1 files changed, 105 insertions, 0 deletions
diff --git a/src/main/model/pki/AlgorithmIdentifier.java b/src/main/model/pki/AlgorithmIdentifier.java
new file mode 100644
index 0000000..421aa5a
--- /dev/null
+++ b/src/main/model/pki/AlgorithmIdentifier.java
@@ -0,0 +1,105 @@
+package model.pki;
+
+import model.asn1.ASN1Object;
+import model.asn1.ObjectIdentifier;
+import model.asn1.Tag;
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.stream.Stream;
+
+/**
+ * Implements the following:
+ * <pre>
+ *   AttributeTypeAndValue ::= SEQUENCE {
+ *       type ATTRIBUTE.&id({SupportedAttributes}),
+ *       value ATTRIBUTE.&Type({SupportedAttributes}{@type}) OPTIONAL,
+ *   ... }
+ * </pre>
+ */
+public class AlgorithmIdentifier extends ASN1Object {
+    /**
+     * The type of that attribute. For example, <pre>1.2.840.113549.1.1.11</pre> is sha256WithRSAEncryption.
+     */
+    private final ObjectIdentifier type;
+
+    /**
+     * Additional parameters for that algorithm. Optional, and could be ASN.1 NULL or Java null (absent).
+     * According to RFC8017$A.2, it should be NULL for a number of algorithms:
+     * <pre>
+     *     PKCS1Algorithms    ALGORITHM-IDENTIFIER ::= {
+     *        { OID rsaEncryption                PARAMETERS NULL } |
+     *        { OID md2WithRSAEncryption         PARAMETERS NULL } |
+     *        { OID md5WithRSAEncryption         PARAMETERS NULL } |
+     *        { OID sha1WithRSAEncryption        PARAMETERS NULL } |
+     *        { OID sha224WithRSAEncryption      PARAMETERS NULL } |
+     *        { OID sha256WithRSAEncryption      PARAMETERS NULL } |
+     *        { OID sha384WithRSAEncryption      PARAMETERS NULL } |
+     *        { OID sha512WithRSAEncryption      PARAMETERS NULL } |
+     *        { OID sha512-224WithRSAEncryption  PARAMETERS NULL } |
+     *        { OID sha512-256WithRSAEncryption  PARAMETERS NULL } |
+     *        { OID id-RSAES-OAEP   PARAMETERS RSAES-OAEP-params } |
+     *        PKCS1PSourceAlgorithms                               |
+     *        { OID id-RSASSA-PSS   PARAMETERS RSASSA-PSS-params },
+     *        ...  -- Allows for future expansion --
+     *    }
+     * </pre>
+     */
+    private final ASN1Object parameters;
+
+    /**
+     * EFFECT: Init the object with tag, parentTag, type, and parameters. For tag and parentTag, see {@link ASN1Object}.
+     * REQUIRES: The values must match the type. Type tag should be UNIVERSAL OID. Parameters nullable.
+     */
+    public AlgorithmIdentifier(Tag tag, Tag parentTag,
+                               ObjectIdentifier type, ASN1Object parameters) {
+        super(tag, parentTag);
+        this.type = type;
+        this.parameters = parameters;
+    }
+
+    /**
+     * EFFECTS: Parse input DER. Parameters are not checked against the type.
+     *   Throws {@link ASN1Object} if invalid:
+     *    - Any fields missing
+     *    - Any fields having an incorrect tag (as seen in the ASN.1 definition)
+     *    - Any fields with encoding instructions that violate implicit / explicit encoding rules
+     *    - Other issues found during parsing the object, like early EOF (see {@link ASN1Object})
+     * MODIFIES: this, encoded
+     */
+    public AlgorithmIdentifier(BytesReader encoded, boolean hasParentTag) throws ParseException {
+        super(encoded, hasParentTag);
+        int i = encoded.getIndex();
+        this.type = new ObjectIdentifier(encoded, false);
+        this.type.getTag().enforce(ObjectIdentifier.TAG);
+        i = encoded.getIndex() - i;
+
+        if (getLength() > i) {
+            this.parameters = ASN1Object.parse(encoded, false);
+        } else {
+            this.parameters = null;
+        }
+    }
+
+    /**
+     * EFFECTS: Encode the fields into DER, in the order.
+     */
+    @Override
+    public Byte[] encodeValueDER() {
+        return Stream.of(Arrays.asList(type.encodeDER()),
+                parameters == null ? Collections.<Byte>emptyList() : Arrays.asList(parameters.encodeDER()))
+                .flatMap(Collection::stream)
+                .toArray(Byte[]::new);
+    }
+
+    public ObjectIdentifier getType() {
+        return type;
+    }
+
+    public ASN1Object getParameters() {
+        return parameters;
+    }
+}