Android gets signature public key and public key private key plus decryption

public class Getpublickey {/** * Gets the signature key * @param mcontext * @return * */protected static String        Getsigninfo (Context mcontext) {String signcode = ""; try {packageinfo packageinfo = Mcontext.getpackagemanager (). Getpackageinfo (GETAPPINFO.GETP            Ackagename (Mcontext), packagemanager.get_signatures);            Signature[] signs = packageinfo.signatures;             Signature sign = signs[0];            Signcode = Parsesignature (Sign.tobytearray ());        Signcode = Signcode.tolowercase ();        } catch (Exception e) {log.e (Constants.tag, E.getmessage (), E);    } return signcode;        } protected static string Parsesignature (byte[] signature) {String sign = "";            try {certificatefactory certfactory = certificatefactory. getinstance ("the"); X509Certificate cert = (x509certificate) certfactory. Generatecertificate (NewBytearrayinputstream (signature));            String PubKey = Cert.getpublickey (). toString ();            String ss = subString (PubKey);            SS = Ss.replace (",", "");            SS = Ss.tolowercase ();            int aa = Ss.indexof ("modulus");            int bb = ss.indexof ("publicexponent");        Sign = ss.substring (aa + 8, BB);        } catch (Certificateexception e) {log.e (Constants.tag, E.getmessage (), E);    } return sign;        public static string SubString (String sub) {Pattern pp = pattern.compile ("\\s*|\t|\r|\n");        Matcher mm = Pp.matcher (sub);    Return Mm.replaceall (""); }}

