/*
* Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"). You may
* not use this file except in compliance with the License. A copy of the
* License is located at
*
* http://aws.amazon.com/apache2.0/
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.amazonaws.sensornetwork;
import javax.xml.bind.DatatypeConverter;
import java.io.*;
import java.math.BigInteger;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.KeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.RSAPrivateCrtKeySpec;
/**
* A class for reading RSA or ECC private key from PEM file
* based on based on https://github.com/aws/aws-iot-device-sdk-java/blob/master/aws-iot-device-sdk-java-samples/src/main/java/com/amazonaws/services/iot/client/sample/sampleUtil/PrivateKeyReader.java
* It can read PEM files with PKCS#8 or PKCS#1 encodings.
* It doesn't support encrypted PEM files.
*/
public class PrivateKeyReader {
// Private key file using PKCS #1 encoding
public static final String P1_BEGIN_MARKER = "-----BEGIN RSA PRIVATE KEY"; //$NON-NLS-1$
public static final String P1_END_MARKER = "-----END RSA PRIVATE KEY"; //$NON-NLS-1$
// Private key file using PKCS #8 encoding
public static final String P8_BEGIN_MARKER = "-----BEGIN PRIVATE KEY"; //$NON-NLS-1$
public static final String P8_END_MARKER = "-----END PRIVATE KEY"; //$NON-NLS-1$
/**
* Get a RSA Private Key from InputStream.
*
* @param fileName
* file name
* @return Private key
* @throws IOException
* IOException resulted from invalid file IO
* @throws GeneralSecurityException
* GeneralSecurityException resulted from invalid key format
*/
public static PrivateKey getPrivateKey(String fileName) throws IOException, GeneralSecurityException {
try (InputStream stream = new FileInputStream(fileName)) {
return getPrivateKey(stream, null);
}
}
/**
* Get a Private Key from InputStream.
*
* @param fileName
* file name
* @param algorithm
* the name of the key algorithm, for example "RSA" or "EC"
* @return Private key
* @throws IOException
* IOException resulted from invalid file IO
* @throws GeneralSecurityException
* GeneralSecurityException resulted from invalid key data
*/
public static PrivateKey getPrivateKey(String fileName, String algorithm) throws IOException,
GeneralSecurityException {
try (InputStream stream = new FileInputStream(fileName)) {
return getPrivateKey(stream, algorithm);
}
}
/**
* Get a Private Key for the file.
*
* @param stream
* InputStream object
* @param algorithm
* the name of the key algorithm, for example "RSA" or "EC"
* @return Private key
* @throws IOException
* IOException resulted from invalid file IO
* @throws GeneralSecurityException
* GeneralSecurityException resulted from invalid key data
*/
public static PrivateKey getPrivateKey(InputStream stream, String algorithm) throws IOException,
GeneralSecurityException {
PrivateKey key = null;
boolean isRSAKey = false;
BufferedReader br = new BufferedReader(new InputStreamReader(stream, "UTF-8"));
StringBuilder builder = new StringBuilder();
boolean inKey = false;
for (String line = br.readLine(); line != null; line = br.readLine()) {
if (!inKey) {
if (line.startsWith("-----BEGIN ") && line.endsWith(" PRIVATE KEY-----")) {
inKey = true;
isRSAKey = line.contains("RSA");
}
continue;
} else {
if (line.startsWith("-----END ") && line.endsWith(" PRIVATE KEY-----")) {
inKey = false;
isRSAKey = line.contains("RSA");
break;
}
builder.append(line);
}
}
KeySpec keySpec = null;
byte[] encoded = DatatypeConverter.parseBase64Binary(builder.toString());
if (isRSAKey) {
keySpec = getRSAKeySpec(encoded);
} else {
keySpec = new PKCS8EncodedKeySpec(encoded);
}
KeyFactory kf = KeyFactory.getInstance((algorithm == null) ? "RSA" : algorithm);
key = kf.generatePrivate(keySpec);
return key;
}
/**
* Convert PKCS#1 encoded private key into RSAPrivateCrtKeySpec.
*
*
* The ASN.1 syntax for the private key with CRT is
*
*
* --
* -- Representation of RSA private key with information for the CRT algorithm.
