder.getIssuer());
+            Extension ext = certHolder.getExtension(Extension.subjectKeyIdentifier);
+
+            if (ext != null)
+            {
+                ASN1OctetString str = ASN1OctetString.getInstance(ext.getParsedValue());
+
+                return new AuthorityKeyIdentifier(
+                                str.getOctets(), new GeneralNames(genName), certHolder.getSerialNumber());
+            }
+            else
+            {
+                SubjectPublicKeyInfo info = certHolder.getSubjectPublicKeyInfo();
+
+                return new AuthorityKeyIdentifier(
+                        calculateIdentifier(info), new GeneralNames(genName), certHolder.getSerialNumber());
+            }
+        }
+    }
+
+    public AuthorityKeyIdentifier createAuthorityKeyIdentifier(SubjectPublicKeyInfo publicKeyInfo)
+    {
+        return new AuthorityKeyIdentifier(calculateIdentifier(publicKeyInfo));
+    }
+
+    /**
+     * Return a RFC 3280 type 1 key identifier. As in:
+     * <pre>
+     * (1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
+     * value of the BIT STRING subjectPublicKey (excluding the tag,
+     * length, and number of unused bits).
+     * </pre>
+     * @param publicKeyInfo the key info object containing the subjectPublicKey field.
+     * @return the key identifier.
+     */
+    public SubjectKeyIdentifier createSubjectKeyIdentifier(
+        SubjectPublicKeyInfo publicKeyInfo)
+    {
+        return new SubjectKeyIdentifier(calculateIdentifier(publicKeyInfo));
+    }
+
+    /**
+     * Return a RFC 3280 type 2 key identifier. As in:
+     * <pre>
+     * (2) The keyIdentifier is composed of a four bit type field with
+     * the value 0100 followed by the least significant 60 bits of the
+     * SHA-1 hash of the value of the BIT STRING subjectPublicKey.
+     * </pre>
+     * @param publicKeyInfo the key info object containing the subjectPublicKey field.
+     * @return the key identifier.
+     */
+    public SubjectKeyIdentifier createTruncatedSubjectKeyIdentifier(SubjectPublicKeyInfo publicKeyInfo)
+    {
+        byte[] digest = calculateIdentifier(publicKeyInfo);
+        byte[] id = new byte[8];
+
+        System.arraycopy(digest, digest.length - 8, id, 0, id.length);
+
+        id[0] &= 0x0f;
+        id[0] |= 0x40;
+
+        return new SubjectKeyIdentifier(id);
+    }
+
+    private byte[] calculateIdentifier(SubjectPublicKeyInfo publicKeyInfo)
+    {
+        byte[] bytes = publicKeyInfo.getPublicKeyData().getBytes();
+
+        OutputStream cOut = calculator.getOutputStream();
+
+        try
+        {
+            cOut.write(bytes);
+
+            cOut.close();
+        }
+        catch (IOException e)
+        {   // it's hard to imagine this happening, but yes it does!
+            throw new CertRuntimeException("unable to calculate identifier: " + e.getMessage(), e);
+        }
+
+        return calculator.getDigest();
+    }
+}