Package Com.example.xscamera; Import Java.io.bytearrayoutputstream;import Java.security.key;import Java.security.keyfactory;import Java.security.keypair;import Java.security.keypairgenerator;import Java.security.privatekey;import Java.security.publickey;import Java.security.signature;import Java.security.interfaces.rsaprivatekey;import Java.security.interfaces.rsapublickey;import Java.security.spec.pkcs8encodedkeyspec;import Java.security.spec.x509encodedkeyspec;import Java.util.hashmap;import Java.util.map;import Javax.crypto.Cipher; /** * <p> * RSA public/private key/Signature Toolkit * <p> * The key in string format is BASE64 encoded format without special instructions <br/> * Due to the extremely slow speed of asymmetric encryption, The generic file does not use it for encryption but instead uses symmetric encryption,<br/> * Asymmetric encryption algorithm can be used to encrypt the symmetric encryption key, so that the security of the key to ensure the security of the data * </p> * */public class rsautils{/         * * Cryptographic algorithm RSA */public static final String key_algorithm = "RSA";     /** * Signature Algorithm */public static final String signature_algorithm = "Md5withrsa"; /** * Get the key for public keys */private static final StrinG Public_key = "Locatorpublickey";         /** * Gets the private key of key */private static final String Private_key = "Locatorprivatekey";         /** * RSA Maximum encrypted clear Text size */private static final int max_encrypt_block = 117;     /** * RSA Max decryption size */private static final int max_decrypt_block = 128; /** * <p> * Generate key pair (public and private) * </p> * * @return * @throws Exception * * IC map<string, object> Genkeypair () throws Exception {Keypairgenerator Keypairgen = Keypairgenerator.getinst        Ance (Key_algorithm);        Keypairgen.initialize (1024);        KeyPair KeyPair = Keypairgen.generatekeypair ();        Rsapublickey PublicKey = (rsapublickey) keypair.getpublic ();        Rsaprivatekey Privatekey = (rsaprivatekey) keypair.getprivate ();        map<string, object> keyMap = new hashmap<string, object> (2);        Keymap.put (Public_key, PublicKey);        Keymap.put (Private_key, Privatekey); Return KeymaP /** * <p> * Generate digital signatures for information with private key * </p> * * @param data encrypted * @param privatekey private Key (BASE64 encoding) * * @return * @throws Exception */public static string sign (byte[] data, String Privateke        Y) throws Exception {byte[] keybytes = Base64utils.decode (Privatekey);        Pkcs8encodedkeyspec Pkcs8keyspec = new Pkcs8encodedkeyspec (keybytes);        Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);        Privatekey Privatek = keyfactory.generateprivate (Pkcs8keyspec);        Signature Signature = signature.getinstance (signature_algorithm);        Signature.initsign (Privatek);        Signature.update (data);    Return Base64utils.encode (Signature.sign ());      }/** * <p> * Verify Digital signature * </p> * * @param data encrypted * @param publickey public key (BASE64 encoded) * @param sign Digital Signature * * @return * @throws Exception * */public static Boolean verify (Byte[] Data, StringPublicKey, String sign) throws Exception {byte[] keybytes = Base64utils.decode (PublicKey);        X509encodedkeyspec KeySpec = new X509encodedkeyspec (keybytes);        Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);        PublicKey Publick = Keyfactory.generatepublic (KeySpec);        Signature Signature = signature.getinstance (signature_algorithm);        Signature.initverify (Publick);        Signature.update (data);    Return signature.verify (Base64utils.decode (sign)); /** * <P> * Private key decryption * </p> * * @param encrypteddata Encrypted data * @param privatekey private key (B ASE64 code) * @return * @throws Exception */public static byte[] Decryptbyprivatekey (byte[] EncryptedData, St        Ring Privatekey) throws Exception {byte[] keybytes = Base64utils.decode (Privatekey);        Pkcs8encodedkeyspec Pkcs8keyspec = new Pkcs8encodedkeyspec (keybytes); Keyfactory keyfactory = keyfactory.getinstance (key_aLGORITHM);        Key Privatek = keyfactory.generateprivate (Pkcs8keyspec);        Cipher Cipher = cipher.getinstance (Keyfactory.getalgorithm ());        Cipher.init (Cipher.decrypt_mode, Privatek);        int inputlen = Encrypteddata.length;        Bytearrayoutputstream out = new Bytearrayoutputstream ();        int offSet = 0;        Byte[] Cache;        int i = 0;                Fragment decryption of data while (Inputlen-offset > 0) {if (Inputlen-offset > Max_decrypt_block) {            Cache = Cipher.dofinal (EncryptedData, OffSet, Max_decrypt_block);            } else {cache = cipher.dofinal (EncryptedData, OffSet, Inputlen-offset);            } out.write (cache, 0, cache.length);            i++;        OffSet = i * max_decrypt_block;        } byte[] Decrypteddata = Out.tobytearray ();        Out.close ();    return decrypteddata; }/** * <p> * Public Key decryption * </p> * * @param encrypteddata Encrypted data * @paraM PublicKey Public Key (BASE64 encoded) * @return * @throws Exception * * * static byte[] Decryptbypublickey (byte[) en        Crypteddata, String PublicKey) throws Exception {byte[] keybytes = Base64utils.decode (PublicKey);        X509encodedkeyspec X509keyspec = new X509encodedkeyspec (keybytes);        Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);        Key Publick = Keyfactory.generatepublic (X509keyspec);        Cipher Cipher = cipher.getinstance (Keyfactory.getalgorithm ());        Cipher.init (Cipher.decrypt_mode, Publick);        int inputlen = Encrypteddata.length;        Bytearrayoutputstream out = new Bytearrayoutputstream ();        int offSet = 0;        Byte[] Cache;        int i = 0;                Fragment decryption of data while (Inputlen-offset > 0) {if (Inputlen-offset > Max_decrypt_block) {            Cache = Cipher.dofinal (EncryptedData, OffSet, Max_decrypt_block); } else {cache = cipher.dofinal (encrypteDData, OffSet, Inputlen-offset);            } out.write (cache, 0, cache.length);            i++;        OffSet = i * max_decrypt_block;        } byte[] Decrypteddata = Out.tobytearray ();        Out.close ();    return decrypteddata;     }/** * <p> * Public key Encryption * </p> * * @param data source * @param publickey Public key (BASE64 encoded)            * @return * @throws Exception */public static byte[] Encryptbypublickey (byte[] data, String PublicKey)        Throws Exception {byte[] keybytes = Base64utils.decode (PublicKey);        X509encodedkeyspec X509keyspec = new X509encodedkeyspec (keybytes);        Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);        Key Publick = Keyfactory.generatepublic (X509keyspec);        Encrypt the data Cipher Cipher = Cipher.getinstance (Keyfactory.getalgorithm ());        Cipher.init (Cipher.encrypt_mode, Publick);        int inputlen = Data.length; Bytearrayoutputstream out = NEW Bytearrayoutputstream ();        int offSet = 0;        Byte[] Cache;        int i = 0;                Fragment encryption for data while (Inputlen-offset > 0) {if (Inputlen-offset > Max_encrypt_block) {            Cache = cipher.dofinal (data, OffSet, Max_encrypt_block);            } else {cache = cipher.dofinal (data, OffSet, Inputlen-offset);            } out.write (cache, 0, cache.length);            i++;        OffSet = i * max_encrypt_block;        } byte[] EncryptedData = Out.tobytearray ();        Out.close ();    return EncryptedData;     }/** * <p> * Private key encryption * </p> * * @param data source * @param privatekey private key (BASE64 encoded)            * @return * @throws Exception */public static byte[] Encryptbyprivatekey (byte[] data, String Privatekey)        Throws Exception {byte[] keybytes = Base64utils.decode (Privatekey); Pkcs8encodedkeyspec Pkcs8keyspec = new Pkcs8encodedkeyspec (keybytES);        Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);        Key Privatek = keyfactory.generateprivate (Pkcs8keyspec);        Cipher Cipher = cipher.getinstance (Keyfactory.getalgorithm ());        Cipher.init (Cipher.encrypt_mode, Privatek);        int inputlen = Data.length;        Bytearrayoutputstream out = new Bytearrayoutputstream ();        int offSet = 0;        Byte[] Cache;        int i = 0;                Fragment encryption for data while (Inputlen-offset > 0) {if (Inputlen-offset > Max_encrypt_block) {            Cache = cipher.dofinal (data, OffSet, Max_encrypt_block);            } else {cache = cipher.dofinal (data, OffSet, Inputlen-offset);            } out.write (cache, 0, cache.length);            i++;        OffSet = i * max_encrypt_block;        } byte[] EncryptedData = Out.tobytearray ();        Out.close ();    return EncryptedData; }/** * <p> * Get private key * </p> * * @param keyMap Key Pair * @return * @throws Exception */public static String Getprivatekey (map<string, object& Gt        KEYMAP) throws Exception {key key = (key) keymap.get (Private_key);    Return Base64utils.encode (key.getencoded ());      }/** * <p> * Get public key * </p> * * @param keyMap Key pair * @return * @throws Exception */public static String Getpublickey (map<string, object> keyMap) throws Exception {Key ke        y = (Key) keymap.get (Public_key);    Return Base64utils.encode (key.getencoded ()); } }

Android gets signature public key and public key private key plus decryption