* --
* RSAPrivateKey ::= SEQUENCE {
* version Version,
* modulus INTEGER, -- n
* publicExponent INTEGER, -- e
* privateExponent INTEGER, -- d
* prime1 INTEGER, -- p
* prime2 INTEGER, -- q
* exponent1 INTEGER, -- d mod (p-1)
* exponent2 INTEGER, -- d mod (q-1)
* coefficient INTEGER, -- (inverse of q) mod p
* otherPrimeInfos OtherPrimeInfos OPTIONAL
* }
*
*
* @param keyBytes
* PKCS#1 encoded key
* @return KeySpec
* @throws IOException
* IOException resulted from invalid file IO
*/
private static RSAPrivateCrtKeySpec getRSAKeySpec(byte[] keyBytes) throws IOException {
DerParser parser = new DerParser(keyBytes);
Asn1Object sequence = parser.read();
if (sequence.getType() != DerParser.SEQUENCE)
throw new IOException("Invalid DER: not a sequence"); //$NON-NLS-1$
// Parse inside the sequence
parser = sequence.getParser();
parser.read(); // Skip version
BigInteger modulus = parser.read().getInteger();
BigInteger publicExp = parser.read().getInteger();
BigInteger privateExp = parser.read().getInteger();
BigInteger prime1 = parser.read().getInteger();
BigInteger prime2 = parser.read().getInteger();
BigInteger exp1 = parser.read().getInteger();
BigInteger exp2 = parser.read().getInteger();
BigInteger crtCoef = parser.read().getInteger();
RSAPrivateCrtKeySpec keySpec = new RSAPrivateCrtKeySpec(modulus, publicExp, privateExp, prime1, prime2, exp1,
exp2, crtCoef);
return keySpec;
}
}
/**
* A bare-minimum ASN.1 DER decoder, just having enough functions to decode
* PKCS#1 private keys. Especially, it doesn't handle explicitly tagged types
* with an outer tag.
*
*
* This parser can only handle one layer. To parse nested constructs, get a new
* parser for each layer using Asn1Object.getParser().
*
*
* There are many DER decoders in JRE but using them will tie this program to a
* specific JCE/JVM.
*
* @author zhang
*
*/
class DerParser {
// Classes
public final static int UNIVERSAL = 0x00;
public final static int APPLICATION = 0x40;
public final static int CONTEXT = 0x80;
public final static int PRIVATE = 0xC0;
// Constructed Flag
public final static int CONSTRUCTED = 0x20;
// Tag and data types
public final static int ANY = 0x00;
public final static int BOOLEAN = 0x01;
public final static int INTEGER = 0x02;
public final static int BIT_STRING = 0x03;
public final static int OCTET_STRING = 0x04;
public final static int NULL = 0x05;
public final static int OBJECT_IDENTIFIER = 0x06;
public final static int REAL = 0x09;
public final static int ENUMERATED = 0x0a;
public final static int RELATIVE_OID = 0x0d;
public final static int SEQUENCE = 0x10;
public final static int SET = 0x11;
public final static int NUMERIC_STRING = 0x12;
public final static int PRINTABLE_STRING = 0x13;
public final static int T61_STRING = 0x14;
public final static int VIDEOTEX_STRING = 0x15;
public final static int IA5_STRING = 0x16;
public final static int GRAPHIC_STRING = 0x19;
public final static int ISO646_STRING = 0x1A;
public final static int GENERAL_STRING = 0x1B;
public final static int UTF8_STRING = 0x0C;
public final static int UNIVERSAL_STRING = 0x1C;
public final static int BMP_STRING = 0x1E;
public final static int UTC_TIME = 0x17;
public final static int GENERALIZED_TIME = 0x18;
protected InputStream in;
/**
* Create a new DER decoder from an input stream.
*
* @param in
* The DER encoded stream
*/
public DerParser(InputStream in) throws IOException {
this.in = in;
}
/**
* Create a new DER decoder from a byte array.
*
* @param The
* encoded bytes
* @throws IOException
* IOException resulted from invalid file IO
*/
public DerParser(byte[] bytes) throws IOException {
this(new ByteArrayInputStream(bytes));
}
/**
* Read next object. If it's constructed, the value holds encoded content
* and it should be parsed by a new parser from
* Asn1Object.getParser.
*
* @return A object
* @throws IOException
* IOException resulted from invalid file IO
*/
public Asn1Object read() throws IOException {
int tag = in.read();
if (tag == -1)
throw new IOException("Invalid DER: stream too short, missing tag"); //$NON-NLS-1$
int length = getLength();
byte[] value = new byte[length];
int n = in.read(value);
if (n < length)
throw new IOException("Invalid DER: stream too short, missing value"); //$NON-NLS-1$
Asn1Object o = new Asn1Object(tag, length, value);
return o;
}
/**
* Decode the length of the field. Can only support length encoding up to 4
* octets.
