/**
* EdDSA-Java by str4d * * To the extent possible under law, the person who associated CC0 with * EdDSA-Java has waived all copyright and related or neighboring rights * to EdDSA-Java. * * You should have received a copy of the CC0 legalcode along with this * work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>. * */
package net.i2p.crypto.eddsa;
import java.security.PublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.X509EncodedKeySpec; import java.util.Arrays;
import net.i2p.crypto.eddsa.math.GroupElement; import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable; import net.i2p.crypto.eddsa.spec.EdDSAParameterSpec; import net.i2p.crypto.eddsa.spec.EdDSAPublicKeySpec;
/**
* An EdDSA public key. *<p> * Warning: Public key encoding is is based on the current curdle WG draft, * and is subject to change. See getEncoded(). *</p><p> * For compatibility with older releases, decoding supports both the old and new * draft specifications. See decode(). *</p><p> * Ref: https://tools.ietf.org/html/draft-ietf-curdle-pkix-04 *</p><p> * Old Ref: https://tools.ietf.org/html/draft-josefsson-pkix-eddsa-04 *</p> * @author str4d * */
public class EdDSAPublicKey implements EdDSAKey, PublicKey {
private static final long serialVersionUID = 9837459837498475L;
private final GroupElement A;
private final GroupElement Aneg;
private final byte[] Abyte;
private final EdDSAParameterSpec edDsaSpec;
// OID 1.3.101.xxx
private static final int OID_OLD = 100;
private static final int OID_ED25519 = 112;
private static final int OID_BYTE = 8;
private static final int IDLEN_BYTE = 3;
public EdDSAPublicKey(EdDSAPublicKeySpec spec) {
this.A = spec.getA();
this.Aneg = spec.getNegativeA();
this.Abyte = this.A.toByteArray();
this.edDsaSpec = spec.getParams();
}
public EdDSAPublicKey(X509EncodedKeySpec spec) throws InvalidKeySpecException {
this(new EdDSAPublicKeySpec(decode(spec.getEncoded()),
EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.ED_25519)));
}
@Override
public String getAlgorithm() {
return KEY_ALGORITHM;
}
@Override
public String getFormat() {
return "X.509";
}
/**
* Returns the public key in its canonical encoding.
*<p>
* This implements the following specs:
*<ul><li>
* General encoding: https://tools.ietf.org/html/draft-ietf-curdle-pkix-04
*</li></li>
* Key encoding: https://tools.ietf.org/html/rfc8032
*</li></ul>
*</p><p>
* For keys in older formats, decoding and then re-encoding is sufficient to
* migrate them to the canonical encoding.
*</p>
* Relevant spec quotes:
*<pre>
* In the X.509 certificate, the subjectPublicKeyInfo field has the
* SubjectPublicKeyInfo type, which has the following ASN.1 syntax:
*
* SubjectPublicKeyInfo ::= SEQUENCE {
* algorithm AlgorithmIdentifier,
* subjectPublicKey BIT STRING
* }
*</pre>
*
*<pre>
* AlgorithmIdentifier ::= SEQUENCE {
* algorithm OBJECT IDENTIFIER,
* parameters ANY DEFINED BY algorithm OPTIONAL
* }
*
* For all of the OIDs, the parameters MUST be absent.
*</pre>
*
*<pre>
* id-Ed25519 OBJECT IDENTIFIER ::= { 1 3 101 112 }
*</pre>
*
* @return 44 bytes for Ed25519, null for other curves
*/
@Override
public byte[] getEncoded() {
if (!edDsaSpec.equals(EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.ED_25519)))
return null;
int totlen = 12 + Abyte.length;
byte[] rv = new byte[totlen];
int idx = 0;
// sequence
rv[idx++] = 0x30;
rv[idx++] = (byte) (totlen - 2);
// Algorithm Identifier
// sequence
rv[idx++] = 0x30;
rv[idx++] = 5;
// OID
// https://msdn.microsoft.com/en-us/library/windows/desktop/bb540809%28v=vs.85%29.aspx
rv[idx++] = 0x06;
rv[idx++] = 3;
rv[idx++] = (1 * 40) + 3;
rv[idx++] = 101;
rv[idx++] = (byte) OID_ED25519;
// params - absent
// the key
rv[idx++] = 0x03; // bit string
rv[idx++] = (byte) (1 + Abyte.length);
rv[idx++] = 0; // number of trailing unused bits
System.arraycopy(Abyte, 0, rv, idx, Abyte.length);
return rv;
}
/**
* Extracts the public key bytes from the provided encoding.
