2 files changed, 61 insertions, 0 deletions
diff --git a/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/util/CertificateUtils.java b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/util/CertificateUtils.java
new file mode 100644
index 00000000..2f4fbe10
--- /dev/null
+++ b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/util/CertificateUtils.java
@@ -0,0 +1,53 @@
+package at.gv.egiz.pdfas.lib.util;
+
+import iaik.asn1.structures.AlgorithmID;
+import iaik.x509.X509Certificate;
+import java.security.NoSuchAlgorithmException;
+import java.security.PublicKey;
+import java.security.interfaces.ECPublicKey;
+import java.security.spec.ECParameterSpec;
+
+public class CertificateUtils {
+	public static AlgorithmID[] getAlgorithmIDs(X509Certificate signingCertificate)
+			throws NoSuchAlgorithmException {
+		PublicKey publicKey = signingCertificate.getPublicKey();
+		String algorithm = publicKey.getAlgorithm();
+		AlgorithmID[] algorithms = new AlgorithmID[2];
+		AlgorithmID signatureAlgorithm;
+		AlgorithmID digestAlgorithm;
+
+		if ("DSA".equals(algorithm)) {
+			signatureAlgorithm = AlgorithmID.dsaWithSHA256;
+			digestAlgorithm = AlgorithmID.sha256;
+		} else if ("RSA".equals(algorithm)) {
+			signatureAlgorithm = AlgorithmID.sha256WithRSAEncryption;
+			digestAlgorithm = AlgorithmID.sha256;
+		} else if (("EC".equals(algorithm)) || ("ECDSA".equals(algorithm))) {
+
+			int fieldSize = 0;
+			if (publicKey instanceof ECPublicKey) {
+				ECParameterSpec params = ((ECPublicKey) publicKey).getParams();
+				fieldSize = params.getCurve().getField().getFieldSize();
+			}
+
+			if (fieldSize >= 512) {
+				signatureAlgorithm = AlgorithmID.ecdsa_With_SHA512;
+				digestAlgorithm = AlgorithmID.sha512;
+			} else if (fieldSize >= 256) {
+				signatureAlgorithm = AlgorithmID.ecdsa_With_SHA256;
+				digestAlgorithm = AlgorithmID.sha256;
+			} else {
+				signatureAlgorithm = AlgorithmID.ecdsa_With_SHA1;
+				digestAlgorithm = AlgorithmID.sha1;
+			}
+		} else {
+			throw new NoSuchAlgorithmException("Public key algorithm '"
+					+ algorithm + "' not supported.");
+		}
+		
+		algorithms[0] = signatureAlgorithm;
+		algorithms[1] = digestAlgorithm;
+		
+		return algorithms;
+	}
+}
diff --git a/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/util/package-info.java b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/util/package-info.java
new file mode 100644
index 00000000..e635fb93
--- /dev/null
+++ b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/util/package-info.java
@@ -0,0 +1,8 @@
+/**
+ * 
+ */
+/**
+ * @author afitzek
+ *
+ */
+package at.gv.egiz.pdfas.lib.util;
+\ No newline at end of file