Signal-Android/libsignal/service/src/main/java/org/whispersystems/signalservice/api/crypto/DigestingOutputStream.java

56 lines
1.3 KiB
Java

package org.whispersystems.signalservice.api.crypto;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public abstract class DigestingOutputStream extends FilterOutputStream {
private final MessageDigest runningDigest;
private byte[] digest;
public DigestingOutputStream(OutputStream outputStream) {
super(outputStream);
try {
this.runningDigest = MessageDigest.getInstance("SHA256");
} catch (NoSuchAlgorithmException e) {
throw new AssertionError(e);
}
}
@Override
public void write(byte[] buffer) throws IOException {
runningDigest.update(buffer, 0, buffer.length);
out.write(buffer, 0, buffer.length);
}
public void write(byte[] buffer, int offset, int length) throws IOException {
runningDigest.update(buffer, offset, length);
out.write(buffer, offset, length);
}
public void write(int b) throws IOException {
runningDigest.update((byte)b);
out.write(b);
}
public void flush() throws IOException {
digest = runningDigest.digest();
out.flush();
}
public void close() throws IOException {
out.close();
}
public byte[] getTransmittedDigest() {
return digest;
}
}