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package sun.security.util;

import java.io.IOException;
import java.security.AlgorithmParametersSpi;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidParameterSpecException;
import javax.crypto.spec.GCMParameterSpec;
import sun.security.util.HexDumpEncoder;
import sun.security.util.*;

This class implements the parameter set used with GCM encryption, which is defined in RFC 5084 as follows:
   GCMParameters ::= SEQUENCE {
     aes-iv      OCTET STRING, -- recommended size is 12 octets
     aes-tLen    AES-GCM-ICVlen DEFAULT 12 }
   AES-GCM-ICVlen ::= INTEGER (12 | 13 | 14 | 15 | 16)
Since:13
/** * This class implements the parameter set used with * GCM encryption, which is defined in RFC 5084 as follows: * * <pre> * GCMParameters ::= SEQUENCE { * aes-iv OCTET STRING, -- recommended size is 12 octets * aes-tLen AES-GCM-ICVlen DEFAULT 12 } * * AES-GCM-ICVlen ::= INTEGER (12 | 13 | 14 | 15 | 16) * * </pre> * * @since 13 */
public final class GCMParameters extends AlgorithmParametersSpi { // the iv private byte[] iv; // the tag length in bytes private int tLen; public GCMParameters() {} protected void engineInit(AlgorithmParameterSpec paramSpec) throws InvalidParameterSpecException { if (!(paramSpec instanceof GCMParameterSpec)) { throw new InvalidParameterSpecException ("Inappropriate parameter specification"); } GCMParameterSpec gps = (GCMParameterSpec) paramSpec; // need to convert from bits to bytes for ASN.1 encoding this.tLen = gps.getTLen()/8; if (this.tLen < 12 || this.tLen > 16 ) { throw new InvalidParameterSpecException ("GCM parameter parsing error: unsupported tag len: " + this.tLen); } this.iv = gps.getIV(); } protected void engineInit(byte[] encoded) throws IOException { DerValue val = new DerValue(encoded); // check if IV or params if (val.tag == DerValue.tag_Sequence) { byte[] iv = val.data.getOctetString(); int tLen; if (val.data.available() != 0) { tLen = val.data.getInteger(); if (tLen < 12 || tLen > 16 ) { throw new IOException ("GCM parameter parsing error: unsupported tag len: " + tLen); } if (val.data.available() != 0) { throw new IOException ("GCM parameter parsing error: extra data"); } } else { tLen = 12; } this.iv = iv.clone(); this.tLen = tLen; } else { throw new IOException("GCM parameter parsing error: no SEQ tag"); } } protected void engineInit(byte[] encoded, String decodingMethod) throws IOException { engineInit(encoded); } protected <T extends AlgorithmParameterSpec> T engineGetParameterSpec(Class<T> paramSpec) throws InvalidParameterSpecException { if (GCMParameterSpec.class.isAssignableFrom(paramSpec)) { return paramSpec.cast(new GCMParameterSpec(tLen * 8, iv)); } else { throw new InvalidParameterSpecException ("Inappropriate parameter specification"); } } protected byte[] engineGetEncoded() throws IOException { DerOutputStream out = new DerOutputStream(); DerOutputStream bytes = new DerOutputStream(); bytes.putOctetString(iv); // Only put non-default values if (tLen != 12) { bytes.putInteger(tLen); } out.write(DerValue.tag_Sequence, bytes); return out.toByteArray(); } protected byte[] engineGetEncoded(String encodingMethod) throws IOException { return engineGetEncoded(); } /* * Returns a formatted string describing the parameters. */ protected String engineToString() { String LINE_SEP = System.lineSeparator(); HexDumpEncoder encoder = new HexDumpEncoder(); StringBuilder sb = new StringBuilder(LINE_SEP + " iv:" + LINE_SEP + "[" + encoder.encodeBuffer(iv) + "]"); sb.append(LINE_SEP + "tLen(bits):" + LINE_SEP + tLen*8 + LINE_SEP); return sb.toString(); } }