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 IETF draft, and is subject to change. See getEncoded().
*</p><p>
* Ref: https://tools.ietf.org/html/draft-josefsson-pkix-eddsa-04
*</p>
*
* @since 0.9.15
* @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;
public EdDSAPublicKey(EdDSAPublicKeySpec spec) {
this.A = spec.getA();
this.Aneg = spec.getNegativeA();
this.Abyte = this.A.toByteArray();
this.edDsaSpec = spec.getParams();
}
/**
* @since 0.9.25
*/
public EdDSAPublicKey(X509EncodedKeySpec spec) throws InvalidKeySpecException {
this(new EdDSAPublicKeySpec(decode(spec.getEncoded()),
EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.CURVE_ED25519_SHA512)));
}
public String getAlgorithm() {
return "EdDSA";
}
public String getFormat() {
return "X.509";
}
/**
* This follows the spec at
* ref: https://tools.ietf.org/html/draft-josefsson-pkix-eddsa-04
* which matches the docs from
* java.security.spec.X509EncodedKeySpec
* quote:
*<pre>
* The SubjectPublicKeyInfo syntax is defined in the X.509 standard as follows:
* SubjectPublicKeyInfo ::= SEQUENCE {
* algorithm AlgorithmIdentifier,
* subjectPublicKey BIT STRING }
*</pre>
*
*<pre>
* AlgorithmIdentifier ::= SEQUENCE
* {
* algorithm OBJECT IDENTIFIER,
* parameters ANY OPTIONAL
* }
*</pre>
*
* @return 47 bytes for Ed25519, null for other curves
* @since implemented in 0.9.25
*/
public byte[] getEncoded() {
if (!edDsaSpec.equals(EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.CURVE_ED25519_SHA512)))
return null;
int totlen = 15 + Abyte.length;
byte[] rv = new byte[totlen];
int idx = 0;
// sequence
rv[idx++] = 0x30;
rv[idx++] = (byte) (13 + Abyte.length);
// Algorithm Identifier
// sequence
rv[idx++] = 0x30;
rv[idx++] = 8;
// OID 1.3.101.100
// 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++] = 100;
// params
rv[idx++] = 0x0a;
rv[idx++] = 1;
rv[idx++] = 1; // Ed25519
// 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;
}
/**
* This is really dumb for now.
* See getEncoded().
*
* @return 32 bytes for Ed25519, throws for other curves
* @since 0.9.25
*/
private static byte[] decode(byte[] d) throws InvalidKeySpecException {
try {
int idx = 0;
if (d[idx++] != 0x30 ||
d[idx++] != 45 ||
d[idx++] != 0x30 ||
d[idx++] != 8 ||
d[idx++] != 0x06 ||
d[idx++] != 3 ||
d[idx++] != (1 * 40) + 3 ||
d[idx++] != 101 ||
d[idx++] != 100 ||
d[idx++] != 0x0a ||
d[idx++] != 1 ||
d[idx++] != 1 ||
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);
}
}
public EdDSAParameterSpec getParams() {
return edDsaSpec;
}
public GroupElement getA() {
return A;
}
public GroupElement getNegativeA() {
return Aneg;
}
public byte[] getAbyte() {
return Abyte;
}
/**
* @since 0.9.25
*/
@Override
public int hashCode() {
return Arrays.hashCode(Abyte);
}
/**
* @since 0.9.25
*/
@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());
}
}