*<p>
* This will decode data conforming to the current spec at
* https://tools.ietf.org/html/draft-ietf-curdle-pkix-04
* or the old spec at
* https://tools.ietf.org/html/draft-josefsson-pkix-eddsa-04.
*</p><p>
* Contrary to draft-ietf-curdle-pkix-04, it WILL accept a parameter value
* of NULL, as it is required for interoperability with the default Java
* keystore. Other implementations MUST NOT copy this behaviour from here
* unless they also need to read keys from the default Java keystore.
*</p><p>
* This is really dumb for now. It does not use a general-purpose ASN.1 decoder.
* See also getEncoded().
*</p>
*
* @return 32 bytes for Ed25519, throws for other curves
*/
private static byte[] decode(byte[] d) throws InvalidKeySpecException {
try {
//
// Setup and OID check
//
int totlen = 44;
int idlen = 5;
int doid = d[OID_BYTE];
if (doid == OID_OLD) {
totlen = 47;
idlen = 8;
} else if (doid == OID_ED25519) {
// Detect parameter value of NULL
if (d[IDLEN_BYTE] == 7) {
totlen = 46;
idlen = 7;
}
} else {
throw new InvalidKeySpecException("unsupported key spec");
}
//
// Pre-decoding check
//
if (d.length != totlen) {
throw new InvalidKeySpecException("invalid key spec length");
}
//
// Decoding
//
int idx = 0;
if (d[idx++] != 0x30 ||
d[idx++] != (totlen - 2) ||
d[idx++] != 0x30 ||
d[idx++] != idlen ||
d[idx++] != 0x06 ||
d[idx++] != 3 ||
d[idx++] != (1 * 40) + 3 ||
d[idx++] != 101) {
throw new InvalidKeySpecException("unsupported key spec");
}
idx++; // OID, checked above
// parameters only with old OID
if (doid == OID_OLD) {
if (d[idx++] != 0x0a ||
d[idx++] != 1 ||
d[idx++] != 1) {
throw new InvalidKeySpecException("unsupported key spec");
}
} else {
// Handle parameter value of NULL
//
// Quote https://tools.ietf.org/html/draft-ietf-curdle-pkix-04 :
// For all of the OIDs, the parameters MUST be absent.
// Regardless of the defect in the original 1997 syntax,
// implementations MUST NOT accept a parameters value of NULL.
//
// But Java's default keystore puts it in (when decoding as
// PKCS8 and then re-encoding to pass on), so we must accept it.
if (idlen == 7) {
if (d[idx++] != 0x05 ||
d[idx++] != 0) {
throw new InvalidKeySpecException("unsupported key spec");
}
}
}
if (d[idx++] != 0x03 ||
d[idx++] != 33 ||
d[idx++] != 0) {
throw new InvalidKeySpecException("unsupported key spec");
}
byte[] rv = new byte[32];
System.arraycopy(d, idx, rv, 0, 32);
return rv;
} catch (IndexOutOfBoundsException ioobe) {
throw new InvalidKeySpecException(ioobe);
}
}
@Override
public EdDSAParameterSpec getParams() {
return edDsaSpec;
}
public GroupElement getA() {
return A;
}
public GroupElement getNegativeA() {
return Aneg;
}
public byte[] getAbyte() {
return Abyte;
}
@Override
public int hashCode() {
return Arrays.hashCode(Abyte);
}
@Override
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof EdDSAPublicKey))
return false;
EdDSAPublicKey pk = (EdDSAPublicKey) o;
return Arrays.equals(Abyte, pk.getAbyte()) &&
edDsaSpec.equals(pk.getParams());
}
}