iOS 代碼：//step 1//start of key pair genrationNSString * PrivTagString = @"com.manish.rsa.privIdentifier";NSString * PubTagString = @"com.manish.rsa.pubIdentifier"; privateTag = [PrivTagString dataUsingEncoding:NSUTF8StringEncoding]; publicTag = [PubTagString dataUsingEncoding:NSUTF8StringEncoding];NSDictionary *privateAttributes = @{(NSString *)kSecAttrIsPermanent: @YES, (NSString *)kSecAttrApplicationTag: privateTag};NSDictionary *publicAttributes = @{(NSString *)kSecAttrIsPermanent: @YES, (NSString *)kSecAttrApplicationTag: publicTag};NSDictionary *pairAttributes = @{(NSString *)kSecAttrKeyType: (NSString *)kSecAttrKeyTypeRSA, (NSString *)kSecAttrKeySizeInBits: @2048, (NSString *)kSecPublicKeyAttrs: publicAttributes, (NSString *)kSecPrivateKeyAttrs: privateAttributes};OSStatus osStatus = SecKeyGeneratePair((CFDictionaryRef)pairAttributes, &publicKeyRef, &privateKeyRef);switch (osStatus) {    case noErr:        break;    default:        break;}//end of key pair key genration//step2//export ublic key for java serverNSLog(@"%@",[self getPublicKeyAsBase64ForJavaServer]);//step3//Create the SHA256 digest of the custom string with CC_SHA256NSString *stringToSign = @"Manish";NSMutableData *hash = [NSMutableData dataWithLength:(NSUInteger)CC_SHA256_DIGEST_LENGTH];NSData *data = [stringToSign dataUsingEncoding:NSUTF8StringEncoding];CC_SHA256(data.bytes, (CC_LONG)data.length, hash.mutableBytes);//step4// Sign the hash with the private keysize_t blockSize = SecKeyGetBlockSize(privateKeyRef);NSUInteger hashDataLength = hash.length;const unsigned char *hashData = (const unsigned char *)hash.bytes;NSMutableData *result = [NSMutableData dataWithLength:blockSize];uint8_t *signedHashBytes = malloc(blockSize * sizeof(uint8_t));memset((void *) signedHashBytes, 0x0, blockSize);size_t encryptedDataLength = blockSize;