1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.content.pm; 18 19 import android.os.Parcel; 20 import android.os.Parcelable; 21 22 import java.io.ByteArrayInputStream; 23 import java.lang.ref.SoftReference; 24 import java.security.PublicKey; 25 import java.security.cert.Certificate; 26 import java.security.cert.CertificateException; 27 import java.security.cert.CertificateFactory; 28 import java.util.Arrays; 29 30 /** 31 * Opaque, immutable representation of a signature associated with an 32 * application package. 33 */ 34 public class Signature implements Parcelable { 35 private final byte[] mSignature; 36 private int mHashCode; 37 private boolean mHaveHashCode; 38 private SoftReference<String> mStringRef; 39 40 /** 41 * Create Signature from an existing raw byte array. 42 */ Signature(byte[] signature)43 public Signature(byte[] signature) { 44 mSignature = signature.clone(); 45 } 46 parseHexDigit(int nibble)47 private static final int parseHexDigit(int nibble) { 48 if ('0' <= nibble && nibble <= '9') { 49 return nibble - '0'; 50 } else if ('a' <= nibble && nibble <= 'f') { 51 return nibble - 'a' + 10; 52 } else if ('A' <= nibble && nibble <= 'F') { 53 return nibble - 'A' + 10; 54 } else { 55 throw new IllegalArgumentException("Invalid character " + nibble + " in hex string"); 56 } 57 } 58 59 /** 60 * Create Signature from a text representation previously returned by 61 * {@link #toChars} or {@link #toCharsString()}. Signatures are expected to 62 * be a hex-encoded ASCII string. 63 * 64 * @param text hex-encoded string representing the signature 65 * @throws IllegalArgumentException when signature is odd-length 66 */ Signature(String text)67 public Signature(String text) { 68 final byte[] input = text.getBytes(); 69 final int N = input.length; 70 71 if (N % 2 != 0) { 72 throw new IllegalArgumentException("text size " + N + " is not even"); 73 } 74 75 final byte[] sig = new byte[N / 2]; 76 int sigIndex = 0; 77 78 for (int i = 0; i < N;) { 79 final int hi = parseHexDigit(input[i++]); 80 final int lo = parseHexDigit(input[i++]); 81 sig[sigIndex++] = (byte) ((hi << 4) | lo); 82 } 83 84 mSignature = sig; 85 } 86 87 /** 88 * Encode the Signature as ASCII text. 89 */ toChars()90 public char[] toChars() { 91 return toChars(null, null); 92 } 93 94 /** 95 * Encode the Signature as ASCII text in to an existing array. 96 * 97 * @param existingArray Existing char array or null. 98 * @param outLen Output parameter for the number of characters written in 99 * to the array. 100 * @return Returns either <var>existingArray</var> if it was large enough 101 * to hold the ASCII representation, or a newly created char[] array if 102 * needed. 103 */ toChars(char[] existingArray, int[] outLen)104 public char[] toChars(char[] existingArray, int[] outLen) { 105 byte[] sig = mSignature; 106 final int N = sig.length; 107 final int N2 = N*2; 108 char[] text = existingArray == null || N2 > existingArray.length 109 ? new char[N2] : existingArray; 110 for (int j=0; j<N; j++) { 111 byte v = sig[j]; 112 int d = (v>>4)&0xf; 113 text[j*2] = (char)(d >= 10 ? ('a' + d - 10) : ('0' + d)); 114 d = v&0xf; 115 text[j*2+1] = (char)(d >= 10 ? ('a' + d - 10) : ('0' + d)); 116 } 117 if (outLen != null) outLen[0] = N; 118 return text; 119 } 120 121 /** 122 * Return the result of {@link #toChars()} as a String. 123 */ toCharsString()124 public String toCharsString() { 125 String str = mStringRef == null ? null : mStringRef.get(); 126 if (str != null) { 127 return str; 128 } 129 str = new String(toChars()); 130 mStringRef = new SoftReference<String>(str); 131 return str; 132 } 133 134 /** 135 * @return the contents of this signature as a byte array. 136 */ toByteArray()137 public byte[] toByteArray() { 138 byte[] bytes = new byte[mSignature.length]; 139 System.arraycopy(mSignature, 0, bytes, 0, mSignature.length); 140 return bytes; 141 } 142 143 /** 144 * Returns the public key for this signature. 145 * 146 * @throws CertificateException when Signature isn't a valid X.509 147 * certificate; shouldn't happen. 148 * @hide 149 */ getPublicKey()150 public PublicKey getPublicKey() throws CertificateException { 151 final CertificateFactory certFactory = CertificateFactory.getInstance("X.509"); 152 final ByteArrayInputStream bais = new ByteArrayInputStream(mSignature); 153 final Certificate cert = certFactory.generateCertificate(bais); 154 return cert.getPublicKey(); 155 } 156 157 @Override equals(Object obj)158 public boolean equals(Object obj) { 159 try { 160 if (obj != null) { 161 Signature other = (Signature)obj; 162 return this == other || Arrays.equals(mSignature, other.mSignature); 163 } 164 } catch (ClassCastException e) { 165 } 166 return false; 167 } 168 169 @Override hashCode()170 public int hashCode() { 171 if (mHaveHashCode) { 172 return mHashCode; 173 } 174 mHashCode = Arrays.hashCode(mSignature); 175 mHaveHashCode = true; 176 return mHashCode; 177 } 178 describeContents()179 public int describeContents() { 180 return 0; 181 } 182 writeToParcel(Parcel dest, int parcelableFlags)183 public void writeToParcel(Parcel dest, int parcelableFlags) { 184 dest.writeByteArray(mSignature); 185 } 186 187 public static final Parcelable.Creator<Signature> CREATOR 188 = new Parcelable.Creator<Signature>() { 189 public Signature createFromParcel(Parcel source) { 190 return new Signature(source); 191 } 192 193 public Signature[] newArray(int size) { 194 return new Signature[size]; 195 } 196 }; 197 Signature(Parcel source)198 private Signature(Parcel source) { 199 mSignature = source.createByteArray(); 200 } 201 } 202