*
*
* In BER/DER encoding, length can be encoded in 2 forms,
*
* - Short form. One octet. Bit 8 has value "0" and bits 7-1 give the
* length.
*
- Long form. Two to 127 octets (only 4 is supported here). Bit 8 of
* first octet has value "1" and bits 7-1 give the number of additional
* length octets. Second and following octets give the length, base 256,
* most significant digit first.
*
*
* @return The length as integer
* @throws IOException
* IOException resulted from invalid file IO
*/
private int getLength() throws IOException {
int i = in.read();
if (i == -1)
throw new IOException("Invalid DER: length missing"); //$NON-NLS-1$
// A single byte short length
if ((i & ~0x7F) == 0)
return i;
int num = i & 0x7F;
// We can't handle length longer than 4 bytes
if (i >= 0xFF || num > 4)
throw new IOException("Invalid DER: length field too big (" //$NON-NLS-1$
+ i + ")"); //$NON-NLS-1$
byte[] bytes = new byte[num];
int n = in.read(bytes);
if (n < num)
throw new IOException("Invalid DER: length too short"); //$NON-NLS-1$
return new BigInteger(1, bytes).intValue();
}
}
/**
* An ASN.1 TLV. The object is not parsed. It can only handle integers and
* strings.
*
* @author zhang
*
*/
class Asn1Object {
protected final int type;
protected final int length;
protected final byte[] value;
protected final int tag;
/**
* Construct a ASN.1 TLV. The TLV could be either a constructed or primitive
* entity.
*
*
* The first byte in DER encoding is made of following fields,
*
*
* -------------------------------------------------
* |Bit 8|Bit 7|Bit 6|Bit 5|Bit 4|Bit 3|Bit 2|Bit 1|
* -------------------------------------------------
* | Class | CF | + Type |
* -------------------------------------------------
*
*
*
* - Class: Universal, Application, Context or Private
*
- CF: Constructed flag. If 1, the field is constructed.
*
- Type: This is actually called tag in ASN.1. It indicates data type
* (Integer, String) or a construct (sequence, choice, set).
*
*
* @param tag
* Tag or Identifier
* @param length
* Length of the field
* @param value
* Encoded octet string for the field.
*/
public Asn1Object(int tag, int length, byte[] value) {
this.tag = tag;
this.type = tag & 0x1F;
this.length = length;
this.value = value;
}
public int getType() {
return type;
}
public int getLength() {
return length;
}
public byte[] getValue() {
return value;
}
public boolean isConstructed() {
return (tag & DerParser.CONSTRUCTED) == DerParser.CONSTRUCTED;
}
/**
* For constructed field, return a parser for its content.
*
* @return A parser for the construct.
* @throws IOException
* IOException resulted from invalid file IO
*/
public DerParser getParser() throws IOException {
if (!isConstructed())
throw new IOException("Invalid DER: can't parse primitive entity"); //$NON-NLS-1$
return new DerParser(value);
}
/**
* Get the value as integer
*
* @return BigInteger
* @throws IOException
* IOException resulted from invalid file IO
*/
public BigInteger getInteger() throws IOException {
if (type != DerParser.INTEGER)
throw new IOException("Invalid DER: object is not integer"); //$NON-NLS-1$
return new BigInteger(value);
}
/**
* Get value as string. Most strings are treated as Latin-1.
*
* @return Java string
* @throws IOException
* IOException resulted from invalid file IO
*/
public String getString() throws IOException {
String encoding;
switch (type) {
// Not all are Latin-1 but it's the closest thing
case DerParser.NUMERIC_STRING:
case DerParser.PRINTABLE_STRING:
case DerParser.VIDEOTEX_STRING:
case DerParser.IA5_STRING:
case DerParser.GRAPHIC_STRING:
case DerParser.ISO646_STRING:
case DerParser.GENERAL_STRING:
encoding = "ISO-8859-1"; //$NON-NLS-1$
break;
case DerParser.BMP_STRING:
encoding = "UTF-16BE"; //$NON-NLS-1$
break;
case DerParser.UTF8_STRING:
encoding = "UTF-8"; //$NON-NLS-1$
break;
case DerParser.UNIVERSAL_STRING:
throw new IOException("Invalid DER: can't handle UCS-4 string"); //$NON-NLS-1$
default:
throw new IOException("Invalid DER: object is not a string"); //$NON-NLS-1$
}
return new String(value, encoding);
}
}