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Android RSA加密

Android RSA加密

作者: 橙果子 | 来源:发表于2019-10-14 16:46 被阅读0次

    在线根据公钥私钥加密解密网址

    Base64工具类

    public class Base64Util {
        static private final int BASELENGTH = 128;
        static private final int LOOKUPLENGTH = 64;
        static private final int TWENTYFOURBITGROUP = 24;
        static private final int EIGHTBIT = 8;
        static private final int SIXTEENBIT = 16;
        static private final int FOURBYTE = 4;
        static private final int SIGN = -128;
        static private final char PAD = '=';
        static private final boolean fDebug = false;
        static final private byte[] base64Alphabet = new byte[BASELENGTH];
        static final private char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];
    
        static {
            for (int i = 0; i < BASELENGTH; ++i) {
                base64Alphabet[i] = -1;
            }
            for (int i = 'Z'; i >= 'A'; i--) {
                base64Alphabet[i] = (byte) (i - 'A');
            }
            for (int i = 'z'; i >= 'a'; i--) {
                base64Alphabet[i] = (byte) (i - 'a' + 26);
            }
    
            for (int i = '9'; i >= '0'; i--) {
                base64Alphabet[i] = (byte) (i - '0' + 52);
            }
    
            base64Alphabet['+'] = 62;
            base64Alphabet['/'] = 63;
    
            for (int i = 0; i <= 25; i++) {
                lookUpBase64Alphabet[i] = (char) ('A' + i);
            }
    
            for (int i = 26, j = 0; i <= 51; i++, j++) {
                lookUpBase64Alphabet[i] = (char) ('a' + j);
            }
    
            for (int i = 52, j = 0; i <= 61; i++, j++) {
                lookUpBase64Alphabet[i] = (char) ('0' + j);
            }
            lookUpBase64Alphabet[62] = (char) '+';
            lookUpBase64Alphabet[63] = (char) '/';
    
        }
    
        private static boolean isWhiteSpace(char octect) {
            return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
        }
    
        private static boolean isPad(char octect) {
            return (octect == PAD);
        }
    
        private static boolean isData(char octect) {
            return (octect < BASELENGTH && base64Alphabet[octect] != -1);
        }
    
        /**
         * Encodes hex octects into Base64
         *
         * @param binaryData Array containing binaryData
         * @return Encoded Base64 array
         */
        public static String encode(byte[] binaryData) {
    
            if (binaryData == null) {
                return null;
            }
    
            int lengthDataBits = binaryData.length * EIGHTBIT;
            if (lengthDataBits == 0) {
                return "";
            }
    
            int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
            int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
            int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
            char encodedData[] = null;
    
            encodedData = new char[numberQuartet * 4];
    
            byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
    
            int encodedIndex = 0;
            int dataIndex = 0;
            if (fDebug) {
                System.out.println("number of triplets = " + numberTriplets);
            }
    
            for (int i = 0; i < numberTriplets; i++) {
                b1 = binaryData[dataIndex++];
                b2 = binaryData[dataIndex++];
                b3 = binaryData[dataIndex++];
    
                if (fDebug) {
                    System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
                }
    
                l = (byte) (b2 & 0x0f);
                k = (byte) (b1 & 0x03);
    
                byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
                byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
                byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
    
                if (fDebug) {
                    System.out.println("val2 = " + val2);
                    System.out.println("k4   = " + (k << 4));
                    System.out.println("vak  = " + (val2 | (k << 4)));
                }
    
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
            }
    
            // form integral number of 6-bit groups
            if (fewerThan24bits == EIGHTBIT) {
                b1 = binaryData[dataIndex];
                k = (byte) (b1 & 0x03);
                if (fDebug) {
                    System.out.println("b1=" + b1);
                    System.out.println("b1<<2 = " + (b1 >> 2));
                }
                byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
                encodedData[encodedIndex++] = PAD;
                encodedData[encodedIndex++] = PAD;
            } else if (fewerThan24bits == SIXTEENBIT) {
                b1 = binaryData[dataIndex];
                b2 = binaryData[dataIndex + 1];
                l = (byte) (b2 & 0x0f);
                k = (byte) (b1 & 0x03);
    
                byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
                byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
    
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
                encodedData[encodedIndex++] = PAD;
            }
    
            return new String(encodedData);
        }
    
        /**
         * Decodes Base64 data into octects
         *
         * @param encoded string containing Base64 data
         * @return Array containind decoded data.
         */
        public static byte[] decode(String encoded) {
    
            if (encoded == null) {
                return null;
            }
    
            char[] base64Data = encoded.toCharArray();
            // remove white spaces
            int len = removeWhiteSpace(base64Data);
    
            if (len % FOURBYTE != 0) {
                return null;//should be divisible by four
            }
    
            int numberQuadruple = (len / FOURBYTE);
    
            if (numberQuadruple == 0) {
                return new byte[0];
            }
    
            byte decodedData[] = null;
            byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
            char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
    
            int i = 0;
            int encodedIndex = 0;
            int dataIndex = 0;
            decodedData = new byte[(numberQuadruple) * 3];
    
            for (; i < numberQuadruple - 1; i++) {
    
                if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
                        || !isData((d3 = base64Data[dataIndex++]))
                        || !isData((d4 = base64Data[dataIndex++]))) {
                    return null;
                }//if found "no data" just return null
    
                b1 = base64Alphabet[d1];
                b2 = base64Alphabet[d2];
                b3 = base64Alphabet[d3];
                b4 = base64Alphabet[d4];
    
                decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
            }
    
            if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
                return null;//if found "no data" just return null
            }
    
            b1 = base64Alphabet[d1];
            b2 = base64Alphabet[d2];
    
            d3 = base64Data[dataIndex++];
            d4 = base64Data[dataIndex++];
            if (!isData((d3)) || !isData((d4))) {//Check if they are PAD characters
                if (isPad(d3) && isPad(d4)) {
                    if ((b2 & 0xf) != 0)//last 4 bits should be zero
                    {
                        return null;
                    }
                    byte[] tmp = new byte[i * 3 + 1];
                    System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                    tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                    return tmp;
                } else if (!isPad(d3) && isPad(d4)) {
                    b3 = base64Alphabet[d3];
                    if ((b3 & 0x3) != 0)//last 2 bits should be zero
                    {
                        return null;
                    }
                    byte[] tmp = new byte[i * 3 + 2];
                    System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                    tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                    tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                    return tmp;
                } else {
                    return null;
                }
            } else { //No PAD e.g 3cQl
                b3 = base64Alphabet[d3];
                b4 = base64Alphabet[d4];
                decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
    
            }
    
            return decodedData;
        }
    
        /**
         * remove WhiteSpace from MIME containing encoded Base64 data.
         *
         * @param data the byte array of base64 data (with WS)
         * @return the new length
         */
        private static int removeWhiteSpace(char[] data) {
            if (data == null) {
                return 0;
            }
    
            // count characters that's not whitespace
            int newSize = 0;
            int len = data.length;
            for (int i = 0; i < len; i++) {
                if (!isWhiteSpace(data[i])) {
                    data[newSize++] = data[i];
                }
            }
            return newSize;
        }
    }
    

    RSA 加密工具类

    import java.io.ByteArrayInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.InputStream;
    import java.security.KeyFactory;
    import java.security.NoSuchAlgorithmException;
    import java.security.PrivateKey;
    import java.security.PublicKey;
    import java.security.spec.PKCS8EncodedKeySpec;
    import java.security.spec.X509EncodedKeySpec;
    
    import javax.crypto.Cipher;
    
    /**
     * RSA加密类
     */
    public class RSAencrypt {
    
    
        /**
         * 使用私钥解密
         *
         * @param content
         * @param private_key
         * @param input_charset
         * @return
         * @throws Exception
         */
        public static String decrypt(String content, String private_key, String input_charset) throws Exception {
            PrivateKey prikey = getPrivateKey(private_key);
    
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, prikey);
    
            InputStream ins = new ByteArrayInputStream(Base64Util.decode(content));
            ByteArrayOutputStream writer = new ByteArrayOutputStream();
            byte[] buf = new byte[128];
            int bufl;
    
            while ((bufl = ins.read(buf)) != -1) {
                byte[] block = null;
    
                if (buf.length == bufl) {
                    block = buf;
                } else {
                    block = new byte[bufl];
                    for (int i = 0; i < bufl; i++) {
                        block[i] = buf[i];
                    }
                }
    
                writer.write(cipher.doFinal(block));
            }
    
            return new String(writer.toByteArray(), input_charset);
        }
    
        /**
         * 获得私钥
         *
         * @param key 私钥
         * @throws Exception
         */
        public static PrivateKey getPrivateKey(String key) throws Exception {
    
            byte[] keyBytes;
    
            keyBytes = Base64Util.decode(key);
    
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
    
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    
            PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
    
            return privateKey;
        }
    
        /**
         * 得到公钥
         *
         * @param bysKey
         * @return
         */
        private static PublicKey getPublicKeyFromX509(String bysKey) throws NoSuchAlgorithmException, Exception {
            byte[] decodedKey = Base64Util.decode(bysKey);
            X509EncodedKeySpec x509 = new X509EncodedKeySpec(decodedKey);
    
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            return keyFactory.generatePublic(x509);
        }
    
        /**
         * 使用公钥加密
         *
         * @param content 密文
         * @return
         */
        public static String encryptByPublic(String content,String pulickey) {
            try {
                PublicKey pubkey = getPublicKeyFromX509(pulickey);
    
                Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
                cipher.init(Cipher.ENCRYPT_MODE, pubkey);
    
                byte plaintext[] = content.getBytes("UTF-8");
                byte[] output = cipher.doFinal(plaintext);
    
                String s = new String(Base64Util.encode(output));
    
                return s;
    
            } catch (Exception e) {
                return null;
            }
        }
    }
    

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